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The discriminative stimulus properties of 2,5-dimethoxy-4-methylamphetamine (DOM): differentiation from amphetamine.

Rats were trained in a two-lever operant procedure to discriminate either 1.0 mg/kg (+)amphetamine or 1.5 mg/kg DOM from saline. Rats trained to discriminate DOM from saline showed generalization with the DOM training condition when tested with mescaline or 2,5-dimethoxy-4-ethylamphetamine (DOET), but not when tested with (+)amphetamine or methylphenidate. Both isomers of DOM generalized with racemic training compound, the (-)isomer being more potent. The DOM stimulus was completely blocked by the serotonin (5-HT) antagonists cinanserin and methysergide, but not by the peripheral 5-HT antagonist xylamidine nor the dopamine antagonist haloperidol. Rats trained to discriminate (+)amphetamine from saline generalized with the amphetamine training condition when tested with methylphenidate but not when tested with mescaline, DOET, racemic DOM, or either isomer of DOM. The amphetamine stimulus was blocked by pretreatment with haloperidol but not by cinanserin, methysergide, or xylamidine. The results show that, despite their structural similarity, amphetamine and DOM induce pharmacologically distinct stimuli.

DOM 2,5-Dimethoxy-4-Methylamphetamine↗

5HT-2 mediation of acute behavioral effects of hallucinogens in rats.

In rats tested during their first exposure to a Behavioral Pattern Monitor chamber, acute injections of the 5HT-2 agonists mescaline, quipazine, 2,5-dimethoxy-4-iodoamphetamine (DOI), 2,5-dimethoxy-4-methylamphetamine (DOM), or 2,5-dimethoxy-4-ethylamphetamine (DOET) produced an inhibition of locomotor and investigatory behavior during the first 30 min of the test session. This suppression of exploratory behavior was attenuated when rats were familiarized with the testing chamber prior to the administration of DOI. Hence, as previously observed with both LSD and DOM, 5HT-2 agonists appear to potentiate the normal neophobic reaction to a novel environment. The mixed 5HT-1 and 5HT-2 agonist 5-methoxy-N,N-dimethyltryptamine (5MeODMT) also produced a decrease in activity when animals were tested in the novel environment. However, as previously found with 5HT-1A agonists, this effect was unchanged when animals were tested in the familiar environment and may therefore reflect a generalized sedation. The receptor specificity of these differential effects of 5HT-1 and 5HT-2 agonists in this paradigm was tested by assessing the ability of selective 5HT-2 antagonists to block the effects of the agonists. A dose of the 5HT-2 antagonist ketanserin which had no effect by itself significantly reduced the behavioral effects of mescaline, DOM, and quipazine. Similarly, the selective 5HT-2 antagonist ritanserin blocked the effect of quipazine. In contrast, ketanserin had no significant effect on the suppression of activity produced by the 5HT-1A agonist 8-hydroxy-2(di-n-propylamino)tetralin (8OHDPAT).(ABSTRACT TRUNCATED AT 250 WORDS)

DOM 2,5-Dimethoxy-4-Methylamphetamine↗

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↗

Direct comparison of hallucinogenic phenethylamines and D-amphetamine on dorsal raphe neurons.

We compared the effects of the hallucinogens 2,5-dimethoxy-4-methylamphetamine (DOM), mescaline and the simulant D-amphetamine, applied by microiontophoresis to rat dorsal raphe (DR) units. DR neuron firing rate was relatively insensitive to DOM and unaffected by mescaline, but was clearly inhibited by D-amphetamine. Intravenous DOM usually inhibited, but this effect was correlated with blood pressure changes; i.v. D-amphetamine produced inconsistent responses. These results suggest that most of the effects seen on i.v. administration of phenethylamines are not mediated directly on the serotonergic cell.

DOM 2,5-Dimethoxy-4-Methylamphetamine↗

Modification of the pigment screening of the frog retina following administration of neuroactive drugs.

Pigment screening (PS) occurs in the retina of lower vertebrates and consists of the bidirectional migration (vitreally or sclerally) of melanin granules into processes of the pigment epithelium that extend between photoreceptors, in response to changes in the illumination conditions. We have studied the effect of some neuroactive drugs on the PS of frogs maintained under cyclic lighting conditions or dark-adapted. The drugs, administered intravenously were: lysergic acid diethylamide (LSD), mescaline, d-amphetamine, the LSD analogue lisuride and the LSD derivative 2-bromolysergic acid (BOL). All the drugs used--with the exception of mescaline--modify the bidirectional migration of the pigment induced by the two illumination conditions in a different way. This suggests that in general these substances interact in some way with those processes which normally produce the well-defined PS pattern. It has been possible to discriminate two opposite effects on the retinal PS induced by two chemically related substances (LSD and lisuride) only one of which (LSD) has potent hallucinogenic properties.

Animals↗

Determination of psychotropic phenylalkylamine derivatives in biological matrices by high-performance liquid chromatography with photodiode-array detection.

Several procedures using high-performance liquid chromatography with photodiode-array detection have been developed to create phytochemical and toxicological profiles of phenylalkylamine derivatives in biological samples (e.g. plant materials and urine). Mescaline-containing cactus samples were extracted with basic methanol, using methoxamine as internal standard; the extraction and clean-up of urine samples were performed on cation-exchange solid-phase extraction columns. The extracts were separated on a 3-micron ODS column with acetonitrile-water-phosphoric acid-hexylamine as the mobile phase. Peak detection was performed at 198 or 205 nm; peak identity and homogeneity were ascertained by on-line scanning of the UV spectra from 190 to 300 nm. The detection limit of phenylalkylamine derivatives in urine and cactus material was 0.026-0.056 micrograms/ml and 0.04 micrograms/mg, respectively. Following a single oral dose of 1.7 mg/kg methylenedioxymethylamphetamine (MDMA) the concentrations found in urine ranged from 1.48 to 5.05 micrograms/ml MDMA and 0.07-0.90 micrograms/ml methylenedioxyamphetamine (a metabolite of MDMA). The mescaline content of the cactus Trichocereus pachanoi varied between 1.09 and 23.75 micrograms/mg.

Amphetamines↗

LDS-25 as a discriminative stimulus for response selection by pigeons.

Pigeons (N=4) were trained to discriminate between the effects induced by intramuscular (IM) injections of d-LSD and saline using a discrete-trial discrimination paradigm (choice between left and right hand key) in a conventional operant box. The solutions were administered IM 15 min prior to the sessions. A FR 15 schedule was in operation to produce food. Which of the two keys was correct on a given training session depended upon whether LSD or saline had been given. Three of the birds were trained and maintained with a dose of 40 microgram/kg of LSD and the fourth pigeon finally was maintained on 50 microgram/kg of LSD. The dose resulting in 50% LSD appropriate responding (ED50) was 18 microgram/kg and the median time-interval for the decay of the LSD stimulus (40 microgram/kg) was 84 min. Tests with psilocybin (ED50=0.55 mg/kg) and N,N-dimethyltryptamine (ED50=5.7 mg/kg) resulted in responding appropriate for the LSD training condition. Mescaline injections above 10 mg/kg severely suppressed responding. The few responses emitted after tests with 15 and 20 mg/kg of mescaline were directed to the LSD associated key. Tests with BOL (0.1 to 3 mg/kg) as well as three other psychotropic drugs (delta 9-tetrahydrocannabinol, morphine and, pentobarbital) did not result in responding above 50%) LSD appropriate responses. As a possible antidote, methergoline, a pubetative antagonist of post-synaptic serotonin receptor sites, was administered 75 min prior to testing the cueing properties of LSD. No definitive role for a blocking effect of the LSD-cue is provided by the present data.

Animals↗

LSD and other related hallucinogens elicit myoclonic jumping behavior in the guinea pig.

1. We evaluated the behavioral response of guinea pigs to hallucinogenic agents in order to characterize the response of this species to a variety of known hallucinogenic drugs. 2. The systemic injection of LSD in the guinea pig elicited a "myoclonic-like" response the frequency of which was dose-dependent. This behavior exhibited rapid tolerance which was more prominent at higher doses. 3. Subacute mescaline pretreatment reduced the myoclonic response to LSD suggesting cross-tolerance. 4. Mescaline, DOM, TMA, DMA and 5 Me-ODMT also elicited myoclonus in a dose-dependent manner and in potency ratios which approximate the human experience for hallucinogenic activity. 5. Brom-LSD failed to induce myoclonus. 6. Since the myoclonic response of the guinea pig shares a number of pharmacologic characteristics with the human hallucinogenic event, this species may be useful in the study of hallucinogenic compounds.

Animals↗

Prehistoric peyote use: alkaloid analysis and radiocarbon dating of archaeological specimens of Lophophora from Texas.

Two archaeological specimens of peyote buttons, i.e. dried tops of the cactus Lophophora williamsii (Lem.) Coulter, from the collection of the Witte Museum in San Antonio, was subjected to radiocarbon dating and alkaloid analysis. The samples were presumably found in Shumla Cave No. 5 on the Rio Grande, Texas. Radiocarbon dating shows that the calibrated 14C age of the weighted mean of the two individual dated samples corresponds to the calendric time interval 3780-3660 BC (one sigma significance). Alkaloid extraction yielded approximately 2% of alkaloids. Analysis with thin-layer chromatography (TLC) and gas chromatography-mass spectrometry (GC-MS) led to the identification of mescaline in both samples. No other peyote alkaloids could be identified. The two peyote samples appear to be the oldest plant drug ever to yield a major bioactive compound upon chemical analysis. The identification of mescaline strengthens the evidence that native North Americans recognized the psychotropic properties of peyote as long as 5700 years ago.

Alkaloids↗

Characterisation of human 5-hydroxytryptamine2A and 5-hydroxytryptamine2C receptors expressed in the human neuroblastoma cell line SH-SY5Y: comparative stimulation by hallucinogenic drugs.

Stable transfection of the human neuroblastoma cell line SH-SY5Y with the human 5-hydroxytryptamine2A (5-HT2A) or 5-HT2C receptor cDNA produced cell lines demonstrating ligand affinities that correlated closely with those for the corresponding endogenous receptors in human frontal cortex and choroid plexus, respectively. Stimulation of the recombinant receptors by 5-HT induced phosphoinositide hydrolysis with higher potency but lower efficacy at the 5-HT2C receptor (pEC50 = 7.80 +/- 0.06) compared with the 5-HT2A receptor (pEC50 = 7.30 +/- 0.08). Activation of the 5-HT2A receptor caused a transient fourfold increase in intracellular Ca2+ concentration. Whole-cell recordings of cells clamped at -50 mV demonstrated a small inward current (2 pA) in response to 10 microM 5-HT for both receptors. There were no differences in potency or efficacy of phosphoinositide hydrolysis among four hallucinogenic [d-lysergic acid diethylamide (LSD), 1-(4-iodo-2,5-dimethoxyphenyl)-2-aminopropane (DOI), 5-methoxy-N,N-dimethyltryptamine, and mescaline] and three nonhallucinogenic drugs (m-chlorophenylpiperazine, quipazine, and ergotamine). Comparison of equipotent doses producing 20% of the maximal response induced by 5-HT revealed selective activation of the 5-HT2A receptor by LSD and to a lesser degree by DOI, mescaline, and ergotamine. Quipazine and 5-methoxy-N,N-dimethyltryptamine were relatively nonselective, whereas m-chlorophenylpiperazine selectively activated the 5-HT2C receptor. It is unlikely therefore that hallucinosis is mediated primarily by activity at the 5-HT2C receptor, whereas activity at the 5-HT2A receptor may represent an important but not unique mechanism associated with hallucinogenic drug action.

Adrenergic alpha-Agonists↗

The effects of hallucinogenic drugs on maze exploration in the rat over a 24 hour period.

1. The variation with clock-hour in the behaviour of naive rats in a Y-maze has been recorded.2. The number of entries recorded was highest during the light period while the number of faecal boluses was highest during the dark period. Rearing showed a biphasic periodicity.3. The responses to LSD, mescaline and amphetamine also showed significant variation with clock-hour.4. In general, amphetamine, 1.25 mg/kg, increased the number of entries and the number of rears, the effect being greatest at the end of the light period. LSD, 100 mug/kg, and mescaline, 12.5 mg/kg, decreased the number of entries and the number of rears.5. All three drugs decreased the number of faecal boluses. The possible significance of these responses in terms of an effect on the emotional state of the animals is discussed.

Amphetamine↗

The integrity of the social hierarchy in mice following administration of psychotropic drugs.

1 Mice in small groups develop a despotic type of social hierarchy, a feature of which is to resist alteration through the medium of psychotropic drugs. This makes a rapid pharmacologically induced change in the social hierarchy impossible. 2 Patrolling the territory and a certain level of social interaction are both critical factors in maintaining the phenomenon of inertia in the social hierarchy. Psychotropic drugs (diazepam, droperidol and mescaline) altered both these factors to a varying degree and also displayed a differing ability to maintain the inertia of the social hierarchy. 3 A drug-induced alteration in the level of aggression in a subordinate mouse in a group of three does not cause an alteration in its social position. 4 Chronic administration of diazepam, droperidol or mescaline, all of which alter the level of aggression in different ways, can result in an inversion of the social hierarchy where a competitive rival is present in the group of mice. The rate of inversion of the social hierarchy depends on the type of pre-existing social hierarchy. 5 It is suggested that the ability of psychotropic drugs to maintain the inertia of the hierarchy be used as an index of their effect upon certain types of species-specific behaviour; in particular aggression.

Aggression↗

A depressant cortical reaction induced by afferent stimulation.

A depressant reaction of the electrocortical activity of the brain cortex is described. The changes consist in decrease in the amplitude and frequency of the basal waves of the electrocorticogram together with the appearance of slow waves similar to those of the sleep state. The results are more clear upon the dendritic action potentials induced by the topical application of strychnine or mescaline. They include a rise in the threshold to the electrical stimulation applied to elicit these potentials together with a lengthening of their latencies. The depressant effects were obtained by low threshold vagal, carotid sinus, low threshold sciatic and tactile afferent stimulation. Similar depressant effects were produced by serotonin (5-HT) topically applied. The effects of afferent stimulation were reduced in magnitude by an intracisternal injection of 5,6-dihydroxytryptamine. A serotonergic mechanism acting in a diffuse, humoral, way is postulated. The methodological importance of studying the strychnine or mescaline spikes is emphasized.

Action Potentials↗

Detection and validated quantification of nine herbal phenalkylamines and methcathinone in human blood plasma by LC-MS/MS with electrospray ionization.

The herbal stimulants Ephedra species, Catha edulis (khat), and Lophophora williamsii (peyote) have been abused for a long time. In recent years, the herbal drug market has grown owing to publicity on the Internet. Some ingredients of these plants are also ingredients of cold remedies. The aim of the presented study is to develop a multianalyte procedure for detection and validated quantification of the phenalkylamines ephedrine, pseudoephedrine, norephedrine, norpseudoephedrine, methylephedrine, methylpseudoephedrine, cathinone, mescaline, synephrine (oxedrine), and methcathinone in plasma. After mixed-mode solid-phase extraction of 1 ml of plasma, the analytes were separated using a strong cation exchange separation column and gradient elution. They were detected using a Q-Trap LC-ESI-MS/MS system (MRM mode). Calibration curves were used for quantification using norephedrine-d3, ephedrine-d3, and mescaline-d9 as internal standards. The method was validated according to international guidelines. The assay was selective for the tested compounds. It was linear from 10 to 1000 ng/ml for all analytes. The recoveries were generally higher than 70%. Accuracy ranged from - 0.8 to 20.0%, repeatability from 2.5 to 12.3%, and intermediate precision from 4.6 to 20.0%. The lower limit of quantification was 10 ng/ml for all analytes. No instability was observed after repeated freezing and thawing or in processed samples. The applicability of the assay was tested by analysis of authentic plasma samples after ingestion of different cold medications containing ephedrine or pseudoephedrine, and after ingestion of an aqueous extract of Herba Ephedra. After ingestion of the cold medications, only the corresponding single alkaloids were detected in human plasma, whereas after ingestion of the herb extract, all six ephedrines contained in the plant were detected. The presented LC-MS/MS assay was found applicable for sensitive detection and accurate and precise quantification of all studied analytes in plasma.

Chromatography, High Pressure Liquid↗

Discriminable effects of phencyclidine analogs evaluated by multiple drug (PCP versus OTHER) discrimination training.

This study tested structural analogs of phencyclidine (PCP) using drug discrimination procedures to determine which analogs produced discriminable effects similar to those of PCP. It also tested the utility of multiple-drug discrimination training (PCP versus other drugs or saline) as a method for increasing the specificity produced by training. All discrimination training took place in two-lever operant compartments using FR-10 reinforcement of presses on the correct lever. During training, rats were required to concurrently discriminate PCP from one or more other drug conditions. Rats in group 1 discriminated PCP (lever 1) versus saline (lever 2). Rats in group 2 discriminated PCP (lever 1) versus saline, fentanyl, phenobarbital, amphetamine, or mescaline (lever 2). In both groups 1 and 2, the required discriminations were rapidly learned. The percentage of PCP choices and the ED50 doses obtained during tests for generalization did not differ significantly in groups 1 and 2. Drugs to which responding on the PCP lever generalized included 1-[1-(2-thienyl)cyclohexyl]piperidine, N-ethyl-1-phenylcyclohexylamine, 1-phenylcyclohexylamine, ketamine, 1-(1-phenylcyclohexyl)morpholine, 1-[1-(2-thienyl)cyclohexyl]morpholine, N,N-diethyl-1-phenylcyclohexylamine, N-(iso-propyl)-1-phenylcyclohexylamine, N-methyl-1-phenylcyclohexylamine, N-(n-propyl)-1-phenylcyclohexylamine, Dextrorphan, (dl)-N-allyl-N-normetazocine, N-N-dimethyl-1-phenylcyclohexylamine, N-(n-butyl)-1-phenylcyclohexylamine, 1-[1-(2-thienyl)cyclohexyl]pyrrolidine, and N-(s-butyl)-1-phenylcyclohexylamine, in agreement with previous reports. Rats in group 3 discriminated PCP (lever 1) versus saline, cyclazocine, dextrorphan, phenobarbital, or mescaline (lever 2).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Analysis of illicit drugs by nonaqueous capillary electrophoresis and electrochemical detection.

Nonaqueous capillary electrophoresis (NACE) was applied to the determination of illicit drugs. The complete separation of amphetamine, methamphetamine, 3,4-methylene dioxy amphetamine (MDA), 3,4-methylene dioxy methamphetamine (MDMA), mescaline, cocaine and benzoylecgonine was obtained using an acetonitrile based buffer solution containing 10 mM sodium acetate and 1 M acetic acid. Electrochemical detection using a Pt microdisk electrode set to a potential of +1.8 V was found to be selective for MDA, MDMA and mescaline. The detection limits for these compounds were in the low ng/mL range which is between 2 and 3 orders of magnitude lower compared to UV-detection.

3,4-Methylenedioxyamphetamine↗

Antagonism of the effects of the hallucinogen DOM and the purported 5-HT agonist quipazine by 5-HT2 antagonists.

Rats trained to discriminate 1.0 mg/kg of 1-(2,5-dimethoxy-4-methylphenyl)-2-aminopropane (DOM) from saline in a two-lever operant choice task were administered doses of mescaline, LSD, 5-methoxy-N,N-dimethyltryptamine (5-OMe DMT), quipazine, TFMPP and RU-24969. The DOM-stimulus generalized to the three hallucinogenic agents and to quipazine, but not to the purported serotonin agonists TFMPP or RU-24969. Pretreatment of the animals with the 5-HT2 antagonists ketanserin and pirenperone antagonized the effect produced by DOM. Pirenperone also blocked DOM-stimulus generalization to mescaline, LSD, 5-OMe DMT and quipazine. The results of this study suggest that the discriminative stimulus effects of DOM, the three hallucinogenic agents to which DOM-stimulus generalization occurred, and quipazine, may involve those sub-populations of serotonin receptors that are labeled by tritiated ketanserin (i.e. 5-HT2 sites).

DOM 2,5-Dimethoxy-4-Methylamphetamine↗