Serum Progesterone and Immuno-Reactive Insulin Levels in the Pregnant Rat[*]

Abstract

Plasma glucose, progesterone and IRI levels were measured in a systematical study from day 10 to day 21 of gestation in pregnant rats. Plasma glucose, first stable, decreases before term and there is no parallelism between plasma glucose and IRI levels except at the end of gestation. If all the fetuses are removed at 17 days but the placentae left in utero, pregnancy continues and no decrease in glucose and IRI levels is observed before term. IRI and progesterone levels are higher at 10 days of gestation than in non-pregnant rats; thereafter they present grossly parallel evolutions with a peak on day 16 followed by a decrease until parturition. We thus postulate that progesterone might be a factor of resistance to insulin and that IRI levels in the pregnant rat are controlled by, at least, two factors, blood glucose and blood progesterone levels.

Key words

Gestation - Glucose - Progesterone - Insulin

1 These studies were presented in part at the Sixth Congress of the European Association for the Study of Diabetes, 23-27 September 1970 in Warsawa (Poland) and at the XXV International Congress of Physiological Sciences, 25-31 July 1971 in München (Germany).

1 These studies were presented in part at the Sixth Congress of the European Association for the Study of Diabetes, 23-27 September 1970 in Warsawa (Poland) and at the XXV International Congress of Physiological Sciences, 25-31 July 1971 in München (Germany).