| Project/Area Number |
13680883
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Neuroscience in general
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| Research Institution | Nippon Medical School |
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Principal Investigator |
KATO Masakatsu Nippon Medical School, Department of Physiology, Associate Professor, 医学部, 助教授 (90143239)
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| Co-Investigator(Kenkyū-buntansha) |
SAKUMA Yasuo Nippon Medical School, Department of Physiology, Professor, 医学部, 教授 (70094307)
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| Project Period (FY) |
2001 – 2002
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| Project Status |
Completed (Fiscal Year 2002)
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| Budget Amount *help |
¥3,300,000 (Direct Cost: ¥3,300,000)
Fiscal Year 2002: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 2001: ¥1,900,000 (Direct Cost: ¥1,900,000)
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| Keywords | GnRH neuron / EGFP / transgenic / calcium channel / R-type calcium channel / T-type calcium channel / patch clamp |
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| Research Abstract |
Gonadotropin releasing hormone (GnRH) neurons play an important role in reproductive neuroendocrinology. Functional analysis of these neurons is, however, limited although it has been facilitated by producing transgenic mice to specifically label GnRH neurons with enhanced green fluorescence protein (EGFP). In the present study we produced transgenic rats to label GnRH neurons with EGFP. The brains were excised from 1-7 day-old pups (neonate) or 35-40 day-old rats (puberty) under ether anesthesia. A diagonal band of Broca and the medial preoptic area were cut and were enzymatically dispersed. The neurons were incubated in Neurobasal-A medium for 1 das. A perforated patch clamp was applied to the identified GnRH neurons to analyze the voltage-gated Ca^<2+> currents. In neonatal GnRH neurons, high voltage-activated Ca^<2+> currents were clearly observed but low voltage-activated Ca^<2+> currents were negligible. Nimodipine (L-type channel blocker) and ω-conotoxin GVIA (N-type channel blocker) each attenuated the current by 〜20%. The R-type channel blocker SNX-482 attenuated the current by 〜55%. Inhibition by P/Q-type channel blocker ω-agatoxin IVA was small. In pubertal GnRH neurons, however, both high and low voltage-activated Ca^<2+> currents were observed. Inhibitions by nifedipine, ω-conotoxin GVIA and SNX-482 were similar to that in neonatal neurons, whereas the inhibition by oo-agatoxin IVA was clearly seen in 40-61% of GnRH neurons examined. There was no sex difference in the profile of expression of the voltage-gated Ca^<2+> currents. These results indicate that GnRH neurons functionally express L-, N-, P/Q-, R- and T-type channels. Expressions of P/Q- and T-type channels are develonmentally regulated.
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