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Chromium treatment decreases the sensitivity of 5-HT2A receptors
M-J Attenburrow1, J Odontiadis, B J Murray
1University Department of Psychiatry, Neurosciences Building, Warneford Hospital, Oxford OX3 7JX, UK.
Rationale:
Recent case series suggest that chromium picolinate in doses of 400 microg daily may have antidepressant properties, perhaps through increasing the peripheral availability of tryptophan for brain serotonin (5-HT) synthesis.
Objectives:
To determine the effects of chromium treatment on plasma tryptophan availability and on brain 5-HT function in human and animal models.
Methods:
We studied the effects of short-term chromium supplementation on plasma concentrations of tryptophan and other large neutral amino acids. Brain 5-HT function was assessed by measuring the corticosterone/cortisol response to the 5-HT precursor, 5-hydroxytryptophan (5-HTP), a response believed to be mediated via indirect activation of 5-HT(2A) receptors.
Results:
In rats, chromium increased peripheral and central tryptophan availability and elevated brain 5-HT content. Changes in peripheral tryptophan availability were not seen in humans but in both rats and humans, chromium lowered the cortisol response to challenge with 5-HTP.
Conclusions:
Chromium can modify brain 5-HT function in humans and animals, perhaps by altering the sensitivity of central 5-HT(2A) receptors.