Neurons co-expressing kisspeptin
neurokinin B (NKB)
and dynorphin in the hypothalamic arcuate nucleus
named KNDy neurons
are directly affected by sex hormones
and are well known for regulating the secretion of gonadotropin-releasing hormone. However
recent studies have shown that KNDy neurons also project and terminate to tuberoinfundibular dopaminergic (TIDA) neurons
suggesting a role in prolactin secretion. Moreover
there is a possibility that other neurosecretory dopaminergic neurons regulating prolactin secretion
such as periventricular hypophyseal dopaminergic (PHDA) neurons
may also be innervated by KNDy neurons. In the present study
by means of double immunohistochemistry and retrograde neural tracer
we examined whether KNDy neurons project directly to PHDA neurons that project to blood vessels
as well as to TIDA neurons. The results revealed that KNDy neurons are widely projecting to neurosecretory dopaminergic neurons of the PHDA and TIDA neurons in rats and mice. Secondary
presence of a major receptor for NKB
neurokinin-3 receptor (NK3R)
in PHDA and TIDA neurons was examined and it appeared that most TIDA and PHDA neurons possess NK3R. These findings indicate that
in rodents
KNDy neurons widely project to neurosecretory dopaminergic neurons distributed in the hypothalamus
and may affect them via the NKB-NK3R signaling pathway. (C) 2014 Elsevier Ireland Ltd and the Japan Neuroscience Society. All rights reserved.
