Role of neurokinin B in ovine puberty.

Puberty is the process whereby an individual acquires the ability to reproduce, and the attainment of puberty in a timely manner is critical for both humans and livestock. For livestock, the initiation of puberty at the appropriate time aids in increasing lifetime productivity, thus maximizing profitability for producers. For humans, particularly females, early or late puberty is associated with several adverse health outcomes, including polycystic ovary syndrome, obesity, metabolic syndrome, osteoporosis, and psychosocial distress. Therefore, characterizing the mechanisms responsible for puberty onset would have a significant impact on human and animal health. It has been postulated that a group of neurons in the arcuate nucleus of the hypothalamus may play a role in puberty onset. These neurons contain kisspeptin, neurokinin B (NKB), and dynorphin and are often called KNDy neurons. Although the role of kisspeptin in puberty onset has been heavily researched, the involvement of NKB and dynorphin is not well defined. This mini-review focuses on the role of NKB in the initiation of puberty in female sheep. Stimulation of the receptor for NKB, NK3R, elicits LH secretion in a GnRH-dependent manner in prepubertal ewes, and both functional and neuroanatomical changes to the NKB system, particularly within the preoptic area, appear to occur as female sheep transition from a prepubertal to an adult state. Thus, NKB is likely an important component of puberty onset in sheep, although its integration with other systems that impact the pubertal process, such as photoperiod and nutrition, remains to be elucidated.