Nimodipine decreases resuscitability in a cardiopulmonary arrest model in the rat

Moderate hypothermia alters interleukin-6 and interleukin-1alpha reactions in ischemic brain in mice

Female C57BL/6 mice were decapitated and their brains were removed and cultured at either 37 or 33 degrees C for 48 h to investigate whether or not moderate hypothermia alters the cytokine reactions in the ischemic brain. The interleukin-6 and interleukin-1alpha levels in the culture media were significantly elevated in a time-dependent manner. The interleukin-6 levels after the incubation at 33 degrees C were significantly lower than those at 37 degrees C. The interleukin-1alpha levels at 33 degrees C were significantly higher than those at 37 degrees C. The interleukin-1alpha levels incubated with interleukin-6 antibody were significantly higher than those without IL-6 antibody. At 37 degrees C, the mRNA expression of interleukin-6 was observed from 2 to 48 h after incubation, but the same expression of interleukin-1alpha was only detected until 12 h. Accordingly, the ischemic brain incubated at 33 degrees C showed a decreased interleukin-6 production in comparison with that at 37 degrees C and the level of interleukin-6 showed negative feedback for the production of interleukin-1alpha. The temperature should, therefore, be carefully considered when evaluating the cytokine reaction for cerebral ischemia.

Failure of nimodipine to prevent brain damage in a global brain ischemia model in the rat

In view of our negative results with the calcium antagonist nimodipine as a cerebroprotective agent in a cardiopulmonary resuscitation model in the rat, we examined the protective effects of nimodipine in the four-vessel (carotid and vertebral) occlusion model, a model of global brain ischemia without important cardiovascular depression. Survival and neurological status were monitored and after 72 h the hippocampus was resected and examined for histological evaluation. The animals were treated blindly and randomly with either nimodipine, its solvent or saline given subcutaneously. In two separate studies, high doses (total dose: 5 mg/kg) or low doses of nimodipine (total dose: 1.6 mg/kg) were administered. In the high dose series, the survival rates at 72 h in the nimodipine group, the saline group and the solvent group were 4% (2/44), 19% (7/37) and 20% (8/41), respectively; in the low dose series, the figures were 26% (13/50), 34% (15/44) and 39% (18/46), respectively. The differences between nimodipine, solvent and saline were not statistically significant. Likewise, no differences in neurological status or histological brain damage were found. These data suggest that nimodipine offers no cerebral protection in global brain ischemia and may even be toxic, especially when given in high doses.