This (2008) review summarises the published research into hallucinogen-induced stimulus control in phenethylamine- and tryptamine-based hallucinogens, highlighting the receptors involved in their mechanism of action.
Abstract of Hallucinogens as discriminative stimuli in animals
“Background: Although man’s first encounters with hallucinogens predate written history, it was not until the rise of the sister disciplines of organic chemistry and pharmacology in the nineteenth century that scientific studies became possible. Mescaline was the first to be isolated and its chemical structure determined. Since then, additional drugs have been recovered from their natural sources and synthetic chemists have contributed many more. Given their profound effects upon human behavior and the need for verbal communication to access many of these effects, some see humans as ideal subjects for study of hallucinogens. However, if we are to determine the mechanisms of action of these agents, establish hypotheses testable in human subjects, and explore the mechanistic links between hallucinogens and such apparently disparate topics as idiopathic psychosis, transcendental states, drug abuse, stress disorders, and cognitive dysfunction, studies in animals are essential. Stimulus control by hallucinogens has provided an intuitively attractive approach to the study of these agents in nonverbal species.
Objective: The intent of this review is to provide a brief account of events from the time of the first demonstration of hallucinogen-induced stimulus control to the present. In general, the review is limited to lysergic acid diethylamide (LSD) and the hallucinogenic derivatives of phenethylamine and tryptamine.
Results: The pharmacological basis for stimulus control by LSD and hallucinogenic phenethylamines and tryptamines is serotonergic in nature. The 5-HT2A receptor appears to be the primary site of action with significant modulation by other serotonergic sites including 5-HT2C and 5-HT1A receptors. Interactions with other neurotransmitters, especially glutamate and dopamine, are under active investigation. Most studies to date have been conducted in the rat but transgenic mice offer interesting possibilities.
Conclusions: Hallucinogen-induced stimulus control provides a unique behavioral tool for the prediction of subjective effects in man and for the elucidation of the pharmacological mechanisms of the action of these agents.”
Author: Jerrold C. Winter
Summary of Hallucinogens as discriminative stimuli in animals
Hallucinogens have been known to man for thousands of years, but it was not until the rise of organic chemistry and experimental pharmacology in the nineteenth century that a well-defined substance could be said to produce hallucinations.
Self-administration of psychoactive drugs was a prominent role in the initial investigation of these drugs. However, ethical considerations have placed significant constraints on the type of experiments undertaken, so investigators have often turned to infrahuman species in their quest for the mechanism of action of drugs.
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Hallucinogens as discriminative stimuli in animals: LSD, phenethylamines, and tryptamines
https://doi.org/10.1007/s00213-008-1356-8
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Winter, J. C. (2009). Hallucinogens as discriminative stimuli in animals: LSD, phenethylamines, and tryptamines. Psychopharmacology, 203, 251-263.