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Inhibitory effects of melatonin on testosterone but not on androstenedione production during winter in the vespertilionid bat, Scotophilus heathi
Author(s) -
Singh Kavita,
Krishna A.
Publication year - 1995
Publication title -
journal of pineal research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.881
H-Index - 131
eISSN - 1600-079X
pISSN - 0742-3098
DOI - 10.1111/j.1600-079x.1995.tb00181.x
Subject(s) - melatonin , androstenedione , dormancy , testosterone (patch) , biology , medicine , endocrinology , reproduction , luteinizing hormone , androgen , hormone , botany , ecology , germination
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°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 17β‐hydroxy steroid dehydrogenase (17β‐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 17β‐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 17β‐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 17β‐HSD activity. This may be the reason for the decline in testicular activity during winter dormancy.