DISTURBED SMALL-INTESTINAL MOTILITY IN THE LATE RAT PREGNANCY

We investigated whether various periods of pregnancy might disturb rat gastrointestinal motility. When the proestrus of female rats occurred , they were housed with male rats. Motility studies were conducted on day 7 (first period), day 14 (second) and day 21 (third) of pregnancy, respectively. After the orogastric feeding of radiochromium marker, r ats were sacrificed 15 min later. Gastric emptyings of pregnant rats m easured at various periods did not differ from the nonpregnant diestru s controls. The geometric center represented intestinal transits in th e first, second and third periods of pregnancy and controls were (mean +/- SEM) 4.54 +/- 0.25, 4.47 +/- 0.17, 3.61 +/- 0.27 and 4.98 +/- 0.1 3, respectively (p < 0.01) while their plasma progesterone levels were 15.6 +/- 2.6, 18 +/- 1.4, 7.1 +/- 0.5 and 8.6 +/- 0.4 ng/ml, respecti vely (p < 0.01). This shows that late pregnancy inhibits small intesti nal transit, whereas gastric emptying remains unchanged. Altered proge sterone during pregnancy is not a main mediator to disturb intestinal transit.