gms | German Medical Science

Temperature regulation has a strong influence on the functional outcome after ischemic injury. Temperature reduction (hypothermia) of even 1°C is able to decrease lesion size, whereas hyperthermia deteriorates the outcome. Pharmacological methods to induce fast, effective, and safe hypothermia are still an unmet need in vascular related disorders. During ischemia, brain temperature underlies local regulation and differs from body temperature. To understand the dynamics of thermoregulation during and/or after ischemic stroke and to develop novel approaches for hypothermia-induced neuroprotection, it is necessary to measure body and brain temperature separately. Our objectives were to establish a telemetric system to measure brain and body temperature and motor activity in freely moving rats, with high sensitivity for rapid temperature changes. A guide cannula was stereotactically implanted into the caudate putamen and fixed by dental cement on the skull of 8-week old male Wistar rats. Using this guide cannula a thermocouple thermometer probe was inserted to measure brain temperature. A wireless telemetry probe was implanted into the abdominal cavity through a small incision to measure core temperature and motor activity. The measurements were carried out prior and after application of compounds known to induce hypo- and hyperthermia. Both parameters, body and brain temperature, were sensitive to rapid temperature changes caused by motor activity, hypothermia- and hypothermia-inducing agents. In summary, the present system enables continuous measurement and storage of body and brain temperature and motor activity data separately without anesthesia. This approach is well suited for pharmacological studies on thermoregulation and screening of hypothermia-inducing agents for stroke treatment.