Disturbance in brain neurotransmitters,
specifically acetylcholine is involved in
developing nicotine addiction.
A new understanding of how nicotine addiction has emerged. One reason people find it hard to quit smoking is that each time they have a cigarette, feelings of craving, irritability and anxiety melt away. This is known as negative reward. The neurotransmitters acetylcholine and glutamate are thought to influence nicotine dependence. Neurotransmitters are the chemical messengers of the brain. Even a small upset in the balance of neurotransmitters can affect behavior. In the case of acetylcholine, it can influence our ability to cope with addiction. The researchers created an animal model where a key gene involved in acetylcholine processing was missing; this prevented acetylcholine production in brain region. The elimination of acetylcholine affected glutamate in the brain in two ways.
First, the amount of glutamate released by neurons was reduced; second, the reuptake of glutamate back into vesicles was impaired. Both of these mechanisms disrupt normal signaling, thus affecting the excitability of neurons. Based on these findings, the researchers suggest that acetylcholine regulates how much glutamate is released into the synapse, and at what frequency. It also facilitates the packaging of glutamate into vesicles. Studies confirmed that the neurotransmitters are in the same place at the same time and are able to affect one another. When the researchers removed acetylcholine from the brain region, insensitivity towards rewards of nicotine was developed. The research showed that neither tolerance was developed to continued nicotine exposure, nor withdrawal symptoms, such as body shakes and scratching. The findings suggest that without acetylcholine, nicotine addiction would not occur. They also disclose new clues about the brain circuitry involved in nicotine dependence, which is relevant to opioid and cannabinoid addiction.
Source: Medical news today