O0092 PSYCHOLOGICAL STRESS ALTERS GLUCOSE ABSORPTION IN RAT JEJUNUM

Abstract

Introduction: Humans frequently react to chronic stress with decreased appetite and loss of body weight. In our experiments, we have repeatedly observed that rats exposed to chronic psychological stress fail to gain weight in spite of normal food intake. We hypothesized that nutrient absorption may be impaired by psychological stress, explaining the reduced weight gain. This study was designed to investigate glucose absorption in rats submitted to different periods of water avoidance stress (WAS). Methods: Rats were subjected to WAS (1 h/day) for 1, 5 or 10 consecutives days. Body weight and food intake were recorded daily before and during the stress period. Four hours after the last WAS session, rats were sacrificed and segments of jejunum mounted in Ussing chambers to study the flux of glucose (using 3H-3-o-methylglucose) and SGLT-1 kinetics. Mucosa was obtained to prepare brush border membrane (BBM) vesicles, used to measure 14C-fructose uptake as well as SGLT-1 and GLUT2 expression by Western blots. Results: Net absorptive flux (Jnet) of glucose decreased with the duration of the stress procedure, due to both a decrease in Jm-s and an increase in Js-m (Table). The decrease in Jm-s was paralleled by a decrease of Vmax of SGLT-1. The increase in Js-m could not be accounted for by an increase in paracellular permeability since the conductance (G) was not altered by stress. On the other hand, we observed a time-dependent increase in phloretin-sensitive uptake of 14C-fructose by BBM vesicles of rats after 1, 5 or 10 days of WAS, which was not present in control animals. This suggested the presence of GLUT2, a transporter able to transport glucose or fructose in both directions, in the BBM. Western blots confirmed the increase in GLUT2 expression in the BBM after 1, 5 and 10 days of WAS.Table 1Conclusion: Psychological stress induces a decrease in the absorption of glucose in the jejunum of rats resulting from a concomitant decrease in SGLT-1 activity and an increase in GLUT2 expression in the enterocyte apical membrane. Glucose malab-sorption may explain the growth arrest observed in rats under stress. In addition, altered mucosal metabolism may be involved in the stress-induced changes in mucosal barrier function.