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Discriminative stimulus properties of mescaline: mescaline or metabolite?

The purpose of this study was to investigate possible similarities in the interoceptive stimuli produced by mescaline and its metabolites. Rats were trained in a 2 lever operant chamber to discriminate between the drugged state (mescaline 25 mg/kg) and the nondrugged state (saline). Following acquisition of discriminative response control the rats were pretreated with either saline, aldehyde dehydrogenase inhibitors or amine oxidase inhibitors and tested stimulus generalization produced by i.p. injections of 3, 4, 5-trimethoxyphenylethanol (TMPE), 3, 4, 5-trimethoxyphenylacetaldehyde (TMPA), N-acetylmescaline, mescaline or saline. The results indicated that both aldehyde dehydrogenase and amine oxidase inhibitors enhanced the effects of mescaline, while TMPE, TMPA and N-acetylmescaline failed to exhibit generalization to the mescaline state, regardless of pretreatment. These findings do not indicate the role of a metabolite in the interoceptive cue produced by mescaline.

Aldehyde Oxidoreductases

Neurolepticlike actions of l-methadone: effect on mescaline-induced altered behavior and on tissue levels of mescaline in mice.

Mice were injected ip with either saline, l-methadone (2.5, 5, 20 mg/kg), perphenazine (1, 10, 15 mg/kg), or chlorprothixene (1.25, 2.5, 15 mg/kg) 30 min prior to mescaline-14C (25 mg/kg). Mescaline-induced behavioral changes such as agitation, excitement, slight increase in ventilation, and fright to sound stimuli were prevented by all doses of three drugs, and head-shaking, scratching, and locomotor-increasing effects by 5 and 20 mg/kg methadone and by all doses of both neuroleptics. Catalepticlike state and moderate to marked hypothermia induced by all doses of chlorprothixene, 10 and 15 mg/kg perphenazine, and 20 mg/kg methadone were not reversed by mescaline. Chlorprothixene (all doses), perphenazine (10, 15 mg/kg), and methadone (5, 20 mg/kg) caused marked retention of mescaline and its deaminated metabolite, 3, 4, 5-trimethoxyphenyl acetic acid in both brain and plasma. The fact that relatively higher doses of methadone than neuroleptics are needed to ensure effective antagonism to mescaline action tends to indicate a less specific interaction of the opiate with the neuroleptic/dopamine receptor proposed for central mescaline effects.

Animals

Mescaline-induced changes of brain-cortex ribosomes. Mescaline demethylase activity of brain-cortex soluble supernatant.

Brain-cortex slices demethylate mescaline and p-methoxyacetanilide, a reference O-demethylating substrate, though the rate of demethylation of mescaline is about one third that of the reference substrate. The demethylase activity is localized mostly in the soluble supernatant (105 000 x g). It is purified 47-fold with respect to the demethylation of mescaline by ammonium sulfate precipitation and DEAE cellulose chromatography. The partially purified demethylase, which is stable for 3-5 days at -5 degrees C in the presence of dithiothreitol and glutathione and is inhibited by p-chloromercuribenzoate, has maximal activity at pH between 7.2 and 8.0. It demethylates mescaline into 3,4-dimethoxy-5-hydroxyphenethylamine and 3,5-dimethoxy-4-hydroxyphenethylamine and some unidentified derivatives.

Acetamides

Binding of mescaline with subcellular fractions upon incubation of brain cortex slices with [14C] mescaline.

Incubation of brain cortex slices in the presence of glucose resulted in the permeation of about 65% of [14C] mescaline into slices. Of this, about one-third radioactivity was bound with nuclei, mitochondria, microsomes, and ribosomes. Dialysis of subcellular fractions did not markedly reduce the amounts of radioactivity bound to the fractions. The permeation into slices and the binding of mescaline to subcellular fractions were fairly time-dependent, but were inhibited by the presence of potassium cyanide, or by the absence of glucose and by heating to 80 degrees C for 1 min.

Animals

3H-metaraminol releasing action of mescaline from rat hypothalamus in vitro.

The amine releasing action of mescaline was investigated in rat isolated hypothalamus labeled with 3H-metaraminol. Mescaline had no effect on the uptake of 3H-metaraminol but produced its release in a concentration-related manner. 4 x 10(-4) M mescaline, which produced submaximal effects was used for subsequent experiments. 3 x 10(-5) M cocaine had no effect on the 3H-metaraminol releasing action of mescaline. Mescaline was fully effective in Ca2+-free medium while 6 x 10(-2) M KCl was ineffective. 3 x 10(-7) M tetrodotoxin or 6 x 10(-5) M lidocaine partially blocked mescaline-induced release but substantially or completely blocked 3 x 10(-2) M KCl-induced release. Prior exposure of hypothalamus to 3 x 10(-4) M tyramine reduced the releasing action of mescaline. Thus, mescaline appears to release 3H-metaraminol both by Ca2+-independent (tyramine-like) and Ca2+-dependent (lidocaine-sensitive) mechanisms. 3 x 10(-4) M tyramine and 6 x 10(-2) M KCl released 14C from control hypothalamus labelled with 14C-mescaline, but not from reserpinized hypothalamus. The amounts of 14C recovered in 14C-mescaline labeled control and reserpinized hypothalamus at the end of 50 min of efflux were similar suggesting a poor retention of 14C-mescaline by storage particles.

Animals

The effects of 2,5-dimethoxy-4-methylamphetamine (DOM), 2,5-dimethoxy-4-ethylamphetamine (DOET), d-amphetamine, and cocaine in rats trained with mescaline as a discriminative stimulus.

The effects of mescaline (3,4,5-trimethoxyphenylethylamine), a hallucinogen, can function as a discriminative stimulus in appropriately trained rats. As a test of the hypothesis that those pharmacologic properties which distinguish hallucinogens and non-hallucinogens in man are reflected in distinctive stimuli in rats, the present experiments examined the effects of 2,5-dimethoxy-4-methylamphetamine (DOM), 2,5-dimethoxy-4-ethylamphetamine (DOET), d-amphetamine, and cocaine in rats trained with mescaline as a discriminative stimulus. Administration of a range of doses of DOM and DOET to subjects in which saline functioned as SD and mescaline as Sdelta revealed that a dose of 0.3 mg of either DOM or DOET was equivalent to the training dose of mescaline. When tested in rats in which mescaline served as SD, DOM and DOET were likewise found to mimic mescaline. In contrast, doses of d-amphetamine and cocaine (1 and 30 mg/kg, respectively) which were equivalent to the training dose of mescaline as Sdelta, did not result in responding appropriate for the mescaline condition when mescaline was trained as SD. When DOET (0.3 mg/kg) was substituted for saline as Sdelta, no evidence of discriminated responding was obtained in the course of 50 sessions. The present data, in conjunction with previous observations, suggest that those effects of mescaline in the rat which function as a discriminative stimulus are better correlated with pre-hallucinogenic LSD-like activity in man then with hallucinogenic activity per se. Thus, these effects in rats represent a necessary but not a sufficient condition for prediction of hallucinogenic activity in man.

DOM 2,5-Dimethoxy-4-Methylamphetamine

Disposition of 14C-mescaline by rabbit lung.

Metabolism of mescaline by several rabbit tissues was examined in vitro. Mescaline-oxidizing activity (micromoles per milligram of protein/15 min) of lung homogenates was 4 times greater than that of either liver or kidney. Brain and plasma each had comparatively little capacity to metabolize mescaline. Mescaline metabolism in vitro was sensitive to inhibition by semicarbazide. Removal of mescaline from the medium perfusing the isolated rabbit lung was explained by intrapulmonary metabolism. Semicarbazide (10(-3) M pargyline. Semicarbazide-treated lungs accumulated more mescaline than did untreated lungs. Mescaline efflux from lung was slower than that of its metabolite. These results indicate that the intact lung removes perfused mescaline and may be important in the disposition of circulating mescaline in vivo.

Animals

The uptake and distribution of 14-C-mescaline in different organs of developing rat.

Rats of 1,4,8,12,20, and 60 days postnatal age were injected ip with 14-C-mescaline (50 nCi/g). The levels of mescaline and its deaminated metabolite, 3,4,5-trimethoxyphenylacetic acid, were examined in the brain, liver, heart, spleen, lung, and kidney at 30, 60, 90, and 120 min. Mescaline was rapidly taken up by all the organs examined. In general, the organs of younger rats accumulated much larger amounts than those of adult animals. Brain concentrated the lowest amounts in comparison with other tissues. In the brain, the uptake was the highest in 1-day-old rats and decreased with age. The disappearance of mescaline in various organs was comparatively slower in younger animals than in 20-day or older rats. Rats immediately after birth and uptake was the highest in 1-day-old rats and decreased with age. The disappearance of mescaline in various organs was comparatively slower in younger animals than in 20-day or older rats. Rats immediately after birth and up to 20 days of age metabolized mescaline less efficiently than adults. From the data, it appears that the blood-brain barrier for mescaline develops gradually with age but is not completely impermeable in adults.

Aging

Mescaline-induced psychopathological, neuropsychological, and neurometabolic effects in normal subjects: experimental psychosis as a tool for psychiatric research.

The psychological, neuropsychological, and neurometabolic effects of the hallucinogenic agent mescaline were investigated in 12 normal men who were volunteers. Mescaline produced an acute psychotic state 3 1/2-4 hr after drug intake, as measured by the Brief Psychiatric Rating Scale (BPRS) and Paranoid Depression Scale (PDS). The Assessment of Altered States of Consciousness (APZ) questionnaire revealed specific effects of mescaline in the visual system. Neuropsychological effects were studied with a face/nonface decision task with known right-hemisphere advantage, in which mescaline induced a decrease of functioning of the right hemisphere. In functional brain imaging using single photon emission computed tomography (SPECT), mescaline produced a "hyperfrontal" pattern with an emphasis on the right hemisphere, which was correlated with mescaline-induced psychotic psychopathology. Our findings question the validity of the concept of hypofrontality as an explanation for schizophrenic symptomatology. The study of psychoactive substances under controlled laboratory conditions has the methodological advantage of intraindividual control, and hence, minimal variability of data.

Adult

Role of serotonin in the discriminative stimulus properties of mescaline.

Rats were trained to discriminate intraperitoneally administered mescaline from saline in a two-lever operant chamber for food reinforcement. Reward was contingent upon responses made greater than 15 sec apart (DRL-15) on the appropriate lever paired with either drug or saline administration. Following the establishment of discriminative response control by mescaline, the animals were tested for stimulus generalization produced by mescaline after: (a) blockade of periphreral and central serotonin (5-HT) receptors with cinanserin, methysergide, or cyproheptadine; (b) blockade of peripheral 5-HT receptors with xylamidine tosylate; and (c) depletion of brain 5-HT with the tryptophan hydroxylase inhibitor p-chlorophenylalanine (PCPA). The results show that all three central 5-HT antagonists greatly reduced the discriminability of mescaline while the peripheral antagonist, xylamidine tosylate, was without effect. Furthermore, these agents at the doses employed did not effect the discriminability of saline. Depletion of 5-HT with PCPA potentiated the effects of a sub-threshold dose of mescaline and slightly reduced the discriminability of saline. The results indicate that mescaline produces its discriminative stimulus properties by directly stimulating central serotonergic receptors.

Animals

A comparison of the effect of mescaline on activity and emotional defaecation in seven strains of mice.

1 Mescaline hemi-sulphate (35 mg/kg body weight) was injected intraperitoneally into male mice (Mus musculus) from seven genetically diverse laboratory strains. 2 The effect of mescaline was found by comparison of the emotional defaecation and open field activity of mice after mescaline injection with the performance of the same mice after a subsequent saline (0.9% w/v NaCl solution) control injection. 3 In strains A2G, C3H/He, C57BR/cd, CBA/Cam and F/St, mescaline inhibited emotional defaecation and stimulated open field activity. These effects did not occur in strains 1CFW and Schneider. 4 A positive relationship was found between the degree of emotional defaecation characteristic of each strain in the saline control experiment and the inhibitory effect of mescaline on emotional defaecation. 5 Pre-treatment of mice with tranylcypromine (20 mg/kg body weight, i.p.) had no effect on emotional defaecation or on its inhibition by mescaline.

Animals

Studies on accumulation of (14C)-mescaline in brain homogenates: effects of psychotropic and other agents.

Incubation of rat brain homogenates or 14,500 g pellet isolated from the homogenate with (14C)-mescaline was associated with accumulation of (14C)-mescaline in the pellet. 1.33 mumol/ml of chlorpromazine, trifluoperazine, fluphenazine, imipramine, desmethylimipramine, nortriptyline and amitriptyline inhibited the accumulation of mescaline. Lower concentrations (0.133-0.44 mumol/ml) of the psychotropic drugs were less effective. The tricyclic antidepressants were less potent than the tranquilizers. Although the trimethoxyphenylacetic acid (TMPA) levels of the pellet were also reduced by the psychotropic drugs, the TMPA:mescaline ratios were unchanged indicating that the drugs had no effect on the metabolism of mescaline. The inhibition of accumulation of mescaline by the high concentrations of tranquilizers may divert more of the hallucinogen to the receptor site. Thus, an explanation for the reported worsening of clinical syndrome of hallucinogenic poisoning by tranquilizers is provided.

Animals

Development of tolerance to the antinociceptive effect of mescaline intraventricularly administered to rabbits.

Some effects of intraventricular injection of mescaline are examined in conscious rabbits. By means of electrical stimulation of the tooth pulp it is shown that an acute treatment with 70, 100, 150 mug/kg of mescaline elicits analgesia, the intensity of which is dose-dependent: with daily administration of 100 mug/kg for 5 days a complete tolerance develops to the antinociceptive effect. A tolerance also develops to the behavioral effects of mescaline after repeated administrations, with the exception of the stuporous state, a symptom which, on the contrary, is accentuated as the treatment proceeds. An EEG arousal is induced in the rabbit by acutely administered mescaline; the chronic treatment (100 mug/kg) makes the return of voltage to original levels progressively slower. Finally, the confrontation of certain of the mescaline-induced effects with those of morphine suggests some biochemical and neural patterns common to the 2 drugs.

Analgesia

Blockade of the stimulus properties of mescaline by a serotonin antagonist.

It is known that the effects of mescaline (3, 4, 5-trimethoxyphenylethylamine), a hallucinogen, can function as a discriminative stimulus. The present investigation examined the ability of cinanserin, a serotinin antagonist, to block the stimulus properties of mescaline in the rat. After a reliable discrimination was established between the effects following the injection of mescaline (10 mg/kg) and those following administration of saline, subjects were pretreated with cinanserin HC1 (3 mg/kg) and then treated with mescaline. Such pretreatment was found to block discrimination, i.e., the response rate following the administration of mescaline plus cinanserin was appropriate for the saline condition. The present data suggest that antagonists of serotonin may be useful in furthering our understanding of phenethylamine hallucinogens.

Animals

Interaction of mescaline with phenothiazines: effect on behavior, body temperature, and tissue levels of hallucinogen in mice.

Mescaline (25 mg/kg; 66 muc/kg) was injected (ip) in mice 45 min before chlorpromazine (CPZ, 2.5, 5, 15 mg/kg), thioridazine (10, 30, 45 mg/kg), or chlorpromazine-sulfoxide (CPZ-SO, 15 mg/kg). Excitement, agitation, slight increase in ventilation and occasional head-shaking were seen 30 min after mescaline and continued for 30-45 min thereafter; locomotor activity and the number of scratching events were significantly increased during this period. CPZ (2.5, 5, 15 mg/kg) and thioridazine (10, 30, 45 mg/kg) partially or completely blocked mescaline-induced gross behavior; CPZ-SO (15 mg/kg) was not effective. Increased scratching responses and locomotor activity induced by mescaline were antagonized by all doses of CPZ and thioridazine; at higher doses, both CPZ (7.5, 15 mg/kg) and thioridazine (45 mg/kg) induced cataleptic-like condition and marked hypothermia. Tissue levels of mescaline, examined 3 hr after its administration, were increased by all doses of CPZ and a higher dose of thioridazine (45 mg/kg); CPZ-SO and lower doses of thioridazine had no effect.

Animals

Cactus alkaloids. XXXVI. Mescaline and related compounds from Trichocereus peruvianus.

Agurell has previously detected (tlc, glc-ms) tyramine, 3-methoxytyramine, and two unknown alkaloids in the Peruvian cactus, Trichocereus peruvianus Br. and R. The presence of mescaline in other similar Trichocereus species prompted us to reinvestigate this species, which is commercially available in the United States. The nonphenolic alkaloid extracts yielded an abundance of crystalline mescaline hydrochloride (0.82% yield) and a trace of 3,4-dimethoxyphenethylamine (tlc-ms). Crystalline tyramine hydrochloride, 3-methoxytyramine hydrochloride, and 3,5 dimethoxy-4-hydroxphenethylamine hydrochloride were isolated from the phenolic alkaloid extracts; the last compound has not been previously crystallized from nature, although it is the immediate biosynthetic precursor of mescaline. Crystalline 2-chloromescaline hydrochloride was isolated drom the nonphenolic extracts; but, as determined by mass-analyzed ion kinetic energy spectrometry, this new compound is an extraction artifact. Both 2-chloromescaline and 2.6-dichloromescaline hydrochlorides were prepared synthetically from mescaline. This cactus species has a mescaline content equal or superior to peyote and should be legally controlled as an item of drug abuse.

Chemical Phenomena