Abstract:
:Kisspeptin is a potent regulator of the hypothalamo-pituitary-gonadal axis. The activation of several vernal and pubertal behaviors involves the action of locally synthesized estradiol by hypothalamic aromatase-expressing neurons. Little is known about kisspeptin in non-mammalian systems, and its interaction with aromatase remains unexamined. The Mallard drake is a seasonal breeder and an excellent model for studying the neural mechanisms that regulate the HPG. The goals of these studies were to determine (a) if and how kisspeptin regulates the drake HPG, (b) if kisspeptin and aromatase are expressed in the Mallard brain, and (c) if kisspeptin is co-localized or in apposition with, aromatase- and gonadotropin hormone releasing hormone (GnRH) positive neurons. Central kisspeptin administration increased plasma luteinizing hormone, an effect blocked by pretreatment with the GnRH antagonist, acyline, suggesting a conservation of kisspeptin function and mechanism of action in birds and mammals. The distribution of kisspeptin in the mallard brain was examined with immunocytochemistry (ICC). Neurons that express kisspeptin-like immunoreactive (ir) protein were observed in the medial preoptic nucleus (POM) and in ir fibers throughout the drake brain. Virtually all POM kisspeptin-ir soma also expressed aromatase-ir, suggesting that autocrine mechanisms may predominate in the interaction between steroid provision and kisspeptin expression. No co-localization was observed between KP-ir and GnRH-ir, although both were easily detected in close-proximity in the tuberoinfundibular area. Taken together, these data suggest that in the drake, estradiol synthesized by aromatase and kisspeptin co-expressing POM neurons may regulate the HPG via an effect on GnRH secretion.
journal_name
Gen Comp Endocrinoljournal_title
General and comparative endocrinologyauthors
Saldanha CJ,Walters BJ,Fraley GSdoi
10.1016/j.ygcen.2010.01.007subject
Has Abstractpub_date
2010-05-01 00:00:00pages
606-13issue
3eissn
0016-6480issn
1095-6840pii
S0016-6480(10)00010-9journal_volume
166pub_type
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