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.