Is morphine-induced akinesia related to inhibition of reflex activation of flexor alpha-motoneurones? Role of the nucleus accumbens.
Unilateral injections of morphine (5-15 micrograms) into the nucleus accumbens of non-anesthetized rats produces a decrease of locomotor activity and a catalepsy. In a similar dose-response relationship, injections of morphine into this area inhibited the reflex activation of alpha-motoneurones by mild tetanic stimulation of the ipsilateral peroneal nerve (flexor alpha-motoneurones) in halothane-anesthetized rats. All these effects were antagonized by systemic administration of naloxone. Our results suggest that a reduction in reflex activation of flexor alpha-motoneurones by proprioceptive stimuli seems to be relevant for the development and/or mediation of akinesia and catalepsy, and that the nucleus accumbens plays a key role in these effects produced by morphine.
D000818:Animals; D002375:Catalepsy / Q000139:chemically induced; D004305:Dose-Response Relationship, Drug; D006801:Humans; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D009043:Motor Activity / Q000187:drug effects; D009046:Motor Neurons / Q000187:drug effects*; D009069:Movement Disorders; D009714:Nucleus Accumbens / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D012018:Reflex / Q000187:drug effects*; D012686:Septal Nuclei / Q000502:physiology*
D009020:Morphine