Citation

Poirier-Littre MF. Psychiatrie Psychobiol. 1990; 5(3): 179-185.

Copyright

(Copyright © 1990, Psychiatrie & psychobiologie)

DOI

unavailable

PMID

unavailable

Abstract

The simultaneous discovery of the antidepressive action of imipramine and of its biochemical effect on 5HT-transmission corroborated the hypothesis of concomitant biological disorder in depression. There is no in vivo access to the central nervous system. Therefore, these investigations assessed the neurotransmitter, its precursor tryptophan, its catabolite 5HIAA, synthesis and catabolism enzymes, as well as 5HT uptake and storage. In depression, free plasma tryptophan appears to be decreased in patients compared to controls but some authors found this parameter either unchanged or even increased. There are two possible explanations for this contradiction: a bimodal distribution in depressed patients or a different seasonal variation of the plasma levels between depressed patients and controls. Anorexia, often observed in depressed patients, could also result in a decrease of this amino acid. According to Ashcroft et al (1966), many studies have shown a decrease of CSF 5HIAA in some depressed patients versus controls. This modification could correspond to reduction of the turnover of 5HT although this was not observed by all authors. This could be explained by the evidence of a 5HIAA bimodal distribution of depressed patients. Approximately 30% of patients would show a decrease of the 5HIAA level in the CSF and would be characterized by increased suicidal behavior, and more evident aggressivity. Serotonin and 5HIAA concentrations were measured post-mortem in patients having committed suicide or who died from other causes. These studies tend to show a decrease in serotonin and 5HIAA cerebral levels, without however reaching a consensus. It appears that the results are far more specific according to the explored areas, otherwise, numerous non specific factors must be taken into consideration. This decrease in 5HT cerebral level in suicidal cases 'could also be due to the result of an activation of the amine turnover as well as a decrease of this synthesis' (Tissot, 1975). Various authors observed a significant decrease of the plasma serotonin level in patients with major depression. Approximately 60% of the studies show a decrease of the platelet concentration in 5HT. After several negative attempts, where weak substratum concentration was not used, Tuomisto and Tukiainen were the first to prove a decrease of the 5HT platelet-uptake in depressed patients. Since then, a consensus seems to have been reached on this decrease in endogenous depression. All these results should be interpreted with caution, as the changes are not always evident and do vary. It is difficult to know whether they represent a cause or a consequence of the illness. They probably represnt an intermediate step in the permanent regulation of a multifactorial and multiconnected system.

Language: fr

Keywords

human; Depression; depression; review; serotonin; anorexia; psychological aspect; imipramine; priority journal; 5 hydroxyindoleacetic acid; plasma; season; tryptophan; theoretical study; cerebrospinal fluid; Tryptophan; 5-Hydroxyindoleacetic acid; 5-Hydroxytryptamine platelet uptake