[Biological rhythms of thyrotropin secretion].
The rhythmic pattern of TSH secretion is now well-established and is characterized by a circadian (24 h) periodicity with a pre-sleep acrophase which is modulated by endogenous oscillators and environmental synchronisers. Among external synchronisers, the sleep-waking cycle has been extensively studied and sleep onset appears to have a negative influence on the nycthemeral TSH peak. Nutritional status may affect the TSH rhythmicity since a short term starvation induces a shift in the acrophase time. Major neurotransmitter involved in the TSH rhythms are serotonine which could be responsible for the TSH nadir. By contrast dopamine is not directly implicated in the circadian pattern of TSH secretion. TRH, the main neuropeptide controlling the thyrotrope cell, certainly has a major role in the mediation of the TSH rhythmicity. The involvement of somatostatine is less clear but as assumed for dopamine, its negative influence on TSH secretion would be stronger at the time of TSH peak than at the time of nadir. The major inhibitory effect of thyroid hormones on TSH secretion and release is evident on mean serum TSH levels but does not seem responsible for serum circadian variations. Likewise, the TSH rhythm is present in both sex and influence of estrogens and androgens would only be to modulate the mean serum TSH level. Finally the physiological influence of glucocorticoids on TSH secretion has not been clearly demonstrated.
D000328:Adult; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001679:Biogenic Amines / Q000502:physiology; D001683:Biological Clocks; D002940:Circadian Rhythm; D005215:Fasting; D005260:Female; D006801:Humans; D008297:Male; D009747:Nutritional Physiological Phenomena; D010455:Peptides / Q000502:physiology; D051381:Rats; D012621:Seasons; D012727:Sex Characteristics; D012890:Sleep / Q000502:physiology; D013963:Thyroid Hormones / Q000502:physiology; D013972:Thyrotropin / Q000097:blood / Q000378:metabolism*; D013973:Thyrotropin-Releasing Hormone / Q000502:physiology; D014851:Wakefulness / Q000502:physiology
D001679:Biogenic Amines; D010455:Peptides; D013963:Thyroid Hormones; D013973:Thyrotropin-Releasing Hormone; D013972:Thyrotropin
Les rythmes biologiques de la sécrétion thyréotrope.