Dopamine: a modulator of circadian rhythms/biological clock

Circadian rhythm describes the physical, psychological, and behavioural patterns of living organisms that respond to day and night light levels. The important bodily functions like hunger, sleep, gastrointestinal motility, mood, coordination, body temperature, gene transcription, sensory perceptions, sleep-wake cycles and hormone release etc are influenced by circadian rhythm. Abnormal circadian rhythm may result obesity, depression, diabetes, seasonal affective disorder, bipolar disorders and various sleep disorders. The neuromodulator dopamine, originate from small groups of neurons in the mesencephalon (the ventral tegmental area, the substantia nigra) and in the diencephalon. In the retina, olfactory bulb, striatum, midbrain, and hypothalamus, it has been shown to have that dopamine shows circadian like activities, where it regulates, clock genes in some of these areas. Thus, it is likely that dopamine is essential to mechanisms that maintain proper rhythmicity of these five brain areas. Dopamine receptors are located centrally and peripherally. Growing evidence that dopamine is involved in regulating circadian rhythms, either directly or indirectly, in the brain areas through various pathways and dopaminergic receptor groups centrally and peripherally, and plays vital role.