Hallucinogenic psilocybin is known to alter the subjective experience of time. However, there is no study that systematically investigated objective measures of time perception under psilocybin. Therefore, we studied dose-dependent effects of the serotonin (5-HT)2A/1A receptor agonist psilocybin (4-phosphoryloxy-N, N-dimethyltryptamine) on temporal processin...
The hallucinogenic serotonin(1A&2A) agonist psilocybin is known for its ability to induce illusions of motion in otherwise stationary objects or textured surfaces. This study investigated the effect of psilocybin on local and global motion processing in nine human volunteers. Using a forced choice direction of motion discrimination task we show that psilocyb...
RationaleAyahuasca, a South American psychotropic plant tea, combines the psychedelic agent and 5-HT(2A/2C) agonist N, N-dimethyltryptamine (DMT) with beta-carboline alkaloids showing monoamine oxidase-inhibiting properties. Current human research with psychedelics and entactogens has explored the possibility that drugs displaying agonist activity at the 5-H...
The role of 5-HT2A-mediated stimulation of phosphoinositide hydrolysis in the discriminative effects of hallucinogens was investigated in PC12 cells stably expressing the rat 5-HT2A receptor (PC12-5-HT2A cells). The hallucinogenic compounds, D-lysergic acid diethylamide (LSD), (-)2,5-dimethoxy-4-methylamphetamine (DOM), psilocybin, N,N-dimethyltryptamine (DM...
The modulating effects of serotonin on dopamine neurotransmission are not well understood, particularly in acute psychotic states. Positron emission tomography was used to examine the effect of psilocybin on the in vivo binding of [11C]raclopride to D2-dopamine receptors in the striatum in healthy volunteers after placebo and a psychotomimetic dose of psiloc...
Psilocybin, an indoleamine hallucinogen, produces a psychosis-like syndrome in humans that resembles first episodes of schizophrenia. In healthy human volunteers, the psychotomimetic effects of psilocybin were blocked dose-dependently by the serotonin-2A antagonist ketanserin or the atypical antipsychotic risperidone, but were increased by the dopamine antag...
To date, there is no doubt that dopamine plays a key role in the behavioural disorders associated with schizophrenia. However, dopamine is not the only neurotransmitter involved in this syndrome, as it interacts with many neuronal systems in brain. Of special interest is the interaction between dopaminergic and serotoninergic systems with evidence from pharm...
Tactile startle responding by male Sprague-Dawley rats given 60 presentations of air-puff stimuli (37.5 psi) was measured after the intraperitoneal administration of graded doses of hallucinogens and other psychoactive drugs. Among the drugs tested were the indoleamine-derived compounds, lysergic acid diethylamide (LSD), N,N-dimethyltryptamine and psilocin, ...
The hallucinogenic indoleamine drugs N,N-dimethyltryptamine (N,N-DMT), psilocybin, bufotenin, 5-methoxy-N,N-dimethyltryptamine, and N-methyltryptamine, increased rat plasma prolactin (PRL) levels. The increase in plasma PRL produced by N,N-DMT, psilocybin, and bufotenin was inhibited by methysergide, a serotonin receptor blocker. Parachlorophenylalanine (PCP...
The startle reflex was measured in 7 groups of 10 rats each after intraperitoneal injection of saline or 0.25, 0.50, 0.75, 1.0, 2.0, 4.0 or 8.0 mg/kg psilocybin. Low doses (0.75-2.0 mg/kg) increased startle amplitude whereas high doses (4.0-8.0 mg/kg) depressed startle. Selected low (0.71 mg/kg) or high (5.70 mg/kg) doses of psilocin also had a biphasic dose...
9 Ss were requested to perceive simultaneously the taste of beer and a rhythmic sound, the pitch of which could be varied. The frequencies at which Ss experienced harmony between the taste and the sound were determined. At the pitch of harmony Ss reported characteristic experiences, e.g., optimum taste of the beer, rhythmic sensations in the head, and tickli...
Investigations were carried out on the interactions of the hallucinogenic drug, D-lysergic acid diethylamide (D-LSD), and other serotonin antagonists with catecholamine-sensitive adenylate cyclase systems in cell-free preparations from different regions of rat brain. In equimolar concentration, D-LSD, 2-brono-D-lysergic acid diethylamide (BOL), or methysergi...
It was analysed five hallucinogens on the effect of nerve stimulation of isolated organs. Bulbocapnine and Mescaline 50 ug/ml decreased the effect of nerve stimulation. LSD and Psilocybin 50 ug/ml increased the effect of gastric nerve stimulation and hypogastric adrenergic nerve stimulation. LSD and Psilocybin were effective applied on mucose side of isolate...
Evidence has been presented that d-amphetamine interacts with various types of behavior in the context of a conditioning paradigm. Rats exposed simultaneously to a locomotor activity measurement and three dose levels of d-amphetamine on repeated occasions gradually developed dose-related enhancement of drug-stimulated activity, which persisted after disconti...
1. LSD-25, psilocybin and JB-329 reduced the noradrenaline content of the rat hypothalamus.2. All three drugs affected the acquisition of a conditioned avoidance response, LSD-25 and psilocybin retarding and JB-329 enhancing the acquisition. With the exception of JB-329, doses affecting the acquisition of a conditioned avoidance response were lower than thos...
