In vivo recording from calcitonin receptor-expressing neurons in the medial preoptic area during affiliative social behaviors.

Social animals, including mice, are motivated to seek social contact and avoid being alone due to the benefit of the group living in survival and reproductive values. We have previously reported that pup exposure and co-housing with adult female mice can induce the expression of c-Fos in calcitonin receptor (Calcr) neurons located in the medial preoptic area (MPOA) of female mice. These neurons mediate maternal and social contact behaviors among adult virgin females. However, the correlation of the activity of MPOA^Calcr+ neurons with specific social behaviors remains unclear. In this study, we used in vivo fiber photometry to study MPOA^Calcr+ neuron activity during affiliative social behaviors. We found that MPOA^Calcr+ neurons are activated during proactive contact with adult female mice but not during passive contact, suggesting that motivation to seek social contacts is associated with the activation of these neurons. MPOA^Calcr+ neurons are not activated during contact with non-social objects, such as novel foods and nesting materials, supporting their specific involvement in social behavior. Furthermore, these neurons are more robustly activated during alloparental behaviors such as pup retrieval. Overall, this study demonstrates the involvement of MPOA^Calcr+ neurons in motivated social interactions with pups and peer females.