Effects of Adiponectin on Glucose Metabolism in the Hepatopancreas of Grass Carp (Ctenopharyngodon idella)

Abstract

Adiponectin plays critical roles in the regulation of energy metabolism in mammals. However, its roles in fish remain to be evaluated. In this study, we examined the tissue distribution characteristics of two adiponectin genes, namely, adipoqa and adipoqb, at transcriptional level, and detected the changes of their mRNA expressions during oral glucose tolerance test (OGTT). Furthermore, we prepared recombinant proteins of grass carp adiponectin A and adiponectin B and studied their roles in the regulation of glucose metabolism in the hepatopancreas of grass carp in vivo. The results showed that adipoqa mRNA was mainly expressed in the heart of grass carp, followed by red muscle, white muscle, and adipose tissue, while adipoqb mRNA was highly expressed in adipose tissue, red muscle, and white muscle. The mRNA levels of adipoqa and adipoqb in the white muscle and heart were significantly decreased at 1 h post OGTT, and their expressions in the heart were also suppressed at 3 h, whereas the transcriptional levels of adipoqa and adipoqb in the red muscle were elevated significantly at 12 h after glucose load. Intraperitoneal injection of adiponectin A or adiponectin B reduced basal serum glucose levels of grass carp and caused an increase of glycogen content in the hepatopancreas. Adiponectin A upregulated the expression of enzyme genes related to glycolysis (gk and pk) and glycogen synthesis (gys) in the hepatopancreas, and adiponectin B promoted the expression of pk and gys, as well as g6pase in the glycogenetic pathway. Besides, adiponectin A and adiponectin B have opposite regulatory effects on glut2 mRNA expression. These results suggested that adiponectin A and adiponectin B promoted glycolysis, gluconeogenesis, and glycogen synthesis, increased glycogen content of hepatopancreas, and reduced basal blood glucose level, and they may have an antagonistic regulatory mechanism in regulating glucose uptake.

Identification of Isthmin‐1 in common carp (Cyprinus carpio L.) and the effects on glucose metabolism in vivo and in vitro

“…Our study detected that Ism1 mRNA was highly expressed in the heart, gill, head, kidney, skin, and liver tissues of common carp. Similar to our results, Ism1 is expressed in various tissues of zebrafish as the report (Li et al, 2021) and grass carp (Yang et al, 2022). These results…”

“…The prokaryotic system is widely utilized for laboratory-scale production of recombinant protein (Chen, 2012). In fish, numerous recombinant products, such as Irisin and Adiponectin, have been cloned in fish, and their biological activities have been tested in vitro and in vivo (Yang et al, 2020(Yang et al, , 2021Qin et al, 2022). In this study, we successfully cloned the full-length ORF sequence of the common carp Ism1 gene.…”

Recent advances in the crosstalk between adipose, muscle and bone tissues in fish

“…This is the case of Nile tilapia ( Oreochromis niloticus ), black carp ( Mylopharyngodon piceus ), Japanese puffer ( Takifugu rubripes ), medaka ( Oryzias latipes ), three-spined stickleback ( Gasterosteus aculeatus ) and green spotted puffer ( Tetraodon nigroviridis ) ( 8 ). On the other hand, there are two isoforms of adiponectin genes, namely adipoqa and adipoqb , in cyprinid fishes, including grass carp ( Ctenopharyngodon idella ) ( 48 ) and zebrafish ( 44 ). For perciform fishes, only one adiponectin gene has been reported in the literature.…”

“…The highest expression level of adiponectin in ayu is found in the adipose tissue, as reported in mammals ( 49 ). In zebrafish, rainbow trout, large yellow croaker, common carp, and grass carp, the expression in the muscle is higher than that in the adipose tissue ( 5 , 8 , 44 , 45 , 47 , 48 ), but still remains to be evaluated whether this peptide could be also considered a myokine in these species. adiponectin is also expressed in other tissues, such as brain, liver, kidney or heart with variable levels depending on the species ( 8 ).…”

“…Regarding adiponectin receptors, and similarly to mammals, some fish species have two forms (AdipoR1 and AdipoR2), while zebrafish, grass carp and common carp have two isoforms of AdipoR1 besides AdipoR2 ( 44 , 47 , 48 ). The homologies with mammalian sequences are between 70 and 80%.…”