Effect of 16,16-dimethyl prostaglandin E2 on small intestinal mucosa in suckling rats

Suckling rats were treated every 8 h by intragastric instillation of 16,16-dimethyl prostaglandin E2 (PG) in a dose of 25 micrograms kg-1 (PG25), or 100 micrograms kg-1 (PG100), or saline from postnatal day 7-11. PG increased small intestinal villus length and crypt depth, most markedly in the duodenum, leading to a mucosal height of 543 +/- 24 microns after saline, 670 +/- 26 microns after PG25 and 823 +/- 40 microns after PG100. In the proximal small bowel, PG100 raised the mean activities of sucrase by 439%, maltase by 98%, trehalase by 584%, lactase by 58% and alkaline phosphatase by 76%. In the distal small intestine, only sucrase and trehalase activities were stimulated whereas other enzymes were depressed. PG25 caused similar but less pronounced changes of enzyme activities. Eight hours after both the last PG25 and the last PG100 dose, plasma gastrin and corticosterone levels were decreased while thyroxine remained unchanged. The effect of a single dose of 100 micrograms kg-1 PG or saline was also tested on 5- and 11-day-old rats; they were killed 16 h after PG administration. An increase in villus length occurred along the entire small intestine of rats treated on day 5, and also in the ileum of rats treated on day 11. In the proximal intestine, maltase and trehalase were stimulated after early and late treatment and, in addition, sucrase and lactase after late treatment. Serum corticosterone levels were found to be significantly higher 2-6 h after PG100 than in the controls and then decreased gradually.(ABSTRACT TRUNCATED AT 250 WORDS)