title: Treatment of rats with thyrotropin (TSH) reduces the adrenoceptor sensitivity of adenylate cyclase from cerebral cortex.
abstract: Prolonged treatment of rats with TSH attenuates the noradrenaline (NA) sensitivity of the cerebral cortical cAMP generating system. This effect can be measured in slices from brain cortex and with a membraneous, cellfree adenylate cyclase preparation from the same brain region. The development of this downregulation is time (7 d treatment required) and dose dependent (EC(50) = 3.5 mU/kg for 9 d). After discontinuation of treatment, about 12 d were required for reversal of this effect. Density of ?-adrenoceptors in cerebral cortex as measured by (?) [ (3)H]dihydroalprenolol (DHA) binding was reduced by TSH treatment (22% reduction). The catalytic activity of adenylate cyclase as tested with guanosinemonophosphate phosphoimidophosphate (GMPPNP) was unaffected by TSH treatment. It is suggested that TSH-mediated feedback mechanisms on TRH levels and receptors in brain are responsible for the changes of the central adrenoceptor system. The data are discussed with respect to the blunted TSH-response to TRH observed in certain psychiatric illnesses.
authors.affiliation: Pharmazeutisches Institut, Universität Tübingen, Morgenstelle 8, 7400 Tübingen, F.R.G.
authors.forename: J E
authors.initials: JE
authors.lastname: Schultz
authors.forename: B H
authors.initials: BH
authors.lastname: Schmidt