The effect of thyrotropin releasing hormone on local cerebral blood flow in humans

The effect of thyrotropin releasing hormone on local cerebral flow (CBF) was examined in 33 patients with mild or mederate disturbance of consciousness (Japan coma scale : I-1～II-2). Clinical diagnoses of these patients were subarachnoid hemorrhage (14 cases) intracerebral hemorrhage (9 cases) and cerebral inferction (10 cases). TRH (1mg) was acministered intravenously twice a day for a week. CBF was measuredst chromic stage by single photon emissions computed tomography (SPECT) using N-isopropyl-^<123>I-p-iodoamphetamine (^<123>I-IMP). SPECT was performed at 20 minutes (early scan) and 4hours (delayed scan) after administration of ^<123>I-IMP. Local CBF was evaluated by relative perfusion rate (e-RPR), as defined by the following equation, on the early scan. E-RPR＝(average RI counts of each cerebral lobe) / (avarage RI counts of cerebellar hemisphere) In regions with mild or moderate decrease of e-RPR, e-RPR and redistribution on the delayed scan significantly increased after TRH administration. In regions with normal or severe decrease of e-RPR, e-RPR and redistribution did not change after TRH administration. The effect of TRH ws the greatest in cases of subarachnoid hemorrhage. These results suggestet that TRH improved local CBF and the brain tissue viability which was disturbed midly or moderately in cases with cerebrovascular disease.