Endocannabinoids Elevated Mood State in Mice but Chronic Nicotine Changed This Response | Research

The takeaway

Blocking endocannabinoid signaling decreased positive taste reactions and increased negative ones in mice, effects that were altered by chronic nicotine exposure, suggesting endocannabinoid-nicotine interactions in emotional state regulation.

Read this if you are interested in how the endocannabinoid system affects mood and how nicotine changes that.

Endocannabinoid blockade worsened emotional state; chronic nicotine modified this relationship

What the researchers found

Researchers used taste reactivity (reactions to sweet and bitter tastes) to measure emotional state in mice during chronic nicotine treatment and withdrawal.

Chronic nicotine itself did not change taste reactions, and neither did spontaneous nicotine withdrawal.

However, the CB1 receptor blocker AM251 had clear effects: it decreased positive reactions to sucrose (sweet) and increased negative reactions to quinine (bitter), suggesting that endocannabinoids normally contribute to positive emotional state.

In nicotine-treated mice, the effects of AM251 were modified: the decrease in positive reactions was attenuated while the increase in negative reactions was enhanced, suggesting chronic nicotine exposure alters endocannabinoid emotional regulation.

Why it matters

This study revealed that endocannabinoids contribute to normal emotional state and that chronic nicotine exposure changes how the endocannabinoid system regulates emotion, potentially relevant to understanding tobacco-cannabis co-use patterns.

The numbers in context

Nicotine dose: 12 mg/kg/day. AM251 doses: 1, 3, 10 mg/kg. AM251 decreased positive sucrose reactions and increased negative quinine reactions. Chronic nicotine modified both AM251 effects.

How the study worked

Mouse study using intraoral taste reactivity to measure affective state. Mice received chronic nicotine (12 mg/kg/day via osmotic minipump) or vehicle. The CB1 antagonist AM251 (1, 3, 10 mg/kg) was administered during chronic nicotine to test endocannabinoid involvement.

What this study cannot tell us

Taste reactivity is an indirect measure of emotional state. Mouse emotional responses may not translate to human subjective experiences. The nicotine doses and administration method (continuous infusion) may not model typical human smoking patterns.

How to read the evidence

Preclinical study using an indirect measure of emotional state in mice. Provides mechanistic insight but limited translational value.

When this study was published

Published in 2009. Endocannabinoid-nicotine interactions have continued to be an area of active research.

The bigger picture

Tobacco and cannabis are frequently used together. Understanding how nicotine exposure alters endocannabinoid emotional regulation could explain why some tobacco users turn to cannabis and vice versa.

Questions still open

Do endocannabinoid-nicotine interactions explain the high rates of cannabis-tobacco co-use? Could targeting the endocannabinoid system help with tobacco cessation? Does tobacco use alter how people experience cannabis?

Common questions

What is taste reactivity and what does it measure?

Taste reactivity measures facial and body reactions to sweet or bitter tastes, which are thought to reflect underlying emotional state. Positive reactions to sweet tastes and negative reactions to bitter tastes serve as indicators of how an animal is "feeling."

Why did chronic nicotine not affect emotional state but the endocannabinoid blocker did?

Nicotine may maintain emotional state through compensatory mechanisms, including the endocannabinoid system. When endocannabinoid signaling was blocked, these compensatory mechanisms were disrupted, revealing the altered state underlying chronic nicotine exposure.

Read the original research

Measurement of affective state during chronic nicotine treatment and withdrawal by affective taste reactivity in mice: the role of endocannabinoids.

Biochemical pharmacology, 78(7), 825-35

View on PubMed ↗Publisher’s paper ↗

Citation

Wing, Victoria C; Cagniard, Barbara; Murphy, Niall P; Shoaib, Mohammed. (2009). Measurement of affective state during chronic nicotine treatment and withdrawal by affective taste reactivity in mice: the role of endocannabinoids.. Biochemical pharmacology, 78(7), 825-35. https://doi.org/10.1016/j.bcp.2009.06.017