Title

Nicotine Enhances the Hypnotic and Hypothermic Effects of Alcohol in the Mouse

Student Author(s)

Lindsey G. Soll

Academic Program

Neuroscience

UMMS Affiliation

Brudnick Neuropsychiatric Research Institute, Department of Psychiatry; Tapper Lab

Publication Date

2016-01-01

Document Type

Article

Disciplines

Neuroscience and Neurobiology | Psychiatry and Psychology | Substance Abuse and Addiction

Abstract

BACKGROUND: Ethanol (EtOH) and nicotine abuse are 2 leading causes of preventable mortality in the world, but little is known about the pharmacological mechanisms mediating co-abuse. Few studies have examined the interaction of the acute effects of EtOH and nicotine. Here, we examine the effects of nicotine administration on the duration of EtOH-induced loss of righting reflex (LORR) and characterize the nature of their pharmacological interactions in C57BL/6J mice.

METHODS: We assessed the effects of EtOH and nicotine and the nature of their interaction in the LORR test using isobolographic analysis after acute injection in C57BL/6J male mice. Next, we examined the importance of receptor efficacy using nicotinic partial agonists varenicline and sazetidine. We evaluated the involvement of major nicotinic acetylcholine receptor (nAChR) subtypes using nicotinic antagonist mecamylamine and nicotinic α4- and α7-knockout mice. The selectivity of nicotine's actions on EtOH-induced LORR was examined by testing nicotine's effects on the hypnotic properties of ketamine and pentobarbital. We also assessed the development of tolerance after repeated nicotine exposure. Last, we assessed whether the effects of nicotine on EtOH-induced LORR extend to hypothermia and EtOH intake in the drinking in the dark (DID) paradigm.

RESULTS: We found that acute nicotine injection enhances EtOH's hypnotic effects in a synergistic manner and that receptor efficacy plays an important role in this interaction. Furthermore, tolerance developed to the enhancement of EtOH's hypnotic effects by nicotine after repeated exposure of the drug. α4* and α7 nAChRs seem to play an important role in nicotine-EtOH interaction in the LORR test. In addition, the magnitude of EtOH-induced LORR enhancement by nicotine was more pronounced in C57BL/6J than DBA/2J mice. Furthermore, acute nicotine enhanced ketamine and pentobarbital hypnotic effects in the mouse. Finally, nicotine enhanced EtOH-induced hypothermia but decreased EtOH intake in the DID test.

CONCLUSIONS: Our results demonstrate that nicotine synergistically enhances EtOH-induced LORR in the mouse.

Keywords

Ethanol, Nicotine, Mice, Loss of Righting Reflex

DOI of Published Version

10.1111/acer.12918

Source

Alcohol Clin Exp Res. 2016 Jan;40(1):62-72. doi: 10.1111/acer.12918. Link to article on publisher's website

Journal/Book/Conference Title

Alcoholism, clinical and experimental research

Related Resources

Link to article in PubMed

PubMed ID

26727524

Link to Full Text

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