A correlative evaluation of cyclazocine,LSD and naloxone on continuous discriminated avoidance in rats

Cyclazocine, a long acting narcotic antagonist, induces disorientation, hyperirritability and hallucinations. In contrast, naloxone is devoid of any psychotomimetic affects. Cyclazocine (2.5 mg/kg) and LSD (1.0 mg/kg) induced strikingly similar behavioural disruptions on well-established discriminated (Sidman) avoidance performance in rats. Cyclazocine and LSD administration resulted in periods of response-inhibition and a subsequent enhancement of response rates. In the presence of the warning signal rats often failed to lever-press and as a consequence received more shocks. Naloxone (30 mg/kg) had little effect on avoidance responding. The effects of cyclazocine and LSD in rats may be mediated through similar mechanisms.