title: Effect of hypophysectomy and growth hormone on tryptophan and serotonin metabolism.
abstract: The present study reports data on brain serotonin (5-HT) metabolism in two experimental conditions which have in common a lack of pituitary growth hormone (GH) and refers also the effect of a GH replacement therapy. In hypophysectomized female rats or genetically dwarf mice, which have a more selective deficiency of GH, brain tryptophan (TP) and 5-hydroxyindoleacetic acid (5-HIAA) concentrations were significantly higher than in age-matched controls. Brain levels of 5-HT were practically unchanged. A GH replacement therapy resulted in both hypophysectomized rats and dwarf mice in a significant reduction of brain TP and 5-HIAA concentrations. These results suggest that GH may exert an inhibitory action on 5-HT metabolism. Consonant with this view are the preliminary findings that in 7 individuals with elevated plasma GH levels for acromegaly, plasma TP levels were lower than in control subjects.
mesh_terms: D000172:Acromegaly / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000187:drug effects / Q000378:metabolism; D005260:Female; D013006:Growth Hormone / Q000494:pharmacology*; D006801:Humans; D006897:Hydroxyindoleacetic Acid / Q000378:metabolism; D007016:Hypophysectomy; D051379:Mice; D051381:Rats; D012701:Serotonin / Q000378:metabolism*; D014364:Tryptophan / Q000378:metabolism*
chemical_list: D012701:Serotonin; D006897:Hydroxyindoleacetic Acid; D014364:Tryptophan; D013006:Growth Hormone