The Experts below are selected from a list of 1833 Experts worldwide ranked by ideXlab platform
Toshio Narahashi - One of the best experts on this subject based on the ideXlab platform.
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Fipronil is a potent open channel blocker of glutamate-activated chloride channels in cockroach neurons. J Pharmacol Exp Ther 310(1
2020Co-Authors: Xilong Zhao, Jay Z Yeh, Vincent L Salgado, Toshio NarahashiAbstract:ABSTRACT Fipronil, a phenylpyrazole insecticide, displays high insecticidal activity and reduced mammalian toxicity. To better elucidate the mechanism of its selective toxicity between insects and mammals and activity against dieldrin-resistant insects, we studied fipronil action on glutamate-gated chloride channels (GluCls), unique invertebrate ligand-gated chloride channels, in cockroach Thoracic Ganglion neurons, using the whole-cell patch clamp technique. Glutamate evoked two types of chloride currents, a desensitizing current and a nondesensitizing current. Fipronil differentially inhibited these two types of currents with different potencies and with different rates of reversibility. Fipronil inhibited the desensitizing and nondesensitizing GluCls with IC 50 values of 801 and 10 nM, respectively. Kinetic analysis revealed that fipronil blocks required channel opening. Recovery of the desensitizing current from fipronil block required channel opening, whereas recovery of nondesensitizing current from block was independent of channel opening. The high potency of fipronil against the nondesensitizing current was due to a slow unblocking rate constant. In addition, when the nondesensitizing GluCls were occupied by picrotoxinin, the receptors became less sensitive to fipronil block. It is concluded that GluCls are a critical target for fipronil, especially for the selective toxicity between mammals and insects, and that fipronil block of GluCls may play a role in the lack of the cross-resistance with dieldrin
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fipronil is a potent open channel blocker of glutamate activated chloride channels in cockroach neurons
Journal of Pharmacology and Experimental Therapeutics, 2004Co-Authors: Xilong Zhao, Jay Z Yeh, Vincent L Salgado, Toshio NarahashiAbstract:Fipronil, a phenylpyrazole insecticide, displays high insecticidal activity and reduced mammalian toxicity. To better elucidate the mechanism of its selective toxicity between insects and mammals and activity against dieldrin-resistant insects, we studied fipronil action on glutamate-gated chloride channels (GluCls), unique invertebrate ligand-gated chloride channels, in cockroach Thoracic Ganglion neurons, using the whole-cell patch clamp technique. Glutamate evoked two types of chloride currents, a desensitizing current and a nondesensitizing current. Fipronil differentially inhibited these two types of currents with different potencies and with different rates of reversibility. Fipronil inhibited the desensitizing and nondesensitizing GluCls with IC50 values of 801 and 10 nM, respectively. Kinetic analysis revealed that fipronil blocks required channel opening. Recovery of the desensitizing current from fipronil block required channel opening, whereas recovery of nondesensitizing current from block was independent of channel opening. The high potency of fipronil against the nondesensitizing current was due to a slow unblocking rate constant. In addition, when the nondesensitizing GluCls were occupied by picrotoxinin, the receptors became less sensitive to fipronil block. It is concluded that GluCls are a critical target for fipronil, especially for the selective toxicity between mammals and insects, and that fipronil block of GluCls may play a role in the lack of the cross-resistance with dieldrin.
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fipronil modulation of glutamate induced chloride currents in cockroach Thoracic Ganglion neurons
Neurotoxicology, 2003Co-Authors: Tomoko Ikeda, Xilong Zhao, Jay Z Yeh, Yoshiaki Kono, Toshio NarahashiAbstract:Abstract Fipronil is the first phenylpyrazole insecticide introduced for pest control. It is effective against some insects that have become resistant to other insecticides, and exhibits low mammalian toxicity. Although fipronil is known to block GABA receptors, the mechanisms of its selective toxicity and efficacy against insects with dieldrin-resistant GABA receptors are not fully understood. We studied the effects of fipronil on the inhibitory glutamate receptor–chloride channel complex, which is found only in invertebrates. Glutamate-activated chloride currents were recorded from neurons isolated from cockroach Thoracic ganglia using the whole-cell patch clamp technique. When glutamate was applied to a neuron, it evoked inward currents with an EC50 of 36.8 ± 3.0 μM and a Hill coefficient of 1.56 ± 0.17. The similarity between the reversal potential and the calculated chloride equilibrium potential indicated that glutamate-induced currents were carried by chloride ions. Fipronil suppressed the glutamate-induced peak currents in a dose-dependent manner with an IC50 of 0.73 ± 0.27 μM and a Hill coefficient of 0.68 ± 0.15. The current decay phases were greatly prolonged after fipronil application in a concentration-dependent manner. Picrotoxinin (PTX) at 100 μM slightly suppressed glutamate-induced currents to 87.8 ± 3.7% of the control, and dieldrin at 100 μM had no effect (96.7 ± 3.1%). AP5 and CNQX, mammalian glutamate receptor antagonists, were without effect on glutamate-induced Cl− currents. It is concluded that the potent blocking action of fipronil against glutamate-gated chloride channels may contribute to the higher toxicity against insects than mammals, as well as the efficacy against insects resistant to other insecticides.
Guizhong Wang - One of the best experts on this subject based on the ideXlab platform.
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the identification and distribution of progesterone receptors in the brain and Thoracic Ganglion in the mud crab scylla paramamosain crustacea decapoda brachyura
Invertebrate Neuroscience, 2010Co-Authors: Huiyang Huang, Ping Song, Guizhong WangAbstract:The existence of progesterone receptors (PR) in the Scylla paramamosain (mud crab) was studied using immunological techniques. By Western blotting, PR with an apparent molecular weight of 70 kDa is identified in both the brain and the Thoracic Ganglion. By immunohistochemistry, PR immunoreactive neurons are detected mainly in the protocerebrum, the subesophageal Ganglion and the leg Ganglion. PR immunoreactivity is localized mainly in the nuclei of these neurons, while only a few neurons show such activities in their cytoplasm. Our results provide evidence that progesterone modulates the neuroendocrine system mainly via nucleus receptors.
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occurrence of gonadtropins like substance in the Thoracic Ganglion mass of the mud crab scylla paramamosain crustacea decapoda brachyura
海洋学报(英文版), 2009Co-Authors: Huiyang Huang, Guizhong WangAbstract:National Natural Science Foundation of China [40406030, 40776084]; National High Technology Research and Development Program of China [2006AA10A406]; Program for New Century Excellent Talents in Fujian Province University
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immunorecognition of estrogen and androgen receptors in the brain and Thoracic Ganglion mass of mud crab scylla paramamosain
Progress in Natural Science, 2008Co-Authors: Huiyang Huang, Guizhong WangAbstract:Abstract The brain and the Thoracic Ganglion of a crustacean can synthesize and secrete gonad-stimulating hormone (GSH) which stimulates the maturation of gonad. In the previous experiments, sex steroid hormones (estradiol, testosterone, progesterone, etc.) have been detected from the crustacean. However, the feedback regulation of sex steroid hormones on the brain and the Thoracic Ganglion of the crustacean has not been reported so far. In the present experiment, monoclonal antibodies were applied to investigate the immunorecognition of estrogen receptor (ER) and androgen receptor (AR) in the brain and the Thoracic Ganglion mass of Scylla paramamosain. The results showed that the distribution of the immunopositive substances of ER and AR was extremely similar. They distributed in the protocerebrum, deutocerebrum and tritocerebrum of the brain, and mainly in protocerebrum. In the Thoracic Ganglion mass, immunopositive substances distributed in the subesophageal Ganglion, Thoracic Ganglion and abdominal Ganglion, and mostly in subesophageal Ganglion. Immunopositive substances of ER and AR mostly existed in the cytoplasm of neurons. The present study will provide morphological evidence for the origin and the evolution of ER and AR. In addition, the immunoreactivities of ER and AR suggested that the estrogen and androgen may be involved in the feedback regulation of crustacean neuroendocrine.
Huiyang Huang - One of the best experts on this subject based on the ideXlab platform.
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identification of differentially expressed genes in the Thoracic Ganglion of the mud crab scylla paramamosain during ovarian maturation
Marine Biology Research, 2011Co-Authors: Hui Zeng, Jingru Huang, Huiyang HuangAbstract:Abstract The Thoracic Ganglion is an important neuroendocrine organ in crabs. In order to isolate and clone differentially expressed genes in the Thoracic Ganglion of the mud crab, Scylla paramamosain, during ovarian maturation, a forward suppression subtractive hybridization cDNA library was constructed (crabs at maturation stage were used as the ‘tester’ and those at an early developmental stage as the ‘driver’). cDNA obtained from suppression subtractive hybridization was inserted into an expression vector and was transferred into Escherichia coli. A total of 500 randomly selected clones were sequenced and 410 expressed sequence tags (ESTs) were obtained. The inserted fragment size was from 200 to 1500 bp. The insertion rate was up to 82%. This confirmed the successful construction of the library. The ESTs were recognized based on the BLAST searches in NCBI, clustered and assembled, annotated and finally categorized. Among the total of 139 genes, 124 genes (89.2%) were similar to known genes, while 15 ...
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the identification and distribution of progesterone receptors in the brain and Thoracic Ganglion in the mud crab scylla paramamosain crustacea decapoda brachyura
Invertebrate Neuroscience, 2010Co-Authors: Huiyang Huang, Ping Song, Guizhong WangAbstract:The existence of progesterone receptors (PR) in the Scylla paramamosain (mud crab) was studied using immunological techniques. By Western blotting, PR with an apparent molecular weight of 70 kDa is identified in both the brain and the Thoracic Ganglion. By immunohistochemistry, PR immunoreactive neurons are detected mainly in the protocerebrum, the subesophageal Ganglion and the leg Ganglion. PR immunoreactivity is localized mainly in the nuclei of these neurons, while only a few neurons show such activities in their cytoplasm. Our results provide evidence that progesterone modulates the neuroendocrine system mainly via nucleus receptors.
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occurrence of gonadtropins like substance in the Thoracic Ganglion mass of the mud crab scylla paramamosain crustacea decapoda brachyura
海洋学报(英文版), 2009Co-Authors: Huiyang Huang, Guizhong WangAbstract:National Natural Science Foundation of China [40406030, 40776084]; National High Technology Research and Development Program of China [2006AA10A406]; Program for New Century Excellent Talents in Fujian Province University
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immunorecognition of estrogen and androgen receptors in the brain and Thoracic Ganglion mass of mud crab scylla paramamosain
Progress in Natural Science, 2008Co-Authors: Huiyang Huang, Guizhong WangAbstract:Abstract The brain and the Thoracic Ganglion of a crustacean can synthesize and secrete gonad-stimulating hormone (GSH) which stimulates the maturation of gonad. In the previous experiments, sex steroid hormones (estradiol, testosterone, progesterone, etc.) have been detected from the crustacean. However, the feedback regulation of sex steroid hormones on the brain and the Thoracic Ganglion of the crustacean has not been reported so far. In the present experiment, monoclonal antibodies were applied to investigate the immunorecognition of estrogen receptor (ER) and androgen receptor (AR) in the brain and the Thoracic Ganglion mass of Scylla paramamosain. The results showed that the distribution of the immunopositive substances of ER and AR was extremely similar. They distributed in the protocerebrum, deutocerebrum and tritocerebrum of the brain, and mainly in protocerebrum. In the Thoracic Ganglion mass, immunopositive substances distributed in the subesophageal Ganglion, Thoracic Ganglion and abdominal Ganglion, and mostly in subesophageal Ganglion. Immunopositive substances of ER and AR mostly existed in the cytoplasm of neurons. The present study will provide morphological evidence for the origin and the evolution of ER and AR. In addition, the immunoreactivities of ER and AR suggested that the estrogen and androgen may be involved in the feedback regulation of crustacean neuroendocrine.
Brian M H Bush - One of the best experts on this subject based on the ideXlab platform.
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proprioceptive input from two basal joint stretch receptors to leg motoneurones in the isolated Thoracic Ganglion of the shore crab
The Journal of Experimental Biology, 1992Co-Authors: Steward I Head, Brian M H BushAbstract:The reflex effects and interactions of two proprioceptors upon motoneurones supplying the four basal leg muscles of the shore crab Carcinus maenas have been studied in a new in vitro preparation consisting of the Thoracic-coxal muscle receptor organ (TCMRO) and the coxo-basal chordotonal organ (CBCO) isolated together with the whole Thoracic Ganglion complex to which they were still connected by their afferent nerves. Each receptor strand was stimulated mechanically, while recording intracellularly from motoneurones in the Ganglion, and extracellularly from the cut motor nerves innervating the promotor and remotor muscles of the Thoracic-coxal (T—C) joint and the levator and depressor muscles of the coxo-basal (C—B) joint. Stretch of the TCMRO evoked reflex firing in several units in the promotor motor nerve, confirming previous studies. In addition to this ‘intrajoint’ reflex, however, TCMRO stretch also elicited ‘interjoint’ reflex responses in motoneurones of both the levator and depressor muscles. Similarly, stretch and release of the CBCO produced intrajoint resistance reflexes in levator and depressor motoneurones, respectively, as well as interjoint reflexes in promotor and remotor motoneurones. In general, the CBCO produced stronger reflex effects in all four motor nerves than did the TCMRO. Intracellular recordings from individual motoneurones of all four muscles revealed that the majority of them received convergent input from both proprioceptors. The importance of such convergent input in vivo is discussed
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reflex actions of one proprioceptor on the motoneurones of a muscle receptor and their central modulation in the shore crab
The Journal of Physiology, 1991Co-Authors: S I Head, Brian M H BushAbstract:1. Reflex efferent control of a muscle stretch receptor by a joint proprioceptor of the same limb was studied in an isolated CNS preparation from the shore crab. The influence of 'fictive locomotor' activity on this interjoint reflex was also examined. 2. The Thoracic-coxal muscle receptor organ (TCMRO) and the coxo-basal chordotonal organ (CBCO), which monitor movement and position of the first and second joints of the posterior leg, were isolated together with the whole Thoracic Ganglion complex. The TCMRO, functionally analogous to a mammalian muscle spindle, has two receptor motoneurones. RM1 innervating the receptor muscle alone and RM2 which also supplies the 'extrafusal' promotor muscle. The CBCO is a typical arthropod elastic strand organ, with many sensory neurones but lacking an efferent supply. The TCMRO was fixed at its mid-length, and stretch-hold-release stimuli were applied to the CBCO. Efferent activity was recorded from the cut nerve roots of the four basal limb muscles and intracellularly as excitatory junction potentials (EJPs) from the receptor muscle. 3. A dynamic increase in the frequency of action potentials in RM1 occurred on both stretch and release of the CBCO. During the hold phase the RM1 activity declined from the dynamic response but remained elevated compared to the resting tonic discharge. RM2, identified by EJPs occurring 1:1 with a unit in the promoter nerve, responded in a similar way. 4. One or more promotor motoneurones were usually co-activated with the two receptor efferents in response to input from the CBCO. In a typical example the average spike frequency of RM1 rose from 0 to 27 Hz during the dynamic phases (stretch and release) of the CBCO stimulus, falling to 2.5 Hz during the hold phase, while the corresponding promotor spike frequencies were 25 and 7.5 Hz, respectively. The other three muscle nerves recorded from generally also showed reflex driving by the CBCO. 5. The totally isolated Thoracic Ganglion could produce a rhythmic, bursting motor output in the absence of any sensory input. During this centrally generated activity the receptor motor innervation was strongly co-activated with the promotor bursts, and the reflex input from the CBCO was overridden or modulated in a phase-dependent manner. 6. The proximally directed interjoint reflex to the receptor muscle probably functions to maintain the tension on the sensory endings of the TCMRO, and so enable them to respond effectively at all times to movements of the basal leg joint.(ABSTRACT TRUNCATED AT 400 WORDS)
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proprioceptive reflex interactions with central motor rhythms in the isolated Thoracic Ganglion of the shore crab
Journal of Comparative Physiology A-neuroethology Sensory Neural and Behavioral Physiology, 1991Co-Authors: Steward I Head, Brian M H BushAbstract:Experiments were carried out on an isolated central nervous system preparation of the shore crab,Carcinus maenas, comprising the fused Thoracic Ganglion complex with two proprioceptors of one back leg still attached. These, the Thoracic-coxal muscle receptor organ and the coxo-basal chordotonal organ, monitor movement and position of the first and second joints, respectively. Motor activity was recorded extracellularly from the central cut ends of the nerves innervating the promotor and remotor muscles of the Thoracic-coxal joint, and the levator and depressor muscles of the coxal-basal joint of the same leg. Simultaneous intracellular recordings were made from central processes of individual motoneurones of each muscle.
Xilong Zhao - One of the best experts on this subject based on the ideXlab platform.
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Fipronil is a potent open channel blocker of glutamate-activated chloride channels in cockroach neurons. J Pharmacol Exp Ther 310(1
2020Co-Authors: Xilong Zhao, Jay Z Yeh, Vincent L Salgado, Toshio NarahashiAbstract:ABSTRACT Fipronil, a phenylpyrazole insecticide, displays high insecticidal activity and reduced mammalian toxicity. To better elucidate the mechanism of its selective toxicity between insects and mammals and activity against dieldrin-resistant insects, we studied fipronil action on glutamate-gated chloride channels (GluCls), unique invertebrate ligand-gated chloride channels, in cockroach Thoracic Ganglion neurons, using the whole-cell patch clamp technique. Glutamate evoked two types of chloride currents, a desensitizing current and a nondesensitizing current. Fipronil differentially inhibited these two types of currents with different potencies and with different rates of reversibility. Fipronil inhibited the desensitizing and nondesensitizing GluCls with IC 50 values of 801 and 10 nM, respectively. Kinetic analysis revealed that fipronil blocks required channel opening. Recovery of the desensitizing current from fipronil block required channel opening, whereas recovery of nondesensitizing current from block was independent of channel opening. The high potency of fipronil against the nondesensitizing current was due to a slow unblocking rate constant. In addition, when the nondesensitizing GluCls were occupied by picrotoxinin, the receptors became less sensitive to fipronil block. It is concluded that GluCls are a critical target for fipronil, especially for the selective toxicity between mammals and insects, and that fipronil block of GluCls may play a role in the lack of the cross-resistance with dieldrin
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fipronil is a potent open channel blocker of glutamate activated chloride channels in cockroach neurons
Journal of Pharmacology and Experimental Therapeutics, 2004Co-Authors: Xilong Zhao, Jay Z Yeh, Vincent L Salgado, Toshio NarahashiAbstract:Fipronil, a phenylpyrazole insecticide, displays high insecticidal activity and reduced mammalian toxicity. To better elucidate the mechanism of its selective toxicity between insects and mammals and activity against dieldrin-resistant insects, we studied fipronil action on glutamate-gated chloride channels (GluCls), unique invertebrate ligand-gated chloride channels, in cockroach Thoracic Ganglion neurons, using the whole-cell patch clamp technique. Glutamate evoked two types of chloride currents, a desensitizing current and a nondesensitizing current. Fipronil differentially inhibited these two types of currents with different potencies and with different rates of reversibility. Fipronil inhibited the desensitizing and nondesensitizing GluCls with IC50 values of 801 and 10 nM, respectively. Kinetic analysis revealed that fipronil blocks required channel opening. Recovery of the desensitizing current from fipronil block required channel opening, whereas recovery of nondesensitizing current from block was independent of channel opening. The high potency of fipronil against the nondesensitizing current was due to a slow unblocking rate constant. In addition, when the nondesensitizing GluCls were occupied by picrotoxinin, the receptors became less sensitive to fipronil block. It is concluded that GluCls are a critical target for fipronil, especially for the selective toxicity between mammals and insects, and that fipronil block of GluCls may play a role in the lack of the cross-resistance with dieldrin.
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fipronil modulation of glutamate induced chloride currents in cockroach Thoracic Ganglion neurons
Neurotoxicology, 2003Co-Authors: Tomoko Ikeda, Xilong Zhao, Jay Z Yeh, Yoshiaki Kono, Toshio NarahashiAbstract:Abstract Fipronil is the first phenylpyrazole insecticide introduced for pest control. It is effective against some insects that have become resistant to other insecticides, and exhibits low mammalian toxicity. Although fipronil is known to block GABA receptors, the mechanisms of its selective toxicity and efficacy against insects with dieldrin-resistant GABA receptors are not fully understood. We studied the effects of fipronil on the inhibitory glutamate receptor–chloride channel complex, which is found only in invertebrates. Glutamate-activated chloride currents were recorded from neurons isolated from cockroach Thoracic ganglia using the whole-cell patch clamp technique. When glutamate was applied to a neuron, it evoked inward currents with an EC50 of 36.8 ± 3.0 μM and a Hill coefficient of 1.56 ± 0.17. The similarity between the reversal potential and the calculated chloride equilibrium potential indicated that glutamate-induced currents were carried by chloride ions. Fipronil suppressed the glutamate-induced peak currents in a dose-dependent manner with an IC50 of 0.73 ± 0.27 μM and a Hill coefficient of 0.68 ± 0.15. The current decay phases were greatly prolonged after fipronil application in a concentration-dependent manner. Picrotoxinin (PTX) at 100 μM slightly suppressed glutamate-induced currents to 87.8 ± 3.7% of the control, and dieldrin at 100 μM had no effect (96.7 ± 3.1%). AP5 and CNQX, mammalian glutamate receptor antagonists, were without effect on glutamate-induced Cl− currents. It is concluded that the potent blocking action of fipronil against glutamate-gated chloride channels may contribute to the higher toxicity against insects than mammals, as well as the efficacy against insects resistant to other insecticides.
