Sexually dimorphic hypothalamic circuit for maternal behavior and oxytocin secretion
Parental care is a complex stereotypic behaviour toward offspring that is shared by numerous species. In mice, there are striking sex differences in offspring directed behavior. For example, nulliparous females (i.e. not having given birth) behave maternally toward alien pups while males will usually ignore the pups or attack them. Interestingly, Tali Kimchi’s group shows that tyrosine hydroxylase (TH)-expressing neurons in the anteroventral periventricular nucleus (AVPV) of the mouse hypothalamus are more numerous in mothers than in virgin females and males, and govern parental behaviours in a sex-specific manner. In females, ablating the AVPV TH+ neurons impaired maternal behaviour whereas optogenetic stimulation or increased TH expression in these cells enhance maternal care. In males, however, this same neuronal cluster has no effect on parental care but rather suppresses adult-directed aggression. Optogenetic activation or increased TH expression in the AVPV TH+ neurons of female mice increases circulating oxytocin, whereas their ablation reduces oxytocin levels. Using neuroanatomical tracing and optogenetic stimulation, we found that AVPV TH+ cells relay a monosynaptic input to oxytocin-expressing neurons in the paraventricular nucleus, suggesting an important role for this neuronal cluster in the control of maternal care and oxytocin secretion, and providing a causal relationship between sexual dimorphism in the adult brain and sex differences in parental behavior.
Note: This work was presented as poster but has already been published in Nature.
Source:
Scott et. al (2015). A sexually dimorphic hypothalamic circuit controls maternal care and oxytocin secretion. Nature 525(7570): 519-22.
