Years of drinking alcohol may interfere with your body's ability to maintain its equilibrium. By blunting the brain's natural stress response, long-term boozing can impair the way in which a body protects itself from damage. So concludes a new study in the journal
Catherine Rivier of The Salk Institute, La Jolla, California and colleagues, repeatedly exposed rats to alcohol vapours in a way that mimicked long-term alcohol intake by humans. They found that this significantly dulled the animals' hormonal and neuronal responses to stress. These 'alcoholic' rats produced far less of some of the hormones that help mammals cope with stress than did healthy rats.
Apparently, alcohol impairs the process of 'homeostasis'. Homeostasis is the concert of physiological processes that work to maintain our bodily functions within certain limits, no matter what stressors are threatening to push us over those limits. Homeostasis is essential for survival as tiny variations of, for instance, temperature and pH can have devastating effects on the finely tuned physical and chemical machinery of the body.
Many of the processes of homeostasis are mediated by hormones. A part of the brain called the hypothalamus, for instance, secretes two: corticotropin-releasing factor or CRF, and vasopressin or VP. CRF can be thought of as the central stress hormone. It co-ordinates the stress response by triggering an integrated series of physiological and behavioural reactions.
From the hypothalamus CRF and VP go to the pituitary gland at the base of the brain where they cause the release of adrenocoricotropin (ACTH). ACTH enters the blood stream and travels to the adrenal glands at the top of the kidneys where it stimulates them to produce corticosteroids. Via the blood, these corticosteroids guide the body's redirection of nutrients to those parts of the body that, being under stress, need them.
Under conditions of chronic stress -- when someone is grieving or suffering from an infection for instance -- the body may fail to compensate with an efficient stress response and this can suppress growth, alter the immune system and even affect learning and memory.
The rats in Rivier and colleagues' study released less CRF and VP, and hence less ACTH and corticosteroids, indicating that chronic exposure to alcohol, in rats at least, erodes the mechanisms of homeostasis.
"People who abuse alcohol have all kinds of health related problems," said Rivier, "What we showed here is that alcoholics may become unable to activate their stress axis appropriately when they are faced with a challenge, and that can be damaging."