Impaired prenatal development and glycemic status in the offspring of rats with experimental streptozotocin-induced diabetes and their correction with afobazole

Construction of the experimental rat model of gestational diabetes

Objective

Numerous methods for modeling gestational diabetes mellitus (GDM) in rats exist. However, their repeatability and stability are unclear. This study aimed to compare the effects of high-fat and high-sugar (HFHS) diet, HFHS diet combined with streptozotocin (STZ) administration, and HFHS diet combined with movement restriction (MR) modeling methods on rat models to confirm the best method for constructing a rat model of GDM.

Method

Forty female Sprague-Dawley rats were randomly divided into four groups (n = 10): the normal control (NC), HFHS, HFHS+STZ, and HFHS+MR groups. The rats in the NC group were fed with a standard diet, and those in the remaining groups were fed with a HFHS diet. The rats in the HFHS+STZ group received 25 mg/kg STZ on their first day of pregnancy, and those in the HFHS+MR group were subjected to MR during pregnancy. Bodyweight, food intake, water intake, fasting blood glucose (FBG), fasting insulin (FINS), homeostasis model assessment of insulin resistance (HOMA-IR), homeostasis model assessment of insulin sensitivity (HOMA-IS), homeostasis model assessment of β-cell function, pancreatic and placental morphology, and the expression levels of glucose transporter 1 (GLUT1) and glucose transporter 3 (GLUT3) in placentas were then quantified. Moreover, iTRAQ was used to identify placental proteomics.

Results

During pregnancy, the rats in the HFHS+STZ group showed FBG levels that were kept stable in a state of moderate hyperglycemia; the typical GDM symptoms of polydipsia, polyphagia, polyuria, and increased body weight; and the modeling rate of 87.5%. On the first and 19th days of pregnancy, the rats in the HFHS group showed higher FBG than that of the NC group, increasing body weight and food intake and the modeling rate of 50%. On the 19th day of pregnancy, the FBG of the rats in the HFHS+MR group was higher than that of the rats in the NC group, and the modeling rate of 42.9%. Comparison with the NC group revealed that the three modeling groups exhibited increased FINS and HOMA-IR, decreased HOMA-IS, and different degrees of pathological changes in pancreases and placentas. Among the groups, the HFHS+STZ group displayed the greatest changes with significant reductions in the numbers of pancreatic and placental cells and appeared cavitation. The expression levels of GLUT1 and GLUT3 in the placentas of the HFHS+STZ and HFHS+MR groups were higher than those in the placentas of the NC and HFHS groups. The above results indicated that the rats in the HFHS+STZ group showed the best performance in terms of modeling indicators. After the changes in placental proteomics in the HFHS+STZ group were compared with those in the NC group, we found that in the HFHS+STZ group, five proteins were up-regulated and 18 were down-regulated; these proteins were enriched in estrogen signaling pathways.

Conclusion

HFHS combined with the intraperitoneal injection of 25 mg/kg STZ was the best modeling method for the nonspontaneous model of experimentally induced GDM, and its modeling rate was high. The pathological characteristics of the constructed GDM rat model were similar to those of human patients with GDM. Moreover, the model was stable and reliable. The modeling method can provide a basis for constructing a GDM rat model for subsequent research on the prevention and treatment of GDM.

Neuroprotective substances: are they able to protect the pancreatic beta-cells too?

BACKGROUND

Growing evidences demonstrate a close relationship between type 2 diabetes (T2D) and neurodegenerative disorders such as Alzheimer's disease. The similarity of physiological and pathological processes, occurring in pancreatic β-cells and neurons over the course of these pathologies, allows to raise the question of the practicability of studying neuroprotective substances for their potential antidiabetic activity.

OBJECTIVE

This review analyzes studies of antidiabetic and cytoprotective action on pancreatic β-cells of the neuroprotective compounds that can attenuate the oxidative stress and enhance the expression of neurotrophins: low-molecular-weight NGF mimetic compound GK-2, selective anxiolytic afobazole, antidepressants lithium chloride and lithium carbonate on the rat streptozotocin model of T2D.

RESULTS

It was found that all above-listed neuroprotective substances have a pronounced antidiabetic activity. The decrease in the β-cells number, the average area of the pancreatic islets, as well as the violation of their morphological structure caused by the streptozotocin was significantly weakened by the therapy with the investigated neuroprotective substances. The extent of these morphological changes clearly correlates with the antihyperglycemic effect of these compounds.

CONCLUSION

The presented data indicate that the neuroprotective substances attenuating the damaging effect of oxidative stress and neurotrophins deficit cannot only protect neurons but also exert their cytoprotective effect towards pancreatic β-cells. These data may provide a theoretical basis for the further study of neuroprotective drugs as potential therapeutic options for T2D prevention and treatment.

Intranasal insulin reverts central pathology and cognitive impairment in diabetic mother offspring

Background

Adverse effects in diabetic mothers offspring (DMO) are a major concern of increasing incidence. Among these, chronic central complications in DMO remain poorly understood, and in extreme cases, diabetes can essentially function as a gestational brain insult. Nevertheless, therapeutic alternatives for DMO are limited.

Methods

Therefore, we have analyzed the central long-term complications in the offspring from CD1 diabetic mothers treated with streptozotozin, as well as the possible reversion of these alterations by insulin administration to neonates. Brain atrophy, neuronal morphology, tau phosphorylation, proliferation and neurogenesis were assessed in the short term (P7) and in the early adulthood (10 weeks) and cognitive function was also analyzed in the long-term.

Results

Central complications in DMO were still detected in the adulthood, including cortical and hippocampal thinning due to synaptic loss and neuronal simplification, increased tau hyperphosphorylation, and diminished cell proliferation and neurogenesis. Additionally, maternal diabetes increased the long-term susceptibility to spontaneous central bleeding, inflammation and cognition impairment in the offspring. On the other hand, intracerebroventricular insulin administration to neonates significantly reduced observed alterations. Moreover, non-invasive intranasal insulin reversed central atrophy and tau hyperphosphorylation, and rescued central proliferation and neurogenesis. Vascular damage, inflammation and cognitive alterations were also comparable to their counterparts born to nondiabetic mice, supporting the utility of this pathway to access the central nervous system.

Conclusions

Our data underlie the long-term effects of central complications in DMO. Moreover, observed improvement after insulin treatment opens the door to therapeutic alternatives for children who are exposed to poorly controlled gestational diabetes, and who may benefit from more individualized treatments.

Effect of Afobazole and Betaine on Cognitive Disorders in the Offspring of Rats with Streptozotocin-Induced Diabetes and Their Relationship with DNA Damage

Cognitive activity in 60-day-old offspring of rats (intrauterine development in experimental streptozotocin-induced diabetes) was studied on the model of food-seeking behavior under conditions of free choice in a 6-arm maze. The formation of the food-procuring skill was significantly delayed, which attests to impairment of cognitive functions in these animals. Peroral administration of afobazole (10 and 50 mg/kg) and betaine (50 and 100 mg/kg) significantly and dose-dependently alleviated this disorder. Correlation analysis of the data on delayed formation of a food-procuring skill and results of DNA comet attests to a strong relationship between DNA damage in cells of the embryo and placenta during intrauterine development and cognitive dysfunction in the postnatal offspring of animals with streptozotocin-induced diabetes.