Posted by Jim on April 14, 1999, at 7:37:18
In reply to Re: Refractory depression--naltrexone theories?, posted by Steve on April 14, 1999, at 3:29:09
Steve wrote:
> The brain cleaves its opiates out of one big
> peptide called ACTH, which is undersecreted in
> some forms of depression. It is conceivable that
> by blocking the mu opiate receptor you can trick
> the brain into churning out more ACTH, and therefore
> more opiates which do elevate mood.
>
>
Steve--
Actually, my unschooled hypothesis is somewhat different, though you're probably right to a certain extent. From what I've seen, however, most clinical efficacy of naltrexone seems to come from the opiate antagonism itself--one of the best supported examples of this might be in self-cutting patients, who are probably literally "addicted" to the endogenous opiates (endorphins) they can produce by hurting themselves. The same could be said for binge-eating and compulsive gambling patients, who have also apparently shown some good responses to naltrexone treatment. I suppose my underlying hypothesis here is that certain types of depression may have similar processes at work, even if they are not manifested in outright behaviors. (Opioids are produced in response to stress, and stress is both a causal factor and a feature of depression...) Naltrexone may help to extinguish these kinds of psychological / physiological" short circuits" that, like morphine addiction, flood the system with opiates and thereby downregulate (i.e., decrease the number of) the opoid receptors. A good part of naltrexone's efficacy may come from its ability, through antagonism, to help restore the receptor population to normal levels so that opioids can function more "normally" in the body once again, perhaps in some cases even at *lower* levels than before treatment. (The research I've seen is very inconclusive about what naltrexone does to endorphin blood levels.) Once again, all my spoutings here to be taken with a healthy adjunctive grain of salt, since they are basically those of an armchair neuropharmacologist!
Best,
Jim
poster:Jim
thread:4588
URL: http://www.dr-bob.org/babble/19990501/msgs/4860.html