Neuroprotective effect of niacin in a rat model of obesity induced by high-fat-rich diet

This study investigates the impact of a high-fat-rich diet (HFRD) on behavioral, biochemical, neurochemical, and histopathological studies using the hypothalamus of rats following niacin (NCN) administration. The rats were divided into HFRD and normal diet (ND)-fed groups and administered selected doses of NCN, i.e., 25 mg/mL/kg (low dose) and 50 mg/mL/kg (high dose), for 8 weeks. The grouping of male rats (n = 8) was as follows: (i) Vehicle (Veh) + ND; (ii) ND + NCN (low dose); (iii) ND + NCN (high dose); (iv) Veh + HFRD; (v) HFRD + NCN (low dose); and (vi) HFRD + NCN (high dose). Behavioral tests assessed depression-like symptoms and spatial memory; after that, the hypothalamus was isolated for various analyses of sacrificed animals. NCN at both doses decreased food intake and growth rate in both diet groups and demonstrated antidepressant and memory-enhancing effects. HFRD-induced oxido-neuroinflammation decreased with both doses of NCN. HFRD-induced decreases in serotonergic neurotransmission, 5-HT1A receptor expression, and morphological alterations in the rat's hypothalamus were normalized by both doses of NCN. In conclusion, NCN, as a potential antioxidant and neuromodulator, can normalize feeding behavior and produce antidepressant and memory-improving effects in a rat model of obesity following HFRD intake.