Effects of paternal deprivation on cocaine-induced behavioral response and hypothalamic oxytocin immunoreactivity and serum oxytocin level in female mandarin voles.

Early paternal behavior plays a critical role in behavioral development in monogamous species. The vast majority of laboratory studies investigating the influence of parental behavior on cocaine vulnerability focus on the effects of early maternal separation. However, comparable studies on whether early paternal deprivation influences cocaine-induced behavioral response are substantially lacking. Mandarin vole (Microtus mandarinus) is a monogamous rodent with high levels of paternal care. After mandarin vole pups were subjected to early paternal deprivation, acute cocaine- induced locomotion, anxiety- like behavior and social behavior were examined in 45day old female pups, while hypothalamic oxytocin immunoreactivity and serum oxytocin level were also assessed. We found that cocaine increased locomotion and decreased social investigation, contact behavior and serum oxytocin level regardless of paternal care. Cocaine increased anxiety levels and decreased oxytocin immunoreactive neurons of the paraventricular nuclei and supraoptic nuclei in the bi-parental care group, whilst there were no specific effects in the paternal deprivation group. These results indicate that paternal deprivation results in different behavioral response to acute cocaine exposure in adolescents, which may be in part associated with the alterations in oxytocin immunoreactivity and peripheral OT level.