Socio‐sexual behaviours in rats after neonatal and adult β‐endorphin treatment

This study is concerned with the influence of neuropeptides, in particular β‐endorphin (β‐END), on behaviour. Neuropeptides participate in the chemical transmission of the central nervous communication processes. The effects of β‐END on socio‐sexual behaviours were examined in laboratory rats. The methodological approach was based on a multivariate analysis. β‐END was found to change the socio‐sexual behaviour profile in a way indicating that the subject may have difficulties in interpreting incoming information. The effects of neonatal administration of β‐END on the adult performance of sexual behaviour are also described. Early exposure to β‐END altered the response to β‐END in the adult individual. A working hypothesis is proposed that the behaviour in the adult may to a certain extent be conditioned during sensitive periods of pre‐adult development by environmental stimuli releasing endogenous neurohormones.