Influence of cortisol on osmoregulation and energy metabolism in gilthead seabream Sparus aurata

Abstract

Gilthead seabream Sparus aurata were injected intraperitoneally with slow-release implants of coconut oil alone or containing cortisol (50 and 100 microg x g(-1) body weight), and sampled after two, five, and seven days to assess the simultaneous effects of cortisol on both osmoregulation and energy metabolism. Plasma cortisol levels increased in treated fish to 50-70 ng x ml(-1). An enhanced hypoosmoregulatory capacity of cortisol-implanted fish is suggested by the increase observed in gill Na+, K+-ATPase activity, and the decrease observed in plasma ion concentration (Na+ and Cl-) and osmolality. Cortisol also elicited metabolic changes in liver (increased gluconeogenic potential suggested by elevated FBPase activity, and decreased potential of glycolysis and pentose-phosphate shunt, suggested by the decreased activities of both PK and G6PDH) supporting changes in levels of plasma metabolites suitable for use in other tissues. Thus in this study, we demonstrate for the first time in fish that cortisol treatments elicit changes in the use of exogenous glucose in gills (decreased HK activity) and an increased glycolytic and glycogenic potential in brain (increased GPase, PK and PFK activities).

Effects of cortisol and thyroid hormone on peripheral outer ring deiodination and osmoregulatory parameters in the Senegalese sole (Solea senegalensis)

“…In addition to its glucocorticoid actions, the role of cortisol as a mineralocorticoid is obvious in S. senegalensis, as cortisolinjected animals showed lowered plasma Na C and Cl K levels and increased Na C , K C -ATPase activities in gills and kidney 3 days after injection. These results agree with the classical osmoregulatory role of cortisol in teleosts (Seidelin et al 1999, Laiz-Carrión et al 2003, Sherwani & Parwez 2008.…”

“…The use of coconut oil as a vehicle for i.p. hormonal implants has been shown to be an effective and practical method to raise plasma cortisol or thyroid hormone levels in different teleost species (Laiz-Carrión et al 2003, Morgado et al 2007. Nine fish did not receive any treatment and served as the pre-injection group.…”

Chronic cortisol and the regulation of food intake and the endocrine growth axis in rainbow trout

“…The reduction in liver and muscle lipid content in the cortisol-treated fish is consistent with the increased lypolytic capacity of chronically stressed fish (Mommsen et al 1999). Cortisol may deplete lipid reverses in fish by increasing the activity of various lipases (Sheridan 1986, Baltzegar et al 2014) and glycerol utilization (Vijayan et al 1991), and by reducing the lipogenic potential of the liver (Vijayan et al 1990, Laiz-Carrió n et al 2003, Ló pez-Patino et al 2014. Moreover, given the known lipolytic properties of GH in the liver (Björnsson et al 2002), our results suggest that cortisol may also promote lipolysis via its stimulatory effects on liver ghr2 expression.…”

“…However, whether cortisol has a direct glycolytic effect on the liver is equivocal. Previous studies in fish have shown that cortisol exposure can increase, decrease, or have no effect on liver glycogen content and there is generally no consensus as to the role of cortisol in liver glycogen metabolism (Mommsen et al 1999, De Boeck et al 2001, Laiz-Carrió n et al 2003. In tilapia (O. mossambicus), while injections of both cortisol and leptin increase plasma glucose levels, only leptin decreases liver glycogen content (Baltzegar et al 2014).…”

The co-existence of two growth hormone receptors in teleost fish and their differential signal transduction, tissue distribution and hormonal regulation of expression in seabream

“…In the present study, cortisol was found to upregulate sbGHR1 expression but not sbGHR2 in black seabream. It has been reported recently that cortisol could elicit metabolic changes in seabream liver by decreasing the glucose-6-phosphate dehydrogenase (G6PDH) activity (Laiz-Carrion et al 2003). The enhanced expression of sbGHR1 by cortisol might provide a possible explanation for this report since GH has been shown to reduce hepatic G6PDH activity in fish (Leena et al 1999).…”