Erowid References Database
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Green JP, Maayani S, Weinstein H, Hough LB.
“Histamine and Psychotroic Drugs”.
Psychopharmacol.Bull.. 1980;16(1):36-38.
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Abstract
The H2-linked adenylate cyclase system was examined as a site of action of psychotropic drugs. Adenylate cyclase in guinea pig hippocampal and cortical homogenates was confirmed as an H2-receptor, and shown by measurement of pA2 values of H2-antagonists (imidazolylpropyl methylthiourea, NQ-guanylhistamine, imidazolylpropylguanidine, thiaburimamide, metiamide and cimetidine). The activities of H2 agonists (Na,NQ-dimethylhistamine, 4-methylhistamine and 2 methylhistamine) was similar to that on peripheral H2-receptors. 3 Hl-antagonists (including cyproheptadine) blocked the H2 receptor (as shown by inhibition of dimaprit). Both D-LSD and 2-bromo-LSD, but not L-LSD, competitively blocked the H2-linked cyclase with pA2 values of 6.0 and 7.2, - respectively. All tricyclic antidepressants tested blocked the H2 stimulated adenylate cyclase in a competitive manner. The pA2 values were: amitriptyline 7.4; doxepin 6.8; desipramine 5.9; dibenzopine 508; protriptyline 5.7; and iprindole 5.5. Affinities for the H2-receptor were greater for some drugs than for blocking noradrenaline and 5-HT uptake by synaptosomes. Neuroleptic drugs also blocked the H2-linked adenylate cyclase; pA2 values were: chlorprothixene 7.2; chlorpromazine 6.7; thiethylperazine 6.—; a-fluphenthxol 6.6; fluphenazine 6.3; beta-fluphenthixol 5.5; (+)-butaclamol 7.2; trifluperidol 6.8; haloperidol 6.7; spiroperidol 6.3; (-)-butaclamol 5.3; clozapine 7.0; and sulpiride 5.7. Affinities for H2-receptor were far less than those for haloperidol-binding sites or for dopamine-linked cyclase, except for clazapine which had similar affinities for all 3. Inactive as either antagonists or agonists on the H2-receptor were psilocin, bufotenine, mescaline, different classes of anticonvulsant drugs, barbiturates and narcotic agonists and antagonists, as well as lithium chloride, chlordiazepc, ice, THC and procaine.
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