1. ¹Department of Psychology, University of Alberta, Edmonton, Canada
2. ²Centre for Neuroscience, University of Alberta, Edmonton, Canada

Correspondence: CL MacLellan, Department of Psychology, P-217 Biological Sciences Building, University of Alberta, Edmonton, Alberta, Canada, T6G 2E9. E-mail: clmac@ualberta.ca

Received 13 December 2004; Revised 24 January 2005; Accepted 24 January 2005; Published online 2 March 2005.

Abstract

Hyperthermia worsens outcome in clinical and experimental studies of ischemic stroke. Thus, we tested whether hyperthermia aggravates intracerebral hemorrhage (ICH) in rats. A striatal hemorrhage was produced via an infusion of bacterial collagenase. In a preliminary experiment, we compared brain and core temperatures (via telemetry) during heating (infrared lamp). The brain temperature rise exceeded that produced by enforced core hyperthermia, which was used subsequently. In these experiments up to three hyperthermia conditions (versus normothermia) were tested including: hyperthermia (>38.5°C) over the first (HYP-1) or second 24 h period (HYP-2) after ICH and 3 h of 40°C hyperthermia starting 12 h after ICH (HYP-3). The HYP-1, HYP-2, and HYP-3 treatments did not affect functional deficits (e.g., spontaneous forelimb use, skilled reaching) or the volume of injury at 30 days. Furthermore, the HYP-1 treatment did not aggravate injury or deficits at 7 days. Bleeding and inflammation, which contribute to pathology, were not significantly altered by HYP-1 and HYP-3 treatments. Bleeding was assessed at 1 day, and macrophages and neutrophils were counted at 2 and 4 days. Accordingly, hyperthermia, under the present conditions, did not worsen outcome after striatal ICH.