Effects of hydrocortisone on the lymphoid organs of Rana temporaria.

In vivo and in vitro effects of hydrocortisone hemisuccinate (HC) on the lymphoid organs were studied in the European common frog Rana temporaria. Single HC injection at the dose of 0.5 mg/g body weight induced rapid but fully reversible changes in thymuses and jugular bodies while its effect on spleens was negligible. In vitro studies confirmed HC-sensitivity of thymuses and jugular bodies and relative HC-resistance of spleens of this species. In vitro exposition of thymic and jugular body cell suspensions to 0.25-1.00 mg/ml HC solution revealed a dose-dependent and time-dependent impairment of sample activities associated with massive cell death as judged by MTT reduction assay and Trypan blue uptake, respectively. Evolutionary implications of these results are discussed.