Erowid References Database
“Neurohumoral Determinants of Sensitivity to LSD”.
Psychopharmacol. Bull.. 1979;15(1):50-51.
The relationship between the behavioral effects of hallucinogens and the biological activity of chemically defined neuronal systems in the brain was investigated. Rats were trained to detect the presence or absence of hallucinogens in a 2-lever choice situation. Ability to discriminate between the presence or absence of drug was tested twice weekly. LSD had strong discriminative stimulus properties. It produced a state which could readily be distinguished from nondrug or other drug states. Following training to discriminate between LSD and saline, administration of amphetamine, morphine, tetrahydrocannabinol, p-chlorophenylalanine (PCPA) or chlorpromazine caused the animals to respond as if saline had been administered. The only compounds perceived as either qualitatively or quantitatively similar to LSD were other hallucinogens or putative serotonin agonists (psilocybin, mescaline or quipazine). Discriminative properties of LSD were enhanced by depletion of serotonin with PCPA and blocked by serotonin antagonists methiothepin, methysergide, d-2-bromolysergic acid diethylamide, cyproheptadine and cinanserin. I-Tryptophan, chlorimipramine and fluoxetine neither blocked nor by themselves mimicked LSD. The discriminative properties of LSD appear to be mediated by postsynaptic serotonin or possibly endogenous LSD receptors. The involvement of dopamine or norepinephrine was not indicated. Quipazine exerted discriminative stimulus properties similar to those of LSD.
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