Psychoactivity of normacromerine in animals

Mescaline effects on rat behavior and its time profile in serum and brain tissue after a single subcutaneous dose

RATIONALE

Mescaline is a nonselective serotonin receptor agonist. It has relatively delayed onset of action and prolonged duration. Mescaline attenuates various behavioral parameters in rats; however, no information is available about its pharmacokinetics in rats and its relation to the behavioral changes produced by the drug.

OBJECTIVES

The present study evaluates the spontaneous locomotor activity and sensorimotor gating in relation to mescaline concentrations in the serum and the brain of rats

MATERIALS AND METHODS

Behavioral changes induced by mescaline [10, 20, and 100 mg/kg subcutaneously (s.c.)] were evaluated in an open-field test and testing of the prepulse inhibition of acoustic startle reaction (PPI) 15 and 60 min after drug administration. The time disposition of mescaline 20 mg/kg s.c. in rat serum and brain homogenates was analyzed by gas chromatography-mass spectrometry.

RESULTS

Mescaline produced significant inhibitory effects on locomotion in low doses and a biphasic effect with the highest dose. In the PPI test, only when tested 60 min after drug administration, all doses of mescaline disrupted PPI. Besides the experimental protocol, we have observed that approximately 50% of animals receiving 100 mg/kg died within 12 h post-injection. The serum levels of mescaline rapidly increased within 30 min and subsequently quickly decreased; however, the brain concentrations reached a maximum 1 h after administration and remained high for an additional 60 min.

CONCLUSIONS

Mescaline had a delayed onset of the main behavioral changes in rats compared to other hallucinogens. Behavioral changes correlated with the pharmacokinetics of the drug.

Mescaline-induced motor impairment in rats, assessed by two different methods

Motor impairment, especially ataxia, is often mentioned as a 'side effect' of doses of psychoactive drugs which depress animal behaviour; it is difficult to determine it accurately from visual observation, but relatively few attempts have been made to measure it objectively and quantitatively. Mescaline, in moderate to large doses, can induce biphasic--depressant followed by stimulant--effects on learnt and other performance of laboratory rodents. Motor impairment, using three doses, was accordingly measured during the depressant phase by two methods. An 'ataxia' test, involving analyses of footprints, showed few irregularities of gait splay due to mescaline, but the drug markedly reduced the length of steps ('stride') in a dose-related manner. In a 'tilt plane' test for general motor control, the animals' ability to cling to a tilted plane decreased with 25 mg/kg mescaline, at 30 and 40 minutes after administration. Deficits of this kind can be relevant to interpreting drug actions on forms of behaviour which involve movements for responding, and they also have interesting potential in their own right.

[14C]normacromerine fate in the rat

The biological fate of [14C] normacromerine , a dimethoxylated phenethylamine derivative with putative hallucinogenic properties, was evaluated in male Sprague-Dawley rats at 100 mg/kg po. Urine was the primary elimination route accounting for 50% of administered carbon-14 after 24 h. Of this urine radioactivity, normacromerine comprised 30% at 8 h decreasing to nondetectable levels at 24h. Carbon-14 in feces represented less than 10% of the administered dose at 24 h, and 14CO2 expiration was not detected. Studies of normacromerine fate in comparison with previously studied phenethylamines may enhance evaluation of hallucinogenic potential of normacromerine .

Catecholamine metabolism in a psychoactive cactus

The Dona Ana cactus, Coryphantha macromeris (Engelm.) Br. and R. and its runyonii (Br. and R.) L. Benson variety are being promoted as natural and legal psychedelic agents with about one-fifth potency of peyote [Lophophora williamsii (Lem.) Coult.]. Like peyote, Dona Ana produces and accumulates various methylated catecholamine derivatives. Of these phenethylamines, normacromerine (N-methyl-3,4-dimethoxy-beta-hydroxyphenethylamine) is by far the most abundant and has been shown to affect animal behavior in such a way as to suggest psychoactivity. It has been demonstrated that the catecholamines epinephrine and norepinephrine occur naturally in C. macromeris var. runyonii and serve as biosynthetic intermediates in normacromerine biosynthesis. Catecholamine precursors and derivatives have also been shown to be part of the metabolic pathway leading to the formation of normacromerine in Dona Ana. Normacromerine appears to be the end product of catecholamine metabolism since recent studies have revealed that very little of this compound is metabolized once it has been formed by the cactus. Completed research of this type has allowed the comparison of catecholamine metabolism leading to the formation of a mind-altering drug in a cactus plant and the metabolism of catecholamines in humans. These data together with evidence from future research will allow biochemical analogies which may suggest etiologies for certain types of mental illness.

Macromerine and normacromerine biosynthesis in Coryphantha macromeris var. runyonii

The biosynthetic conversion of epinephrine to normacromerine in Coryphantha macromeris (Engelm.) Br. and R. var. runyonii (Br. and R.) L. Benson (Cactacae) has been studied. Metanephrine, which has been isolated from this cactus and is a normal metabolite of epinephrine in mammalian systems, appeared to be the likely intermediate between epinephrine and normacromerine. Normacromerine turnover studies suggested a 16-day interval between metanephrine administration and harvest of the cacti. During this incubation period, the cacti specifically converted 4.77% of the administered DL-7-3H-metanephrine to normacromerine. Based on biochemical precedents, the postulated metabolic fate of normacromerine in the cactus was an enzymatic N-methylation to give macromerine. However, radiolabeled normacromerine was a very ineffecient precursor to macromerine.