Abstract 81: Time Course of Hypothermia after Continuous Intracerebroventricular Administration of Neurotensin
Background and Goal: Global cerebral ischemia due to cardiac arrest leads to neuronal degeneration. Experimental data as well as two recent randomized clinical trials demonstrated beneficial effects of therapeutic mild hypothermia. Induction of hypothermia by altering temperature set point might be beneficial. Since hypothermia after bolus application of neurotensin seems to be short-lasting, the effect of a continuous infusion was investigated.
Materials and Methods: After approval was obtained from the Governmental Animal Care Committee, 13 male wistar rats obtained intracerebroventricular infusion of different doses of neurotensin (10, 30, 50 μg/h; n=3) or saline vehicle (n=3) for 48 hours using implanted osmotic minipumps. At the same time, rats’ body temperature was recorded every minute by temperature telemetry probes implanted into the abdominal cavity.
Results: Application of neurotensin led to a rapid decrease of body temperature as shown in the Figure⇓. Body temperature of rats receiving neurotensin 10, 30 or 50 μg/h was significantly lower compared to control group at 3 h (p=0.043 p=0.014 and p=0.007, respectively). Differences in the hypothermic effect between the three neurotensin groups did not reach the significance level, although there was a trend to a dose dependency. Rats became normothermic by 12–24 h.
Conlusion: Continuous intracerebroventricular administration of neurotensin leads to prolongation of the hypothermic response. Therefore, this application regimen might be useful to induce hypothermia after various kinds of neuronal ischemia, e.g. global cerebral ischemia due to cardiac arrest.