title: Regional distribution in rat brain of tryptophan hydroxylase apoenzyme determined by enzyme-linked immunoassay.
abstract: Tryptophan hydroxylase apoenzyme was measured in 21 regions of the rat brain by a competitive enzyme-linked immunoassay (ELISA) technique using a recently developed antiserum from the sheep to this protein. Highest apoenzyme levels were found in the pineal gland and in the dorsal raphé. An insignificant level was observed in the cerebellum. In general, the distribution of tryptophan hydroxylase apoenzyme follows the distribution of serotonin previously detected by immunocytochemistry. A turnover number for tryptophan hydroxylase in a rat brain supernatant fraction of 7.5 s-1 was estimated, a value far higher than that estimated for serotonin turnover in vivo. This result confirms that serotonin biosynthesis is additionally regulated by factors other than tryptophan hydroxylase apoenzyme concentration.
mesh_terms: D000818:Animals; D001051:Apoenzymes / Q000032:analysis*; D001059:Apoproteins / Q000032:analysis*; D001921:Brain / Q000201:enzymology*; D004797:Enzyme-Linked Immunosorbent Assay; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D014365:Tryptophan Hydroxylase / Q000032:analysis*
chemical_list: D001051:Apoenzymes; D001059:Apoproteins; D014365:Tryptophan Hydroxylase