The study shows that the hormone‑like peptide kisspeptin and its partner neurokinin B, along with their receptors, are naturally present in the uterus, ovaries, and fallopian tubes of women, especially in the lining cells. This suggests they might help regulate local reproductive functions, but the research does not test any treatments or give dosing advice.

To investigate the presence of neurokinin B (NKB)/NK(3) receptor (NK(3)R) and kisspeptin/KISS1 receptor (KISS1R) messenger RNA (mRNA) and proteins throughout the human female genital tract. In vitro study. Academic research laboratories and academic hospitals. Fifteen reproductive-age women and 16 postmenopausal women provided fresh samples of uterus, ovary, or oviduct, and 12 women provided archival samples of endometrium or oviduct. Fresh and archival samples of uterus, ovary, and oviduct obtained from reproductive-age and postmenopausal women. Results of reverse-transcription polymerase chain reaction (RT-PCR) and immunohistochemistry to investigate the pattern of expression of NKB/NK(3)R and kisspeptin/KISS1R in target tissues. Expression of the genes encoding NKB (TAC3) and NK(3)R (TACR3), and kisspeptin (KISS1) and its receptor (KISS1R) was found in the uterus, ovary, and oviduct. Both NKB and NK(3)R immunoreactivity was detected in the endometrium, the oviduct, and the ovary, with marked expression in endometrial and oviductal epithelial cells, where intense coexpression of kisspeptin and KISS1R was also detected. Positive staining for NKB and NK(3)R was found in the myometrium where, in contrast, kisspeptin and KISS1R were absent. NKB/NK(3)R and kisspeptin/KISS1R are present in female peripheral reproductive tissues with colocalization of both systems in some non-neuronal cell populations of the human female genital tract. Our findings are compatible with a potential modulatory role of NKB and kisspeptin at peripheral reproductive tissues.