More research is needed to determine how and under what drinking conditions alcohol consumption is affected by different serotonin receptor antagonists. In addition, researchers must investigate whether the effects of these drugs vary among subgroups of alcoholics (e.g., alcoholics with different drinking patterns or with co-occurring mental disorders). For example, recent evidence indicates that buspirone—an agent that binds to the 5-HT1A receptor and which is used as an anxiety-reducing (i.e., anxiolytic) medication—also increases the time of abstinence from heavy drinking (Litten et al. 1996; Pettinati 1996).
Consequently, an alcohol-induced increase in 5-HT3 receptor activity would enhance dopamine release in these brain regions, thereby contributing to alcohol’s rewarding effects. This hypothesis is supported by the results of studies in animal models (Campbell and McBride 1995; Grant 1995; Wozniak et al. 1990), which also found that 5-HT3 receptor antagonists interfered with the serotonin-induced dopamine release in the brain’s reward systems. These findings may help explain the antagonists’ ability to reduce drinking behavior. Serotonin is an important brain chemical that acts as a neurotransmitter to communicate information among nerve cells.
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These two subtypes are namely GABA A receptor α1 (GABRA1) and GABA A receptor α6 (GABRA6). The gene encoding GABRA1 is located on chromosome 5 at 5q34-35 while the gene encoding GABRA6 is located on the same chromosome at 5q34. According to a study by, a significant correlation was found with the GABRA1 genotype and Collaborative Study of the Genetics of Alcoholism (COGA) AD, history of blackouts, age at first drunkenness as well as the level of response to alcohol.
Some studies have shown that short-term alcohol exposure inhibits glutamate receptor function (Lovinger et al. 1990) and stimulates GABAA receptor function in the hippocampus (Weiner et al. 1994). Indeed, Morrisett and Swartzwelder (1993) reported that short-term alcohol exposure decreased LTP in the hippocampus (Bliss and Collingridge 1993). Thus, if LTP does play a role in memory storage processes, alcohol’s general inhibitory effect on memory could be related in part to its effects on glutamate and GABA systems (Weiner et al. 1997; Valenzuela and Harris 1997). Several studies have shown that changes in the DA system in the CNS can influence drinking behaviors both in animals and in humans.
Dopamine’s Tonic-Nonsynaptic Actions
Furthermore, the trend toward decreased dopamine release in the males with no abstinence might have become significant had those subjects been put through abstinence periods like the male subjects in Cohort 3 of this study. The main inhibitory neurotransmitter in the brain is gamma-aminobutyric acid (GABA). Acting through a receptor subtype called GABAA, GABA leads to a state of sedation and decreased anxiety.
Researchers currently are trying to determine whether alcoholics with abnormal serotonin metabolite levels have specific variations in the gene that codes for the enzyme tryptophan hydroxylase, which produces serotonin from other molecules in the cells. Several variants of the tryptophan hydroxylase gene exist; one variant how does alcohol affect dopamine appears to be particularly common in alcoholics with histories of aggression and suicidal tendencies (Virkkunen et al. 1995). Alcohol reduces glutamate excitotoxicity (VTA); enhances GABA inhibitory activity (VTA) and enhances dopamine release from the VTA to NA by disinhibiting GABA via endogenous opioids.
What Is Dopamine?
Current research strongly suggests that alcohol affects multiple neurotransmitter systems in the brain. Virtually all brain functions depend on a delicate balance between excitatory and inhibitory neurotransmission. Research findings indicate that the consequences of short- and long-term brain exposure to alcohol result from alterations in this balance. However, many questions remain about the effects of alcohol on this delicate equilibrium. In addition, little is known about the molecular mechanisms of craving and addiction. Knowledge of the higher levels of neural integration is required to completely determine how alcohol affects these processes.
In addition, one of the latest studies on this pathway found an association between a polymorphism in the promoter of a glutamate receptor subunit gene and alcoholism. The study was conducted by and the study found that short alleles were significantly less frequent among AD subjects. The study concludes by stating that it was the 1st time that such an association was found with the stated polymorphism and AD. Candidate genes suggested in the development of alcohol addiction are involved in the dopaminergic, serotoninergic, GABA and glutamate pathways.
An activated neuron sends chemical signaling molecules called neurotransmitters through the neural circuit which bind to specific molecules called the receptors. Depending upon the circuit involved, the binding of these neurotransmitters may cause excitatory or inhibitory signals to be passed further along the circuit. Dopaminergic neurons that relay information to the NAc shell are extremely sensitive to alcohol. For example, in studies performed in rats, alcohol injected into the blood in amounts as low as 2 to 4 milligrams per kilogram of body weight increased dopamine release in the NAc shell and maintained chronic alcohol self-administration (Lyness and Smith 1992).
This is why the signs of overindulgence include slurred speech, bad or antisocial behavior, trouble walking, and difficulty performing manual tasks. Alcohol is especially taxing on the liver because the organ must break down harmful substances, including alcohol. People who drink heavily for long periods of time might develop steatosis, a condition in which fat accumulates in the liver and causes fatigue and abdominal pain. Other liver diseases can develop including hepatitis, which is an inflammatory condition of the liver, or cirrhosis, which involves liver damage and scar tissue and can lead to an early death. Low concentrations of ethanol can directly interact with several molecules (Cui and Koob, 2017).