Lack of effect of chronically administered thyrotropin-releasing hormone (TRH) on regional rat brain tyrosine hydroxylase activity.
Chronic treatment of adult male rats with TRH (1 or 10 mg/kg IP) for 5 or 9 days failed to alter the activity of tyrosine hydroxylase (TH), the enzyme regulating the rate-limiting step in catecholamine biosynthesis. In contrast, as previously described, chronic reserpine administration (0.5 mg/kg IP: 9 days) resulted in a significant rise in TH activity in midbrain, hypothalamus, pons-medulla and forebrain. These results suggest that the enhanced brain norepinephrine turnover reported to occur after treatment with TRH is not due to synthesis of new TH enzyme protein.
D000818:Animals; D001921:Brain / Q000187:drug effects / Q000201:enzymology*; D004347:Drug Interactions; D008297:Male; D051381:Rats; D012110:Reserpine / Q000008:administration & dosage / Q000494:pharmacology; D013973:Thyrotropin-Releasing Hormone / Q000008:administration & dosage / Q000494:pharmacology*; D013997:Time Factors; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism*
D013973:Thyrotropin-Releasing Hormone; D012110:Reserpine; D014446:Tyrosine 3-Monooxygenase