| PrefaceDavid Barker et al found that there was a relationship between low birth weight and the risk of chronic diseases in adults. From then on, epidemiologists had focused on the relationships between fetus growth and chronic diseases in adults. Foetus was living in the mother's womb during gestation, so the growth of fetus was completely depending on the nutrition provided by the mother. As the result, motherly nutrition and metabolism conditions had a direct impact on the foetal growth and development. If mother was hyperglycemia during gestation, there was inevitabl effect on the foetal growth and development in prenatal and postnatal. In our country, the incidence of diabetes and gestational diabetic mellitus both have higher values, which taking on ascending tendency year by year. In abroad, the studies of the gestational hyperglycemia focus on the teratism and macrosomia. The studies in our country focus on the bad perinatal outcomes. That the long-effect of mother hyperglycemia during gestation on the health of the postnatal offspring had few been reported. By setting up rat model of hyperglycemia during gestation, this study would observe the postnatal growth and development of offspring with mother hyperglycemia during gestation, and to provide theoretical basis for taking early interference methods.Materials and methods1. Materials(1) Animals: Wistar rats (♀36, 230～270g;♂18, 360～400g) were obtained from the experimental animals center of China Medical University.(2) Main reagents: streptozotocin, slip of papers for detecting plasma glucose, radioimmunoassy kits for detecting serum insulin.2. Methods(1) Setting up rat model of hyperglycemia during gestationBefore mating, the rats were maintained one week. Then female rats were made pregnant by controlled mating. The first day of gestation was estimated by the presence of spermatozoids in vaginal smears. Pregnant rats were housed individually in wood-chip bedded plastic cages at constant temperature (22±3℃) and humidity (45%～55%) with a 12-h light-dark cycle. They had free access to water and a commercial diet. Hyperglycemia was induced by intra-peritoneal injection of streptozotocin (40 mg/kg body weight) in 0.1 M citrate buffer, pH 4.5, on the fifth day of gestation. Seven pregnant dams were injected with citrate buffer alone as a control group. On days 13, 16 and 19 of gestation, maternal blood was collected for plasma glucose concentrations by cutting off the tip of the tail and squeezing it gently. Pregnant rats with plasma glucose levels above 5.55 mM were designated as hyperglycemic and were included in the study. Record the changes of maternal weights during gestation. The newborn rats were weighed weekly up to 12 weeks of age. The gender of pups was identified at 3 weeks by examining the external genitalia. Pups were weaned at 4 weeks of age. Male and female rats were separately housed.(2) Examining the physiological development indexes: ears stretching, teething, eyes opening(3) Examining the reflex development indexes: the escarpment evading reflex, the turning over reflex, the opposite geotaxis reflex(4) Examining the learning and memory ability: jump platform experiment(5) Samples collected①Blood samples: At 6 and 12 weeks of age, after overnight fasting, rats from each group were anesthetized with ethylether and then bled from the abdominal vein. Serum was obtained by high-speed centrifugation (3,000r/min, 20 min), then stored at -70℃. ②Tissue collection: These organs (livers, kidneys, cerebrum) were removed, washed with cold saline, quickly blotted, and weighed.(6) Indexes detected①The levels of fasting serum glucose were measured by ortho-toluidine method.②The levels of fasting serum insulin were measured by radioimmunoassay.(7) Statistical analysisResults are expressed as means±SEM. The significance of differences between experimental and control rats at each age was assessed by two tailed Student's t -test. The differences in the frequency of behavior indexes were assessed by X~2 analysis. Differences were considered significant at P<0.05.Results1. Setting up the rat models of hyperglycemia during gestation(1) The levels of maternal plasma glucoseOn days 13, 16 and 19 of gestation, the levels of plasma glucose in hyperglycemic group were higher than the control group (P<0.05).(2) Compared the maternal body weight on days of 1 of gestation, weight gains during gestation and the numbers of newborn ratsThere was no difference in maternal body weights on days 1 of gestation and the numbers of newborn rats between experimental and control groups. The maternal weight gains during gestation in experimental were lighter than the control rats (P<0.05).2. The effects of maternal hyperglycemia during gestation on thebody growth and development of offspring(1) The changes of the offspring body weight in both groupsFrom delivery to 12 weeks in postnatal, the body weights of pups were taking on ascending tendency in both groups. The body weight curve in experimental group was all along lower than the control group (P<0.05). (2) Compared the ratios (organs and body weight) of offspring in both groupsThere was no difference in the ratios (liver/body weight, kidney/body weight, cerebrum /body weight) between experimental and control group (P>0.05).3. The effects of maternal hyperglycemia during gestation on thedevelopment of centre nerves system of offspring(1) Compared the physiological and reflex development of offspring in bothgroupsThe experimental rats preformed worse than the control rats in the reflex ofturning over and the reflex of opposite geotaxis (P<0.05). There was no difference inother indexes between experimental and control group (P>0.05).(2) Compared the learning and memory ability of offspring in both groupsThe female offspring in experimental group performed worse than the controlfemale offspring (P<0.05), but there was no difference in memory capability betweenthe two groups (P>0.05). The male offspring had no difference in learning and memoryability in the two groups (P>0.05).4. The effects of maternal hyperglycemia during gestation on theglucose metabolism of offspring(1) Changes in serum glucose and insulin concentrationsAt 6 weeks of age, there was no difference in serum glucose and insulin concentrations between experimental and control group (P>0.05). At 12 weeks of age, the levels of serum glucose and insulin in experimental rats were higher than control rats (P<0.05).Conclusions1. Maternal hyperglycemia during gestation influenced the prenatal development of the offspring and leaded to low birth weight lasting to adulthood.2. Maternal hyperglycemia during gestation had bad effects on the reflex and learning ability of the offspring. But it had no effects on the physiological development of the offspring.3. The offspring with maternal hyperglycemia during gestation had abnormality glucose metabolism in adulthood. |
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