Role of oxytocin in mate-choice copying of female rats

Abstract

Mate-choice copying occurs when animals made decisions based on the mate choice of the conspecifics. Mate copying in rats is currently understudied. Past studies in oxytocin-knockout mice suggested the involvement of oxytocin, but the neurobiological mechanisms underlying mate choice have not been fully elucidated. Building on this, we investigated if female rats in oestrous exhibit mate-choice copying and whether oxytocin plays a role. The rats were injected with oxytocin (1 mg/kg), a cocktail of oxytocin (1 mg/kg) and its antagonist L-368,899 hydrochloride (5 mg/kg), or saline as control. We observed that both oxytocin and its antagonist reduced mate-choice copying instead of enhancing it. Furthermore, these treatments resulted in sedated behaviour up to 1h after injection. Locomotor activity recovered 24h post-injection. On the other hand, control rats showed mate-choice copying and no loss of locomotor activity. However, any learned mate choices did not seem to be strong enough to induce short- (30 min) and long-term (24h) memory. This might be due to a lack of information provided to the observer rat. To fill the gap in the proximate mechanisms behind Toxoplasma infections in female rats, the behaviours of oxytocin-treated and Toxoplasma-infected rats were compared. Toxoplasma infection leaves mate-choice copying behaviours intact and unchanged in female rats. Strangely, cat odour aversion was not observed in all tested rats (oxytocin-treated, Toxoplasma-infected, and their controls). The current findings suggest a possible role for oxytocin in mate-choice copying, but further investigation is required.