Influence of temperature regime on endocrine parameters and vitellogenesis during experimental maturation of European eel (Anguilla anguilla) females

We examined the effect of temperature in European silver eels during their maturation induced by injections of carp pituitary extract on endocrine parameters: pituitary fsh beta and lh beta expression, plasma 17 beta-estradiol (E2) and vitellogenin, estrogen receptor 1 (esr1), and vitellogenin 2 (vtg2) expression in liver. A variable thermal regime (T10) that increased from 10 degrees to 14 degrees and 17 degrees C was compared with a constant 20 degrees C regime (T20) during 12 weeks. T10 caused a faster development until week 8, higher fsh beta, lh beta, esr1 expression, and higher E2 levels. The results strongly suggest that T10 is inducing a higher endogenous FSH level which increases the E2 circulating level during vitellogenesis. A variable thermal regime induced an fsh beta expression and E2 profile in vitellogenic hormonally matured eel females that were more similar to the profile observed in other naturally maturing fish. (C) 2011 Elsevier Inc. All rights reserved.