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 

aggressive 

as other mechanisms are trigged.

But this is another story.

To be continued…

Love,

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.

Why Alcohol Is Addicting? (Part I)

Drinking alcohol leads to the release of endorphins in areas of the brain that produce feelings of pleasure and reward, according to a study led by researchers at the Ernest Gallo Clinic and Research Center at the University of California, San Francisco (UCSF).

Endorphins are small proteins with opiate-like effects

that are produced naturally in the brain.

The researchers used positron emission tomography, or

PET imaging,

to observe the immediate effects of alcohol in the brains of 13 heavy drinkers and 12 matched "control" subjects who were not heavy drinkers.

In all of the subjects, alcohol intake led to a release of endorphins. And, in all of the subjects, the more endorphins released in the nucleus accumbens,

the nucleus accumbens

the greater the feelings of pleasure reported by each drinker.

orbitofrontal cortex

In addition, the more endorphins released in the orbitofrontal cortex, the greater the feelings of intoxication in the heavy drinkers, but not in the control subjects.

Orbitofrontal  cortex (OFC) green area on diagram

The human OFC is involved in sensory integration, in representing the affective value of reinforcers, in  decision-making and expectation.

In particular, the OFC is important in signaling the expected rewards/punishments of an action given the particular details of a situation.

In doing this, the brain is capable of comparing the expected reward/punishment with the actual delivery of reward/punishment.

To be continued…

Love,

Natalia Levis-Fox

Journal Reference

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