Essay On The Mechanism Of Alcohol

The mechanism of action of ethanol

Jade Lim is young Asian student with little previous exposure to alcohol. After consuming one and a half Bacardi Breezer’s (1.5 standard drinks) she begins to feel nauseas and has a pulsating headache. It is important to understand the mechanism of action of ethanol in order to determine the potential effects on the patient. This report will investigate the underlying molecular mechanisms of ethanol.

Ethanol is a central nervous system (CNS) depressant. It is the principal psychoactive constituent in alcoholic beverages making it the most commonly available drug in society. Ethanol can cause alcohol intoxication when consumed in high amounts. Once consumed, ethanol diffuses rapidly from the digestive tract into the bloodstream. As ethanol is a small, uncharged molecule it can easily cross the blood-brain barrier (Chandra 2008). Ethanol affects neuronal activity by altering the function of specific proteins, and inhibiting neurotransmission. Ethanol primarily exerts its effects by potentiating the action of endogenous neurotransmitters at the inhibitory receptor GABAA, or via inhibiting the excitatory effects of glutamate on the NMDA receptor (Harris et. al. 2008).

γ-aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the CNS. GABAA is a ligand gated ion channel composed of five subunits. Through positive allosteric modulation ethanol binds to the δ subunit of the receptor and enhances the inhibitory effect of GABA. Once ethanol has bound to the GABAA receptor, chloride ions enter the post-synaptic neuron. This cascade of ions hyperpolarises the neuron, thus increasing inhibitory effects and makes the neuron less excitable. Ethanol alters the enzyme kinetics enabling the ion...

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...y binding to the α2 subunit of glycine receptors on the spinal cord (Ye et. al. 1998). Ethanol also helps to increase the release of dopamine, by a process that is still poorly understood but that appears to involve restricting the activity of monoamine oxidase, the enzyme that breaks dopamine down (DiChiara 1997). The precise molecular mechanisms of ethanol are extremely complex and still not fully understood.

The pathways discussed above are responsible for CNS depression. The patient’s symptoms of nausea and headaches are not consistent with the depression of the CNS. These negative side effects may be due to the toxic actions of ethanol metabolites in the body, however require further investigation. A detailed understanding of the mechanisms underlying the action of ethanol would facilitate development in managing the unwanted symptoms of alcohol consumption.