Nicotine Alters Brain Circuits to Heighten Food-Seeking Behavior, Study Finds

A recent study demonstrated that long-term nicotine exposure reprograms certain neural circuits in the brain, substantially enhancing the drive to seek and obtain food.

According to the journal Biological Psychiatry, researchers clarified that this effect is not due to increased enjoyment of eating but results from an intensified compulsive urge to consume food. They suggested that this neural mechanism might explain why smokers often exhibit compulsive behaviors linked to reward systems.

A research team led by neuroscientist Renan Campos from Purdue University conducted an experiment on male mice, providing them with water containing gradually increasing doses of nicotine over six weeks. Subsequently, the mice were trained to press a lever to receive palatable food pellets. Their motivation was assessed using a progressive test where the number of lever presses required for each pellet increased incrementally. The results showed that nicotine-exposed mice pressed the lever at a significantly higher rate compared to the control group.

The researchers explained that continuous nicotine exposure mimics the effect of the neurotransmitter acetylcholine, leading to reduced sensitivity of nicotine receptors in dopaminergic neurons within the ventral tegmental area. The dopaminergic system compensates for this reduction by increasing its activity, creating a state of heightened motivation.

Additionally, scientists observed disruptions in neural circuits extending to the dorsal raphe nucleus. Three-dimensional tissue reconstructions revealed a marked decrease in connectivity between the ventral tegmental area and the dorsal raphe nucleus, characterized by a sharp decline in synaptic contact points and shrinkage of remaining synapses. This results in the removal of acetylcholine's inhibitory influence on dopaminergic neurons.

The team noted that restoring the function of this neural circuit through chemogenetic techniques completely eliminated the excessive food-seeking behavior in nicotine-exposed mice.