Nutritionally Responsive <scp>PMv DAT</scp> Neurons Are Dynamically Regulated During Pubertal Transition

Pubertal development is tightly regulated by energy balance. The crosstalk between metabolism and reproduction is orchestrated by complex neural networks, and leptin action in the hypothalamus plays a critical role. The ventral premammillary nucleus (PMv) leptin receptor (LepRb) neurons act as an essential relay for leptin action on reproduction. Here, we show that mouse PMv cells expressing the dopamine transporter (DAT) gene, Slc6a3 (PMv^DAT), form a novel subpopulation of LepRb neurons. Virtually, all PMv^DAT neurons expressed Lepr mRNA and responded to acute leptin treatment. Electrophysiological recordings from DAT^CRE; tdTomato mice showed that PMv^DAT cells in prepubertal females have a hyperpolarized resting membrane potential compared to diestrous females. Slc6a3 mRNA expression in the PMv was higher in prepubertal than in adult females. In prepubertal females, Slc6a3 mRNA expression was higher in overnourished females from small size litters than in controls. Prepubertal Lep^ob females showed decreased PMv Slc6a3 mRNA expression that recovered to control levels after 3 days of leptin injections. Using a tracer adenoassociated virus in the PMv of adult DAT^Cre; Kiss1^hrGFP females, we observed PMv^DAT projections in the anteroventral periventricular and periventricular nucleus (AVPV/PeN), surrounding Kiss1^hrGFP neurons, a population critical for sexual maturation and positive estrogen feedback in females. The DAT^CRE; tdTomato projections to the AVPV were denser in adult than in prepubertal females. In adults, they are in close apposition to tyrosine hydroxylase neurons. Overall, these findings suggest that the DAT expressing PMv^LepRb subpopulation play a role in leptin regulation of sexual maturation via actions on AVPV kisspeptin/tyrosine hydroxylase neuron.