Effect of hypertension on the integrity of blood brain and blood CSF barriers,cerebral blood flow and CSF secretion in the rat

Hypertension has been related to the development of brain damage, dementia and other CNS dysfunctions. Disruption of the blood-brain barrier (BBB) is thought to contribute to these disorders. In this study, the integrity of both blood-brain and blood-CSF barriers during chronic hypertension was investigated. For this, the entry of [14C]sucrose and of lanthanum into brain tissue, choroid plexus, and CSF was studied. Also brain regional blood flow and brain [14C]sucrose volume of distribution were measured using indicator fractionation and ventriculo-cisternal perfusion methods, respectively. The above measurements were performed in normotensive (WKY) rats and in the spontaneously hypertensive rats (SHR). Choroid plexus and CSF uptakes of [14C]sucrose were found to be significantly greater in SHR compared to WKY rats (P<0.05). Intercellular entry of lanthanum was observed in choroidal tissue of SHR but not in that of WKY rats and at the BBB. Choroid plexus blood flow was significantly greater in SHR, 2.82+/-0.21 ml g(-1) min(-1), compared to 2.4+/-0.08 ml g(-1) min(-1) in WKY (P<0.05). There were no significant differences (P>0.05) in brain % water content and extracellular fluid [14C]sucrose volume of distribution between SHR and WKY rats. However, choroid plexus showed greater % water content in SHR (85.7+/-1.9%) compared to the WKY rats (81.5+/-1.7%). These results suggest that chronic hypertension in SHR may cause more pronounced defects in the integrity of the blood-CSF barrier than in the BBB.