A comparison of the acute toxicity of some centrally acting drugs measured under crowded and uncrowded conditions

The effect of home or novel environment on the facilitation of passive avoidance by post-training ethanol

Passive avoidance behavior of mice is improved when mice are injected with ethanol immediately after footshock training. Further study has shown that avoidance can be affected by ethanol injections given within 1 h, but not at 90 or 180 min, after training. The present study was conducted to investigate the possibility that events which occur in the homecage during this sensitive period may influence the effect of ethanol on subsequent avoidance. Male Swiss-Webster mice were housed either singly in a novel environment for 90 min or returned to their (group) homecage following one-trial, step-through, passive avoidance training (0.1 mA footshock) and intraperitoneal injection of 3.0 g/kg ethanol (15% v/v) or saline. As in previous studies, when ethanol-treated mice were returned to their homecage, avoidance was significantly increased at 24 h compared to the behavior of saline-treated mice. However, when mice were isolated in the novel environment for 90 min immediately following treatment, the memory facilitating effects of ethanol were not observed. The avoidance behavior of mice injected with saline was the same regardless of their post-training environment. Also, the number of mice (6 or 10) housed per homecage did not significantly influence the effects of ethanol or post-training environment on avoidance. These findings indicate that environmental factors may interact with the effects of ethanol to modify avoidance behavior. The possible influence of variables such as aggression, thermoregulation, and behavioral arousal on the effects of ethanol in this paradigm are discussed.

Naloxone in shock and toxic coma

In summary, naloxone has proved to be effective and safe during its years of use for narcotic antagonism. Its usefulness in non-narcotic coma and shock remains controversial, although some encouraging but inconclusive evidence exists. The final answer lies on the horizon of medicine; it awaits further delineation of the role of endogenous opioids in health and disease and clear statistical verification of naloxone's efficacy in such disease states.

The effects of aggregation on the lethality of phencyclidine in mice

The lethal effects of d-amphetamine and phencyclidine (PCP) were compared when adult male mice were placed into isolated or aggregated (12 mice/cage) conditions. The LD50 of d-amphetamine decreased approx. 30-fold between isolated (87.9 mg/kg) and aggregated (2.8 mg/kg) conditions. In contrast, PCP showed only a 1.3-fold increase in toxicity between isolated (64.5 mg/kg) and aggregated (48.4 mg/kg) conditions. These results suggest different mechanisms for the acute lethal effects of d-amphetamine and PCP in mice.