Opposite motivational effects of endogenous opioids in brain and periphery

摘要: Many psychoactive drugs, including the opiates, have been shown to paradoxical reinforcing effects. Opiates produce positive effects when they are paired with visual and textural environmental stimuli in rats, yet, at similar doses over same routes of administration, aversive effects, as taste stimuli. Similarly, human, opiates well known addicts recreational drug users, yet patients receiving analgesics often report nauseous reactions. At present there is no evidence differentiate between neural substrates that mediate these opposite motivational We now an initial step resolution this paradox by demonstrating endogenous exogenous opioids through action on brain opiate receptors, peripheral receptors (especially gut).