Neuromedin B and Its Receptor: Gene Cloning, Tissue Distribution and Expression Levels of the Reproductive Axis in Pigs

Abstract

Neuromedin B is one member of a family of bombesin-like peptides, which performs a variety of physiological functions via their receptor (NMBR) in most mammals. However, the genes encoding NMB and NMBR and their functions especially reproduction of the pigs are currently not fully understood. To research the physiological functions of NMB, we cloned and analyzed the NMB and NMBR genes, and systematically investigated the expression levels of NMB and NMBR mRNA using relative real-time PCR and the distribution of NMBR by immunohistochemistry (IHC). Experimental results show that the sequences of the amino acid and gene of NMB and NMBR were highly conservative and homology in many species, Significantly, the relative RT-PCR results revealed that NMB was mainly expressed in the central nervous system (CNS), whereas NMBR is highly expressed in peripheral tissues and organs, such as endocrine tissues, glands and reproductive organs. The IHC results show that NMBR positive cells were widely distributed in the body, such as respiratory and circulatory system, digestive system, urogenital system, in lymphatic organs and in the endocrine system. We also systematically investigated expression levels of NMB and NMBR in the reproductive axis using relative real-time PCR. In sow estrous cycle, the hypothalamic levels of both NMB and NMBR mRAN were similar, but the expression levels of the pituitary were negatively correlated. Expression levels in the ovarian system are lowest in metestrus phases and highest in proestrus and estrus phases. In boar post-natal development stages, the hypothalamic, pituitary and testicular levels of NMB and NMBR mRNAs showed developmental changes on postnatal day 30, 60, 90 and 120. Taken together, this study provided molecular and morphological data necessary for further research of physiological function of NMB/NMBR system in the pigs.

Characterization of NMB, GRP and their receptors (BRS3, NMBR and GRPR) in chickens

“…7). This finding is consistent with those reports in humans (Sano et al 2004), pigs (Ma et al 2016) and rats (Wada et al 1992), suggesting that cNMB may act as a neuropeptide to regulate some physiological processes, such as food intake, as demonstrated in chickens and mammals (Jensen et al 2008, Tachibana et al 2010a.…”

“…7). As in chickens, both NMB and NMBR are highly expressed in the testes of humans (Sano et al 2004), pigs (Ma et al 2016) and mice (Ohki-Hamazaki et al 1997a). These findings strongly suggest that NMB may act as an autocrine/paracrine factor to regulate the functions of testes in vertebrates.…”

Differential Regulation of Gonadotropins as Revealed by Transcriptomes of Distinct LH and FSH Cells of Fish Pituitary

“…In mammals, little is known regarding its activity. In the HPG axis, a recent study cloning NMB and its receptor in pigs reveals differential expression of NMB and NMBR during development and reproductive stages in the pituitary [ 118 ], connecting its activity to the HPG axis.…”

Neuropeptide Neuromedin B does not alter body weight and glucose homeostasis nor does it act as an insulin-releasing peptide

“…There were no apparent changes in glucose tolerance or insulin sensitivity in NestinCre-Nmb flox/flox mice fed standard diet (Figure 2D and E). As intestinal neurons can modulate systematic responses to glucose level changes and Nmb is expressed in intestinal neurons 16,17 , we also performed an oral glucose tolerance test (OGTT). Although we observed a mild defect in NestinCre-Nmb flox/flox mice, the effect was not significant when the areas under the curve were calculated and compared between the experimental cohorts (Figure 2F and G).…”

“…Neuromedin B receptor (NMBR) is a member of the G protein-coupled receptor (GPCR) family with broad expression in the CNS (caudate nucleus, amygdala, thalamus, hippocampus, brain stem, hypothalamus, spinal cord and olfactory region) as well as peripheral tissues such as testis, urogenital smooth muscles, gastrointestinal system, esophagus and adipose tissues 17 , suggesting that its activation upon NMB binding might regulate multiple physiological functions.…”