Sodium Loading Increases Micro-aneurisms In Stroke-prone Spontaneously Hypertensive Rats

Stroke-prone spontaneously hypertensive rats (SHR-SP) died of stroke at age of 9 months (male) or 13 months (female). Cerebral hemorrhage is a complication of hypertension and SHR-SP is considered to be the best model studying on cerebral hemorrhage. Died of cerebral hemorrhage in most cases, the life span of SHR-SP is short. When they are fed with high salt fodder, the cerebral hemorrhage happens earlier. Therefore we postulate that high salt fodder may activate inflammatory reaction, and result in the formation of cerebral aneurysm. It was well known that during inflammatory reaction, 5-LO played an important role in the formation of inflammatory factors, such as IL-1, IL-6, TNFa, Ang II etc, which may determine the incidence of cerebral aneurysm in SHR-SP. And salt loading may deteriorate the inflammatory process, and together with arterial baroreflex and hemodynamic indexes. Therefore in this study, impact of salt loading in SHR-SP on the relationship between cerebral aneurysm number and these indexes were evaluated.Methods:Thirty-six female SHR-SPs were used in this study. At the age of 3 months, they were divided into two groups: one fed high-sodium (containing 4% NaCI) diet for 3 months and another fed normal rat diet as control. At the age 6 months, the blood pressure and baroreflex sensitivity were measured inconscious state. Then rats were killed and the brains were taken for pathological examination and samples of blood were collected for the determination of inflammatory factors.Results: It was found that sodium loading significantly increased blood pressure and decreased baroreflex sensitivity (0.227+0.037 vs 0J28±0.084 ms/mmHg, P<0.01). The aneurisms were significantly (P<0.05) increased in sodium loading rats (2.54+1.6) compared with control SHR-SP (1.73±1.28). There were no differences in serum levels of TNFa between these two groups. However, sodium loading significantly (P<0.05) increased serum levels of IL-l(0.31+0.08 vs 0.23±0.09ng/mL), IL-6 (157±39 vs 120±37pg/mL) and angiotensin H (219±87 vs 155+50pg/mL).Conclusion: In conclusion, sodium loading increases micro-aneurism, which may importantly contribute to stroke in SHR-SP.