Effects of reproductive experience on paternal behavior, levels of testosterone, prolactin in serum and dendritic spines in medial prefrontal cortex of mandarin voles.

Maternal behaviors and brain change dramatically along with pregnancy, parturition and other mothering experience. However, whether paternal behavior, brain plasticity, levels of relevant hormones also change along with fathering experience and pups' age remains unclear. Using socially monogamous mandarin voles (Microtus mandarinus), we found that experienced fathers exhibited more active paternal behaviors such as licking, retrievals and nest building, but less paternal care such as huddling than new fathers. The high levels of licking and nest building appeared at earlier days of lactation of mate. Experienced fathers retrieved 9-13 old pups more frequently. However, these paternal behaviors did not show significant changes with age of pups in new fathers. In addition, experienced fathers had dramatically higher prolactin levels than new fathers, but had similar concentrations of testosterone with new fathers. New fathers had lower levels of testosterone, but higher levels of prolactin than new paired males. The fathers had higher prolactin levels at earlier days of lactation of mate. The new and experienced fathers have similar dendritic length, and spine density on pyramidal neurons in medial prefrontal cortex, but displayed higher levels than new paired males. Taken together, these results indicate that reduction of testosterone levels and increase of prolactin levels may be associated with initiation of paternal care. Fathering experience significantly affects levels of parental care and paternal behaviors to different ages of pups, and brain plasticity can also be enhanced by transition to fatherhood. This article is protected by copyright. All rights reserved.