Experimental Diabetes in Pregnant Mice: Prevention of Congenital Malformations in Offspring by Insulin

Abstract

The main purpose of these experiments was the prevention of congenital malformations in offspring of alloxan-diabetic mice by insulin injections administered during pregnancy. The optimum dose of insulin and timing of its administration are described for mice made hyperglycemic by injection of alloxan of 80 mg. per kilogram of body weight. Copulated female mice were given alloxan intravenously on the fourth day of gestation, followed by 0.4 units of Lente insulin every twelve hours beginning thirty to thirty-six hours after alloxan injection, and continuing until the sixteenth day of gestation. The control group was given only the alloxan injection on the fourth day of gestation. Pregnant mice were sacrificed on the nineteenth day of gestation; fetuses were removed by laparotomy and examined for external defects and skeletal deformities. In fifty successful pregnancies treated with insulin, only one fetus (0.2 per cent) of 472 was malformed with a cleft palate; in fifty successful pregnancies given alloxan alone fourteen or 28 per cent of mice had one or more malformed fetuses. Altogether, twenty-two or 5.0 per cent of 437 fetuses in the latter group had malformations which included craniorhachischisis (seven fetuses), cleft palate (six fetuses), club foot (five fetuses), spina bifida, anencephalus, open eye, microphthalmia and skeletal deformities in one or more fetuses. The difference between the alloxan group and insulin treated group in the number of mothers having malformed fetuses, and in the number of malformed fetuses produced was statistically significant according to the chi-square test with a probability level of less than 0.01. In the alloxan group, increased body weight associated with advancing pregnancy was less advanced in mice having malformed fetuses than in those having normal fetuses. The foregoing tendency was also statistically significant with a probability level less than 0.01. However, no appreciable correlation was observed between the magnitude of hyperglycemia of mother mice and the frequency of fetuses with congenital malformations.

Hyperglycemia‐induced TGFβ and fibronectin expression in embryonic mouse heart

“…Hyperglycemia due to chemically induced diabetes in pregnant rats produces offspring with brain and heart abnormalities similar to those seen in humans (Eriksson, 1984). The incidence of these defects is normalized by insulin treatment (Horii et al, 1966), supporting the role of hyperglycemia in their pathogenesis. In vitro rodent models, using culture medium supplemented with excess glucose, produce concentrationand time-dependent increases in embryonic defects (Cockroft and Coppola, 1977;Sadler, 1980;Garnham et al, 1993).…”

Hyperglycemia-induced teratogenesis is mediated by a functional deficiency of arachidonic acid.

“…Previous studies in this area have been largely descriptive in nature, serving to define the period of embryonic vulnerability (8,9,17), the protective effects of insulin therapy (8,9,18,19), and the possible teratogenic role of other elements of the disturbed metabolic milieu of the diabetic pregnancy [the "fuel-mediated" hypothesis of Freinkel and co-workers (1) and the studies of Horton and Sadler using elevated concentrations of ketone bodies (20)]. The data presented in this paper provide evidence that the mechanism by which elevated levels of glucose cause teratogenic effects is mediated by a functional deficiency of arachidonic acid at a critical period of organ differentiation.…”

Embryotoxic effects of brief maternal insulin-hypoglycemia during organogenesis in the rat.

“…Although poorly controlled maternal diabetes has been linked to birth defects in offspring both clinically (45)(46)(47) and experimentally (48)(49)(50), the extent to which metabolic control must be improved to mitigate this teratogenesis has not been determined. Miller et al (46) and Ylinen et al (47) failed to detect an increased incidence of birth defects in infants whose mothers had mildly elevated hemoglobin Al, levels near the end of the first trimester of pregnancy (up to 8.5% ofthe total hemoglobin in the former study and up to 7.3% in the latter); the risk ofbirth defects was increased in association with higher glycohemoglobin levels in both studies.…”