7433 Distribution of Kisspeptin Neurons in the Adult Sheep Amygdala

Abstract Disclosure: A. Igler: None. R. Amodei: None. C.E. Roselli: None. Kisspeptin (Kiss1) neurons are primarily recognized for their role in regulating reproductive function by stimulating the release of hormones that control puberty and fertility. While these neurons are more commonly associated with the hypothalamus, recent research has suggested their presence in other brain regions, including the amygdala. The amygdala, a complex brain structure integral to emotional processing and social behaviors, encompasses various nuclei, yet the specific distribution and potential functional implications of Kiss1 neurons within this region remain to be elucidated. Studies in rodent models have indicated the presence of Kiss1-expressing neurons in the posterodorsal medial nucleus of the amygdala and implicated them in the modulation of sexual partner preference and anxiety in male mice. Understanding the distribution of Kiss1 neurons in the sheep amygdala could provide valuable insights into the potential roles of Kiss1 in modulating not only reproductive functions but also emotional and social behaviors in a species more closely related to humans. In this study, RNAscope® was performed to survey the distribution pattern of Kiss1 neurons within various nuclei of the amygdala in the adult sheep brain. In addition, duplex RNAscope® was used to examine co-localization of Kiss1 with estrogen receptor-α (ESR1) mRNA. We found widespread distribution of Kiss1 neurons within the major nuclei of the amygdala in adult male and luteal-phase female sheep. The density of Kiss1 neurons was highest in the cortical nucleus and ventral portion of the basal nucleus. Intermediate densities were observed in the medial, basal and lateral nuclei, while the lowest density was found in the central nucleus. There was extensive co-expression of Kiss1 and ERα mRNA throughout the amygdala. In the medial nucleus where co-localization was quantified, approximately 80% of Kiss1 neurons co-expressed ESR1; whereas only about 60% of ESR1 neurons co-expressed Kiss1. Notably, immunofluorescence histochemistry using antibody #AC564 (from A. Caraty) revealed that kisspeptin fibers were concentrated in the medial nucleus and sparsely distributed throughout other nuclei. These results are the first to establish a map of Kiss1-expressing neurons in different subregions of the amygdala, which provides a useful foundation for investigations into their potential involvement in the neurobiological mechanisms underpinning emotional processing, social and sexual behaviors. Supported by NIH Grant OD11047 to CER. Presentation: 6/3/2024