The effects of estrogen on the intestinal nutrient uptake in channel catfish



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Texas Tech University


Over the past two decades, a number of researchers have found that the gastrointestinal absorption of a diverse group of sugars, amino acids and ions can be modulated by the actions of specific hormones. Because steroids have also been found to increase the growth and food conversion efficiency in animals, interest in this area has grown. In this study, both the in-vitro (short-term) and in-vivo (long-term) effects of estrogen (E2) were studied on the intestinal transport of channel catfish. In conjunction with this overall experimental objective, a number of related projects ensued. The first of these, the discovery of putative Eo receptors (ER) in catfish intestine by immunocytochemistry, prompted the initial study of the effects of Ej on intestinal transport. Secondly, nutrient transport was characterized by assessing any differences seen between sexes using the everted sleeve technique. A tissue viability smdy was also performed to examine how long intestinal tissue remained viable in the in-vitro test system. Since catfish in this study varied in age from young (< 1 year) to three years of age, seasonal and developmental changes in the transport of the amino acid of interest, L-alanine, were followed. The results indicate that short-term (min-to-hours) and long-term (hours-todays) E2 treatments regulate nutrient uptake of the amino acid, L-alanine, in specific gut regions. Taken together, all the results indicate that age, endogenous E2 levels and E2 receptor expression may interact to determine E2's regulation of the channel catfish intestinal transport.



Channel catfish, Biological transport, Estrogen, Intestinal absorption