Opiate action hypothesis

Only one antagonist is known, naloxone, which is used clinically to treat opiate overdoses and, experimentally, to investigate whether physiological or biochemical actions are opiate-mediated. One example of its use is to support the hypothesis that P-endorphin is responsible for the analgesic effects of acupuncture. Not only does low frequency electroacupuncture increase p-endorphin levels in cerebrospinal fluid but naloxone nullifies the analgesic effect of this treatment. 

The development of this hypothesis, should it turn out to be correct, provides a useful blueprint for the design and development of new pain-relieving drugs. Such drugs should probably have chemical structures similar to those of naturally occurring opiates. When taken into the body, they should be able to supplement or replace the action of naturally occurring opiates in the reduction of pain. 

The observation that morphine inhibits c-AMP formation stimulated by PGE- led to the hypothesis that inhibition of a prostaglandin-sensitive adenyl cyclase forms the biochemical basis of the analgesic action of opiates. Morphine also prevents PGE- -mediated inhibition of the aggregation of human platelets and the positive chronotropic effects of PGE- and PGE2 on guinea pig atria . Similar to morphine, leucine- and methionine enkephalin inhibit PGE1 stimulated c-AMP formation in hybrid... 

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