Effects of environmental enrichment and caloric restriction on hippocampal changes in early adult rats.

Purpose: This study used an animal model to examine the effects of environmental enrichment (EE) and caloric restriction (CR) on hippocampal changes in early adulthood in a rat model. Methods: Male Sprague-Dawley rats were randomly assigned to control, EE, and CR groups. After 8 weeks of EE and CR, behavioral, biochemical, and molecular biological assessments were performed. Behavioral tests included the open field test for anxiety-like behavior, the eight-arm radial maze test for spatial learning, and the passive avoidance test for short-term memory. Glucose tolerance was assessed with an intraperitoneal glucose tolerance test, and the molecular markers associated with neuroinflammation were evaluated. Results: Both EE and CR reduced anxiety-like behaviors, as evidenced by increased time in the central region of the open field test and decreased rearing. However, neither EE nor CR significantly improved short-term memory or spatial learning. Nonetheless, the CR group showed a decrease in eight-arm radial maze completion time, indicating potential for enhanced learning. Both interventions improved glucose tolerance, with lower fasting blood glucose levels in the CR and EE groups. Molecular biological analyses showed that neuroinflammatory markers interleukin-6 and inducible nitric oxide synthase were reduced in the EE and CR groups and that Iba-1 had anti-inflammatory effects due to its neuroprotective action. Conclusion: EE and CR were beneficial for emotional and metabolic health in early adult rats due to reductions in anxiety-like behaviors and neuroinflammation with a concomitant improvement in glucose metabolism. However, the effects of these modalities on improving cognitive function were limited, illustrating the need for further research.