Spontaneously hypertensive stroke-prone rats (SHRSP) develop brain abnormalities invariably preceded by the accumulation of acute-phase proteins in body fluids. This study describes the sequence of pathological events, and in particular the involvement of inflammation, at the onset of brain injury in this animal model. In SHRSP subjected to permissive dietary treatment, the appearance of brain damage and of altered permeability of the blood-brain barrier (BBB) was monitored over time by magnetic resonance imaging (MRI) after intravenous injection of gadolinium. The protein content in cerebrospinal fluid and brain extracts was analyzed by two-dimensional electrophoresis. Gadolinium diffusion showed impairment of the BBB after 42 +/- 3 days from the start of salt loading, simultaneously with the detection of brain abnormalities by MRI. Tissue lesions were initially localized at one or more small foci and then spread throughout the brain in the form of fibrinoid necrosis. This type of lesion is characterized by fibrin deposition, in particular around the vessels; loss of tissue texture; and infiltration of macrophages and lymphocytes. High levels of plasma-derived proteins of molecular mass up to >130 kDa were detected in the cerebrospinal fluid after MRI had revealed brain abnormalities. Plasma proteins extravasated from brain vessels were immunodetected in tissue homogenates from affected areas. The results obtained in this study provide new insights into the pathogenesis of the spontaneous brain damage in SHRSP and in particular on the involvement of the inflammatory cascade. These studies may be useful in evaluating new pharmacological strategies aimed at preventing/treating brain diseases.
2004 Wiley-Liss, Inc.