Effect of dehydroepiandrosterone on pentose phosphate pathway activity in the rat colon

1. 1. The effects of fasting and fasting followed by refeeding on the activities of the oxidative pentose pathway (OPP) and the non-oxidative pentose pathway (NOPP) were estimated by the rate of production of 14CO 2 from [l- 14C] glucose in isolated rat colonocytes, and the production of hexose 6-phosphates from ribose 5-phosphate in rat colonic cytosols, respectively. 2. 2. The OPP activity in colonocytes from rats in the fasted state was 50% lower when compared to colonocytes from rats refed after a fast. This indicated induction of the rate-limiting enzyme of the OPP, glucose 6-P dehydrogenase (G6-PDH) in the latter instance. No effect on the maximal catalytic activity of the enzymes of the NOPP was seen in colonocytes from rats refed after a fast compared with colonocytes from rats in the fasted state. 3. 3. Isolated colonocytes obtained from the distal colon of rats refed after a fast, showed a significant decrease (30%) in OPP activity when incubated with 50 μ M dehydroepiandrosterone (DHEA). A similar degree of inhibition was seen with 10 mM butyrate ( P