Increased lenticular aldose reductase activity and high incidence of congenital cataract in the offspring of diabetic rats

Maternal diabetes affects rat offspring retinal structure and function: Sex-specific vulnerabilities at infancy

AIMS

Maternal diabetes negatively impacts the offspring's brain, but little is known about its effects on the retina, which is also part of the central nervous system. We hypothesized that maternal diabetes adversely influences offspring retina development leading to structural and functional deficits.

MAIN METHODS

Retinal structure and function were evaluated at infancy, by optical coherence tomography and electroretinography, in male and female offspring of control, diabetic and diabetic-treated with insulin Wistar rats.

KEY FINDINGS

Maternal diabetes induced a delay in male and female offspring eye-opening, while insulin treatment expedited it. Structural analysis showed that maternal diabetes decreased the thickness of the inner and outer segment layer of photoreceptors in male offspring. Electroretinography also revealed that maternal diabetes decreased the amplitude of scotopic b-wave and flicker response in males, suggesting bipolar cells and cone photoreceptor dysfunction, an effect not observed in females. Conversely, maternal diabetes decreased cone arrestin protein levels in female retinas, while not affecting cone photoreceptor number. Dam insulin therapy was efficient in preventing the offspring photoreceptor changes.

SIGNIFICANCE

Our results suggest that photoreceptors are affected by maternal diabetes, which may account for visual impairments at infancy. Notably, both male and female offspring presented specific vulnerabilities to hyperglycemia in this sensitive period of development.

Brain damage and congenital cataract due to autogenously fecal peritonitis in pregnant Wistar rats

PURPOSE

To investigate the morphological aspects of brain and eyes in newborn rats whose mother underwent autogenously fecal peritonitis.

METHODS

Four pregnant rats that underwent fecal peritonitis, with a 10% fecal suspension in dose of 4 ml per kilogram received two antimicrobial treatments: 1. intraperitoneal moxifloxacin and dexamethazone; and 2. Intravenous meropenem. After head inspection, the brain consistencies and the eyes belonging to all offspring were analyzed.

RESULTS

The brains of newborn from rats that received 4 ml/kg of 10% suspension of feces showed, significantly smaller and less than the firm consistency of those in the control group. Congenital cataract was observed in 9 (34.6%). No cataract was observed in the 20 newborn rats from the mothers that received the combination of moxifloxacin and dexamethasone. Cataract could be observed in three (13.6%) offspring from mothers that received meropenem.

CONCLUSIONS

Peritonitis can produce brain damage and congenital cataract in rats. The translation to humans is that intra abdominal infection in pregnant women may be associated with damage in brain and eye structures of their concepts. This can be averting using the adequate early therapeutically approach.

Congenital malformations in experimental diabetic pregnancy: aetiology and antioxidative treatment. Minireview based on a doctoral thesis

Diabetes mellitus in pregnancy causes congenital malformations in the offspring. The aim of this work was to characterize biochemical and morphologic anomalies in the conceptus of an animal model of diabetic pregnancy. In addition, a preventive treatment against diabetes-induced dysmorphogenesis was developed. Congenital cataract was often found in the offspring of diabetic rats. The fetal lenses had increased water accumulation, sorbitol concentration and aldose reductase activity compared to control lenses. The results suggest that the cataracts form via osmotic attraction of water due to sorbitol accumulation in the fetal lens. Another set of malformations, with possible neural crest cell origin, occurred frequently in offspring of diabetic rats. These included low set ears, micrognathia, hypoplasia of the thymus, thyroid and parathyroid glands, as well as anomalies of the heart and great vessels. Furthermore, diabetes caused intrauterine death and resorptions more frequently in the late part of gestation. When the pregnant diabetic rats were treated with the antioxidants butylated hydroxytoluene, vitamin E or vitamin C, the occurrence of gross malformations was reduced from approximately 25% to less than 8%, and late resorptions from 17% to 7%. This suggests that an abnormal handling of reactive oxygen species (ROS) is involved in diabetes-induced dysmorphogenesis in vivo. Indeed, an increased concentration of lipid peroxides, indicating damage caused by ROS, was found in fetuses of diabetes rats. In addition, embryos of diabetic rats had low concentrations of the antioxidant vitamin E compared to control embryos. These biochemical alterations were normalized by vitamin E treatment of the pregnant diabetic rats. The antioxidants are likely to have prevented ROS injury in the embryos of the diabetic rats, in particular in the neural crest cells, thereby normalizing embryonic development. These results provide a rationale for developing new anti-teratogenic treatments for pregnant women with diabetes mellitus.

High glucose concentration inhibits migration of rat cranial neural crest cells in vitro

Cranial neural crest cells give rise to a large part of the facial structures, and disturbed development of these cells may therefore cause congenital malformations affecting the head and face. We studied the effects of increased glucose concentration on the migration and development of cranial neural crest cells, maintained in vitro for 48 h. Pre-migratory cranial neural crest cells were removed from embryos of normal and diabetic rats on gestational day 9. After 24 h in 10 mmol/l glucose the cells were exposed to glucose concentrations of 10, 30, or 50 mmol/l for another 24 h. The cultures were photographed at 24 h and 48 h in a phase-contrast microscope to evaluate cell morphology, cell number, and cell migration. Exposure to 50 mmol/l glucose reduced the total number of neural crest cells, their mean migratory distance and migratory area expansion compared to cells cultured in 10 mmol/l glucose. To investigate the effect of antioxidant agents, high glucose cultures were studied after addition of N-acetylcysteine (NAC), or superoxide dismutase (SOD). Addition of NAC diminished the inhibitory effect of high glucose, whereas SOD did not offer any improvement in cell development. Neural crest cell culture from embryos of diabetic rats showed reduced cell migration in vitro at all glucose concentrations compared to normal cells. In addition, the cells from embryos of diabetic rats showed reduced migratory area expansion after culture in the basal 10 mmol/l glucose concentration, indicating that maternal diabetes permanently influences the future development of premigratory cranial neural crest cells. These findings indicate that high glucose concentration inhibits cranial neural crest development in vitro, and that antioxidant therapy may diminish this inhibition. Free radical oxygen species may be involved in the induction of malformations and antioxidants may therefore have a role in future attempts to block the teratogenic effects of diabetic pregnancy.