Endocrine Abstracts

In microsmatic animals, the olfactory cues initiate wide variety of neuroendocrine and behavioural responses. These behaviours are under the influence of sex hormones however some neuropeptide plays pivotal role. Oxytocin is involved in various social behaviours in mammalian species. However, oxytocin-deficient (OTKO) mice successfully accomplish reproduction although females cannot rear their pups because of lack of lactation. Though oxytocin is not essential for sexual behaviour, it is still possible to have some role in mating interaction. In this study, we employed alternate choice paradigm to assess odour preference to investigate the sociosexual behaviour in two experimental paradigms; social approaching to sexual partner odour evaluated by an alternate choice paradigm, and direct social interaction in the semi-natural environment using OTKO mice of both sexes to determine the functional significance of oxytocin. In preference test, experimental mice were given a choice of two airborne odours derived from active male and estrus female, or active male and castrated male. The odours were presented by airflow through air-inlets on walls of the preference test apparatus, and time spent nose-poking into the inlet was recorded for 5 min to determine olfactory preference. Wild-type mice significantly preferred sexually active opposite-sex odour to the others, whereas OTKO mice showed vigorous but indifferent nose-poking to any odours. Following odour preference, the OTKO and wild-type mice were placed with an opposite-sex individual in the semi-natural environment, and social interactions were tested. OTKO mice required significantly longer time to accomplish sexual behaviour. We concluded that oxytocin plays an important role in regulation of sexual behaviour, especially in a component of olfaction-related behaviour, in both male and female mice.