Different behavioral, neural and neuropeptide responses of fathers to their own and to alien pups in mandarin voles.

Mothers often prefer to care for their own offspring rather than those of other females. However, whether fathers respond differently to their own pups and to alien ones remains unclear. In this study, we found that male mandarin voles (Microtus mandarinus) directed more sniffing toward their own pups than toward alien pups. The numbers of Fos-immunoreactive neurons in the medial preoptic nucleus, bed nucleus of the stria terminalis, nucleus accumbens, anterior cingulate cortex were significantly increased when fathers were exposed to an alien pups; however, more brain regions such as paraventricular nucleus, hypothalamic supraoptic nucleus, lateral habenula, ventral lateral septal nucleus, and medial amygdaloid nucleus showed increased number of Fos-immunoreactive neurons activated when the fathers were exposed to their own pups. Exposure to their own pups also induced a greater number of Fos-immunoreactive neurons in the anterior cingulate cortex, paraventricular nucleus, hypothalamic supraoptic nucleus, lateral habenula, ventral lateral septal nucleus and medial amygdaloid nucleus, as well as higher expression of oxytocin and vasopressin in the paraventricular nucleus, compared with exposure to alien pups. Our results indicated that fathers demonstrated different behavioral and neural responses to their own and to alien pups.