Submitted on June 2, 2005
Accepted on September 1, 2005
Heat stress increases apical glucose transport in the chicken jejunum
Carles Garriga1, Richard R Hunter2, Concepcio Amat1, Joana M Planas1, Malcolm A Mitchell2, and Miquel Moreto1*
1 Departament de Fisiologia, Facultat de Farmacia, Universitat de Barcelona, Barcelona, Spain
2 Division of Genetics and Genomics, Roslin Institute, Roslin, United Kingdom
* To whom correspondence should be addressed. E-mail: mmoreto{at}ub.edu.
In chickens, elevated environmental temperature reduces food intake. We have previously reported that during heat stress the intestinal mucosa has an increased capacity to take up sugars. To investigate whether the effects of warm environment on sugar uptake are an intestinal adaptation to lower energy intake or a response attributable to heat stress, we examined the glucose transport kinetics of apical and basolateral membranes of the jejunum and the mucosal morphology of broiler chickens maintained in climatic chambers for 2 wk. Experimental groups were: Control Ad Libitum (CAL), fed ad libitum and in thermoneutral conditions (20°C); Heat Stress Ad Libitum (HSAL), fed ad libitum and kept in a heated environment (30°C); and Control Pair-Fed (CPF), maintained in thermoneutral conditions and fed the same amount of food as that consumed by the HSAL group. Both the CPF and the HSAL groups showed reduced body weight gain, but only the HSAL chickens had lower plasma thyroid hormones and higher corticosterone than CAL and CPF groups. The fresh weight and length of the jejunum were only reduced in the HSAL group. The activity and expression of apical SGLT1 were increased by about 50% in the HSAL chickens, without effects in the CPF group. No changes in Kd or in SGLT1 and GLUT2 Km were observed in the pair-fed and heated birds. These results support the view that increased intestinal hexose transport capacity is entirely dependent on adaptations of apical SGLT1 expression to heat stress and is not due to reduced food intake.
