| Budget Amount *help |
¥2,800,000 (Direct Cost: ¥2,500,000、Indirect Cost: ¥300,000)
Fiscal Year 2007: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2006: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Research Abstract |
GABA which is an inhibitory neurotransmitter in the mammalian central nervous system has been identified in different mammalian peripheral tissues. In the neuronal tissues and some peripheral non-neuronal tissues, GABA is thought to be involved in the proliferation, migration, differentiation, and promotion of cell survival such as cell death. Furthermore, GABA is shown to be present at the high concentration in the mammalian oviduct in female productive system. The interaction between GABA and GABA_A-like receptor has been shown to promote the acrosome reaction of human spermatozoa exocytotic event essential for fertilization in male productive system. To understand the role of the GABAergic system during spermatogenesis, we examined cellular localization of GABA, GABA_A and GABA_B subunits by immunocytochemistry and carried out electrophysiological analysis. Immunoreactivity for GABA was detected around acrosomal granules of spermatids during cap phase. GABA_<B1> immunoreactivity was
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observed in the acrosomal vesicle. In contrast, GABA_<B2> immunoreactivity was detected in the equatorial region. Electron microscopic immunocytochemistry revealed that, during cap phase, GABA and GABA_<B1> receptor were, distributed within the whole acrosomal vesicle but not in the acrosomal granule. GABA_<B2> immunoreactivity was observed in the narrow space between the inner acrosomal. Furthermore some kinds of GABA_B subunits mRNAs were detected at the beginning process of spermatogenesis and epididymis.
We detected the expression of GABA_A subunits (αl, α5, β1-3, γ3), GAD mRNAs by RT-PCR. The immunoreactivities of GABA and GABA_A subunits except for α1 subunit were observed in whole cytoplasm during spermatogenesis. By whole-cell patch clamp, GABA application induced C1_- current in germ cell. These results indicate that GABAergic system may play physiological role in spermatogenesis. Furthermore, electron microscopic immunocytochemistry revealed that al subunit is observed as some spots within nucleus. These results suggest that the GABAergic system might be involved in regulation of spermatogenesis. Less
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