Expression patterns of GHRL, GHSR, LEP, LEPR, SST and CCK genes in the gastrointestinal tissues of Tibetan and Yorkshire pigs

Abstract

The aim was to characterize the expression patterns of several genes in the gastrointestinal tracts of Tibetan pigs (TP) and Yorkshire pigs (YP) and to explore their correlation with digestion and growth difference of the two breeds. The body weights and growth of YP and TP were studied at 6, 12 and 24 weeks of age, and their plasma levels of ghrelin (GHRL), leptin (LEP), somatostatin (SST) and cholecystokinin (CCK) were determined by enzyme linked immunosorbent assay (ELISA). Blood and gastrointestinal sections (stomach, duodenum, jejunum, ileum, caecum and colon) were collected and assayed for mRNA expression of the six genes (GHRL, ghrelin receptor (GHSR), LEP, leptin receptor (LEPR), SST and CCK) by reverse transcription-qPCR (RT-qPCR). TP generally had higher mRNA expressions of GHSR, LEP, LEPR, SST and CCK genes compared to YP, and expressed lower levels of the GHRL gene in most tissues of the digestive tract. In both breeds, plasma levels of the expressed proteins were more closely correlated with the feed intake and growth than with mRNA levels of the target genes. Our data indicate that TP possess special gene expression patterns in the gastrointestinal tract compared to YP, which is consistent with its unique feed intake and adaptation to harsh environment.

Expression of Genes Encoding Selected Orexigenic and Anorexigenic Peptides and Their Receptors in the Organs of the Gastrointestinal Tract of Calves and Adult Domestic Cattle (Bos taurus taurus)

“…This may seem a coincidence, as the GHSR encodes a receptor for ghrelin, which in turn acts in opposition to leptin encoded by the LEP. However, a study previously cited by us showed a similar pattern of GHSR and LEP gene expression in pigs [33]. As similar results were obtained in studies with two different species, this aspect needs to be carefully examined in future studies.…”

“…On the other hand, studies conducted on young Tibetan and Yorkshire pigs have revealed GHSR mRNA expression in all examined organs of the GIT, namely the stomach, small intestine, cecum, and colon. The highest expression levels have been found in the duodenum and jejunum [ 33 ]. The expression of GHSR has also been studied in rat and guinea pig GIT organs.…”

“…Despite setting a stricter-than-usual significance threshold, this might have influenced our statistical analysis. Nevertheless, a sample size of six or less per group has been previously used in the evaluation of mRNA expression of genes coding for GIT hormones in cattle [ 13 , 25 ], other ruminants [ 26 , 27 , 28 , 43 , 44 ], farm animals [ 30 , 33 ], and even laboratory animals [ 31 , 34 ]. Nonetheless, we believe that this limitation does not completely undermine the novelty of our study.…”

Association of ghrelin gene polymorphisms with slaughter traits in pig

“…This paved the way for the melanocortin pathway (appetite regulation pathway), which consists of the satiety signaling pathway (regulated mainly by LEP, LEPR and MC4R) and the appetite signaling pathway (regulated among others by GHRL) (Męczekalski et al 2008). Ghrelin is a 28-amino acid peptide, identified as an endogenous ligand for the growth hormone secretagogue receptor (GHS-R), and it was isolated from the stomach of rats, humans and pigs (Kojima et al, 1999;Takaya et al, 2000;Salfen et al, 2004;Sun et al, 2019). Ghrelin conducts its biological activity through interaction with its specific cell surface receptor (GHS-R), that belong to G protein-coupled receptors, and for which two subtypes have been described: GHS-R type 1a (functional) and GHS-R type1b (nonfunctional) (van der Lely et al, 2004).…”