Friday, November 1, 2013

Why Alcohol Is Addicting? (Part II)

Continued from  Part  I

Researchers indicate that the brains of heavy or problem drinkers are changed in a way that makes them more likely to find alcohol pleasant. That greater feeling of reward might cause them to drink too much.

Neuroscientists found that endorphins released in response to drinking bind to a specific type of opioid receptor, the Mu receptor.

The receptor sites "lit up" on PET imaging,
allowing the researchers to map their exact locations.

All these colored areas express mu-receptors and peptides on different brain areas

Opioid receptors are distributed throughout the brain and spinal cord.  They mediate a number of activities including analgesia, species-typical behavior, and reward. Both endogenous opioids, (naturally produced within the body) and exogenous opiates, which are produced outside the body (drugs), produce pain relief and euphoria. The effects are produced by opioids binding to opioid receptors throughout the body.

Mu (opioid) receptors (red) on dopamine containing neuron (green)
(we shall speak about dopamine and its role to our satisfying life and addictions later)

Alcohol kicks natural endorphins off

in orbitofrontal cortex and nucleus accumbens.

Part of endorphins gets into intracellular liquid, thus produces the effect of wellness and high spirits.

Another part of these neurochemicals sits on μu-receptors.

These receptors are situated on the receiving neuron; and commands to relax are running from it to other neurons and chains.

As a result, pleasant sensations are spreading all over the body, relaxing the muscles of your face, neck, back, legs and arms.

You feel nice, sexy, healthy and attractive!

Social fears disappear…

You become friendly and good company…

When the number of natural endorphins in cells is expired through aggressive use of alcohol, some people add and add alcohol to prolong the effect of wellness. In vain! There is nothing remained to release from endorphins containing neurons.

Receptors become angry and demanding…

Some people become 

as other mechanisms are trigged.

But this is another story.

To be continued…

Natalia Nevis-Fox

Journal References:
  1. J. M. Mitchell, J. P. O'Neil, M. Janabi, S. M. Marks, W. J. Jagust, H. L. Fields. Alcohol Consumption Induces Endogenous Opioid Release in the Human Orbitofrontal Cortex and Nucleus Accumbens. Science Translational Medicine, 2012; 4 (116): 116ra6 DOI: 10.1126/scitranslmed.3002902 
  2. Schultz W, Tremblay L, Hollerman JR (2000) Reward processing in primate orbitofrontal cortex and basal ganglia. Cerebral Cortex 10: 272-283. doi:10.1093/cercor/10.3.272
  3. H. E. Fisher, L. L. Brown, A. Aron, G. Strong, D. Mashek.Reward, Addiction and Emotion Regulation Systems Associated with Rejection in Love. Journal of Neurophysiology, 2010; DOI: 10.1152/jn.00784.2009
  4. G. Sescousse, J. Redoute, J.-C. Dreher. The Architecture of Reward Value Coding in the Human Orbitofrontal Cortex. Journal of Neuroscience, 2010; 30 (39): 13095 DOI:10.1523/JNEUROSCI.3501-10.2010
  5. Kringelbach ML., Rolls ET. The functional neuroanatomy of the human orbitofrontal cortex: Evidence from neuroimaging and neuropsychology. Prog Neurobiol, volume 72, pp341-342, 2004.
  6. Rolls, Edmund T. and Grabenhorst, Fabian. (2008) The orbitofrontal cortex and beyond: From affect to decision-making. Progress in Neurobiology, 86 (3). pp. 216-244. ISSN 0301-0082.

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