Transient hypothermia induces micronuclei in mice

Area of Science:

• Toxicology
• Genetics
• Cell Biology

Background:

• Hypothermia is a condition of abnormally low body temperature.
• Micronuclei are indicators of chromosomal damage and aneuploidy.
• Understanding the genotoxic effects of hypothermia is crucial for risk assessment.

Purpose of the Study:

• To investigate the genotoxic potential of chlorpromazine-induced hypothermia.
• To determine if hypothermia itself, rather than the drug, causes micronucleus formation.
• To explore the characteristics and potential mechanisms of induced micronuclei.

Main Methods:

• Mice were administered varying doses of chlorpromazine to induce hypothermia.
• Rectal temperature and duration of hypothermia were monitored.
• Micronucleated polychromatic erythrocyte frequencies in bone marrow were assessed.
• Experiments were conducted with and without temperature control to isolate the effect of hypothermia.

Main Results:

• Chlorpromazine doses of 25-100 mg/kg significantly increased micronucleated erythrocytes (p < 0.01).
• Hypothermia (rectal temperature < 33°C for 11 hours) was transiently induced by effective doses.
• When body temperature was maintained, micronucleated erythrocyte frequency did not increase.
• A significant proportion (53-58%) of induced micronuclei were relatively large.

Conclusions:

• Transient hypothermia, specifically below 33°C for 11 hours, induces micronuclei in mouse bone marrow cells.
• The genotoxic effect is attributed to hypothermia itself, not solely to chlorpromazine.
• Disturbance of the mitotic apparatus is a potential mechanism underlying hypothermia-induced genotoxicity.