Effect of cold exposure on testicular delta 5-3 beta and 17 beta hydroxysteroid dehydrogenase activities and plasma levels of testosterone in toad (Bufo melanostictus) in breeding and hibernating season: duration-dependent response.

The purpose of this study was to show the effect of cold exposure on testicular activities in breeding and hibernating seasons in the toad. Adult male toads were placed in a cold chamber in both breeding and hibernating seasons for periods of 7, 14 and 21 days. At the time of sacrifice on the 15th and 22nd days, cold-exposed animals showed a decrease in testicular weight, testicular delta 5-3 beta and 17 beta-hydroxysteroid dehydrogenase activities and low levels of plasma testosterone both in breeding and hibernating seasons. There was no significant alteration in the above mentioned steroidogenic enzymes and plasma levels of testosterone after 7 days of cold exposure, both in breeding and hibernating seasons in respect to the control animals. The results of our present experiment suggest that environmental cold is an important modulator of breeding activities in the male toad. It also indicates that the breeding and hibernating cycle in the toad (seasonal breeders) may be asynchronous to each other.