Morphologic changes of cerebral veins in hypertensive rats: venous collagenosis is associated with hypertension.

The aims of this study were to determine whether arterial hypertension could affect the venous system of brain and to find out the consequent pathologic changes of cerebral veins.Thirty male Sprague-Dawley rats were divided into 2 groups: a sham-clipped group and a stroke-prone renovascular hypertensive rat group. A 2-kidney 2-clip rat model was used to induce renovascular hypertension in the hypertensive group. Systolic blood pressure was measured by tail cuff once each week. Susceptibility-weighted imaging (SWI) was performed at 12, 16, and 20 weeks after surgery. All the rats were sacrificed after the SWI examination at 20 weeks after surgery. The brains were extracted and embedded in paraffin for histologic examination. Masson trichrome staining was performed to identify venous collagenosis.The sham group demonstrated less prominence of cerebral veins compared with hypertensive groups (P < .01); the hypertensive group showed significant venous collagenosis in cerebral venous walls compared with the sham group (P < .01).The increased visibility of cerebral veins on SWI as a sign of venous hypertension and the thickened cerebral venous walls (venous collagenosis), which may play a role in cerebral ischemia and/or infarction, are both consequences of long-term hypertension in hypertensive rats.