title: Effect of dehydroepiandrosterone on pentose phosphate pathway activity in the rat colon.
abstract: 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 14CO2 from [1-14C] glucose in isolated rat colonocytes, and the production of hexose 6-phosphates from ribose 5-phosphate in rat colonic cytosols, respectively. 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. 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 microM dehydroepiandrosterone (DHEA). A similar degree of inhibition was seen with 10 mM butyrate (P < 0.05). In contrast, using colonic cytosols, both DHEA and butyrate had no effect on the maximal catalytic activity of the NOPP. 4. Intraperitoneal injection (i.p.) of DHEA in rats refed after a fast showed a significant increase in the maximal catalytic activity of the NOPP in the distal colon (46%; P < 0.05). A similar elevation in the maximal catalytic activity of the NOPP was seen in the distal colon of DHEA treated pair-fed rats (43%; P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Gastroenterology, Queen Elizabeth Hospital, Woodville, Australia.
authors.forename: R N
authors.initials: RN
authors.lastname: Butler
authors.forename: W J
authors.initials: WJ
authors.lastname: Butler
authors.forename: D
authors.initials: D
authors.lastname: Antoniou
authors.forename: V
authors.initials: V
authors.lastname: Pascoe
mesh_terms: D000818:Animals; D003106:Colon / Q000187:drug effects* / Q000378:metabolism; D003687:Dehydroepiandrosterone / Q000494:pharmacology*; D005260:Female; D010084:Oxidation-Reduction; D010427:Pentose Phosphate Pathway / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013217:Starvation
chemical_list: D003687:Dehydroepiandrosterone