Influence of Pseudopregnancy and Sex Hormones on Conditioned Behaviour in Rats

Progesterone, in conjunction with oestrogen, appeared to be responsible for the behavioural deteriorations in the female rats, but was ineffective in the males; and endogenous augmentation of the luteal hormones by prolactin administration in another group produced effects that were comparable to those seen in PSP, although quantitatively poorer.

Abstract

Performance of a prelearned conditioned avoidance response (CAR) showed gross deterioration in albino female rats during pregnancy and pseudopregnancy (PSP). To create a PSP-like condition, progesterone and oestradiol were given exogenously, singly and in combination, to different groups of rats. Progesterone alone caused a partial deterioration of behaviour; but when administered in combination with oestradiol, it produced effects on the CAR performance and body weight comparable to those observed in PSP. There was also a good correlation between the behavioural deficits and weight gains resulting from such treatment. Endogenous augmentation of the luteal hormones by prolactin administration in another group produced effects that were comparable to those seen in PSP, although quantitatively poorer. Progesterone, in conjunction with oestrogen, appeared to be responsible for the behavioural deteriorations in the female rats, but was ineffective in the males.