INFLUENCE OF GENDER, SEX HORMONES AND TEMPERATURE ON PLASMA IGF-I CONCENTRATIONS IN SUNSHINE BASS

Authors: Davis Jr, Kenneth; McEntire, Matthew - Matt

Submitted to: Proceedings of International Congress on Biology of Fishes
Publication Type: Proceedings
Publication Acceptance Date: 7/14/2006
Publication Date: 7/18/2006
Citation: Davis Jr, K.B., Mcentire, M.E. 2006. Influence of gender, sex hormones and temperature on Plasma IGF-I Concentrations in Sunshine Bass. Proceedings of International Congress on Biology of Fishes. p.43

Interpretive Summary:

Technical Abstract: Plasma insulin-like growth factor-I (IGF-I) concentrations in male and female sunshine bass were determined in March, early April and late April in outdoor ponds at a commercial farm. Growth and IGF-I concentrations in sunshine bass fed with estrogen, testosterone, methyl testosterone or a control diet were also determined. Female fish were always larger than male fish, however plasma IGF-I concentrations were always higher in male fish and increased as the pond temperature increased in both sexes. Gonadal development was largest in both sexes in March and declined to a regressed state by the end of April and the same pattern of change occurred with plasma estrogen and testosterone. Growth was reduced in fish fed all three sex hormones, although the effect of estrogen was the most pronounced. Fish fed the control diet had the highest IGF-I level, androgen fed fish had intermediate levels and estrogen fed fish had the lowest IGF-I concentration after 4 weeks on the diet. Plasma IGF-I concentrations appeared to respond to the increasing temperatures and were suppressed by sex hormones. Exogenous sex hormones caused a decrease in plasma IGF-I, feeding and growth. Plasma IGF-I concentrations do not appear to explain the sexually dimorphic growth in sunshine bass.