Neonatal oxytocin exposure influences oestrous cycle, oestrogen receptor-alpha and oxytocin expression, and cocaine-induced behavioural responses in female mice

Abstract Accumulating evidence has shown that neonatal oxytocin (OT) exposure (NOE) influences the physiology and behaviour of offspring. The present study aimed to evaluate the impact of NOE on the oestrous cycle, central OT and oestrogen receptor-alpha (ER α ) expression, and cocaine-induced behavioural responses of adult female mice offspring. After receiving OT injections from postnatal day (PND) 4 to PND 10, the oestrous cycle and expression of OT- and ER α -immunoreactive (IR) neurons in specific brain regions of adult females during dioestrus were assessed, and acute cocaine-induced locomotion, anxiety levels, and social behaviour were examined. The data indicated that NOE prolonged oestrus, while OT-IR expression in the paraventricular nucleus, ER α -IR expression in the bed nucleus of the stria terminalis, medial preoptic area, arcuate nucleus, and ventromedial hypothalamic nucleus were increased. Moreover, NOE and cocaine had interaction effects on behavioural response. Compared to saline exposure, NOE resulted in greater locomotion and affiliative behaviour, and attenuated cocaine-induced locomotion rather than anxiety levels. These results indicate that NOE might affect oestrus cycles, enhance sociality in adulthood, and inhibit cocaine-induced motivity. Such effects may be associated with NOE-induced developmental changes in OT and ER α expression in relevant brain regions. This finding provides certain insights into mechanisms underlying the effects of NOE on cocaine-induced behavioural changes in female animals.