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PubMed1981

Dissociations between the effects of hallucinogenic drugs on behavior and raphe unit activity in freely moving cats.

The hypothesis that the action of hallucinogenic drugs is mediated by a depression of the activity of brain serotonergic (raphe) neurons was tested by examining the behavioral effects of several hallucinogenic drugs while concurrently monitoring the activity of raphe neurons in freely moving cats. LSD produced a dose-dependent decrease in raphe unit activity and a dose-dependent increase in certain behaviors (e.g. limb flick and abortive groom), and the peak of the behavioral and unit changes were temporally correlated. However, there were three important dissociations between the behavioral and electrophysiological effects of LSD. Firstly, low doses of LSD produced only small decreases in raphe unit activity but significant behavioral changes. Secondly, the duration of LSD-induced behavioral changes significantly outlasted the depression of raphe unit activity. And thirdly, raphe neurons were at least as responsive to LSD during tolerance as they were in the nontolerant condition. Psilocin produced a dose-dependent decrease in raphe unit activity, while the behavioral changes were not dose-related. However, the peak behavioral changes corresponded to the maximal depression of raphe unit activity. The phenylethylamine hallucinogens, DOM and mescaline, both produced large behavioral changes but no overall effect on raphe neurons. Following administration of DOM or mescaline, some raphe units showed a significant increase, while some showed a significant decrease, and others showed no change in activity. Therefore, the phenylethylamine hallucinogens may exert a depressant effect upon a subset of serotonin-containing neurons, and an amphetamine-like excitatory effect upon another subset of these neurons. Consistent with previous studies, all hallucinogens produced a high concentration of slow waves in the cortical EEG. Following administration of LSD or psilocin, the appearance of slow waves in the EEG was often associated with a transitory decrease in unit activity, while this was not observed for the phenylethylamine hallucinogens. The present data, in conjunction with recent data from other laboratories, suggest that the serotonin hypothesis of hallucinogenic drug action should be re-evaluated.

DOM 2,5-Dimethoxy-4-Methylamphetamine↗

PubMed1981

Central 5-hydroxytryptamine and the effects of hallucinogens and phenobarbital on operant responding in rats.

The present study was designed to examine the role of 5-hydroxytryptamine (5-HT) neurons in the behavioral effects of d-lysergic acid diethylamide (LSD), an indolealkylamine hallucinogen, 2.5-dimethoxy-4-methylamphetamine (DOM) and mescaline, phenethylamine hallucinogens, and phenobarbital, a non-hallucinogen. Male rats, maintained at 70-80% of their free-feeding weights, were trained to press a lever for food pellet reinforcement on a fixed ratio-40 operant schedule. When trained, these rats responded at a constant, rapid rate (approximately 100 responses/min) during daily 40 min test sessions. Administration of hallucinogens caused an abrupt cessation of responding (a "pause"), for some portion of the session. The duration of this pause was dose-dependent for LSD (12.5-100 micrograms/kg), DOM (0.125-1.0 mg/kg) and mescaline (7.1-14.2 mg/kg). On the other hand, phenobarbital (12.5-50 mg/kg) did not cause pausing, but resulted in slowed, erratic intrasession response rates. When the same tests were repeated in rats that had previously received an intracerebroventricular injection of 5,7-dihydroxyptamine (5,7-DHT) the dose-response curves for the pausing induced by all three hallucinogens were shifted to the left, while the behavioral disruption produced by phenobarbital was unaltered. In these animals the 5-HT but not the norepinephrine concentrations was markedly reduced in all brain regions examined. These results suggest that 5-HT neurons are involved with the behavioral effects of hallucinogens but not of phenobarbital.

5,7-Dihydroxytryptamine↗

PubMed1986

Effects of hallucinogenic drugs on serotonergic neuronal systems.

Studies indicate that hallucinogens markedly suppress the discharge of serotonin containing neurons in the dorsal raphe nucleus. Forebrain neurons receiving a major serotonergic input are relatively insensitive to hallucinogens. These actions of hallucinogens are not sufficient to explain the psychoactive effects of these drugs. Evidence is presented to indicate that hallucinogens sensitize serotonin and norepinephrine receptors in the facial nucleus. This receptor sensitizing effect is common to all, and specific for, hallucinogens. It is suggested that a mechanism of receptor sensitization might account for the altered perceptual reactivity produced by hallucinogens.

Animals↗

PubMed1982

Neurotransmitter basis of the behavioral effects of hallucinogens.

Indole and phenethylamine-type hallucinogenic drugs were studied in an FR-40 operant behavioral procedure programmed to quantify "pausing,"-a behavioral disruption somewhat specific to hallucinatory drug effects. LSD, DOM, DMT and mescaline showed a potency ratio to produce pausing that is well correlated with the hallucinatory potencies of these agents in man. Furthermore, combinations of the hallucinogens interact with potentiation to cause FR-40 pausing, whereas a variety of non-hallucinogenic psychoactive drugs failed to shift the dose-response patterns of pausing for DOM or LSD. Depletion of brain catecholamines by pretreatment with intraventricular 6-OHDA reduced baseline FR-40 rates and attenuated the disruptive effects of d-amphetamine, but failed to modify the dose-response patterns of indole and phenethylamine hallucinogens. On the other hand, pretreatment with intraventricular 5,7-DHT to deplete brain 5-HT potentiated the pause-producing effects of the hallucinogens, although the disruptive effects of phenobarbital were not altered by this pretreatment. Injection of 5,7-DHT into the medial forebrain bundle at the hypothalamic level slightly potentiated LSD, attenuated DOM, and did not affect the pausing produced by mescaline. Metergoline pretreatment shifted the LSD and DMT dose-response curves for pausing to the right by a factor of 2--3, but shifted the DOM and mescaline dose-response patterns to a much greater extent. Metergoline alone slightly increased FR-40 response rates and decreased pausing from baseline levels. The patterns of imparied FR-40 performance induced by d-amphetamine and phenobarbital were unaltered by pretreatment with metergoline. The indole and phenethylamine classes of hallucinogens appear to disrupt this behavior by an agonistic effect at central 5-HT receptors. However, the two classes of drugs may interact with brain 5-HT systems by somewhat different mechanisms.

DOM 2,5-Dimethoxy-4-Methylamphetamine↗

PubMed2026

Patterns and implications of co-use between vaping and hallucinogens: a systematic review and meta-analysis.

BACKGROUND: The co-occurrence use of e-cigarettes and hallucinogens has become increasingly common, particularly among youth and young adults. However, evidence regarding the association between these behaviors remains limited and fragmented. This systematic review and meta-analysis aimed to synthesize current evidence, examining the correlation between hallucinogen use and the likelihood of being an e-cigarette user. METHODS: A comprehensive search was conducted in PubMed, Scopus, Web of Science, EMBASE, and Cochrane CENTRAL up to June 2025. Eligible studies measured both hallucinogen and e-cigarette use and reported quantitative associations between these behaviors. Data extraction and risk-of-bias assessments were performed independently by three reviewers using the Newcastle-Ottawa Scale. Pooled effect sizes were calculated using a random-effects model (REML). Certainty of evidence was evaluated with the GRADE approach. RESULTS: Eleven studies met the inclusion criteria (n = 247,904), and seven were included in the meta-analysis (n = 217,478). The pooled analysis demonstrated that hallucinogen users had 4.47 times higher odds of being e-cigarette users (OR: 4.47, 95% CI 2.72 to 7.34; p < 0.001; I2 = 95.7%, n = 7). The certainty of evidence was rated as low. CONCLUSIONS: Hallucinogen use is directionally and strongly associated with e-cigarette use across diverse populations. Although the direction of association was consistent across studies, the magnitude of effect was heterogeneous. These behaviors likely share psychosocial and environmental determinants, although alternative explanations, including shared genetic liability, recall bias, and residual confounding, cannot be excluded. Further longitudinal studies are needed to clarify the underlying mechanisms of this association and establish temporality. The findings also support integrating hallucinogen-use screening into e-cigarette prevention and harm-reduction programs targeting youth and young adults.

Humans↗

PubMed2004

Forensic analysis of hallucinogenic fungi: a DNA-based approach.

Hallucinogenic fungi synthesize two controlled substances, psilocin and psilocybin. Possession of the fungal species that contain these compounds is a criminal offence in North America. Some related species that are morphologically similar, do not contain the controlled substances. Therefore, unambiguous identification of fungi to the species level is critical in determining if a mushroom is illegal. We investigate a phylogenetic approach for the identification of species that contain the psychoactive compounds. We analyzed 35 North American specimens representing seven different genera of hallucinogenic and non-hallucinogenic mushrooms. We amplified and sequenced the internal transcribed spacer region of the rDNA (ITS-1) and a 5' portion of the nuclear large ribosomal subunit of rRNA (nLSU rRNA or 28S). ITS-1 locus sequence data was highly variable and produced a phylogenetic resolution that was not consistent with morphological identifications. In contrast, the nLSU rRNA data clustered isolates from the same species and separated hallucinogen containing and non-hallucinogen containing isolates into distinct clades. With this information, we propose an approach that combines the specificity of PCR detection and the resolving power of phylogenetic analysis to efficiently and unambiguously identify hallucinogenic fungal specimens for legal purposes.

Agaricales↗

PubMed2001

Psychometric assessment of the Hallucinogen Rating Scale.

Reliability and convergent-discriminant validity of a Spanish version of the Hallucinogen Rating Scale (HRS) were assessed in two differentiated populations of hallucinogen users involving the retrospective assessment of drug effects. In Study 1 (immediate assessment), 75 European users of the South American hallucinogenic drink ayahuasca answered the HRS 4 h after drug intake in their habitual setting. In Study 2 (delayed assessment), 56 adult polydrug users answered the HRS and a short form of the Addiction Research Center Inventory (ARCI) recalling the effects they experienced when they last took a hallucinogen, in order to test the convergent-discriminant validity of HRS with the scales of the standard questionnaire used in most studies involving psychoactive drugs. The HRS scales showed increases after both the immediate and delayed retrospective assessment of drug effects. Reliability data indicated that four of the six scales show an acceptable level of internal consistency. Significant but limited correlations were found between the Perception and Somaesthesia scales and the ARCI LSD scale, pointing out the questionnaire's construct validity. Thus, the HRS was sensitive to hallucinogenic drug effects other than those elicited by intravenous N,N-dimethyltryptamine (DMT), for which it was originally designed, and showed reasonable reliability and convergent validity. Results suggest its usefulness in the evaluation of subjective effects elicited by psychoactive drugs with hallucinogenic properties, and constitute a preliminary approach to the effects of ayahuasca in European subjects.

Adolescent↗

PubMed1996

Age-specific patterns of hallucinogen use in the US population: an analysis using generalized additive models.

Although there has been growing concern in recent years about an escalation in the use of LSD and other hallucinogens, little is known about the distribution of the use of these drugs in the United States population. In order to fill this gap, we used generalized additive models to analyze data from the 1988, 1990, and 1992 National Household Survey on Drug Abuse, to compare the age-specific prevalence of hallucinogen use by level of socio-economic indicators. In addition, we used survival analysis to compare patterns in the onset of use. Use of hallucinogens in the past year was highest at the age of 19 years for each of the NHSDA surveys, but use was not linked to enrollment in school at this age. Past year prevalence was highest among whites and respondents with high family income. The onset of hallucinogen use was most likely to occur between ages 15-19 years, regardless of birth cohort. These results indicate a stable pattern since hallucinogens were made widely available in the late 1960s, in which the transition from adolescence to adulthood has been the period of highest risk for hallucinogen use.

Adolescent↗

PubMed2000

Effect of ring fluorination on the pharmacology of hallucinogenic tryptamines.

A series of fluorinated analogues of the hallucinogenic tryptamines N,N-diethyltryptamine (DET), 4-hydroxy-N,N-dimethyltryptamine (4-OH-DMT, psilocin), and 5-methoxy-DMT was synthesized to investigate possible explanations for the inactivity of 6-fluoro-DET as a hallucinogen and to determine the effects of fluorination on the molecular recognition and activation of these compounds at serotonin receptor subtypes. The target compounds were evaluated using in vivo behavioral assays for hallucinogen-like and 5-HT(1A) agonist activity and in vitro radioligand competition assays for their affinity at 5-HT(2A), 5-HT(2C), and 5-HT(1A) receptor sites. Functional activity at the 5-HT(2A) receptor was determined for all compounds. In addition, for some compounds functional activity was determined at the 5-HT(1A) receptor. Hallucinogen-like activity, evaluated in the two-lever drug discrimination paradigm using LSD-trained rats, was attenuated or abolished for all of the fluorinated analogues. One of the tryptamines, 4-fluoro-5-methoxy-DMT (6), displayed high 5-HT(1A) agonist activity, with potency greater than that of the 5-HT(1A) agonist 8-OH-DPAT. The ED(50) of 6 in the two-lever drug discrimination paradigm using rats trained to discriminate the 5-HT(1A) agonist LY293284 was 0.17 micromol/kg, and the K(i) at [(3)H]8-OH-DPAT-labeled 5-HT(1A) receptors was 0.23 nM. The results indicate that fluorination of hallucinogenic tryptamines generally has little effect on 5-HT(2A/2C) receptor affinity or intrinsic activity. Affinity at the 5-HT(1A) receptor was reduced, however, in all but one example, and all of the compounds tested were full agonists but with reduced functional potency at this serotonin receptor subtype. The one notable exception was 4-fluoro-5-methoxy-DMT (6), which had markedly enhanced 5-HT(1A) receptor affinity and functional potency. Although it is generally considered that hallucinogenic activity results from 5-HT(2A) receptor activation, the present results suggest a possible role for involvement of the 5-HT(1A) receptor with tryptamines.

3T3 Cells↗

PubMed1995

Hallucinogenic drugs in psychiatric research and treatment. Perspectives and prospects.

Clinical research with hallucinogens has resumed after a generation's hiatus. To place these new studies in context, this article reviews the history of hallucinogens' use and abuse, discusses their pharmacological properties, and highlights previous human studies. Research with lysergic acid diethylamide and related hallucinogens with thousands of patients and control subjects was associated with acceptable safety when subjects were carefully screened, supervised, and followed up. Data were generated regarding hallucinogens' psychopharmacology, overlap with endogenous psychoses, and psychotherapeutic efficacy. Current American and European studies emphasize systematic psychopharmacology, in addition to psychotherapy protocols. Human hallucinogen research will help define unique mind-brain interfaces, and provide mechanistic hypotheses and treatment options for psychiatric disorders. It is critical that human hallucinogen research in the 1990s make use of state of the art methodologies, or consensually define when modifications are required. Training and supervisory issues also must be explicitly addressed.

Combined Modality Therapy↗

PubMed1998

Effects of the hallucinogen psilocybin on habituation and prepulse inhibition of the startle reflex in humans.

Schizophrenic patients exhibit deficits in indices of sensorimotor gating, such as habituation and prepulse inhibition (PPI) of the startle reflex. Hallucinogenic drug-induced states are putative models for the early and acute stages of schizophrenic and schizophrenia-spectrum disorders. Hallucinogenic drugs have been shown to disrupt PPI and/or retard habituation of the startle reflex in animal models of schizophrenia, consistent with the view of hallucinogen-induced states as 'model psychoses'. We evaluated the effects of the hallucinogen psilocybin on PPI and habituation of the startle reflex in a double-blind, placebo-controlled human study with 12 healthy subjects. In contrast to animal studies, in our small human sample, psilocybin increased PPI, while having no clear effect on habituation (n = 6). These findings must be considered preliminary because several factors, including dose regimens and experimental parameters, may influence the results of studies on startle plasticity. Further investigations both with psychotic patients in different stages of the disease and with human and animal models of schizophrenia are needed in order to explore the effects of hallucinogens on sensorimotor gating and the relationship between information processing in hallucinogenic drug-induced states and the naturally occurring psychoses.

Adult↗

PubMed1999

Hallucinogen, opiate, sedative and stimulant use and abuse in a population-based sample of female twins.

OBJECTIVE: Rates of illicit psychoactive substance use and abuse in women have increased substantially over the last 50 years. However, we understand little about the aetiology of these behaviors in women, and almost nothing about the role of familial-environmental and genetic factors. METHODS: We obtained, by means of blind telephone interviews with 1934 individual twins from female-female adult pairs ascertained through a population-based registry, including both members of 500 MZ and 326 DZ pairs, a history of lifetime illicit use, abuse and dependence, as defined by DSM-IV, of hallucinogens, opiates, sedatives and non-cocaine stimulants. RESULTS: Lifetime prevalences for substance use ranged from 3.3% for opiates to 10.4% for hallucinogens. Rates of abuse (ranging from 0.7% for opiates to 3.2% for stimulants) and dependence (ranging from 0.2% for hallucinogens to 1.4% for stimulants) were substantially lower. Significant twin resemblance was found for hallucinogen use, opiate use, sedative use and stimulant use, abuse and symptoms of dependence. The results of twin-model fitting suggested that twin resemblance for hallucinogen and stimulant use was due to both genetic and familial environmental factors, while twin resemblance for opiate and sedative use as well as stimulant abuse and symptoms of dependence was solely the result of genetic factors. Heritability of liability ranged from 21% to 72%. Twin resemblance for substance use, abuse and dependence could not be explained by the similarity of the twins' environment in childhood, adolescence or adulthood. CONCLUSION: Although limited by the rarity in women of these forms of substance use and misuse, our results none the less suggest that familial factors, which are at least in part genetic, strongly influence the vulnerability to hallucinogen, opiate, sedative and stimulant use and abuse in women.

Adult↗

PubMed2001

Hallucinogens on the Internet: a vast new source of underground drug information.

OBJECTIVE: The illicit use of hallucinogens is reemerging in the United States, especially among well-educated adults and teenagers. These same groups are also frequent users of the Internet. The authors sought to characterize the extent of information about hallucinogens available to Internet users. METHOD: Using standard Internet search techniques, the authors located 81 hallucinogen-related sites and categorized the information provided. RESULTS: Internet sites offer thousands of pages of information-albeit of questionable accuracy-on how to obtain, synthesize, extract, identify, and ingest hallucinogens. Much of this information has yet to appear in textbooks. By contrast, the authors found few U.S. government agency sites offering cautionary material about hallucinogen use. CONCLUSIONS: Using the Internet, potential hallucinogen users can bypass traditional channels of medical information and learn in great detail how to obtain and use numerous drugs with unknown hazards.

Adolescent↗

PubMed1992

Hallucinogens and serotonergic mechanisms.

Classical hallucinogens possess 5-HT2 agonist activity; certain structurally related agents are antagonists, but there is no evidence that the antagonists are hallucinogenic. Both the discriminative stimulus and human hallucinogenic potencies of the agonists are significantly correlated with 5-HT2 receptor affinity when [3H]-ketanserin is used as radioligand (Glennon et al., 1984). These agents appear to bind with higher affinity when [3H]DOB, an agent that apparently labels the agonist high-affinity state of 5-HT2 receptors, is used as radioligand (Sadzot et al., 1989). For a series of DOB-related agents, 5-HT2(KET) affinity can be modeled by the lipophilicity of the 4-position substituent; lipophilicity alone does not completely account for the affinity of 5-HT2 agonists. Using [3H]DOB as radioligand to minimize differences observed between agonists and antagonists, 5-HT2 affinity is related both to the lipophilicity and electron withdrawing nature of the 4-position substituents. The difference between 5-HT2(KET) and 5-HT2(DOB) binding may be related to the intrinsic activity of DOB-related agents. Serotonin, with an intrinsic activity of 1.0, is not hallucinogenic whereas hallucinogens may be hallucinogenic because they are high-affinity 5-HT2 partial agonists.

Animals↗

PubMed2005

[Hallucinogenic mushrooms].

The group of hallucinogenic mushrooms (species of the genera Conocybe, Gymnopilus, Panaeolus, Pluteus, Psilocybe, and Stropharia) is psilocybin-containing mushrooms. These "magic", psychoactive fungi have the serotonergic hallucinogen psilocybin. Toxicity of these mushrooms is substantial because of the popularity of hallucinogens. Psilocybin and its active metabolite psilocin are similar to lysergic acid diethylamide. These hallucinogens affect the central nervous system rapidly (within 0.5-1 hour after ingestion), producing ataxia, hyperkinesis, and hallucinations. In this review article there are discussed about history of use of hallucinogenic mushrooms and epidemiology; pharmacology, pharmacodynamics, somatic effects and pharmacokinetics of psilocybin, the clinical effects of psilocybin and psilocin, signs and symptoms of ingestion of hallucinogenic mushrooms, treatment and prognosis.

Adolescent↗

PubMed1988

Radioligand binding evidence implicates the brain 5-HT2 receptor as a site of action for LSD and phenylisopropylamine hallucinogens.

Alterations in brain serotonergic function have been implicated in the mechanism of action of LSD, mescaline, and other similarly acting hallucinogenic drugs of abuse such as STP (2,5-dimethoxyphenylisopropylamine; DOM). In order to test the hypothesis that the mechanism of action of LSD and phenylisopropylamine hallucinogens is through stimulation of a specific brain serotonin receptor sub-type, the affinities of these compounds for radiolabelled 5-HT2, 5-HT1A, 5-HT1B, and 5-HT1C receptors have been determined using recently developed in vitro radioligand binding methodologies. The 5-HT2 receptor was labelled with the agonist/hallucinogen radioligand 3H-DOB (4-bromo-2,5-dimethoxyphenylisopropylamine). The 5-HT1A, 5-HT1B, and 5-HT1C receptors were labelled with 3H-OH-DPAT, 3H-5-HT, and 3H-mesulergine, respectively. In general, the phenylisopropylamines displayed 10-100 fold higher affinities for the 5-HT2 receptor than for the 5-HT1C receptor and 100-1000 fold higher affinities for the 5-HT2 receptor than for the 5-HT1A or 5-HT1B receptor. There was a strong correlation between hallucinogenic potencies and 5-HT2 receptor affinities of the phenylisopropylamines (r = 0.90); the correlation coefficients for the 5-HT1A, 5-HT1B, and 5-HT1C were 0.73, 0.85, and 0.78, respectively. Because there is no evidence that 5-HT1A-selective or 5-HT1B-selective agonists are hallucinogenic and because the phenylisopropylamines are potent hallucinogens, a 5-HT2 receptor interaction is implicated and supports our previous suggestions to this effect. A secondary role for 5-HT1C receptors cannot be discounted at this time.(ABSTRACT TRUNCATED AT 250 WORDS)

DOM 2,5-Dimethoxy-4-Methylamphetamine↗

PubMed1982

Psilocybin as a discriminative stimulus: lack of specificity in an animal behavior model for 'hallucinogens'.

Fifteen rats were trained to discriminate between the tryptamine hallucinogen psilocybin (4-phosphoryloxy-N,N-dimethyltryptamine; 1.0 mg/kg) and saline in a two-lever choice task. Dose-response and time-response curves were obtained. The psilocybin cue generalized to psilocin (the dephosphorylated congener of psilocybin) and to the prototypical indoleamine hallucinogen LSD, but not to the phenylethylamine hallucinogen mescaline. These results indicate that the hallucinogenic effects of these drugs in humans may not be identical with their discriminative stimulus functions in animals, and that these four compounds may not be members of a single drug class. The term 'hallucinogen' may thus be a misnomer in the context of drug discrimination studies in nonhumans.

Animals↗

PubMed1989

Hallucinogenic drug interactions at human brain 5-HT2 receptors: implications for treating LSD-induced hallucinogenesis.

It has been shown that the hallucinogenic potencies of LSD, the phenylisopropylamines, such as DOB (4-bromo-2,5-dimethoxyphenylisopropylamine) and DOI (4-iodo-2,5-dimethoxyphenylisopropylamine), and the indolealkylamines, such as DMT (dimethyltryptamine) and 5-OMe-DMT (5-methoxy-dimethyltryptamine), strongly correlate with their in vitro 5-HT2 receptor binding affinities in rat cortical homogenates. In order to ascertain if this correlation applies to human 5-HT2 receptors as well, we examined the affinities of 13 psychoactive compounds at 3H-ketanserin-labelled 5-HT2 receptors in human cortical samples. Both radioligand binding and autoradiographical procedures were used. As in rat brain, d-LSD was the most potent displacer of 3H-ketanserin specific binding with a Ki of 0.9 nM. The phenylisopropylamine DOI also displayed high affinity (Ki of 6 nM). Stereospecific interactions were found with DOB; (-) DOB had a Ki of 17 nM while (+) DOB had a Ki of 55 nM. The behaviorally active compound DOM (4-methyl-2,5-phenylisopropylamine) had an affinity of 162 nM while its behaviorally less active congener iso-DOM had an affinity of 6299 nM. The indolealkylamines 5-OMe-DMT and DMT competed with moderate affinities (207 and 462 nM, respectively). In general, Hill coefficients were significantly less than unity which is consistent with an agonist interaction with 5-HT2 receptors. MDMA, a substituted amphetamine analog was inactive with a Ki of greater than 10 microM. A strong correlation was found for the hallucinogen affinities and human hallucinogenic potencies (r = 0.97). Also, human and rat brain 5-HT2 receptor affinities were strongly correlated (r = 0.99). These results strongly support the hypothesis that the hallucinogenic effects of these drugs in humans are mediated in whole or in part via 5-HT2 receptors. Furthermore, these studies imply that treatment with 5-HT2 receptor antagonists may be effective in reversing the hallucinogenic effects caused by the ingestion of LSD and LSD-like drugs.

Animals↗