Related Experiment Videos
The effect of aggregation on the lethality of morphine in mice
Abstract:
Morphine was more lethal to mice housed in groups (aggregated) than to mice housed individually (isolated). The aggregation effect on morphine lethality was increased when ambient temperature was increased to 29 degrees C and abolished when ambient temperature was lowered to 19 degrees C. At 29 degrees C morphine produced hypothermia in isolated mice and hyperthermia in aggregated mice. Both isolated and aggregated mice were hypothermic after morphine administration at 19 degrees C. At 29 degrees C the locomotor activity of morphine-treated aggregated mice was significantly greater than that of morphine-treated isolated mice, whereas at 19 degrees C no significant difference was found. The locomotor activity time course of morphine-treated aggregated mice at 29 degrees C closely resembled the rectal temperature time course, which suggests that the hyperthermia in those animals involves an increase in heat production via an increase in locomotor activity. However, the hyperthermia observed was not sufficient to explain the increased lethality in aggregated mice. Differences between the aggregation effect on morphine lethality and that previously reported for amphetamine were discussed.
Insights
Group-housed mice experienced higher morphine lethality than isolated mice, especially at warmer temperatures. This aggregation effect on morphine toxicity is linked to temperature-dependent changes in mouse behavior and physiology.
Area of Science:
- Pharmacology
- Animal Behavior
- Environmental Physiology
Background:
- Social housing significantly influences drug toxicity in animal models.
- Environmental temperature is a critical factor modulating physiological responses to drugs.
Purpose of the Study:
- To investigate the impact of housing density and ambient temperature on morphine lethality in mice.
- To explore the physiological and behavioral mechanisms underlying the observed aggregation effect on morphine toxicity.
Main Methods:
- Mice were housed individually (isolated) or in groups (aggregated) at different ambient temperatures (19°C and 29°C).
- Morphine lethality, rectal temperature, and locomotor activity were measured in both housing conditions and temperatures.
- Physiological and behavioral data were analyzed to correlate with morphine toxicity.
Main Results:
- Aggregated mice exhibited significantly higher morphine lethality compared to isolated mice, particularly at 29°C.
- At 29°C, aggregated mice developed hyperthermia and increased locomotor activity, while isolated mice showed hypothermia.
- At 19°C, both groups became hypothermic, and locomotor activity differences were not significant.
Conclusions:
- Social aggregation exacerbates morphine lethality in mice, an effect strongly modulated by ambient temperature.
- Increased locomotor activity contributes to hyperthermia in aggregated mice at higher temperatures, but does not fully explain the enhanced lethality.
- Findings highlight the complex interplay between social environment, temperature, and drug toxicity, with implications for preclinical research.