Effects of combined administration of L-tryptophan and tricyclic antidepressants on alpha 2- and beta-adrenoceptors and monoamine levels in rat brain.
In order to test whether co-administration of a serotonin precursor with antidepressant drugs could potentiate the effects of the antidepressants on monoamines or adrenoceptors in rat brain, L-tryptophan (20 mg/kg) was administered to rats daily for 7 or 15 days, either alone or in combination with desipramine (10 mg/kg) or amitriptyline (10 mg/kg). After treatment with L-tryptophan for 7 days, increases were observed in rat hypothalamic and frontal cortex 5-hydroxy-3-indoleacetic acid levels as well as in hypothalamic dopamine and nucleus accumbens 3,4-dihydroxyphenylacetic acid levels. After 15 days, hippocampal beta-adrenoceptor density was found to be decreased. There was no evidence of potentiation of desipramine or amitriptyline action when L-tryptophan was administered in combination with the antidepressants. On the contrary, the antidepressants appeared to interact with L-tryptophan to reduce its effects.
D000639:Amitriptyline / Q000008:administration & dosage; D000818:Animals; D000929:Antidepressive Agents, Tricyclic / Q000008:administration & dosage*; D001923:Brain Chemistry / Q000187:drug effects*; D002395:Catecholamines / Q000378:metabolism*; D003891:Desipramine / Q000008:administration & dosage; D004338:Drug Combinations; D007700:Kinetics; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects*; D011943:Receptors, Adrenergic, beta / Q000187:drug effects*; D013997:Time Factors; D014364:Tryptophan / Q000008:administration & dosage*
D000929:Antidepressive Agents, Tricyclic; D002395:Catecholamines; D004338:Drug Combinations; D011942:Receptors, Adrenergic, alpha; D011943:Receptors, Adrenergic, beta; D000639:Amitriptyline; D014364:Tryptophan; D003891:Desipramine