The role of agomelatine in appetite regulation and body weight in rats.

The hypothalamic nuclei play a central role in the synthesis of anorexigenic and orexigenic neuropeptides, which are regulated by peripheral hormones, like leptin and ghrelin. Melatonergic receptors (MT/MT) are prominently expressed in the arcuate nucleus of the hypothalamus - an essential hub for appetite control - and in peripheral metabolic tissues where leptin and ghrelin are secreted. Agomelatine, an antidepressant drug and potent MT/MT agonist, offers potential for modulating appetite. This study aimed to investigate the impact of agomelatine on appetite regulation. Forty male Sprague-Dawley rats were randomly allocated into four groups, control (no treatment), vehicle control, agomelatine 20 mg/kg (Ago-20), and agomelatine 40 mg/kg (Ago-40), and administered oral gavage for 14 days. Body weight and food intake were recorded daily. At the end of the experiment, rats were euthanized and blood and hypothalamic tissue samples were obtained. Agomelatine significantly reduced body weight (Ago-40: 275.2 ± 7.2 g vs. control: 339.7 ± 8.3 g, P < 0.05) and food intake (Ago-40: 20.21 ± 1.32 g vs. control: 32.09 ± 1.58 g, P < 0.05) by day 14, without affecting water intake. Plasma ghrelin levels decreased (Ago-40: 22.54 ± 3.95 ng/dL vs. control: 46.67 ± 4.84 ng/dL, P < 0.05), while leptin increased (Ago-40: 552.30 ± 41.67 pg/mL vs. control: 271.10 ± 32.12 pg/mL P < 0.05). Hypothalamic orexigenic neuropeptides neuropeptide Y (NPY) and agouti-related peptide (AgRP) were suppressed (NPY, Ago40: 0.61 ± 0.02 vs. Control: 1.36 ± 0.1321; AgRP, Ago40: 0.52 ± 0.03 vs. Control: 1.49 ± 0.27, P < 0.05), while anorexigenic cocaine- and amphetamine-regulated transcript (CART) and proopiomelanocortin (POMC) were elevated (CART: Ago40: 1.19 ± 0.08 vs. Control: 0.92 ± 0.06; POMC: Ago40: 1.49 ± 0.17 vs. Control: 0.67 ± 0.10, P < 0.05). These findings suggest agomelatine promotes weight loss by modulating appetite-related hormones and hypothalamic neuropeptides, highlighting its potential as a therapeutic for obesity and metabolic disorders.