Posted by Cam W. on March 2, 2000, at 23:47:47
In reply to Re:Depression - A little more technical, posted by Cam W. on March 2, 2000, at 23:38:02
Deb - Depression occurs when the mechanism with which the body deals with stress has 'broken down'. The HPA axis is this mechanism for the body's 'fright or flight' reaction to stress. The hypothalamus releases a hormone called the corticotropin releasing hormone (CRH) into the hypophyseal (sp?) portal blood system and CRH stimulates the pituitary gland to release adrenocorticotropin releasing hormone (ACTH) (and beta-endorphins) into the body's bloodstream. The ACTH stimulates the adrenal gland (on top of the kidneys) to dump cortisol into the blood stream. The cortisol distributes to organs of the body increasing blood flow to muscles and heightening awareness and decreasing blood flow to non-essential organs (eg stomach, intestines). This prepares the body to 'flee' or 'fight' in a stressful situation. The released cortisol also acts as a negative feedback system to shut off the flow of CRH in the hypothalamus and ACTH in the pituitary. Thus, slowing the body again by turning off the HPA axis.
If this HPA axis is left 'on' due to constant stress (eg abuse) or if it shocked (eg death of a loved one) the feedback system breaks down. The hypothalamus and/or the pituitary do not respond to the 'turn off' signal of the cortisol. This is possibly due to a down regulation or lowering of the concentation of glucorticoid receptors in these two brain areas. Thus, cortisol is continually being dumped into the bloodstream, keeping your body in a high state of arousal. Eventually the stress on the body reduces serotonin levels and skews norepinephrine levels, manifesting itself into the symptoms we call depression (eg lethargy, sleeplessness, etc.).
One can be genetically predisposed to having an sensitive HPA system that breaks down under less stress than would happen in someone without the predisposition. Also, adverse early life events (eg physical or mental abuse) can sensitize the HPA axis to break down easier. So, no matter if a depression is caused by nature or nuture (or both - usually) the result in a biochemical breakdown in the body causing what we call depression.
> Thought I'd add my $0.02. - Cam W.
poster:Cam W.
thread:25549
URL: http://www.dr-bob.org/babble/20000302/msgs/25636.html