Action of Alcohol in the Brain
Why does alcohol relax?
Silvia Helena Cardoso, PhD e Renato M. E. Sabbatini, PhD
André Luis Malavazzi (animation and art)
Alcohol seems to act upon existing channels in the neuron membrane, where these cells exchange ions with the environment.Through them, positive or negative ions enter or leave the neuron, thus enhancing or diminishing their electric activity.
This process, on its turn, affects all brain functions. Normally, ionic channels are opened or closed by the action of neurotransmitters or by variations in the electric potential gradient between the interior and exterior of the neurons.
When ethanol links to the GABA receptor( the channel shown in violet-blue in the image in the middle) it promotes a facilitating action of GABA inhibition. The result is a further inhibitory effect upon the brain, leading to relaxation and sedation of the organism. Several parts of the brain are affected by the sedative effect of alcohol such as those responsible for movement, memory, reasoning, respiration and so on, because there are GABA receptors in many parts of the brain. The sustained usage of alcohol can lead to dependency. Then, if the persons tops drinking, he will experience emotional discomfort, anxiety, trembling, insomnia.
Why does alcohol relax?
Although the relaxing effect of alcohol is well known, until recently nobody could quite explain it exactly.
The reason - that has just been published in the journal Nature - was discovered by a team of researchers led by Toru Kobayashi, from Niigata University, in Japan and Joanne Lewohl, from Texas University, in the USA.
The researchers demonstrated that alcohol opens a specific type of ionic channel, called GIRK. When open, this channel allows that brain cells eliminate potassium, thus reducing their activity. The result is a slow-down in brain function, perceived as a relaxing sensation by the drinker.
The direct action of alcohol has only been confirmed in relation to this specific phenomenon. Other effects of the drug, such as the diminishing motor control, are indirectly caused and required the agency of neuro transmitters or the changing in voltage of neuron's membranes.
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Silvia Helena Cardoso, PhD.Psychobiologist, master and doctor in Sciences, Founder and editor-in-chief,Brain and Mind Magazine, State University of Campinas.
Renato M.E. Sabbatini, PhD.Doctor in Sciences (Neurophysiology) by the State University of São Paulo Associate Director of the Center for Biomedical Informatics of the State University of Campinas, Brazil, and president of the Editorial Board,Brain & Mind Magazine.
André Malavazzi Designer, Instute of Arts and Center for Biomedical Informatics, State University of Campinas.