title: Inhibitory effects of melatonin on testosterone but not on androstenedione production during winter in the vespertilionid bat, Scotophilus heathi.
abstract: The possible effects of melatonin on testosterone and androstenedione production in vitro by testes of wild-caught bats, Scotophilus heathi, during different reproductive phases were investigated. Bats were captured during reproductive quiescent (April-August), recrudescent (September-October), breeding (November-February), and winter dormancy (late December-January) phases. Testes were incubated in media-199 for 2 h at 37 degrees C with luteinizing hormone (LH) and with or without melatonin. Melatonin had no effect on LH-induced testosterone (T) or androstenedione (A) production during the quiescent, recrudescent, and breeding phases. However, it significantly (P < 0.05) suppressed LH-induced T production but had no effect on A during winter dormancy. Testicular 17 beta-hydroxy steroid dehydrogenase (17 beta-HSD) activity was then measured in the testes from bats trapped during quiescence, breeding, and winter dormancy. Interestingly, melatonin along with LH caused suppression of 17 beta-HSD activities (3.56 +/- 0.03 unit/min/mg protein) when compared with levels of LH treated testes (7.10 +/- 1.15 unit/min/mg protein) during winter dormancy, while it had no significant effect on 17 beta-HSD activity during quiescence and breeding phases. These results suggest that in S. heathi, melatonin during winter dormancy suppresses LH-induced T production by the testes via the suppression of 17 beta-HSD activity. This may be the reason for the decline in testicular activity during winter dormancy.
authors: Department of Zoology, Banaras Hindu University, Varanasi, India.
authors: K
authors: K
authors: Singh
authors: A
authors: A
authors: Krishna
mesh_terms: D015067:17-Hydroxysteroid Dehydrogenases / Q000187:drug effects / Q000378:metabolism; D000735:Androstenedione / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D000818:Animals; D002685:Chiroptera; D007986:Luteinizing Hormone / Q000494:pharmacology; D008297:Male; D008550:Melatonin / Q000494:pharmacology*; D012098:Reproduction; D012621:Seasons; D013737:Testis / Q000187:drug effects* / Q000378:metabolism; D013739:Testosterone / Q000037:antagonists & inhibitors / Q000096:biosynthesis*
chemical_list: D013739:Testosterone; D000735:Androstenedione; D007986:Luteinizing Hormone; D015067:17-Hydroxysteroid Dehydrogenases; D008550:Melatonin