Vasoactive intestinal peptide indirectly elicits pituitary LH secretion independent of GnRH in female zebrafish
Loading...
Author/Creator
Author/Creator ORCID
Date
2022-01-03
Type of Work
Department
Program
Citation of Original Publication
Sakura Tanaka, Nilli Zmora, Berta Levavi-Sivan, Yonathan Zohar, Vasoactive intestinal peptide indirectly elicits pituitary LH secretion independent of GnRH in female zebrafish, Endocrinology, 2022;, bqab264, https://doi.org/10.1210/endocr/bqab264
Rights
This is not the final published version.
Attribution-NonCommercial 4.0 International (CC BY-NC 4.0
Access to this item will begin on 1/3/23
Attribution-NonCommercial 4.0 International (CC BY-NC 4.0
Access to this item will begin on 1/3/23
Subjects
Abstract
Vasoactive intestinal peptide (Vip) regulates luteinizing hormone (LH) release through the
direct regulation of gonadotropin-releasing hormone (GnRH) neurons at the level of the brain in
female rodents. However, little is known regarding the roles of Vip in teleost reproduction. Although
GnRH is critical for fertility through the regulation of LH secretion in vertebrates, the exact role of the
hypophysiotropic GnRH (GnRH3) in zebrafish is unclear since GnRH3 null fish are reproductively
fertile. This phenomenon raises the possibility of a redundant regulatory pathway(s) for LH secretion
in zebrafish. Here, we demonstrate that VipA (homologues of mammalian Vip) both inhibits and
induces LH secretion in zebrafish. Despite the observation that VipA axons may reach the pituitary
proximal pars distalis including LH cells, pituitary incubation with VipA in vitro, and intraperitoneal
injection of VipA, did not induce LH secretion and lhβ mRNA expression in sexually mature females,
respectively. On the other hand, intracerebroventricular administration of VipA augmented plasma
LH levels in both wild type and gnrh3-/-
females at 1 hour post-treatment, with no observed changes in
pituitary GnRH2 and GnRH3 contents and gnrh3 mRNA levels in the brains. While VipA’s manner
of inhibition of LH secretion has yet to be explored, the stimulation seems to occur via a different
pathway than GnRH3, dopamine, and E2 in regulating LH secretion. The results indicate that VipA
induces LH release possibly by acting with or through a non-GnRH factor(s), providing proof for the
existence of functional redundancy of LH release in sexually mature female zebrafish.