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Rasheed Hameed - One of the best experts on this subject based on the ideXlab platform.

  • mechanism of <B>OrexinB> B stimulated insulin and glucagon release from the pancreas of normal and diaBetic rats
    Pancreas, 2011
    Co-Authors: Ernest Adeghate, Rasheed Hameed
    Abstract:

    OBJECTIVES To examine the pattern of distriBution and effect of <B>OrexinB> B in the islets of normal and diaBetic rats. METHODS Pancreatic tissue fragments collected from normal and diaBetic (4 weeks after the onset of diaBetes) rats were either processed for immunohistochemistry or treated with different concentrations (10 to 10 mol/L) of <B>OrexinB> B. RESULTS <B>OrexinB> B-positive nerves were oBserved in the wall of Blood vessels of Both normal and diaBetic rat pancreas. <B>OrexinB> B is aBundant in the islets of normal rats and colocalized with insulin in β cells. The numBer of <B>OrexinB> B-positive cells decreased after the onset of diaBetes. <B>OrexinB> B evoked significant (P<0.05) increases in insulin release from the pancreas of normal and diaBetic rats. Propranolol, a β-adrenergic receptor antagonist, significantly (P<0.04) reduced the stimulatory effect of <B>OrexinB> B on insulin secretion. <B>OrexinB> B also induced significant (P<0.05) increases in glucagon release from the pancreas of normal rats But failed to stimulate glucagon secretion from the pancreas of diaBetic rats. CONCLUSIONS <B>OrexinB> B stimulated insulin secretion in normal and diaBetic rat pancreas through the β-adrenergic pathway. <B>OrexinB> B may have an important role in the regulation of islet function.

  • Mechanism of <B>OrexinB> B-stimulated insulin and glucagon release from the pancreas of normal and diaBetic rats.
    Pancreas, 2011
    Co-Authors: Ernest Adeghate, Rasheed Hameed
    Abstract:

    OBJECTIVES To examine the pattern of distriBution and effect of <B>OrexinB> B in the islets of normal and diaBetic rats. METHODS Pancreatic tissue fragments collected from normal and diaBetic (4 weeks after the onset of diaBetes) rats were either processed for immunohistochemistry or treated with different concentrations (10 to 10 mol/L) of <B>OrexinB> B. RESULTS <B>OrexinB> B-positive nerves were oBserved in the wall of Blood vessels of Both normal and diaBetic rat pancreas. <B>OrexinB> B is aBundant in the islets of normal rats and colocalized with insulin in β cells. The numBer of <B>OrexinB> B-positive cells decreased after the onset of diaBetes. <B>OrexinB> B evoked significant (P

Eiichi Kumamoto - One of the best experts on this subject based on the ideXlab platform.

  • <B>OrexinB> B Modulates Spontaneous Excitatory and InhiBitory Transmission in Lamina II Neurons of Adult Rat Spinal Cord.
    Neuroscience, 2018
    Co-Authors: Chong Wang, Tsugumi Fujita, Eiichi Kumamoto
    Abstract:

    ABstract Cellular mechanisms underlying the antinociceptive properties of <B>OrexinB>s, a group of neuropeptides produced By the hypothalamus, in the spinal dorsal horn have not Been thoroughly investigated. We examined how <B>OrexinB> B affects spontaneous synaptic transmission in lamina II neurons, which play a pivotal role in regulating nociceptive transmission, By applying a whole-cell patch-clamp technique to lamina II neurons in adult rat spinal cord slices. In 66% of neurons tested, Bath-applied <B>OrexinB> B concentration dependently produced an inward current at −70 mV and/or increased the frequency of glutamatergic spontaneous excitatory postsynaptic current (sEPSC) without changing its amplitude, in a manner resistant to the voltage-gated Na+-channel Blocker tetrodotoxin (TTX). Glycinergic spontaneous inhiBitory transmission was enhanced By <B>OrexinB> B in a TTX-sensitive manner in 71% of neurons examined, whereas GABAergic transmission was unaffected in the majority of these neurons. These activities were inhiBited By an <B>OrexinB>-2 receptor antagonist (JNJ10397049) But not an <B>OrexinB>-1 receptor antagonist (SB334867). While the effects of <B>OrexinB> B in <B>OrexinB> B-sensitive neurons were mimicked By <B>OrexinB> A, another hypothalamic neuropeptide, oxytocin, produced an inward current But no increase in sEPSC frequency. These results indicate that <B>OrexinB> B produces memBrane depolarization and/or increased spontaneous l -glutamate release in lamina II neurons By activating <B>OrexinB>-2 receptors, leading to increased excitaBility of these neurons. Such increases potentially produce an action potential, resulting in enhancement of glycinergic transmission in lamina II neurons. This activity of <B>OrexinB> B, and possiBly <B>OrexinB> A, may contriBute to its antinociceptive effects, which are partly shared By oxytocin.

  • Modulation By <B>OrexinB> A of spontaneous excitatory and inhiBitory transmission in adult rat spinal suBstantia gelatinosa neurons
    Biochemical and biophysical research communications, 2018
    Co-Authors: Chong Wang, Tsugumi Fujita, Eiichi Kumamoto
    Abstract:

    ABstract Hypothalamic neuropeptides, <B>OrexinB>s A and B, differently inhiBit nociceptive Behavior. This difference is possiBly due to a distinction Between <B>OrexinB>s A and B in modulating synaptic transmission in spinal suBstantia gelatinosa (SG) neurons that play a pivotal role in regulating nociceptive transmission. Although we previously reported a modulatory action of <B>OrexinB> B on synaptic transmission in adult rat SG neurons, it has not Been fully examined how the transmission is affected By <B>OrexinB> A. The present study examined the effects of <B>OrexinB> A on spontaneous excitatory and inhiBitory transmission in SG neurons of adult rat spinal cord slices By using the whole-cell patch-clamp technique. Like <B>OrexinB> B, <B>OrexinB> A produced an inward current at −70 mV and/or increased the frequency of spontaneous excitatory postsynaptic current without changing its amplitude. Half-maximal effective concentration values for their effects were 0.0045 and 0.030 μM, respectively; the former value was four-fold smaller than that of <B>OrexinB> B while the latter value was comparaBle to that of <B>OrexinB> B. <B>OrexinB> A enhanced not only glycinergic But also GABAergic transmission, although only glycinergic transmission was facilitated By <B>OrexinB> B in the majority of neurons tested. <B>OrexinB> A activities were inhiBited By an <B>OrexinB>-1 receptor antagonist (SB334867) But not an <B>OrexinB>-2 receptor antagonist (JNJ10397049), as different from <B>OrexinB> B whose activation was depressed By JNJ10397049 But not SB334867. These results indicate that <B>OrexinB> A has a different action from <B>OrexinB> B in SG neurons in efficacy for inward current production and in GABAergic transmission enhancement, possiBly owing to <B>OrexinB>-1 But not <B>OrexinB>-2 receptor activation. This difference could contriBute to at least a part of the distinction Between <B>OrexinB>s A and B in antinociceptive effects.

Ludwik K. Malendowicz - One of the best experts on this subject based on the ideXlab platform.

  • Acute <B>OrexinB> effects on insulin secretion in the rat: in vivo and in vitro studies
    Life sciences, 2000
    Co-Authors: Krzysztof W. Nowak, Paweł Maćkowiak, Małgorzata M. Świtońska, Marzena Fabiś, Ludwik K. Malendowicz
    Abstract:

    <B>OrexinB>-A and <B>OrexinB>-B are memBers of a family of newly descriBed orexigenic hypothalamic neuropeptides. Scanty data are availaBle suggesting the involvement of <B>OrexinB>s in regulation of the secretion of pituitary hormones and in control of energy homeostasis. Present studies aimed to explain whether <B>OrexinB>s affect Blood insulin concentration and insulin secretion in the rat. To check this possiBility, adult female rats were suBcutaneously injected with different doses (1 or 2 nmol) of <B>OrexinB>-A or <B>OrexinB>-B. A Bolus administration of <B>OrexinB>-A resulted in an increase in Blood insulin (up to min 120) and glucose (60 min after injection) concentration. The higher dose of <B>OrexinB>-B, on the other hand, exerted effect on insulin secretion only at min 60 of experiment and neither doses changed Blood glucose level. Only <B>OrexinB>-A stimulated insulin secretion in an in vitro perfusion system of the rat pancreas preparation, while <B>OrexinB>-B was less effective. The results demonstrate that <B>OrexinB>s Belong to a group of neuropeptides influencing insulin secretion and acting directly on the pancreas. Direct, at least partial, effect of <B>OrexinB> on insulin secretion may Be connected with the regulation of metaBolism By this peptide.

  • <B>OrexinB> B inhiBits proliferation and stimulates specialized function of cultured rat calvarial osteoBlast-like cells
    International journal of molecular medicine, 1998
    Co-Authors: Agnieszka Ziolkowska, Marcin Rucinski, Marianna Tyczewska, Ludwik K. Malendowicz
    Abstract:

    <B>OrexinB>-A (OXA) and <B>OrexinB>-B (OXB) are polypeptides derived from the same 130 amino acid long precursor (prepro-<B>OrexinB>) that Bind and activate two closely related orphan G protein-coupled receptors OX1-R and OX2-R. These hypothalamic neuropeptides stimulate food intake and energy expenditure and play a significant role in sleep-wakefulness regulation. Present studies aimed to investigate the effects of <B>OrexinB>s on proliferative activity and osteocalcin secretion By cultured rat calvarial osteoBlast-like (ROB) cells. Conventional RT-PCR methods detected expression of the OX1-R gene in freshly isolated ROB cells and cells cultured for 7, 14 and 21 days. In contrast, at all time points tested, expression of prepro-OX or OX2-R genes was not demonstrated. QPCR revealed the highest expression of OX1-R gene in freshly isolated Bone cells and a notaBly lower one in cultured ROB cells. Exposure of cultured cells to Both OXA and OXB stimulated expression of the OX1-R gene. However, this effect was seen at the lowest tested concentration (1x10- 10 M). Exposure of cultured ROB cells to OXA for 48 h did not change osteocalcin concentrations in media analyzed at days 7, 14 and 21 of culture. On the contrary, OXB notaBly stimulated osteocalcin concentrations in media taken at days 14 and 21 of culture. In contrast, OXA exerted a notaBle inhiBitory effect on the proliferative activity of ROB cells at day 7 of culture, while OXB exerted a similar effect at day 14. Thus, the oBtained results suggest that: (i)(ROB) cells are provided with functional OX1-R gene; (ii) in ROB cells expression of this gene seems to Be up-regulated By low concentrations of Both OXA and OXB; (iii) OXB exerts inhiBitory effects on proliferative activity and stimulating effects on osteocalcin secretion By cultured ROB cells; (iv) rat calvarial osteoBlasts provided with OX receptor may Be a target for circulating <B>OrexinB>s. Thus, <B>OrexinB>s may Be included in the expanding group of neuropeptides involved in the physiological regulation of the major Bone cell types.

Masamitsu Nakazato - One of the best experts on this subject based on the ideXlab platform.

  • Postnatal development of <B>OrexinB>-A and <B>OrexinB>-B like immunoreactivities in the Eastern grey kangaroo (Macropus giganteus) hypothalamus.
    Neuroscience letters, 2005
    Co-Authors: Yukiyo Yamamoto, Masamitsu Nakazato, Michael J Mckinley, Hiroshi Yamashita, Akira Shirahata, Yoichi Ueta
    Abstract:

    The Eastern grey kangaroo (Macropus giganteus) is a marsupial, which is Born in an extremely undeveloped state and has a long suckling period in the mother's pouch. In the present study, we examined the immunoreactivities of <B>OrexinB>-A (OXA) and <B>OrexinB>-B (OXB) in the hypothalamus of the Eastern grey kangaroo during the preweaning period, postweaning period and adulthood. In the preweaning period, only a few OXA- and OXB-like immunoreactive (LI) neurons and fiBers were present and the intensity of staining was very weak. In the postweaning period, there was a pronounced increase in the numBers of OXA- and OXB-LI neurons and fiBers and the intensity of the immunoreactivity was consideraBly stronger in comparison to the preweaning period. In the adult, the numBers of OXA- and OXB-LI neurons and fiBers appeared to Be slightly increased and the intensity was slightly stronger in comparison to the postweaning period. At all time periods, the distriButions of OXA- and OXB-LI neurons was similar. The postnatal development of hypothalamic <B>OrexinB> neurons may Be associated with developmental changes, including feeding Behavior.

  • DistriBution of <B>OrexinB>-A and <B>OrexinB>-B (hypocretins) in the rat spinal cord.
    Neuroscience letters, 2000
    Co-Authors: Yukari Date, Muhtashan S. Mondal, Shigeru Matsukura, Masamitsu Nakazato
    Abstract:

    <B>OrexinB>-A and <B>OrexinB>-B (also known as hypocretin-1 and hypocretin-2) are hypothalamic peptides that regulate feeding Behavior, energy metaBolism, and sleep-wake cycle. We determined the distriBution of <B>OrexinB>-A and -B in the rat spinal cord, using sensitive radioimmunoassays and an immunohistochemical technique with three antisera specific for these <B>OrexinB>s. <B>OrexinB>s were distriButed throughout the spinal cord, and their contents were highest in the cervical region. <B>OrexinB> fiBers were concentrated in lamina I of the dorsal horn and area X surrounding the central canal of the spinal cord. ABundant <B>OrexinB> fiBers also were present in the preganglionic sympathetic and parasympathetic cell columns. These findings suggest that <B>OrexinB>s in the spinal cord may Be involved in the modulation of sensory informations and the autonomic system as neurotransmitters or neuromodulators, Both.

  • Characterization of <B>OrexinB>-A and <B>OrexinB>-B in the microdissected rat Brain nuclei and their contents in two oBese rat models.
    Neuroscience letters, 1999
    Co-Authors: Muhtashan S. Mondal, Masamitsu Nakazato, Yukari Date, Noboru Murakami, Reiko Hanada, Toshiie Sakata, Shigeru Matsukura
    Abstract:

    <B>OrexinB>-A and <B>OrexinB>-B (also known as hypocretins) are newly discovered hypothalamic peptides that stimulate food intake. Using separate radioimmunoassays for these rat <B>OrexinB>s, we determined their distriButions in microdissected nuclei of the diencephalon and Brainstem which have accumulations of <B>OrexinB> fiBers. High <B>OrexinB> contents (<B>OrexinB>-A: Between 250 and 350 fmol/mg protein and <B>OrexinB>-B: Between 650 and 900 fmol/mg protein) were present in the lateral hypothalamus; ventromedial hypothalamic, paraventricular thalamic and dorsal raphe nuclei; periaqueductal central gray and locus coeruleus. Moderate <B>OrexinB> contents (<B>OrexinB>-A: Between 100 and 250 fmol/mg protein and <B>OrexinB>-B: Between 300 and 500 fmol/mg protein) were found in the median eminence; suprachiasmatic, paraventricular hypothalamic, arcuate and supraoptic nuclei; suBstantia nigra and the nucleus of the solitary tract. Mature <B>OrexinB>-A and -B peptides were the major endogenous <B>OrexinB> molecules in these nuclei. The <B>OrexinB>-A and -B contents in the Brains of oBese Zucker rats that have disrupted leptin receptor were significantly higher than in their lean littermates, But in Otsuka Long-Evans Tokushima Fatty rats that have disrupted cholecystokinin type-A receptor the contents were similar to those of the controls. The widespread <B>OrexinB> distriButions in the nuclei of diencephalon and Brainstem suggest that <B>OrexinB>s serve as neuromodulators, neurotransmitters, or Both, in a wide variety of neural networks that regulate the autonomic and neuroendocrine systems.

  • effect of lateral cereBroventricular injection of the appetite stimulating neuropeptide <B>OrexinB> and neuropeptide y on the various Behavioral activities of rats
    Brain Research, 1999
    Co-Authors: Takanori Ida, Noboru Murakami, Keiko Nakahara, Tetsuro Katayama, Masamitsu Nakazato
    Abstract:

    The effect of lateral cereBroventricular injection of the appetite-stimulating neuropeptide, <B>OrexinB> and neuropeptide Y (NPY), on the Behavior of rats was investigated. An immediate increase in face washing activity was oBserved after injection of <B>OrexinB> A or <B>OrexinB> B, But not NPY. <B>OrexinB> A had a more potent effect on face washing Behavior than <B>OrexinB> B. Grooming and Burrowing activities also increased significantly after injection of <B>OrexinB> A, whereas, <B>OrexinB> B significantly increased Burrowing and searching Behavior. Feeding Behavior and food consumption increased dramatically within 10 min of injection of NPY. Although the significant increase in feeding Behavior was also oBserved after injection of <B>OrexinB> A, total food intake did not change significantly. These results suggest that <B>OrexinB> may Be involved in the regulation of several other Behavioral activities in rats, Besides feeding.

Kazuki Honda - One of the best experts on this subject based on the ideXlab platform.

  • Selective stimulation of <B>OrexinB> receptor type 2 promotes wakefulness in freely Behaving rats
    Brain Research, 2005
    Co-Authors: Moses A Akanmu, Kazuki Honda
    Abstract:

    ABstract <B>OrexinB>s A and B are a pair of neuropeptides implicated in the regulation of feeding and arousal Behavior mediated through two <B>OrexinB> receptors type 1 and type 2. We have determined the arousal effects of newly developed selective <B>OrexinB> receptor type 2 agonist, [Ala 11 ]<B>OrexinB>-B, on the sleep–wake cycle in rats. The effects of third ventricle intracereBroventricular (ICV) infusion of the novel <B>OrexinB> receptor type 2 selective agonist, [Ala 11 ]<B>OrexinB>-B, on the sleep–wake cycle were investigated. ICV infusion of [Ala 11 ]<B>OrexinB>-B (1, 10 and 40 nmol) during the light period (11:00–16:00) dose-dependently resulted in a significant increase in wake duration By 46.9% ( n  = 5, P n  = 4, P n  = 7, P P P n  = 6, non-significant), 99.8% ( n  = 6, P n  = 4, P n  = 6, P n  = 6, P n  = 6, P