Maintenance of Atlantic salmon (Salmo salar) at elevated temperature inhibits cytochrome P450 aromatase activity in isolated ovarian follicles

Abstract

Atlantic salmon (Salmo salar) broodstock were transferred from natural (12-16 o C) to controlled temperatures of 14, 18 or 22 o C for 3 months during vitellogenesis. Fertility and survival were significantly reduced in eggs from broodstock held at 22 o C relative to 14 or 18 o C. Endocrine mechanisms were disrupted after only one month at 22 o C, as evidenced by decreased plasma vitellogenin (Vtg) and increased plasma testosterone (T) levels and, at later stages, decreased levels of plasma 17β-estradiol (E 2 ) . In vitro incubations of isolated ovarian follicles were carried out at monthly intervals, with follicles exposed to human chorionic gonadotropin, N, 2-0-dibutyryladenosine 3,5-cyclic monophosphate, and the gonadal steroid precursors 17-hydroxyprogesterone, androstenedione and T. After one month of exposure to controlled temperature, T synthesis was generally enhanced in response to all treatments at all temperatures, but E 2 synthesis was inhibited at 22 o C, suggesting temperature impairment of cytochrome P450 aromatase (P450 arom ) synthesis or activity. The effect became less marked as follicles matured suggesting that temperature sensitivity is stage dependent. The results of this study suggest that the inhibitory effects of elevated temperature on E 2 and Vtg synthesis, and subsequent egg development found in the present and earlier studies, arise at least partly, from temperature modulation of P450 arom .

Evidence that elevated water temperature affects the reproductive physiology of the European bullhead Cottus gobio

“…If a significant temperature-time interaction effect was observed, different letters mean significant (P \ 0.05) differences between temperatures within a given sampling time follicles observed from January. In the Atlantic salmon Salmo salar, elevated temperatures impaired maturation, ovulation and subsequent fertility in females through the disruption of endocrine processes as shown by the altered levels of plasma 17b-estradiol, vitellogenin and testosterone (King et al 2003;Pankhurst and King 2010;Watts et al 2004).…”

Temperature is the evil twin: effects of increased temperature and ocean acidification on reproduction in a reef fish

“…Previous studies have shown that, under elevated temperatures, the enzyme CYP19 aromatase, which catalyzes the irreversible conversion of testosterone into E 2 , is inhibited (Watts et al 2004). First, elevated temperature resulted in a decrease in E 2 concentrations.…”

The importance of parentage in assessing temperature effects on fish early life history: a review of the experimental literature

“…This included examining temperature effects in relation to photothermal conditioning protocols for producing offspring out of season (Morrison and Smith 1986;Johnston et al 1992;Davies and Bromage 2002;Clark et al 2005;Van der Meeren and Ivannikov 2006), concerns for broodstocks at facilities in geographical locations with elevated ambient thermal profiles (Pankhurst et al 1996;Webb et al 1999Webb et al , 2001Watts et al 2004;Brown et al 2006;Pornsoping et al 2007) and strategies to mitigate temperature stress in broodstock (Dzikowski et al 2001;King and Pankhurst 2004b;Vikingstad et al 2008). Conversely, fewer studies were conducted to address temperature exposures in fish within an ecological or conservation context (Buckley et al 1990;Bonner et al 1998;Ouellet et al 2001;St Mary et al 2001;Hilder and Pankhurst 2003;Ito et al 2008).…”

“…Temperature can also act directly at the level of the oocyte. High temperatures have been shown to disrupt processes involved in final oocyte maturation (FOM) and inhibit ovulation in many individuals (Pankhurst et al 1996;Webb et al 2001;Watts et al 2004). Failure of adults to spawn as a result of experiencing suboptimal temperatures could alter the conspecific density of the surviving offspring.…”