EFFECTS OF CHRONIC PARENTERAL PYRIDOXINE AND ACUTE ENTERIC TRYPTOPHANON PYRIDOXINE STATUS, GLYCEMIA AND INSULINEMIA STIMULATED BY ENTERIC GLUCOSE IN WEANLING PIGLETS

In order to investigate the importance of the relation between pyridox ine and tryptophan on glucose tolerance and insulin response to glucos e, 12 Large White x Pietrain piglets (males and females), weaned at 3 wk of age, were allocated to two treatment groups. Within each of the six pairs (four females and two males), one piglet received daily 3 mt i.m. of pyridoxine.HCl (5 g L-1) and the other received a control inj ection of saline. The animals were fed a liquid feed through a gastric tube surgically inserted on the day of weaning. Seven days later, one catheter was placed in the duodenum and another in the jugular vein. One week after recovery, the piglets received an intraduodenal infusio n of glucose or glucose + tryptophan; 2 d later, each piglet received the opposite treatment. There was no effect (P > 0.18) of the administ ration of pyridoxine.HCl on plasma pyridoxal and pyridoxal-5-phosphate . Whatever the pyridoxine treatment, the plasma glucose response was l ower (P less than or equal to 0.05) after the glucose + tryptophan inf usion than after the glucose infusion. There was, also, an interaction between parenteral pyridoxine and duodenal infusion on changes in pla sma insulin concentrations following the duodenal infusion (P less tha n or equal to 0.02). The greatest response, observed in piglets supple mented with pyridoxine.HCl and infused with glucose, was 55% higher th an for the three other treatments. Further work is needed for an event ual reliable estimate of the pyridoxine status and requirements of wea nling piglets. The tryptophan and pyridoxine effects on insulin metabo lism suggest a different action of these nutrients on sensitivity and release of insulin.