Effects of exposure to pups on maternal behaviour, sexual behaviour and serum prolactin concentrations in male rats.

Male rats showed maternal behaviour within 72 h after the onset of continuous exposure to newborn rat pups. The latency of the behavioural response could be reduced by daily treatment with the dopamine receptor antagonist domperidone (2 X 2.5 mg/rat), which increased serum prolactin concentrations (241.4 +/- 26.5 (S.E.M.) micrograms/l) above those of vehicle-treated males exposed to pups (25.3 +/- 11.7 micrograms/l). Male rats did not respond to exposure to pups by secreting prolactin; keeping endogenous prolactin concentrations at a minimum (2.8 +/- 0.1 micrograms/l) by daily treatment with the dopamine receptor agonist bromocriptine (0.5 mg/rat) did not affect the behavioural response of male rats to newborn pups. Neither exposure to pups nor the modest hyperprolactinaemia induced by daily domperidone treatment affected the display of male sexual behaviour by male rats.