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Possible mechanism for the enhanced lethality of morphine in aggregated mice
Abstract:
Morphine was shown to be more lethal to aggregated mice than to isolated mice at an ambient temperature of 29 degrees C but not at 19 degrees C. After morphine administration at 29 degrees C, convulsions were found to be associated with death, and a higher incidence of convulsions was observed in aggregated mice than in isolated mice. After morphine administration at 19 degrees C, there was no clear association between convulsions and death, and there was no significant difference between the incidence of convulsions in isolated and aggregated mice. When tactile stress was induced upon morphine-treated isolated mice at 29 degrees C, all of the mice convulsed and died. These results suggest that the greater lethality of morphine in aggregated mice is due to a greater incidence of convulsions which results from stress induced on one animal by the other.
Insights
Aggregated mice experienced higher morphine lethality at 29°C, linked to stress-induced convulsions. Lower temperatures (19°C) negated this effect, indicating stress is key to morphine toxicity in groups.
Area of Science:
- Pharmacology
- Animal Behavior
- Toxicology
Background:
- Morphine's lethal effects can vary based on environmental and social factors.
- Previous studies suggest stress influences drug toxicity.
Purpose of the Study:
- To investigate the impact of aggregation and ambient temperature on morphine lethality in mice.
- To determine the role of convulsions and stress in morphine-induced mortality.
Main Methods:
- Mice were housed in isolation or aggregation at 19°C and 29°C.
- Morphine was administered, and lethality, convulsions, and stress responses were recorded.
- Tactile stress was applied to isolated mice at 29°C.
Main Results:
- Morphine was more lethal to aggregated mice at 29°C, correlating with increased convulsions.
- At 19°C, aggregation did not significantly alter morphine lethality or convulsion incidence.
- Stress induction in isolated, morphine-treated mice at 29°C led to 100% mortality via convulsions.
Conclusions:
- Social stress significantly enhances morphine lethality in mice at higher ambient temperatures.
- Convulsions, triggered by stress in aggregated or stimulated mice, are a primary mechanism of morphine toxicity.
- Environmental temperature is a critical factor modulating the social stress-induced potentiation of morphine toxicity.