Gestational diabetes mellitus increased the number of dopaminergic neurons in the olfactory bulb of rat offspring

Gestational Diabetes Mellitus (GDM) is the most common metabolic complication of pregnancy that causes central nervous system and olfactory dysfunction in the offspring. It has been demonstrated that dopamine modulates several aspects of olfactory information processing in vertebrates.   In this study, we investigated the effect of gestational diabetes on the expression of the Dopamine (DA) metabolism genes, tyrosine hydroxylase (TH), and dopa decarboxylase (DDC) in the olfactory bulb (OB) tissue of rats’ offspring. Female Wistar rats were divided into a control group which received citrate buffer and the diabetic group which received 45 mg/kg of streptozotocin (STZ) on day 0 of gestation. Fasting blood glucose levels were measured before and 72 hr after injection. OB tissues of adult offspring were isolated, and TH-positive cells were counted by immunofluorescence staining. Also, TH and DDC expressions were analyzed by qRT- PCR and western blot. The data showed that gestational diabetes could cause up-regulation of TH (P<0.01) and DDC (P<0.05) in the OB tissue of offspring. Furthermore, our results showed that GDM causes a significant increase in TH and DDC protein levels in the OB tissues of offspring. Immunohistochemistry showed a significant increase in the number of TH-positive cells in the offspring of diabetic mothers (P<0.05). This study showed that gestational diabetes could cause an increase in TH and DDC gene expression in the OB tissue in the offspring, which may be correlated with reduced olfactory sensitivity.