GnIH plays a negative role in regulating GtH expression in the common carp, Cyprinus carpio L.

Abstract

a b s t r a c tIn birds and mammals, the gonadotrophin-inhibitory hormone (GnIH) effectively inhibits the expression of gonadotrophin (GtH). In teleosts, the effects of GnIH are still unclear and under much debate. The aim of this study is to evaluate the functions of GnIH/receptors of gonadotrophin-inhibitory hormone (GnIHRs) system during reproduction in the common carp, Cyprinus carpio L. We cloned the full cDNA sequences of GnIH /GnIHRs. Real-time PCR results showed that GnIH/GnIHRs were distributed extensively across the whole hypothalamus-pituitary-gonad (HPG) axis. We also examined the changes of GnIH/GnIHRs in the HPG axis during reproduction. GnIH mRNA expression was decreased to the minimum value in Apr, the spawning month, and increased immediately after the completion of reproduction. Expression pattern of GnIH during reproduction was the opposite to those of Gonadotrophin release hormone 3 (GnRH3) and luteinizing hormone (LH). Expression patterns of GnIHRs were similar to that of GnIH in the hypothalamus. In the pituitary, GnIHR2/3 peaked in March before spawning. In the ovaries, the GnIHR1 decreased to the minimum value in April, but GnIHR2/3 increased. By injection and incubation with synthesized GnIH-III peptide, we confirmed the negative influence of GnIH on mRNAs of the follicle-stimulating hormone-b and LH-b subunits in the common carp. These results show that the GnIH/GnIHRs system is involved in the negative regulation of reproduction in HPG axis of the common carp.

Seasonal Related Multifactorial Control of Pituitary Gonadotropin and Growth Hormone in Female Goldfish: Influences of Neuropeptides and Thyroid Hormone

“…GnIH inhibition of gonadotropin gene expression has also been shown in cinnamon clownfish (Amphiprion melanopus) (33). In common carp (Cyprinus carpio L.), GnIH treatment reduced FSH and LH subunits expression, and minimum GnIH transcript levels were observed in the hypothalamus during spawning season (78). In the cichlid fish (Cichlasoma dimerus), treatment with cd-LPQRF-1 inhibited FSH and LH release, while cd-LPQRF-2 stimulated FSH release in cultured pituitary cells (34).…”

Growth Hormone Overexpression Disrupts Reproductive Status Through Actions on Leptin

“…Increased expression of hypothalamic gnih was accompanied by increased gnihr in pituitary in GH-transgenic common carp. In reproductively active adult goldfish ( 53 ) and carp ( 54 ), GnIH-3 is a strong inhibitor of LH.…”

New techniques, applications and perspectives in neuropeptide research

“…After the organism has been exposed to the neuropeptide or changed condition, it can be euthanized and the tissues of interest collected for quantitative comparison (Abels et al, 2016). Alternatively, the tissue can be removed from the animal and incubated before analysis (Peng et al, 2016). Classically, this has been performed for individual proteins by western blotting, which is still widely reported in the current literature (Bayerl et al, 2016;Liu et al, 2016a).…”

“…Upon understanding the peptide changes, gene analysis can be conducted to help provide information about the global impact on the plasticity of the system. Although the specific neuropeptide, its propeptide and its pre-propeptide cannot be differentiated from each other at the transcript level, global gene analysis is most easily achieved by measuring the mRNA changes by using a quantitative real-time PCR (qPCR) technique (Caers et al, 2016;Peng et al, 2016). This approach differs from western blotting and ELISAs, the latter of which measures the translated peptide but does not require antibodies.…”