Distribution of the pig gastrin-releasing peptide receptor and the effect of GRP on porcine Leydig cells

Evidence Showing Bombesin-Like Peptides Contract Guinea Pig Vas Deferens Smooth Muscle

In this study, we investigated (1) the functional role of large-conductance Ca2+-activated K+ (BKCa) channels in the regulation of guinea pig vas deferens smooth muscle (VDSM) contractions and (2) the potential contractile effects of 33 physiologically active substances and related chemicals that have not been previously reported to contract VDSM. Iberiotoxin (an inhibitor of BKCa channels, 10-7 M) was the most potent enhancer of both noradrenaline (10-5 M)- and ATP (10-6 M)-induced contractions among the 6 types of K+ channel inhibitors. In addition, BKCa channel mRNA expression was the highest among the 32 types of K+ channel mRNAs. Iberiotoxin also enhanced the contractions induced by acetylcholine (10-6 M), histamine (5 × 10-5 M), bradykinin (10-6 M), neurokinin A (10-6 M), neurokinin B (10-6 M), and substance P (10-6 M). In the 33 tested physiologically active substances and related chemicals (15 peptides, 5 amino acids and their derivatives, 11 prostanoid- and isoprostane-related drugs, 1 endocannabinoid, and 1 phospholipid), we found that 3 bombesin-like peptides, neuromedin B (NMB) (10-6 M), gastrin-releasing peptide (GRP, 10-8 M), and NMC (10-6 M), contracted VDSM in the absence of iberiotoxin, and these contractions were strongly enhanced in the presence of iberiotoxin. Among the 3 bombesin receptor subtypes, the mRNA expression level of Grpr (BB2 receptor) was the highest. These findings suggest that (1) BKCa channels are the most powerful negative regulator of VDSM contractility and (2) NMB, GRP, and NMC are physiologically active substances that contract VDSM.

GRPR down-regulation inhibits spermatogenesis through Ca2+ mediated by PLCβ/IP3R signaling pathway in long-term formaldehyde-exposed rats

Formaldehyde (FA), which is known as an air pollutant, has been proven to induce male infertility. However, the underlying mechanism of FA-induced male infertility remains elusive. In this study, 24 male SD rats were exposed to different levels of FA (0, 0.5, 2.46, and 5 mg/m3) for eight consecutive weeks. Through HE staining and sperm smear, we observed that FA exposure resulted in spermatogenic injury and the sperm quality decreased in rats. The qRT-PCR and Western blot analysis further revealed that GRPR was down-regulated in testicular tissues of FA-exposed rats as well as primary spermatogenic cells. Meanwhile, ZDOCK uncovered an interaction between GRPR and PLCβ. In addition, the CCK8, Fluo 3-AM and Flow cytometry results showed that FA exposure suppressed the expression of GRPR, PLCβ and IP3R, consequently reducing the Ca2+ concentration in spermatogenic cells, inducing apoptosis and inhibiting proliferation of spermatogenic cells. Moreover, rescue experiments confirmed that promoting GRPR could improve intracellular Ca2+ concentration by upregulating PLCβ and IP3R, partially reducing the apoptosis and promoting the proliferation of FA-treated spermatogenic cells. These findings revealed that GRPR participates in spermatogenesis through Ca2+ mediated by the PLCβ/IP3R signaling pathway in FA-exposed rats.

Identification of Selection Signals on the X-Chromosome in East Adriatic Sheep: A New Complementary Approach

Sheep are one of the most important livestock species in Croatia, found mainly in the Mediterranean coastal and mountainous regions along the East Adriatic coast, well adapted to the environment and mostly kept extensively. Our main objective was therefore to map the positive selection of the X-chromosome (18,983 SNPs that passed quality control), since nothing is known about the adaptation genes on this chromosome for any of the breeds from the Balkan cluster. Analyses were performed on a sample of eight native Croatian breeds (101 females and 100 males) representing the East Adriatic metapopulation and on 10 mouflons (five females and males), all sampled in Croatia. Three classical within-population approaches (extreme Runs of Homozygosity islands, integrated Haplotype Score, and number of Segregating Sites by Length) were applied along with our new approach called Haplotype Richness Drop (HRiD), which uses only the information contained in male haplotypes. We have also shown that phylogenetic analyses, such as the Median-joining network, can provide additional information when performed with the selection signals identified by HRiD. Our new approach identifies positive selection signals by searching for genomic regions that exhibit a sudden decline in haplotype richness. In total, we identified 14 positive selection signals, 11 using the classical approach and three using the HRiD approach, all together containing 34 annotated genes. The most reliable selection signal was mapped by all four approaches in the same region, overlapping between 13.17 and 13.60 Mb, and assigned to the CA5B, ZRSR2, AP1S2, and GRPR genes. High repeatability (86%) of results was observed, as 12 identified selection signals were also confirmed in other studies with sheep. HRiD offers an interesting possibility to be used complementary to other approaches or when only males are genotyped, which is often the case in genomic breeding value estimations. These results highlight the importance of the X-chromosome in the adaptive architecture of domestic ruminants, while our novel HRiD approach opens new possibilities for research.

Neuromedin B regulates steroidogenesis, cell viability and apoptosis in rabbit Leydig cells

Mammalian bombesin-related peptide, neuromedin B (NMB) action is mediated by its receptor (NMBR), and NMB/NMBR system plays a major role in regulating hormone secretions, reproduction and cell growth. Here we report the functions of NMB in regulating steroidogenesis (testosterone synthesis), cell viability and apoptosis. The primary rabbit Leydig cells were employed as the paradigm for this research. We initially confirmed that NMBR is distributed in Leydig cells of rabbit testis, and a certain dose of NMB could increase the secretion of testosterone in primary cultured rabbit Leydig cells. Subsequently, the accumulated NMBR, StAR, CYP11A1, 3β-HSD and PKC protein could be induced by a certain dose of NMB in Leydig cells. Moreover, we found that NMB could decrease the cell viability, and decreased the expression of PCNA protein in Leydig cells; meanwhile, except for 100 nM, other doses of NMB could suppress the cell apoptosis, and regulate Caspase-3 protein expression in Leydig cells, respectively. These results identify that NMB may be a key factor in regulating testosterone synthesis through taking part in NMBR/PKC/steroidogenesis signaling pathway, as well as the cell viability and proliferation in rabbit Leydig cells.