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K. Murnane

Effects of the synthetic psychedelic 2,5-dimethoxy-4-iodoamphetamine (DOI) on ethanol consumption and place conditioning in male mice.

July 15, 2019 / Papers, Psychology, Publications, Substance Use Disorder / By / , , , ,

Abstract

RATIONALE:
Approximately 20 million adults in the USA have an alcohol use disorder (AUD). There are clinical and preclinical data suggesting that psychedelics may have benefits for AUD.
OBJECTIVE:
To investigate the effects of the synthetic psychedelic 2,5-dimethoxy-4-iodoamphetamine (DOI) on the behavioral effects of ethanol.
METHODS:
The effects of DOI were examined using ethanol-induced place conditioning (1.8 g/kg ethanol) and 2-bottle choice ethanol drinking (20% v/v), using a dose of DOI (3 mg/kg) that produced the maximal response in the serotonin 2A (5-HT2A) receptor-dependent head-twitch assay. Interactions between DOI and ethanol (3 g/kg) were examined using the ethanol-induced loss of righting reflex procedure and blood-ethanol analysis. To examine additional mechanisms by which psychedelics may interact with ethanol, we determined whether DOI reverses ethanol-induced nitric oxide release in macrophages, a marker of inflammation.
RESULTS:
DOI significantly attenuated ethanol-induced place conditioning and ethanol drinking. DOI-induced suppression of alcohol drinking depended upon 5-HT2A receptors, was selective for alcohol over water, and was selective for high alcohol-preferring subjects. DOI had no apparent pharmacokinetic interactions with ethanol, and DOI reduced ethanol-induced nitric oxide release.
CONCLUSIONS:
Our findings demonstrate that DOI blocks ethanol place conditioning and selectively reduces voluntary ethanol consumption. This may be related to modulation of the effects of ethanol in the reward circuitry of the brain, ethanol-induced neuroinflammation, or a combination of both. Additional studies to elucidate the mechanisms through which psychedelics attenuate the effects of ethanol would inform the pathophysiology of AUD and potentially provide new treatment options.
Oppong-Damoah, A., Curry, K. E., Blough, B. E., Rice, K. C., & Murnane, K. S. (2019). Effects of the synthetic psychedelic 2, 5-dimethoxy-4-iodoamphetamine (DOI) on ethanol consumption and place conditioning in male mice. Psychopharmacology, 1-12., https://doi.org/10.1007/s00213-019-05328-7
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The serotonin 5-HT2C receptor and the non-addictive nature of classic hallucinogens

November 15, 2016 / LSD, Mushrooms / Psilocybin, Neuroscience, Papers, Psychology, Publications, Substance Use Disorder / By / ,

Abstract

Classic hallucinogens share pharmacology as serotonin 5-HT2A, 5-HT2B, and 5-HT2Creceptor agonists. Unique among most other Schedule 1 drugs, they are generally non-addictive and can be effective tools in the treatment of addiction. Mechanisms underlying these attributes are largely unknown. However, many preclinical studies show that 5-HT2C agonists counteract the addictive effects of drugs from several classes, suggesting this pharmacological property of classic hallucinogens may be significant. Drawing from a comprehensive analysis of preclinical behavior, neuroanatomy, and neurochemistry studies, this review builds rationale for this hypothesis, and also proposes a testable, neurobiological framework. 5-HT2C agonists work, in part, by modulating dopamine neuron activity in the ventral tegmental area—nucleus accumbens (NAc) reward pathway. We argue that activation of 5-HT2Creceptors on NAc shell, GABAergic, medium spiny neurons inhibits potassium Kv1.x channels, thereby enhancing inhibitory activity via intrinsic mechanisms. Together with experiments that show that addictive drugs, such as cocaine, potentiate Kv1.x channels, thereby suppressing NAc shell GABAergic activity, this hypothesis provides a mechanism by which classic hallucinogen-mediated stimulation of 5-HT2C receptors could thwart addiction. It also provides a potential reason for the non-addictive nature of classic hallucinogens.

Canal, C. E., & Murnane, K. S. (2016). The serotonin 5-HT2C receptor and the non-addictive nature of classic hallucinogens. Journal of Psychopharmacology, 0269881116677104.
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The behavioral pharmacology of hallucinogens

January 1, 2008 / DMT, LSD, MDMA, Mescaline / Cacti, Mushrooms / Psilocybin, Papers, Pharmacology & Chemistry, Publications / By / , ,

Abstract

Until very recently, comparatively few scientists were studying hallucinogenic drugs. Nevertheless, selective antagonists are available for relevant serotonergic receptors, the majority of which have now been cloned, allowing for reasonably thorough pharmacological investigation. Animal models sensitive to the behavioral effects of the hallucinogens have been established and exploited. Sophisticated genetic techniques have enabled the development of mutant mice, which have proven useful in the study of hallucinogens. The capacity to study post-receptor signaling events has lead to the proposal of a plausible mechanism of action for these compounds. The tools currently available to study the hallucinogens are thus more plentiful and scientifically advanced than were those accessible to earlier researchers studying the opioids, benzodiazepines, cholinergics, or other centrally active compounds. The behavioral pharmacology of phenethylamine, tryptamine, and ergoline hallucinogens are described in this review, paying particular attention to important structure activity relationships which have emerged, receptors involved in their various actions, effects on conditioned and unconditioned behaviors, and in some cases, human psychopharmacology. As clinical interest in the therapeutic potential of these compounds is once again beginning to emerge, it is important to recognize the wealth of data derived from controlled preclinical studies on these compounds.

Fantegrossi, W. E.,  Murnane, K. S., & Reissig, C. J. (2008). The behavioral pharmacology of hallucinogens. Biochemical Pharmacology 75(1), 17–33. http://dx.doi.org/10.1016/j.bcp.2007.07.018
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