Histamine turnover in rat brain |
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Authors: | K Dismukes S H Snyder |
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Institution: | Departments of Pharmacology and Experimental Therapeutics and Psychiatry and the Behavioral Sciences, The Johns Hopkins University School of Medicine, Baltimore, Md. 21205 U.S.A. |
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Abstract: | The half-life of histamine in the rat brain was measured by two independent techniques. Intravenous injection of inhibitors of histidine decar?ylase (brocresine or α-hydrazinohistidine) produced a prompt 20–25% depletion of histamine in hypothalamus and thalamus-midbrain. From the slope of the depletion curves, histamine in these regions was estimated to have a half-life of about 30 sec. A method was developed to estimate histamine half-life from the time course of 3H]histamine appearance following intraventricular injection of 3H]histidine. With this method, our data indicate a half-life for hypothalamic histamine of no more than about 1 min, much shorter than values in other parts of the body, where histamine turnover takes hours or weeks. By comparing the extent of reduction of newly synthesized 3H]histamine with that of endogenous histamine, it was determined that all histamine in the brain regions examined apparently lies within this rapidly turning over pool. |
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