[Tryptophan-5-hydroxylase activity in the rabbit brain synaptosomes at different times after the single administration of the opioid peptide Tyr-D-Ala-Gly-Phe-NH2].
The activity of the key enzyme of serotonin biosynthesis--tryptophan-5-hydroxylase (T-5-H) was investigated in the synaptosomes of the motor cortex and caudate nucleus of the rabbit brain 30 min or 5 days after single injection of opioid tetrapeptidamide Tyr-D-Ala-Gly-Phe-NH2 (TPA). TPA was injected subcutaneously at a dose of 500 micrograms/kg of rabbit body weight. T-5-H activity in caudate nucleus synaptosomes was two times higher than that of the motor cortex synaptosomes and accounted for 159.67 and 80.84 pmoles of formed 5-hydroxytryptophan/mg protein per hour. 30 min after single injection of TPA the enzyme activity in the synaptosomes of the motor cortex and caudate nucleus decreased by 64.0 and 43.0%, respectively. 5 days following single TPA injection T-5-H activity in the motor cortex synaptosomes increased by 68.4% and in caudate nucleus synaptosomes decreased by 35.6%. Thus, it was established that TPA displayed a pronounced effect on T-5-H activity. The delayed effect of opioid TPA on T-5-H activity was discovered which was manifested on day 5 after the single injection. Possible mechanisms of TPA effect on T-5-H are discussed.
D000818:Animals; D001921:Brain / Q000187:drug effects* / Q000201:enzymology; D002421:Caudate Nucleus / Q000187:drug effects / Q000201:enzymology; D008297:Male; D009044:Motor Cortex / Q000187:drug effects / Q000201:enzymology; D009842:Oligopeptides / Q000494:pharmacology*; D011817:Rabbits; D013574:Synaptosomes / Q000187:drug effects* / Q000201:enzymology; D013997:Time Factors; D014365:Tryptophan Hydroxylase / Q000378:metabolism*
D009842:Oligopeptides; C037379:tyrosyl alanyl-glycyl-phenylalaninamide; D014365:Tryptophan Hydroxylase
Aktivnost' triptofan-5-gidroksilazy v sinaptosomakh mozga krolika na raznykh srokakh posle odnokratnogo vvedeniia opioidnogo peptida Tyr-D-Ala-Gly-Phe-NH2.