Talipexole

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Tatsuo Furukawa - One of the best experts on this subject based on the ideXlab platform.

  • partial agonistic effects of opc 14597 a potential antipsychotic agent on yawning behavior in rats
    Pharmacology Biochemistry and Behavior, 1996
    Co-Authors: Maiko Fujikawa, Katsushi Yamada, Mariko Nagashima, Tsutomu Inoue, Tatsuo Furukawa
    Abstract:

    Abstract The present experiments were performed to examine the behavioral effects of OPC-14597, which acts on dopamine receptors in rats. OPC-14597 administered subcutaneously (SC) at doses of 0.1–5 mg/kg elicited yawning, as did OPC-4392 (0.5–2 mg/kg, SC) and (−)-3-PPP (2.5–10 mg/kg, SC). These yawning responses were blocked by intraperitoneal (IP) pretreatment with haloperidol (0.5 mg/kg) but were increased by pindolol (20 mg/kg, IP) or reserpine (5 mg/kg, IP), which per se did not elicit yawning. The yawning induced by Talipexole, a selective dopamine D 2 receptor agonist, was inhibited by OPC-14597 (0.5–5 mg/kg, SC) and (−)-3-PPP (10 mg/kg, SC). Apomorphine (0.5 mg/kg, SC), a dopamine D 1 D 2 receptor agonist, elicited stereotypy such as sniffing and licking but OPC-14597 (5–20 mg/kg, SC) did not induce this behavior. The stereotypy induced by apomorphine was inhibited not only by haloperidol (0.5 mg/kg, IP) and (−)-3-PPP (10 mg/kg, SC) but also by OPC-14597 (5–20 mg/kg, SC), without being affected by OPC-4392 (2 mg/kg, SC). In 6-hydroxydopamine (6-OHDA)-treated rats, apomorphine (0.5 mg/kg, SC) elicited rotation behavior whereas OPC-14597, OPC-4392 and (−)-3-PPP did not produce this behavior. These findings suggest that OPC-14597 provokes yawning without causing stereotypy and rotation but markedly antagonizes the Talipexole-induced yawning and apomorphine-induced stereotypy, and that OPC-14597 thus exerts partial agonistic effects on yawning behavior but antagonistic effects on stereotypy in rats.

  • Involvement of catecholamine receptor activities in modulating the incidence of yawning in rats.
    Pharmacology Biochemistry and Behavior, 1996
    Co-Authors: Hiroshi Kimura, Katsushi Yamada, Mariko Nagashima, Tatsuo Furukawa
    Abstract:

    Possible involvement of catecholamine receptor activities in modulating the incidence of yawning, which involves activation of dopaminergic-cholinergic linked neuronal mechanism, was investigated in rats. Subcutaneous injection of Talipexole (B-HT 920), a selective dopamine D2-receptor-agonist, elicited yawning behavior. This behavior was increased by prazosin and bunazosin, alpha 1-adrenoceptor antagonists, and by pindolol, a beta-adrenoceptor antagonist. The yawning induced by physostigmine, an anticholinesterase agent, and pilocarpine, a direct muscarinic receptor agonist, was increased by pindolol, but was unaffected by prazosin and bunazosin. In addition, the yawning induced by the dopaminergic agonists, but not by the cholinergic agonists, was markedly suppressed by ST587, an alpha 1-adrenoceptor agonist. All the yawning responses to dopaminergic and cholinergic agents were reduced not only by scopolamine, a muscarinic receptor antagonist, but also by idazoxan, rauwolscine, and yohimbine, alpha 2-adrenoceptor antagonists. The results suggest that catecholamine receptor activities seem to play different roles in inhibitory modulation of the occurrence of yawning caused by dopaminergic and cholinergic stimulation.

  • Hyperthermia induced by the dopamine D1 receptor agonist SK&F38393 in combination with the dopamine D2 receptor agonist Talipexole in the rat.
    Pharmacology Biochemistry and Behavior, 1992
    Co-Authors: Mariko Nagashima, Hiroshi Kimura, Shin-ichiro Matsumoto, Yamada Katsushi, Tatsuo Furukawa
    Abstract:

    The present experiments were performed to investigate the effects of dopamine D1 receptor agonists given alone or in combination with dopamine D2 receptor agonists on body temperature in rats. The selective dopamine D1 receptor agonist, 1-phenyl-2,3,4,5-tetrahydro-(1H)-3-benzazepine-7,8-diol (SK&F38393), produced hyperthermia. However, the dopamine D2 receptor agonist, B-HT 920 (Talipexole), and the newly synthesized dopamine D2 receptor agonist, (S)-2-amino-4,5,6,7-tetrahydro-6-propylamino-benzothiazole (SND 919), did not change the temperature. Interestingly, the SK&F38393-induced hyperthermia was enhanced by Talipexole and SND 919. The drastic hyperthermia induced by combined administration of dopamine D1 and D2 receptor agonists was blocked by either the dopamine D1 receptor antagonist, SCH23390, or the dopamine D2 receptor antagonist, spiperone. On the other hand, treatment with prazosin, yohimbine, propranolol, scopolamine, or methysergide failed to affect the marked hyperthermia. The present results suggest that a functional link between dopamine D1 and D2 receptors may be synergistic in the regulation of body temperature and that concurrent stimulation of both dopamine D1 and D2 receptors thereby produces marked hyperthermia in the rat.

  • Role of adrenergic neuronal activity in the yawning induced by tacrine and NIK-247 in rats.
    Pharmacology Biochemistry and Behavior, 1992
    Co-Authors: Hiroshi Kimura, Katsushi Yamada, Mariko Nagashima, Shin-ichiro Matsumoto, Yutaka Ishii, Yoshida Shigeru, Kuninobu Fujii, Tatsuo Furukawa
    Abstract:

    Abstract The present experiments were performed to investigate the potential role of central adrenergic neurons in regulating occurrence of yawning in rats. Intraperitoneal injection of tacrine (THA) or 9-amino-2,3,5,6,7,8-hexahydro-1H-cyclopenta(b)-quinoline monohydrate HCl (NIK-247), cholinesterase inhibitors, induced yawning, which was markedly increased by pretreatment with the β-adrenoceptor antagonist, pindolol. The yawning evoked by tacrine or NIK-247 given alone or in combination with pindolol was inhibited by pretreatment with scopolamine but not by mecamylamine or spiperone. Treatment with tacrine or NIK-247 increased acetylcholine content of the striatum, but this effect was not enhanced by pindolol, which per se did not affect basal acetylcholine content. Moreover, pretreatment with the central adrenaline synthesis inhibitors, (±)-2,3-dichloro-α-methylbenzylamine HCl (LY-78335) and 2-cyclooctyl-2-hydroxyethylamine HCl (UK-1187A), increased tacrine-induced yawning. Subcutaneous injection of Talipexole (B-HT 920), a dopamine D2 receptor agonist, evoked yawning, which was also increased by pindolol, LY-78335, and UK-1187A. These receptors antagonists and synthesis inhibitors per se did not cause yawning responses. The results suggest that the β-adrenoceptor blockade and the inhibition of adrenaline synthesis facilitate the occurrence of yawning induced by cholinergic and dopaminergic agonists, and thus the central adrenergic neuronal systems may be implicated in the regulation of yawning responses.

  • Decrease of prolactin secretion via stimulation of pituitary dopamine D-2 receptors after application of Talipexole and SND 919.
    European Journal of Pharmacology, 1990
    Co-Authors: Mariko Domae, Katsushi Yamada, Shin-ichiro Matsumoto, Yasuhiko Hanabusa, Tatsuo Furukawa
    Abstract:

    Abstract The present experiments were performed to investigate the effects of Talipexole (B-HT 920) and SND 919 on prolactin release from the anterior pituitary glands of rats both in vivo and in vitro. The basal serum prolactin levels were reduced dose dependently by s.c. administration of Talipexole or SND 919 at doses of 5–100 μg/kg. Daily treatment with estradiol (35 μg/kg for 3 days) increased serum prolactin levels in male rats to levels 4-fold higher than those of non-primed rats. This increase was suppressed by administration of Talipexole or SND 919. In vitro, the spontaneous prolactin release into perfusates from isolated anterior pituitary was inhibited by Talipexole or SND 919 added at concentrations ranging from 10−9 to 10−6 M. This inhibitory effect of SND 919 was blocked by concurrent application of a dopamine D-2 receptor antagonist, YM-09151-2. The spontaneous prolactin release from the anterior pituitary isolated from estradiol-primed rats was 2-fold higher than that from non-primed rats. This increased release was also inhibited by application of either drug. The inhibitory effects of these drugs were greater in estradiol-primed rats than in non-primed rats when expressed as percent inhibition of control prolactin release. The results suggest that Talipexole and SND 919 have a selective dopamine D-2 receptor agonistic property and are almost completely effective to counteract the enhancement of prolactin release induced by estrogens via stimulation of dopamine D-2 receptors in the anterior pituitary.

Katsushi Yamada - One of the best experts on this subject based on the ideXlab platform.

  • partial agonistic effects of opc 14597 a potential antipsychotic agent on yawning behavior in rats
    Pharmacology Biochemistry and Behavior, 1996
    Co-Authors: Maiko Fujikawa, Katsushi Yamada, Mariko Nagashima, Tsutomu Inoue, Tatsuo Furukawa
    Abstract:

    Abstract The present experiments were performed to examine the behavioral effects of OPC-14597, which acts on dopamine receptors in rats. OPC-14597 administered subcutaneously (SC) at doses of 0.1–5 mg/kg elicited yawning, as did OPC-4392 (0.5–2 mg/kg, SC) and (−)-3-PPP (2.5–10 mg/kg, SC). These yawning responses were blocked by intraperitoneal (IP) pretreatment with haloperidol (0.5 mg/kg) but were increased by pindolol (20 mg/kg, IP) or reserpine (5 mg/kg, IP), which per se did not elicit yawning. The yawning induced by Talipexole, a selective dopamine D 2 receptor agonist, was inhibited by OPC-14597 (0.5–5 mg/kg, SC) and (−)-3-PPP (10 mg/kg, SC). Apomorphine (0.5 mg/kg, SC), a dopamine D 1 D 2 receptor agonist, elicited stereotypy such as sniffing and licking but OPC-14597 (5–20 mg/kg, SC) did not induce this behavior. The stereotypy induced by apomorphine was inhibited not only by haloperidol (0.5 mg/kg, IP) and (−)-3-PPP (10 mg/kg, SC) but also by OPC-14597 (5–20 mg/kg, SC), without being affected by OPC-4392 (2 mg/kg, SC). In 6-hydroxydopamine (6-OHDA)-treated rats, apomorphine (0.5 mg/kg, SC) elicited rotation behavior whereas OPC-14597, OPC-4392 and (−)-3-PPP did not produce this behavior. These findings suggest that OPC-14597 provokes yawning without causing stereotypy and rotation but markedly antagonizes the Talipexole-induced yawning and apomorphine-induced stereotypy, and that OPC-14597 thus exerts partial agonistic effects on yawning behavior but antagonistic effects on stereotypy in rats.

  • Involvement of catecholamine receptor activities in modulating the incidence of yawning in rats.
    Pharmacology Biochemistry and Behavior, 1996
    Co-Authors: Hiroshi Kimura, Katsushi Yamada, Mariko Nagashima, Tatsuo Furukawa
    Abstract:

    Possible involvement of catecholamine receptor activities in modulating the incidence of yawning, which involves activation of dopaminergic-cholinergic linked neuronal mechanism, was investigated in rats. Subcutaneous injection of Talipexole (B-HT 920), a selective dopamine D2-receptor-agonist, elicited yawning behavior. This behavior was increased by prazosin and bunazosin, alpha 1-adrenoceptor antagonists, and by pindolol, a beta-adrenoceptor antagonist. The yawning induced by physostigmine, an anticholinesterase agent, and pilocarpine, a direct muscarinic receptor agonist, was increased by pindolol, but was unaffected by prazosin and bunazosin. In addition, the yawning induced by the dopaminergic agonists, but not by the cholinergic agonists, was markedly suppressed by ST587, an alpha 1-adrenoceptor agonist. All the yawning responses to dopaminergic and cholinergic agents were reduced not only by scopolamine, a muscarinic receptor antagonist, but also by idazoxan, rauwolscine, and yohimbine, alpha 2-adrenoceptor antagonists. The results suggest that catecholamine receptor activities seem to play different roles in inhibitory modulation of the occurrence of yawning caused by dopaminergic and cholinergic stimulation.

  • Role of adrenergic neuronal activity in the yawning induced by tacrine and NIK-247 in rats.
    Pharmacology Biochemistry and Behavior, 1992
    Co-Authors: Hiroshi Kimura, Katsushi Yamada, Mariko Nagashima, Shin-ichiro Matsumoto, Yutaka Ishii, Yoshida Shigeru, Kuninobu Fujii, Tatsuo Furukawa
    Abstract:

    Abstract The present experiments were performed to investigate the potential role of central adrenergic neurons in regulating occurrence of yawning in rats. Intraperitoneal injection of tacrine (THA) or 9-amino-2,3,5,6,7,8-hexahydro-1H-cyclopenta(b)-quinoline monohydrate HCl (NIK-247), cholinesterase inhibitors, induced yawning, which was markedly increased by pretreatment with the β-adrenoceptor antagonist, pindolol. The yawning evoked by tacrine or NIK-247 given alone or in combination with pindolol was inhibited by pretreatment with scopolamine but not by mecamylamine or spiperone. Treatment with tacrine or NIK-247 increased acetylcholine content of the striatum, but this effect was not enhanced by pindolol, which per se did not affect basal acetylcholine content. Moreover, pretreatment with the central adrenaline synthesis inhibitors, (±)-2,3-dichloro-α-methylbenzylamine HCl (LY-78335) and 2-cyclooctyl-2-hydroxyethylamine HCl (UK-1187A), increased tacrine-induced yawning. Subcutaneous injection of Talipexole (B-HT 920), a dopamine D2 receptor agonist, evoked yawning, which was also increased by pindolol, LY-78335, and UK-1187A. These receptors antagonists and synthesis inhibitors per se did not cause yawning responses. The results suggest that the β-adrenoceptor blockade and the inhibition of adrenaline synthesis facilitate the occurrence of yawning induced by cholinergic and dopaminergic agonists, and thus the central adrenergic neuronal systems may be implicated in the regulation of yawning responses.

  • Decrease of prolactin secretion via stimulation of pituitary dopamine D-2 receptors after application of Talipexole and SND 919.
    European Journal of Pharmacology, 1990
    Co-Authors: Mariko Domae, Katsushi Yamada, Shin-ichiro Matsumoto, Yasuhiko Hanabusa, Tatsuo Furukawa
    Abstract:

    Abstract The present experiments were performed to investigate the effects of Talipexole (B-HT 920) and SND 919 on prolactin release from the anterior pituitary glands of rats both in vivo and in vitro. The basal serum prolactin levels were reduced dose dependently by s.c. administration of Talipexole or SND 919 at doses of 5–100 μg/kg. Daily treatment with estradiol (35 μg/kg for 3 days) increased serum prolactin levels in male rats to levels 4-fold higher than those of non-primed rats. This increase was suppressed by administration of Talipexole or SND 919. In vitro, the spontaneous prolactin release into perfusates from isolated anterior pituitary was inhibited by Talipexole or SND 919 added at concentrations ranging from 10−9 to 10−6 M. This inhibitory effect of SND 919 was blocked by concurrent application of a dopamine D-2 receptor antagonist, YM-09151-2. The spontaneous prolactin release from the anterior pituitary isolated from estradiol-primed rats was 2-fold higher than that from non-primed rats. This increased release was also inhibited by application of either drug. The inhibitory effects of these drugs were greater in estradiol-primed rats than in non-primed rats when expressed as percent inhibition of control prolactin release. The results suggest that Talipexole and SND 919 have a selective dopamine D-2 receptor agonistic property and are almost completely effective to counteract the enhancement of prolactin release induced by estrogens via stimulation of dopamine D-2 receptors in the anterior pituitary.

  • Possible involvement of differing classes of dopamine D-2 receptors in yawning and stereotypy in rats
    Psychopharmacology, 1990
    Co-Authors: Katsushi Yamada, Mariko Nagashima, Hiroshi Kimura, Shin-ichiro Matsumoto, Tatsuo Furukawa
    Abstract:

    The present experiments were performed to investigate differences in the properties of the dopamine D-2 receptors related to yawning and stereotypy. Subcutaneous injection of Talipexole (B-HT 920) (10–250 µg/kg) or SND 919 ((S)-2-amino-4,5,6,7-tetrahydro-6-propylamino-benzothiazole) (25–500 µg/kg) evoked yawning behavior with bell-shaped responses. However, SK&F 38393 (1-phenyl-2,3,4,5-tetrahydro-(1H)-3-benzazepine-7,8-diol) (0.5–10 mg/kg SC) did not elicit yawning and decreased yawning responses to low doses of Talipexole (25 µg/kg SC) or SND 919 (100 µg/kg SC). These low but effective doses for inducing yawning of Talipexole or SND 919 in combination with SK&F 38393 (0.5–10 mg/kg SC) did not elicit stereotypy. In contrast, yawning behavior was not produced after very high doses of Talipexole (500 µg/kg SC) or SND 919 (1000 µg/kg SC) given alone or in combination with SK&F 38393 (0.5–10 mg/kg SC). These extremely high doses of Talipexole or SND 919 evoked slight stereotypy, which was enhanced by the combined treatment with SK&F 38393. The present results suggest that the dopamine D-2 receptors related to yawning are more sensitive to dopamine receptor agonists than those related to stereotypy, and that concurrent stimulation of postsynaptic dopamine D-1 receptors with D-2 receptors reduces the incidence of yawning but enhances that of stereotypy.

Taku Amano - One of the best experts on this subject based on the ideXlab platform.

  • Repeated administration of methamphetamine causes hypersensitivity of D2 receptor in rat ventral tegmental area
    Neuroscience Letters, 2003
    Co-Authors: Taku Amano, Masashi Sasa, Hiroaki Matsubayashi, Takahiro Seki, Norio Sakai
    Abstract:

    Abstract To elucidate whether the methamphetamine (MAP)-induced hypersensitivity to dopamine occurs in the ventral tegmental area (VTA), patch clamp studies were performed using brain slice preparations. MAP or physiological saline was administered to 8–10-day-old rats daily for 5 days. On day 5, patch clamp studies were performed on VTA dopamine neurons which were identified by morphological and electrophysiological characteristics. Dopamine (1–100 μM) and Talipexole (a dopamine D2 receptor agonist, 1–100 μM) produced a dose-dependent hyperpolarization in these neurons; treatment with SKF 38393 or PD128907 (Dl and D3 receptor agonists, respectively) had no effect. The extent of hyperpolarization was significantly greater in the MAP group compared to the saline controls, suggesting that repeated MAP administration causes a hypersensitivity to dopamine that is D2 receptor-dependent. This hypersensitivity reduces the excitability of VTA dopamine neurons, thus decreasing dopamine release in the nucleus accumbens area. This may compensate for the MAP-induced elevation of dopamine levels and modulate the dopamine-induced signal transduction cascades, leading to reverse tolerance in nucleus accumbens neurons.

  • Excitation by Talipexole, a dopamine D2 agonist, of caudate nucleus neurons activated by nigral stimulation
    Life Sciences, 2002
    Co-Authors: Naoyuki Todo, Yasuko Kohno, Toshihiko Momiyama, Taku Amano, Masashi Sasa
    Abstract:

    Abstract An electrophysiological study using cats anesthetized with α-chloralose was performed to elucidate whether or not Talipexole (B-HT 920 CL 2 : 6-allyl-2-amino -5, 6, 7, 8-tetrahydro-4H-thiazolo [4, 5 -d] -azepinedihydrochroride), a dopamine D 2 agonist, acts on postsynaptic dopamine receptors in the caudate nucleus (CN) neurons receiving excitatory input from the pars compacta of substantia nigra (SN). Extracellular neuron activities were recorded in the CN using a glass-insulated silver wire microelectrode attached along a seven-barreled micropipette, each of which was filled with Talipexole, quinpirole (dopamine D 2 agonist), domperidone (dopamine D 2 antagonist), glutamate and 2M NaCl. These drugs were microiontophoretically applied to the immediate vicinity of the target neuron. In the same neurons in which the spikes elicited by the SN stimulation were blocked by microiontophoretically applied domperidone, microiontophoretic application of Talipexole and quinpirole induced a dose-dependent increase in spontaneous firing. This increase in firing by Talipexole and quinpirole was blocked during simultaneous application of domperidone, although glutamate-induced firing remained unaffected by domperidone. In the CN neurons, in which the SN stimulation-induced spikes were not blocked by domperidone, spontaneous firing was not affected by Talipexole or quinpirole. These findings suggest that Talipexole activates CN neurons receiving a dopaminergic input from SN via D 2 receptors, as does quinpirole.

  • D2 receptor activation in distinct striatal neurons in comparison with D3 receptors.
    Japanese journal of psychopharmacology, 1997
    Co-Authors: Masashi Sasa, Toshihiko Momiyama, Taku Amano, Kumatoshi Ishihara, Hiroaki Matsubayashi, Naoyuki Todo
    Abstract:

    The role of D2/D3 receptors in striatum was electrophysiologically examined in vitro in chloralose-anesthetized rats. In addition, in vitro patch clamp method with rat brain slices was followed. Stimulations of the substantia nigra pars compacta (SN) in vivo elicited spike generation which was inhibited by microiontophoretically applied domperidone, a D2 antagonist. These domperidone-sensitive neurons were activated by microiontophoretic application of D2 agonists such as Talipexole, quinpirole and bromocriptine as well as the D2 agonist, 7-OH-DPAT. They were also excited by either intravenous injection of bromocriptine or Talipexole in a dose-dependent manner. Furthermore, the SN-induced increases in neuronal firing were blocked during microiontophoretic application of domperidone. In patch clamp whole-cell recording large-sized cells, identified visually under Ramanosky microscope, were depolarized with repetitive firing on bath application of Talipexole and 7-OH-DPAT at a current clamp mode. Talipexole-induced depolarization in the large-sized cell was similarly observed in the presence of TTX and high Mg2+ in Ca(2+)-free physiological solution. In contrast, the medium-sized cells were hyperpolarized on bath application of Talipexole without being affected by 7-OH-DPAT. These findings suggest that the large-sized cells, which were presumably cholinergic interneurons, are activated by dopamine derived from the SN via D2 and/or D3 receptors, while the medium-sized cells are inhibited by dopamine via D2 receptors.

  • Unique Pharmacological Profile of a Novel Antipsychotic Drug, Aripiprazole (OPC-14597)
    Cns Drug Reviews, 1997
    Co-Authors: Masashi Sasa, Taku Amano
    Abstract:

    Aripiprazole (OPC-14597) is a novel antipsychotic agent with an unusual pharmacological profile that is atypical of compounds affecting the dopaminergic system. This agent is a quinolinone derivative related to OPC-4392 (Fig. 1). OPC-4392 acts on dopamine (DA) neurons and their nerve terminals as an autoreceptor agonist, eliciting inhibitory effects on ventral tegmental and nigral DA neurons (14,20). OPC-4392 has no postsynaptic DA receptor blocking activities (20). In clinical trials OPC-4392 improved the negative and the positive symptoms of chronic schizophrenic patients, such as hallucination, delusion, and psychiatric excitement. Similar effects on negative symptoms were observed with other DA autoreceptor agonists, such as EMD 49980, Talipexole and terguride (8,20,17). Further attempts to develop a useful antipsychotic drug that displays both presynaptic DA agonistic and postsynaptic DA antagonistic activities and improves negative as well as positive symptoms in schizophrenic patients resulted in the discovery of aripiprazole. An early phase 11 clinical study on aripiprazole was recently performed in 56 schizophrenic patients by M. Toru et al. in Japan (24). According to the assessment by BPRS in this study, significant global improvement of negative symptoms (emotional withdrawal, motor retardation, blunted affect) and positive signs (suspiciousness, unusual thoughts, hallucinatory behaviors) was achieved. Negligible side effects, including mild extrapyramidal symptoms, were encountered. Aripiprazole may be considered a useful antipsychotic agent with a unique pharmacological profile.

  • Action of intravenously administered Talipexole on the rat striatal neurons receiving excitatory input from nigral dopamine neurons
    Psychopharmacology, 1995
    Co-Authors: H. Matsubayashi, Y Kohno, Taku Amano, Y. Hongjing, M. Sasa
    Abstract:

    Electrophysiological studies using rats anesthetized with chloral hydrate were performed to elucidate whether or not intravenously injected Talipexole acted as a D_2 receptor agonist on the striatal neurons in comparison with the action of bromocriptine. The activities of the striatal neurons were extracellularly recorded using a glass microelectrode attached along a seven-barreled micropipette, each barrel of which was filled with Talipexole, bromocriptine, SCH23390 (D_1 antagonist), domperidone (D_2 antagonist), glutamate or 2 M NaCl. These drugs were iontophoretically applied to the immediate vicinity of the target neuron being recorded. The effects of Talipexole and bromocriptine were examined on the neurons, whose spikes (induced by the stimulation of the substantia nigra pars compacta) were inhibited by the iontophoretic application of domperidone. Iontophoretic application of Talipexole or bromocriptine increased spontaneous firing of these neurons and this increase in firing was also inhibited by iontophoretically applied domperidone. In the same neurons, intravenously administered Talipexole (0.01, 0.02 and 0.04 mg/kg) dose-dependently increased firing, and this increase was inhibited by microiontophoretically applied domperidone, but not by SCH23390. On the other hand, the intravenous injection of bromocriptine (0.1, 0.2 and 0.4 mg/kg) also increased the firing rate. However, the increase was not dose-dependent and fluctuated; the firing transiently decreased during the increase in firing with intravenously administered bromocriptine. However, the bromocriptine-induced increase in firing was also suppressed by domperidone, and decrease in firing was inhibited by SCH23390. These findings suggest that Talipexole acts as a D_2 agonist on the striatal neurons receiving input from substantia nigra pars compacta and increases firing when intravenously applied. However, intravenously administered bromocriptine appears to act as both a D_2 agonist and probably as a D_1 agonist on the striatal neurons to increase and decrease firing, respectively.

Masashi Sasa - One of the best experts on this subject based on the ideXlab platform.

  • Repeated administration of methamphetamine causes hypersensitivity of D2 receptor in rat ventral tegmental area
    Neuroscience Letters, 2003
    Co-Authors: Taku Amano, Masashi Sasa, Hiroaki Matsubayashi, Takahiro Seki, Norio Sakai
    Abstract:

    Abstract To elucidate whether the methamphetamine (MAP)-induced hypersensitivity to dopamine occurs in the ventral tegmental area (VTA), patch clamp studies were performed using brain slice preparations. MAP or physiological saline was administered to 8–10-day-old rats daily for 5 days. On day 5, patch clamp studies were performed on VTA dopamine neurons which were identified by morphological and electrophysiological characteristics. Dopamine (1–100 μM) and Talipexole (a dopamine D2 receptor agonist, 1–100 μM) produced a dose-dependent hyperpolarization in these neurons; treatment with SKF 38393 or PD128907 (Dl and D3 receptor agonists, respectively) had no effect. The extent of hyperpolarization was significantly greater in the MAP group compared to the saline controls, suggesting that repeated MAP administration causes a hypersensitivity to dopamine that is D2 receptor-dependent. This hypersensitivity reduces the excitability of VTA dopamine neurons, thus decreasing dopamine release in the nucleus accumbens area. This may compensate for the MAP-induced elevation of dopamine levels and modulate the dopamine-induced signal transduction cascades, leading to reverse tolerance in nucleus accumbens neurons.

  • Inhibition by Talipexole, a thiazolo-azepine derivative, of dopaminergic neurons in the ventral tegmental area.
    Life Sciences, 2002
    Co-Authors: Toshihiko Momiyama, Masashi Sasa, Shuji Takaori
    Abstract:

    Abstract A microiontophoretic study using rats anesthetized with chloral hydrate and immobilized with gallamine triethiodide was carried out to compare the effect of Talipexole (B-HT 920 CL 2 :2-amino-6-allyl-5,6,7,8-tetrahydro-4H-thiazolo [4,5-d]-azepine-dihydrochloride), a dopamine autoreceptor agonist, on dopaminergic neurons in the ventral tegmental area (VTA) to non-dopaminergic neurons in the VTA. VTA neurons were classified into two types according to the responses to antidromic stimulation of the nucleus accumbens (Acc) : type I neurons with a long spike latency (8.69 ± 0.24 msec) upon Acc stimulation and low spontaneous firing rate (6.80 ± 1.34 /sec), and type II neurons with a short latency (2.76 ± 0.20 msec) and high spontaneous firing rate (26.77 ± 7.05 /sec), probably corresponding to dopaminergic and non-dopaminergic neurons, respectively. In type I neurons, microiontophoretic application of Talipexole and dopamine inhibited antidromic spike generation elicited by Acc stimulation, and Talipexole-induced inhibition was antagonized by domperidone (dopamine D-2 antagonist). In type II neurons, however, the antidromic spikes were not affected by either Talipexole or dopamine. Furthermore, spontaneous firing was also inhibited by iontophoretically applied Talipexole and dopamine in most type I neurons, but rarely affected by either drug. Inhibitory effects of Talipexole were antagonized by domperidone. These results suggest that Talipexole acts on dopamine D-2 receptors, thereby inhibiting the dopaminergic neurons in the VTA.

  • Excitation by Talipexole, a dopamine D2 agonist, of caudate nucleus neurons activated by nigral stimulation
    Life Sciences, 2002
    Co-Authors: Naoyuki Todo, Yasuko Kohno, Toshihiko Momiyama, Taku Amano, Masashi Sasa
    Abstract:

    Abstract An electrophysiological study using cats anesthetized with α-chloralose was performed to elucidate whether or not Talipexole (B-HT 920 CL 2 : 6-allyl-2-amino -5, 6, 7, 8-tetrahydro-4H-thiazolo [4, 5 -d] -azepinedihydrochroride), a dopamine D 2 agonist, acts on postsynaptic dopamine receptors in the caudate nucleus (CN) neurons receiving excitatory input from the pars compacta of substantia nigra (SN). Extracellular neuron activities were recorded in the CN using a glass-insulated silver wire microelectrode attached along a seven-barreled micropipette, each of which was filled with Talipexole, quinpirole (dopamine D 2 agonist), domperidone (dopamine D 2 antagonist), glutamate and 2M NaCl. These drugs were microiontophoretically applied to the immediate vicinity of the target neuron. In the same neurons in which the spikes elicited by the SN stimulation were blocked by microiontophoretically applied domperidone, microiontophoretic application of Talipexole and quinpirole induced a dose-dependent increase in spontaneous firing. This increase in firing by Talipexole and quinpirole was blocked during simultaneous application of domperidone, although glutamate-induced firing remained unaffected by domperidone. In the CN neurons, in which the SN stimulation-induced spikes were not blocked by domperidone, spontaneous firing was not affected by Talipexole or quinpirole. These findings suggest that Talipexole activates CN neurons receiving a dopaminergic input from SN via D 2 receptors, as does quinpirole.

  • Effects of Talipexole on Contraversive Rotation and Functional Impairment in MPTP-Induced Chronic Hemiparkinsonian Monkeys
    Japanese Journal of Pharmacology, 1998
    Co-Authors: Edward F. Domino, Yasuko Kohno, Huilei Zhang, Masashi Sasa
    Abstract:

    The effects of Talipexole on functional motor improvement in comparison with contraversive circling were studied in five chronic (5 - 7 years post MPTP-lesioned) hemiparkinsonian Macaca nemestrina monkeys. Talipexole induced contraversive rotations in a dose of 32 μg/kg for about 1 hr after i.m. injection. Larger doses (56 and 100 μg/kg, i.m.) produced less effect due to sedation. Three different rating scales were used to assess functional improvement, including a clinical parkinsonism rating scale, volitional responses to fruit presentations, and number of significant hand movements. The optimal dose of Talipexole was 32 μg/kg, i.m. Functional improvement by Talipexole, including clinical parkinsonian rating scales and significant hand movements, as well as contraversive circling in hemiparkinsonian monkeys, confirm that this chronic animal model is useful in preclinical testing of drugs for the treatment of human parkinsonism.

  • Talipexole or pramipexole combinations with chloro-APB (SKF 82958) in MPTP-induced hemiparkinsonian monkeys
    European Journal of Pharmacology, 1997
    Co-Authors: Edward F. Domino, Yasuko Kohno, Huilei Zhang, Masashi Sasa
    Abstract:

    Abstract The effects of two predominant dopamine D2-like receptor agonists, Talipexole (6-allyl-2-amino-5,6,7,8-tetrahydro-4H-thiazolo [4,5-d]-azepine dihydrochloride, B-HT 920 CL2) and pramipexole (S(−)2-amino-4,5,6,7-tetrahydro-6-propyl-aminobenzothiazole dihydrochloride, SND 919 CL2Y), were studied alone and in combination with the selective dopamine D1-like receptor agonist chloro-APB ((±)6-chloro-7-8-dihydroxy-3-allyl-1-phenyl-2,3,4,5-tetrahydro-1H-benzazepine hydrobromide, SKF 82958) in five chronic 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) lesioned hemiparkinsonian Macaca nemestrina monkeys. Talipexole induced contraversive rotation in a dose-dependent manner up to 32 μg/kg, i.m. Talipexole was more potent than pramipexole (10 vs. 32 μg/kg, i.m.), but pramipexole was more efficacious in producing contraversive rotational behavior and significant hand movements in the afflicted limb. Larger doses of chloro-APB also produced contraversive rotation. Combinations of each dopamine D2-like receptor agonist in a median effective dose with chloro-APB (23.4 and 74.8 μg/kg, i.m.) had synergistic effects, producing either addition or potentiation, depending upon the dose used. The effects noted with these combinations were less than the effect of a large dose (100 μg/kg) of pramipexole. Talipexole, in the largest dose studied (100 μg/kg, i.m.), produced sedation which was not seen with the same dose of pramipexole. No significant extrapyramidal side effects were noted with either agent.

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  • partial agonistic effects of opc 14597 a potential antipsychotic agent on yawning behavior in rats
    Pharmacology Biochemistry and Behavior, 1996
    Co-Authors: Maiko Fujikawa, Katsushi Yamada, Mariko Nagashima, Tsutomu Inoue, Tatsuo Furukawa
    Abstract:

    Abstract The present experiments were performed to examine the behavioral effects of OPC-14597, which acts on dopamine receptors in rats. OPC-14597 administered subcutaneously (SC) at doses of 0.1–5 mg/kg elicited yawning, as did OPC-4392 (0.5–2 mg/kg, SC) and (−)-3-PPP (2.5–10 mg/kg, SC). These yawning responses were blocked by intraperitoneal (IP) pretreatment with haloperidol (0.5 mg/kg) but were increased by pindolol (20 mg/kg, IP) or reserpine (5 mg/kg, IP), which per se did not elicit yawning. The yawning induced by Talipexole, a selective dopamine D 2 receptor agonist, was inhibited by OPC-14597 (0.5–5 mg/kg, SC) and (−)-3-PPP (10 mg/kg, SC). Apomorphine (0.5 mg/kg, SC), a dopamine D 1 D 2 receptor agonist, elicited stereotypy such as sniffing and licking but OPC-14597 (5–20 mg/kg, SC) did not induce this behavior. The stereotypy induced by apomorphine was inhibited not only by haloperidol (0.5 mg/kg, IP) and (−)-3-PPP (10 mg/kg, SC) but also by OPC-14597 (5–20 mg/kg, SC), without being affected by OPC-4392 (2 mg/kg, SC). In 6-hydroxydopamine (6-OHDA)-treated rats, apomorphine (0.5 mg/kg, SC) elicited rotation behavior whereas OPC-14597, OPC-4392 and (−)-3-PPP did not produce this behavior. These findings suggest that OPC-14597 provokes yawning without causing stereotypy and rotation but markedly antagonizes the Talipexole-induced yawning and apomorphine-induced stereotypy, and that OPC-14597 thus exerts partial agonistic effects on yawning behavior but antagonistic effects on stereotypy in rats.

  • Involvement of catecholamine receptor activities in modulating the incidence of yawning in rats.
    Pharmacology Biochemistry and Behavior, 1996
    Co-Authors: Hiroshi Kimura, Katsushi Yamada, Mariko Nagashima, Tatsuo Furukawa
    Abstract:

    Possible involvement of catecholamine receptor activities in modulating the incidence of yawning, which involves activation of dopaminergic-cholinergic linked neuronal mechanism, was investigated in rats. Subcutaneous injection of Talipexole (B-HT 920), a selective dopamine D2-receptor-agonist, elicited yawning behavior. This behavior was increased by prazosin and bunazosin, alpha 1-adrenoceptor antagonists, and by pindolol, a beta-adrenoceptor antagonist. The yawning induced by physostigmine, an anticholinesterase agent, and pilocarpine, a direct muscarinic receptor agonist, was increased by pindolol, but was unaffected by prazosin and bunazosin. In addition, the yawning induced by the dopaminergic agonists, but not by the cholinergic agonists, was markedly suppressed by ST587, an alpha 1-adrenoceptor agonist. All the yawning responses to dopaminergic and cholinergic agents were reduced not only by scopolamine, a muscarinic receptor antagonist, but also by idazoxan, rauwolscine, and yohimbine, alpha 2-adrenoceptor antagonists. The results suggest that catecholamine receptor activities seem to play different roles in inhibitory modulation of the occurrence of yawning caused by dopaminergic and cholinergic stimulation.

  • Hyperthermia induced by the dopamine D1 receptor agonist SK&F38393 in combination with the dopamine D2 receptor agonist Talipexole in the rat.
    Pharmacology Biochemistry and Behavior, 1992
    Co-Authors: Mariko Nagashima, Hiroshi Kimura, Shin-ichiro Matsumoto, Yamada Katsushi, Tatsuo Furukawa
    Abstract:

    The present experiments were performed to investigate the effects of dopamine D1 receptor agonists given alone or in combination with dopamine D2 receptor agonists on body temperature in rats. The selective dopamine D1 receptor agonist, 1-phenyl-2,3,4,5-tetrahydro-(1H)-3-benzazepine-7,8-diol (SK&F38393), produced hyperthermia. However, the dopamine D2 receptor agonist, B-HT 920 (Talipexole), and the newly synthesized dopamine D2 receptor agonist, (S)-2-amino-4,5,6,7-tetrahydro-6-propylamino-benzothiazole (SND 919), did not change the temperature. Interestingly, the SK&F38393-induced hyperthermia was enhanced by Talipexole and SND 919. The drastic hyperthermia induced by combined administration of dopamine D1 and D2 receptor agonists was blocked by either the dopamine D1 receptor antagonist, SCH23390, or the dopamine D2 receptor antagonist, spiperone. On the other hand, treatment with prazosin, yohimbine, propranolol, scopolamine, or methysergide failed to affect the marked hyperthermia. The present results suggest that a functional link between dopamine D1 and D2 receptors may be synergistic in the regulation of body temperature and that concurrent stimulation of both dopamine D1 and D2 receptors thereby produces marked hyperthermia in the rat.

  • Role of adrenergic neuronal activity in the yawning induced by tacrine and NIK-247 in rats.
    Pharmacology Biochemistry and Behavior, 1992
    Co-Authors: Hiroshi Kimura, Katsushi Yamada, Mariko Nagashima, Shin-ichiro Matsumoto, Yutaka Ishii, Yoshida Shigeru, Kuninobu Fujii, Tatsuo Furukawa
    Abstract:

    Abstract The present experiments were performed to investigate the potential role of central adrenergic neurons in regulating occurrence of yawning in rats. Intraperitoneal injection of tacrine (THA) or 9-amino-2,3,5,6,7,8-hexahydro-1H-cyclopenta(b)-quinoline monohydrate HCl (NIK-247), cholinesterase inhibitors, induced yawning, which was markedly increased by pretreatment with the β-adrenoceptor antagonist, pindolol. The yawning evoked by tacrine or NIK-247 given alone or in combination with pindolol was inhibited by pretreatment with scopolamine but not by mecamylamine or spiperone. Treatment with tacrine or NIK-247 increased acetylcholine content of the striatum, but this effect was not enhanced by pindolol, which per se did not affect basal acetylcholine content. Moreover, pretreatment with the central adrenaline synthesis inhibitors, (±)-2,3-dichloro-α-methylbenzylamine HCl (LY-78335) and 2-cyclooctyl-2-hydroxyethylamine HCl (UK-1187A), increased tacrine-induced yawning. Subcutaneous injection of Talipexole (B-HT 920), a dopamine D2 receptor agonist, evoked yawning, which was also increased by pindolol, LY-78335, and UK-1187A. These receptors antagonists and synthesis inhibitors per se did not cause yawning responses. The results suggest that the β-adrenoceptor blockade and the inhibition of adrenaline synthesis facilitate the occurrence of yawning induced by cholinergic and dopaminergic agonists, and thus the central adrenergic neuronal systems may be implicated in the regulation of yawning responses.

  • Possible involvement of differing classes of dopamine D-2 receptors in yawning and stereotypy in rats
    Psychopharmacology, 1990
    Co-Authors: Katsushi Yamada, Mariko Nagashima, Hiroshi Kimura, Shin-ichiro Matsumoto, Tatsuo Furukawa
    Abstract:

    The present experiments were performed to investigate differences in the properties of the dopamine D-2 receptors related to yawning and stereotypy. Subcutaneous injection of Talipexole (B-HT 920) (10–250 µg/kg) or SND 919 ((S)-2-amino-4,5,6,7-tetrahydro-6-propylamino-benzothiazole) (25–500 µg/kg) evoked yawning behavior with bell-shaped responses. However, SK&F 38393 (1-phenyl-2,3,4,5-tetrahydro-(1H)-3-benzazepine-7,8-diol) (0.5–10 mg/kg SC) did not elicit yawning and decreased yawning responses to low doses of Talipexole (25 µg/kg SC) or SND 919 (100 µg/kg SC). These low but effective doses for inducing yawning of Talipexole or SND 919 in combination with SK&F 38393 (0.5–10 mg/kg SC) did not elicit stereotypy. In contrast, yawning behavior was not produced after very high doses of Talipexole (500 µg/kg SC) or SND 919 (1000 µg/kg SC) given alone or in combination with SK&F 38393 (0.5–10 mg/kg SC). These extremely high doses of Talipexole or SND 919 evoked slight stereotypy, which was enhanced by the combined treatment with SK&F 38393. The present results suggest that the dopamine D-2 receptors related to yawning are more sensitive to dopamine receptor agonists than those related to stereotypy, and that concurrent stimulation of postsynaptic dopamine D-1 receptors with D-2 receptors reduces the incidence of yawning but enhances that of stereotypy.

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