title: Biochemical similarity of rat pituitary and CNS TRH receptors.
abstract: Chemical properties of receptor binding sites for thyrotropin-releasing hormone (TRH) in rat pituitary, retina, amygdala and hypothalamus were compared by examining the influence of sulfhydryl reagents on specific binding of [3H](3-Me-His2)-TRH ([3H]MeTRH). Dithiothreitol-induced reduction of disulfide bonds, alkylation of thiol residues by N-ethylmaleimide and their oxidation by 5,5-dithiobis(2-nitrobenzoic acid) (DTNB), all produced marked reduction of [3H]MeTRH binding, which could be prevented in part by preincubation with exogenous TRH. In all tissues, concentration-dependent loss of binding activity was observed following exposure to micromolar heavy metals and mono- and divalent cations, with apparent additive effects between cations and DTT and NEM. Most changes appeared to reflect only a decrease in receptor density (Bmax). The similar sensitivity of all tissues to these compounds complements existing evidence for a close resemblance of TRH receptors in the CNS and pituitary.
mesh_terms: D000679:Amygdala / Q000378:metabolism*; D000818:Animals; D055598:Chemical Phenomena; D002621:Chemistry; D005260:Female; D007031:Hypothalamus / Q000378:metabolism*; D008297:Male; D008670:Metals / Q000494:pharmacology; D009928:Organ Specificity; D010903:Pituitary Gland, Anterior / Q000378:metabolism*; D011761:Pyrrolidonecarboxylic Acid / Q000031:analogs & derivatives; D051381:Rats; D011956:Receptors, Cell Surface / Q000378:metabolism*; D018025:Receptors, Thyrotropin-Releasing Hormone; D012160:Retina / Q000378:metabolism*; D013438:Sulfhydryl Compounds / Q000494:pharmacology; D013973:Thyrotropin-Releasing Hormone / Q000031:analogs & derivatives* / Q000378:metabolism
chemical_list: D008670:Metals; D011956:Receptors, Cell Surface; D018025:Receptors, Thyrotropin-Releasing Hormone; D013438:Sulfhydryl Compounds; C014109:thyrotropin-releasing hormone, 3-Me-; D013973:Thyrotropin-Releasing Hormone; D011761:Pyrrolidonecarboxylic Acid