Amylin-Calcitonin receptor signaling in the medial preoptic area mediates affiliative social behaviors in female mice.

Social animals actively engage in contact with conspecifics and experience stress upon isolation. However, the neural mechanisms coordinating the sensing and seeking of social contacts are unclear. Here we report that amylin-calcitonin receptor (Calcr) signaling in the medial preoptic area (MPOA) mediates affiliative social contacts among adult female mice. Isolation of females from free social interactions first induces active contact-seeking, then depressive-like behavior, concurrent with a loss of Amylin mRNA expression in the MPOA. Reunion with peers induces physical contacts, activates both amylin- and Calcr-expressing neurons, and leads to a recovery of Amylin mRNA expression. Chemogenetic activation of amylin neurons increases and molecular knockdown of either amylin or Calcr attenuates contact-seeking behavior, respectively. Our data provide evidence in support of a previously postulated origin of social affiliation in mammals.

Calcitonin receptor signaling in the medial preoptic area enables risk-taking maternal care.

Maternal mammals exhibit heightened motivation to care for offspring, but the underlying neuromolecular mechanisms have yet to be clarified. Here, we report that the calcitonin receptor (Calcr) and its ligand amylin are expressed in distinct neuronal populations in the medial preoptic area (MPOA) and are upregulated in mothers. Calcr+ MPOA neurons activated by parental care project to somatomotor and monoaminergic brainstem nuclei. Retrograde monosynaptic tracing reveals that significant modification of afferents to Calcr+ neurons occurs in mothers. Knockdown of either Calcr or amylin gene expression hampers risk-taking maternal care, and specific silencing of Calcr+ MPOA neurons inhibits nurturing behaviors, while pharmacogenetic activation prevents infanticide in virgin males. These data indicate that Calcr+ MPOA neurons are required for both maternal and allomaternal nurturing behaviors and that upregulation of amylin-Calcr signaling in the MPOA at least partially mediates risk-taking maternal care, possibly via modified connectomics of Calcr+ neurons postpartum.

Functional, anatomical, and neurochemical differentiation of medial preoptic area subregions in relation to maternal behavior in the mouse.

In rodents, previous findings indicate critical involvement of the medial preoptic area (MPOA) in the neural control of maternal behavior. However, the specification of the particular MPOA subregions involved in maternal behavior and the identification of the neurochemical phenotype(s) of the essential neurons demands additional study. Therefore, we investigated the chemical neuroanatomy of the essential MPOA subregion for maternal behavior in C57BL/6J female mice. Using the oxytocinergic neurons in the dorsal MPOA as a primary regional marker, we first assessed the distribution of c-Fos-expressing neurons in the MPOA during maternal behavior using immunohistochemistry. Results showed that non-oxytocinergic neurons in the dorsal and ventral MPOA prominently expressed c-Fos during maternal behavior. Then using excitotoxic lesion studies, we determined the specific MPOA area that is necessary for maternal behavior. Bilateral lesions of the central MPOA, where c-Fos was expressed only moderately, effectively disrupted maternal behavior, although lesions to the dorsal and ventral MPOA regions were ineffective. These centrally lesioned females were highly infanticidal irrespective of their previous maternal experience. Neurochemical investigations showed that more than 75% of the c-Fos-expressing neurons in central MPOA were GABAergic. Many of them also expressed galanin, neurotensin, and/or tachykinin2 mRNAs. Finally, the central MPOA was populated by numerous glutamatergic neurons, although only a small percentage of these neurons colocalized with c-Fos. To conclude, the central MPOA is the indispensable subregion for mouse maternal behavior, and GABAergic and/or peptidergic neurons in this area were transcriptionally activated during maternal behavior.