The expression and changes of heat shock protein 70, MDA and haemorheology in rat cortex after diffuse axonal injury with secondary insults

In the present study the role of heat shock protein 70 (HSP70) expression, changes of malonyldialdehyde (MDA) in rat cortex and haemorheology with time after diffuse axonal injury (DAl) only and DAl with secondary insults (SI) were studied. The rat DAl and DAl with Sl model were made according to our previous work and animals were divided into a control and another five injury groups with time after injury. Immunohistochemical assay was used to detect the neuronal expression of HSP70 at 0.5 h, 3 h, 12 h, 24 h, 72 h after DAl or DAl with Sl. In the meantime, the high (eta (h)) and low whole blood viscosity (eta (L)), haematocrit (HCT) and RBC aggregation index (Al = eta (L)/eta (h)) were also detected and calculated. MDA in the homogenised brain tissue was assayed by thiobarbituric acid (TBA) reaction. The results showed that HSP70 positive neurons were not detected at 30 minutes, but the number of HSP70 positive neurons begin to increase obviously at 3 hours, reach a peak at 24 hours (P <0.01), and decrease at 72 hours (P <0.05) after brain injury. The trend of expression of HSP70 was alike for both DAl only or DAl with Sl. Meanwhile, MDA, eta (h), eta (L), HCT and Al changes showed the same tendency. Compared with DAl only group, MDA and blood viscosity indexes in DAl with SI were significantly higher at respective time points (P<0.01). It is concluded that HSP70 expression, MDA and haemorheology indices increased after brain injury and brain injury with SI. Free radicals and haemorheological changes play an important role in the aggravation of brain damage and HSP70 expression upregulation. <(c)> 2001 Harcourt Publishers Ltd.