Effect of an increase in environmental temperature on testicular androgenesis and spermatogenesis in toad (Bufo melanostictus) during hibernating season

Abstract

Activities of key testicular androgenic enzymes [Δ 5, 3β-hydroxysteroid dehydrogenase (Δ 5, 3β-HSD) and 17β-hydroxysteroid dehydrogenase (17β-HSD)], plasma levels of testosterone, and testicular gametogenic activities were studied in heat-exposed adult male toads during hibernating season for two consecutive years. Exposure of toads to an elevated environmental temperature for 14 and 21 days resulted in significant elevation of testicular Δ 5, 3β-HSD and 17β-HSD activities, along with plasma levels of testosterone. Testicular gametogenic activity, by means of quantity of all stages of spermatogenic cycle, were elevated significantly at the same experimental schedule, but 7 days of heat exposure resulted in significant elevation only in stage IV. The results indicated that environmental temperature is an important modulator of breeding activities of male toads. It also demonstrated that testicular activities in seasonally breeding toads are probably not linked to hibernating cycle. © 2010 Wiley Periodicals, Inc.