Heat stress increases apical glucose transport in the chicken jejunum.
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 1) control ad libitum (CAL), fed ad libitum and in thermoneutral conditions (20 degrees C); 2) heat stress ad libitum (HSAL), fed ad libitum and kept in a heated environment (30 degrees C); and 3) 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 sodium-dependent glucose transporter 1 (SGLT-1) were increased by approximately 50% in the HSAL chickens, without effects in the CPF group. No changes in K(d) or in SGLT-1 and glucose transporter-2 K(m) 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 SGLT-1 expression to heat stress and is not due to reduced food intake.
Garriga
Carles
C
Departament de Fisiologia, Facultat de Farmàcia, Av. de Joan XXIII s/n, 08028 Barcelona, Spain.
Hunter
Richard R
RR
Amat
Concepció
C
Planas
Joana M
JM
Mitchell
Malcolm A
MA
Moretó
Miquel
M
D000222:Adaptation, Physiological; D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D002645:Chickens; D005247:Feeding Behavior; D005786:Gene Expression Regulation; D005947:Glucose / Q000378:metabolism*; D051273:Glucose Transporter Type 2 / Q000378:metabolism; D018882:Heat Stress Disorders / Q000503:physiopathology*; D007583:Jejunum / Q000166:cytology / Q000378:metabolism*; D008297:Male; D008871:Microvilli / Q000648:ultrastructure; D051269:Sodium-Glucose Transporter 1 / Q000235:genetics / Q000378:metabolism
D051273:Glucose Transporter Type 2; D051269:Sodium-Glucose Transporter 1; D005947:Glucose