Mescaline treated rats attack immobile targets

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.

Severe aggression in rats induced by mescaline but not other hallucinogens

Pairs of male Sprague-Dawley rats were administered mescaline, lysergic acid diethylamide (LSD), psilocin, N,N-dimethyltryptamine (DMT), 3,4-dimethoxyphenylethylamine (DMPEA), or 5-hydroxydopamine (5-OHDA) IP prior to being placed in a shock-elicited aggression situation. When foot shock was delivered, controls struck each other with their forepaws, but never engaged in either biting or injurious fighting. Mescaline-treated rats (50 or 250 mg) rarely struck each other, but engaged in nearly lethal biting. While LSD (25--400 micrograms/kg), psilocin (2.0 mg/kg), and DMT (5 mg/kg) produced some biting, this did not significantly differ from controls and never resulted in injuries. At higher doses, psilocin, DMT, and DMPEA decreased the amount and intensity of fighting. Rats treated with 5-OHDA (8--200 mg/kg) or LSD (25--400 micrograms/kg) did not differ from controls. These results suggest that mescaline's ability to induce pathological aggression in rats exposed to foot shock is not shared by other hallucinogens or nonhallucinogenic mescaline analogues.