Thermoelectric cooling using the Peltier effect for deep hypothermia anesthesia in neonatal mouse pups

Katharina Ulrich1, Fritz Kutschera2, Dirk Isbrandt1

1 German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
2 Center for Molecular Neurobiology (ZMNH), Hamburg, University of Hamburg

Stereotaxic surgical procedures in neonatal or infant rodents are necessary to explore brain development. Especially in disease models such as neonatal epilepsies, the study of brain development is critical for investigating disease pathophysiology and identify vulnerable time windows for treatment. Surgical procedures in neonatal rodents have been challenging due to the lack of safe standard operating procedures regarding anesthetic regimes. One technique that has been frequently used over the years to overcome those problems is deep hypothermia. However, the mechanisms are still not fully understood and there is a wide variety of different protocols, most of which are more suitable for short procedures but not for longer interventions. Here we show the efficiency of a novel anesthetic technique for deep hypothermia of neonatal mice using the Peltier effect for controlled thermoelectric cooling. After the initiation of deep hypothermia using iced water, subjects were subsequently placed on a Peltier element to control temperature and thus the anesthetic effect. The body temperature of subjects was maintained at a temperature of 4-6°C, thus allowing surgical procedures such as stereotactic implantations to be performed. After completion of the surgical intervention, cooling was stopped, and the subjects' body temperature was slowly broad back to a physiological range in order to proceed with the subsequent experiment. The survival rate was higher than 90% as compared to standard gas volatile anesthetics such as isoflurane. These results suggest that deep hypothermia using the Peltier effect for controlled thermoelectric cooling is a safe alternative anesthetic regime that can be used for short or longer surgical procedures in neonatal rodents.