Corticosterone and prolactin responses to repeated handling and transfer of male rats.

The changes of plasma corticosterone and prolactin levels have been studied in rats after single, repeated or cross exposition to the moderate stressors: handling and transfer. The diminution of corticosterone and prolactin response has been found after repeated handling, but not after repeated transfer. The corticosterone level was significantly elevated in both cross-transfer and cross-handling groups and plasma prolactin level was significantly higher in the cross-handling animals. Both hormones manifested a parallel reaction to stress, prolactin being more difficult to obtain diminution of the reaction, corticosterone being more adaptable to repeated stress. It is concluded that the cross-adaptation between used stressful stimuli apparently could not be demonstrated, but, in contrast, the organism adapted to one stimulus possesses a greater corticosterone and prolactin reaction when being exposed to the new stimuli.