Mescaline produces pathological aggression in rats regardless of age or strain

Effects of hallucinogenic agents mescaline and phencyclidine on zebrafish behavior and physiology

Mescaline and phencyclidine (PCP) are potent hallucinogenic agents affecting human and animal behavior. As their psychotropic effects remain poorly understood, further research is necessary to characterize phenotypes they evoke in various animal models. Zebrafish (Danio rerio) are rapidly emerging as a new model organism for neuroscience research. Here, we examine the effects of mescaline (5-20mg/l) and PCP (0.5-3mg/l) in several zebrafish paradigms, including the novel tank, open field and shoaling tests. Mescaline and PCP dose-dependently increased top activity in the novel tank test, also reducing immobility and disrupting the patterning of zebrafish swimming, as assessed by ethograms. PCP, but not mescaline, evoked circling behavior in the open field test. At the highest doses tested, mescaline markedly increased, while PCP did not affect, zebrafish shoaling behavior. Finally, 20mg/l mescaline did not alter, and 3mg/l PCP elevated, whole-body cortisol levels. Overall, our studies indicate high sensitivity of zebrafish models to hallucinogenic compounds with complex behavioral and physiological effects.

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.

The psychobiology of play: theoretical and methodological perspectives

The social play of pairs of juvenile rats can be brought under tight experimental control using social deprivation, and it can be objectively quantified by measurement of pinning behavior. Research and conceptual issues concerning this paired-encounter procedure are summarized, including issues related to measurement, gender differences (and the absence thereof), relations between play and aggression, the regulatory processes interacting with and underlying play, the neurochemical and neuroanatomical substrates of play, the functions of play in dominance and other adult behaviors. Existing results suggest the operation of a harmoniously operating brain process which generates a unique emotive brain process that is appropriately referred to as social play. Although the concept of play remains to be adequately defined, the position is advocated that rigorous psychobiological analysis will ultimately provide an empirical definition based upon neural circuit characteristics. Analysis of the underlying circuits may help reveal the manner in which more complex levels of behavioral competence arise ontogenically, and work in the area may yield clues to the genesis of several psychopathologies.

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.