Effects of the dexamethasone-induced insulin resistance model on self-care behaviors and brain-derived growth factor in rats

Insulin resistance (IR) is described as an impaired response to insulin stimulation of target cells. The present study was designed to investigate the impact of the dexamethasone-induced IR model on self-care behaviors and brain-derived neurotrophic factor (BDNF). Sixteen adult Wistar albino rats were divided into control and IR groups (n = 8). Dexamethasone was administered intraperitoneally at 1 mg/kg/day for 5 days to induce the IR model. Open field and splash tests were performed to evaluate locomotor activity and self-care depression-like behaviors, respectively. BDNF was analyzed by enzyme-linked immunosorbent assay in the striatum and prefrontal cortex (PFC). Shapiro-Wilk, Student's t-test, and Fisher's exact test were used as statistical tests. Furthermore, the relationship among homeostasis model assessment of insulin resistance (HOMA-IR), BDNF, and total grooming behavior was analyzed using the Pearson correlation test. Total distance traveled, grooming frequency, and grooming time decreased in the IR group compared to the control group. Serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), glucose, insulin, and HOMA-IR values increased in the dexamethasone-applied group (P < 0.05). BDNF decreased in the prefrontal cortex in the IR group (P < 0.05). The striatum BDNF level decreased slightly but was insignificant (P > 0.05). Degeneration of the islets of Langerhans in the pancreas, tubular degeneration in the kidney, degeneration of hepatocytes, and mononuclear cell infiltration in the liver increased in the IR group compared to the control group (P < 0.05). PFC BDNF levels, total grooming, and HOMA-IR values displayed a significant correlation (P < 0.05). The PFC was found to be more vulnerable to IR. Our results suggest that IR deteriorates self-care behaviors and the BDNF level of the prefrontal cortex.