Opioid agonists were used to investigate the modulation of
seizures mediated by mu, kappa and delta
opiate receptors in the seizure-sensitive Mongolian gerbil.
Morphine (1.0-25 mg/kg, s.c.) were used as prototypic agonists for mu, kappa and delta
opiate receptors. Each
opioid decreased the incidence and severity of the seizure as compared to control values. The
anticonvulsant effects of
morphine (10 mg/kg, s.c.) and
ketocyclazocine (0.5 mg/kg, s.c.) were reversed by
naloxone (1.0 mg/kg, s.c.), while the
anticonvulsant effects of
N-allylnormetazocine (2 mg/kg, s.c.) were not significantly changed by
naloxone. Additionally, abnormal behavior was observed following administration of the
opioids.
Morphine (10 mg/kg, s.c.) produced excitation and hyperresponsiveness with intermittent cataleptic-like states.
Ketocyclazocine (10 mg/kg, s.c.) predominantly produced a stuporous, immobile state, accompanied by some loss of posture.
N-allylnormetazocine (10 mg/kg, s.c.) produced
ataxia and stereotypic side-to-side head nodding .
Naloxone was able to reverse the behavioral effects produced by
morphine and
ketocyclazocine but not those produced by
N-allylnormetazocine. The data presented are consistent with earlier studies which demonstrated the
anticonvulsant effects of
beta-endorphin in the gerbil. This study further suggests that
opioids have a protective role against seizure activity in the gerbil and the
opioid anticonvulsant effect is not specific to one type of
opioid agonist.