Differences related to sex in adolescent obese Zucker rats: locomotor activity and dendritic arborization of neurons in layer V of the primary motor cortex

Obesity is a metabolic disorder characterized by the accumulation of excess body fat, which has been linked to skeletal muscle and motor behavior changes. Despite the high prevalence of obesity among children and adolescents in Mexico, it has mostly been studied using adult obese animal models. The objective of the present study was to analyze open-field locomotor activity and dendritic length and dendritic spine density in layer V pyramidal neurons of the primary motor cortex (M1) in adolescent (60-day-old) obese Zucker diabetic fatty (ZDF) rats of both sexes. Long-Evans (LE) rats were used as the control group. Female ZDF rats exhibited increased body weight, Lee index, and abdominal circumference. In contrast, male ZDF rats showed a shorter body length together with increased Lee index and abdominal circumference. However, ZDF rats of both sexes displayed elevated triglyceride and cholesterol levels. In addition, hyperglycemia was observed in male ZDF rats. Female ZDF rats showed decreased exploratory activity. The dendritic length of the basilar arbor of M1 neurons was significantly shorter in female and male ZDF rats, with ZDF males exhibiting a smaller basilar arbor than ZDF females. This last result was also observed in the apical arbor of these neurons. There was also a decrease in basilar and apical dendritic spine density in ZDF rats of both sexes. Our results indicate that female ZDF rats show alterations in exploratory behavior and dendritic arborization, whereas ZDF males are affected in terms of dendritic arborization in M1 neurons, which suggests sex differences in the effects of obesity in adolescent Zucker rats.