Effects of food restriction on glucose tolerance, insulin secretion, and islet-cell proliferation in pregnant rats

Pregnancy is associated with increased glucose-stimulated insulin secretion and increased pancreatic is in-cell proliferation. In the present study it was investigated whether increased food intake, as occurs during pregnancy , Is Involved in the regulation of these phenomena. From Day 0 of pregnancy , rats received each day the mean amount of food they consumed daily during the estrous cycle prior to conception. This food restriction regime result ed in lower maternal body weight, and in lower fetal weight on Day 20 of ge station, but did not affect fetal survival. Food-restricted rats showed dec reased insulin responses to an i.v. glucose challenge on Day 13, and lower islet-cell replication rates on Day 14 of pregnancy than pregnant rats fed ad lib. Plasma lactogenic activity in food-restricted animals was increased on Days 11 and 13; plasma progesterone levels were unchanged, but plasma l eptin concentrations declined progressively during food restriction. Glucos e tolerance was normal, suggesting that food restriction improved insulin a ction. On Day 20 of pregnancy, insulin responses were similar in food restr icted and ad lib-fed rats; glucose tolerance was Still unchanged. It thus s eems that the improved insulin action as present on Day 13 had disappeared on Day 20. Also on Day 20, lactogenic activity as well as progesterone conc entrations were similar in food-restricted and ad lib-fed rats. It was conc luded that increased food intake plays an important role in the stimulation of islet-cell proliferation and insulin secretion, as well as in the dimin ished insulin action during the second week of rat pregnancy. (C) 1999 Else vier Science Inc.