Circadian rhythm: physiological basis to clinical application

Bhatt, Janardan (2002) Circadian rhythm: physiological basis to clinical application. Journal of Applied Basic Medical Sciences, 4 (4). pp. 74-76. ISSN ISSN 0972-4729

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The supra-chiasmatic nucleus receive information of, light via visual pathway from retina. SCN send in turn signal to pineal gland (situated in the brain) and secrete hormone called Melatonin. Melatonin in synthesized from 5-Hydroxy tryptamine (serotonin) in the presence of enzyme. N- Acetyl Transferase. In the presence of Sunlight, there is decreased secretion while in the night, in the absence of light, Pineal Gland secret melatonin in physiological need. In the night time, as the person sleeps, the plasma concentration of melatonin progressively increase usually up to 4 A.M. Then plasma concentration of melatonin starts falling and reaching basal level at 6.8 A.M. This basal level of plasma melatonin will maintain throughout the day and again in the night time/sleep around 10 P.M., plasma concentration of melatonin again progressively rises. This is called phasic secretion of melatonin. This phasis secretion of melatonin is dependa upon the photoperiod i.e. duration of exposure of sunlight throughout the day. There is also a seasonal variation of melatonin secretion. In summer, as the photoperiod is increased, the melatonin secretion is decreased. This leads to increase secretion of Pituitary gland and Hypothalamic hormones, and increase the physical activity / performance, mood - level etc. This is typically observed in birds. With the onset of summer and prolongation of photoperiod various behaviours i.e. nesting, laying eggs, parenting etc. are observed.

EPrint Type:Article
Additional Information:The article summerize the mechanism of circadian rhythms and role of melatonin in regulation of such rhythms. Clinical application and future of melatonin is discussed. Special emphasis is give photo therapy and indications.
Uncontrolled Keywords:Circadian rhythms , Melatonin, Endocrine changes, Clinical applications, Jet lag, Pineal Gland, Serotonin,
Subjects:Physiological Processes > Adaptation, Physiological
Endocrine System > Endocrine Glands
Heterocyclic Compounds > Heterocyclic Compounds, 2-Ring > Indoles
Physiological Processes > Chronobiology
Endocrine System > Neurosecretory Systems
Hormones, Hormone Substitutes, and Hormone Antagonists > Hormones
Behavior and Behavior Mechanisms > Neurobehavioral Manifestations
Behavior and Behavior Mechanisms > Adaptation, Psychological
-Journal Repositories > Journal of Applied Basic Medical Sciences
ID Code:1977
Deposited By:Indian Journal of Applied Basic Medical scieces Ahmedabad
Deposited On:26 January 2007

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