Hormonal response of primary hepatocytes of the clawed toad, Xenopus laevis

Abstract

Freshly isolated hepatocytes of the clawed toad, Xenopus laevis, were cultured for at least 3 days. The viability of the cells was characterized using staining and biochemical methods. In particular, the glucose and glycogen balance was tested. After culture for 16-20 hrs, the cells were subjected to hormonal treatment. Both adrenaline and arginine vasotocin stimulated the release of glucose in a dose dependent manner. 10(-6) M concentrations were strongly effective. The determination of the glycogen balance made it clear that the glucose release is mainly due to glycogenolysis. Using receptor antagonists and agonists, it has been shown that the effect of adrenaline is clearly mediated by beta-type receptors. Arginine vasotocin stimulated glycogenolysis via a type of receptor which is similar to the V2-receptor of mammals. This means that cAMP is involved in the response to both types of hormones which is in contrast to that which is known about the effect of nonapeptides on the liver of mammals.

The effect of starvation and re-feeding on vasotocinergic and isotocinergic pathways in immature gilthead sea bream (Sparus aurata)

“…week (Martos-Sitcha et al, 2014b). AVP has been demonstrated to stimulate hepatic glycogenolysis in mammals (Smith et al, 2003), as has AVT in amphibians (Janssens et al, 1983;Ade et al, 1995) and fishes (Sangiao-Alvarellos et al, 2006). A similar effect has been previously suggested in S. aurata under different stress conditions (Martos-Sitcha et al, 2014a;Cádiz et al, 2015), and our results are consistent with the proposed metabolic role of AVT in the stimulation of glycogenolysis.…”

Cortisol modulates vasotocinergic and isotocinergic pathways in the gilthead sea bream (Sparus aurata, Linnaeus 1758)

“…Furthermore, it is known that glycogenolysis is stimulated in amphibian hepatocytes by AVT (Janssens et al, 1983;Ade et al, 1995) and in mammalian hepatocytes by AVP (Smith et al, 2003).…”

The role of central vasopressin V2 receptors in cardiovascular homeostasis

“…Belment je sa saradnicima pokazao da akutan stres izaziva povećanu koncentraciju mRNA vazotocina u hipotalamusu, kao i porast kortizola u plazmi ribe iverka, što ukazuje na ulogu vazotocina u odgovoru na stres (14). Vazotocin utiče na metabolizam indirektno preko hipotalamo-hipofizne osovine izazivajući sekreciju kortizola koji ubrzava metabolizam, i direktno stimulacijom glikogenolize u hepatocitima ribe (3). Izaziva porast arterijskog krvnog pritiska kod riba tako što smanjuje regionalni protok i distribuciju krvi u škrgama i krvnim sudovima ribe izazivajući vazokonstrikciju (14,132,208).…”

“…Protokol 5 osmišljen je da se izvrši morfološka karakterizacija paraventrikularnog jedra. U toku prethodnih eksperimentalnih protokola (1 -4) paralelno su vaĎeni mozgovi odgovarajućih kontrolnih ţivotinja (po tri mozga za svaki protokol; n = 12), postavljeni su u metalne kalupe za sečenje ovog materijala (brain matrix) i isečeni su uzorci mozga zapremine 5mm 3…”