Estrous Cycle-Dependent Expression of Nucleobindin-2/Nesfatin-1 in the Porcine Hypothalamus: Colocalization with GnRH and Kisspeptin

Nesfatin-1, an 82-amino-acid anorexigenic peptide derived from nucleobindin-2 (NUCB2), is involved in the regulation of energy homeostasis and is increasingly recognized as a modulator of reproductive function. The present study aimed to determine NUCB2 gene and protein expression in the porcine hypothalamus, examine their colocalization with gonadotropin-releasing hormone (GnRH) and kisspeptin (KISS1), and evaluate circulating nesfatin-1 levels during the estrous cycle. Analyses were performed in two hypothalamic regions: the mediobasal hypothalamus (MBH) and preoptic area (POA) collected during the cycle. In the MBH, NUCB2 gene expression was lower on days 17–19 than on the remaining examined days, whereas NUCB2 protein abundance was highest on days 2–3. In the POA, NUCB2 mRNA expression peaked on days 14–16, while the protein abundance was higher on days 10–12 than on days 14–16. In both hypothalamic regions, NUCB2/nesfatin-1 immunoreactivity overlapped with GnRH and KISS1 immunosignals. In addition, plasma nesfatin-1 concentrations were lower on days 17–19 than during the other examined stages of the cycle. Overall, these findings demonstrate cycle-dependent, region-specific expression of NUCB2/nesfatin-1 in the porcine hypothalamus and support a potential association of nesfatin-1 with hypothalamic pathways involved in reproductive regulation.