The Role of the Genitofemoral Nerve and Calcitonin Gene-Related Peptide on Testicular Descent
| Project/Area Number |
07671714
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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 |
Urology
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| Research Institution | SHINSHU UNIVERSITY |
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Principal Investigator |
TERADA Masaur Shinshu Univeresity Hospital, Lecturer, 医学部・附属病院, 講師 (80211390)
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| Project Period (FY) |
1995 – 1996
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| Project Status |
Completed (Fiscal Year 1996)
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| Budget Amount *help |
¥2,300,000 (Direct Cost: ¥2,300,000)
Fiscal Year 1996: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1995: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Keywords | Testicular descent / Cryptorchidism / Genitofemoral nerve / Calcitonin gene-related peptide / TS rat / Curare / Nifedipine / テビドロピリジン |
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| Research Abstract |
Exp.1 : We inverstigated whether prior gubemacular denervation changes a) the gubernacular contractile response to CGRP or b) binding capacity of CGRP receptors. TS rats and Sprague-Dawley rats (controls) underwent GFN transection or sham operation at 0 day after birth. On day 3 their gubernacula were excised and cultured +/- CFRP (714 nM) to document contractions by videocamera. Some gubemacular frozen sections from 10 gubernacula of each group were incubated with [^<125>I] CGRP (<approximately equal>2000 Ci/mmol, 50pM) +/- unlabeled CGRP (1muM). After exposure to the X-ray films, they were quantified by computerized densitometry. GFN transection in TS rats restored both a) gubernacular contractile response to CGRP in vitro and b) binding capacity of CGRP receptors to the same level as normal rats
Exp.2 : Cultured neonatal mice gubernacula show rhythmic contractions in response to CGRP.We investigated if 1) these contractions require calcium ions or 2) acetylcholine receptors. Gubemacu
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la from male mice aged 7 days were pre-incubated for 30 min in aerated culture medium (Krebs-Henseleit solution) +/- 1.8mM of Ca^<2+>. Then they were cultured +/- 714nM of CGRP.Some gubernacula were also pre-incubated in culture medium with Ca^<2+> +/- 2.5 muM of curare, then cultured with CGRP.(n=20/ group). All were observed for 2 days by videocamera. Of gubemacula cultured with Ca^<2+> and CGRP 90% exhibited contractions, which decreased to 20% without CGRP (P<0.001) and 15% without Ca^<2+> (P<0.001). Only 5% of gubernacula cultured without CGRP and Ca^<2+> showed contractions. Of gubernacula cultured with or without curare 95% and 90% respectively exhibited contractions (NS). With increasing dose of nifedipine, the percentage of gubernacula contracting decreased from 95% to 0%.
Conclusions : Our results suggest that the GFN releases excessive CGRP in TS rats, leading to decreased receptor binding as well as decreased contractions. This study shows the importance of CGRP in the GFN in an animal model with UDT.Gubernacular contractile response to CGRP depends on extracellular fluid Ca^<2+> concentration. In this regard neonatal mouse gubemaculum is different from skeletal muscle, which should not be influenced by Ca^<2+> ions. Further, these contractions are not activated via acetylcholine receptors. Less
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