The effect of α-MSH treatment on the hypothalamic-pituitary-gonad axis in the cichlid fish Oreochromis mossambicus

Kumbar, Jyoti; Ganesh, C.B.

doi:10.1007/s10695-021-01005-9

Cited by 1 publication

(2 citation statements)

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“…However, we can unprecedentedly demonstrate that MTII, a chemical agonist of MSH peptides, severely inhibits hCG-induced E2 secretion in the ovary. Such results are well in agreement with those showing that α-MSH treatment provokes a reduction in the number of ovarian follicles while increasing the rate of follicular atresia in tilapia [ 60 ]. Treatment of follicles with melanocortin antagonist had contrasting effects.…”

Section: Discussionsupporting

confidence: 92%

“…The expression of all melanocortin receptors in zebrafish ovaries and testes suggests that MSHs peptides could also have a role in the regulation of the zebrafish gonadal function. In fact, recent studies have demonstrated that in vivo treatment of cichlid fish ( Oreochromis mossambicus ) with α-MSH produces a reduction in the number of previtellogenic and vitellogenic follicles, thus decreasing the gonadosomatic index and increasing the rate of follicular atresia [ 60 ]. The mechanism seems to involve a significant reduction of the luteinizing hormone (LH) secretion mediated by α-MSH effects on the hypothalamic gonadotropin-releasing hormone (GnRH).…”

Section: Discussionmentioning

confidence: 99%

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Role of the Melanocortin System in Gonadal Steroidogenesis of Zebrafish

Navarro

Crespo

Schulz

et al. 2022

Animals

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In teleost, as in other vertebrates, stress affects reproduction. A key component of the stress response is the pituitary secretion of the adrenocorticotropic hormone (ACTH), which binds to the melanocortin 2 receptor (MC2R) in the adrenal glands and activates cortisol biosynthesis. In zebrafish, Mc2r was identified in male and female gonads, while ACTH has been shown to have a physiological role in modulating reproductive activity. In this study, the hypothesis that other melanocortins may also affect how the zebrafish gonadal function is explored, specifically steroid biosynthesis, given the presence of members of the melanocortin signaling system in zebrafish gonads. Using cell culture, expression analysis, and cellular localization of gene expression, our new observations demonstrated that melanocortin receptors, accessory proteins, antagonists, and agonists are expressed in both the ovary and testis of zebrafish (n = 4 each sex). Moreover, melanocortin peptides modulate both basal and gonadotropin-stimulated steroid release from zebrafish gonads (n = 15 for males and n = 50 for females). In situ hybridization in ovaries (n = 3) of zebrafish showed mc1r and mc4r in follicular cells and adjacent to cortical alveoli in the ooplasm of previtellogenic and vitellogenic oocytes. In zebrafish testes (n = 3), mc4r and mc1r were detected exclusively in germ cells, specifically in spermatogonia and spermatocytes. Our results suggest that melanocortins are, directly or indirectly, involved in the endocrine control of vitellogenesis in females, through modulation of estradiol synthesis via autocrine or paracrine actions in zebrafish ovaries. Adult zebrafish testes were sensitive to low doses of ACTH, eliciting testosterone production, which indicates a potential role of this peptide as a paracrine regulator of testicular function.

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Section: Discussionsupporting

confidence: 92%

Section: Discussionmentioning

confidence: 99%