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TRAKYA UNIVERSITY JOURNAL OF NATURAL SCIENCES, vol.26, no.1, pp.93-102, 2025 (ESCI)
Most living organisms have circadian clocks which maintain rhythm in internal cycles of behavior, physiology, and metabolism, allowing them to anticipate the earth's 24hour rotation. In mammals, circadian integration of metabolic systems optimizes energy gathering and usage across the light and dark cycles. Disruption of circadian rhythms may lead to metabolic dysfunctions such as obesity and obesity-related disorders. The molecular and hormonal mechanism behind obesity is mostly related to mRNA expressions in hypothalamus, and leptin, and melatonin hormone levels. In obesity and related disorders, the chronobiotic hormone melatonin regulates physiological functions such as energy metabolism, body fat, and reproduction by cross-interacting with leptin. Leptin signals satiety by inhibiting Neuropeptide Y/Agouti-Related Peptide (NPY/AgRP genes in hypothalamus and exerts its effects on food intake, body weight, and the reproductive system. In this review, the molecular and hormonal mechanisms behind obesity were discussed.