Inflammatory response and peroxisome proliferator-activated receptor isotypes expression in the brain of spontaneously hypertensive rats / 中华神经科杂志

ABSTRACT

Objective To evaluate the inflammatory response and the expressions of peroxisome proliferator-activated receptor(PPAR)isoforms(PPARα,PPARβ/δ,and PPARγ)in the brain(cortex,striatum,cerebellum)of spontaneously hypertensive rats(SHR).Methods Brain tissues(cortex,striatum,and cerebellum)were dissected from SHR and age-matched control Wistar-Kyoto rats.Myeloperoxidase(MPO)activity was measured in brain tissues as an index of neutrophil accumulation and the carbonyl protein content was analyzed by spectrophotometry to evaluate the protein oxidation.RT-PCR and Western blotting were performed to examine the expressions of inflammatory mediators(IL-1β,TNFα,ICAM-1,and iNOS)and nuclear factor PPARs(PPARα,PPARβ/δ,and PPARγ),respectively.Results(1)Systolic blood pressure of SHR was significantly higher than that of Wistar-Kyoto rats,(205.4±9.4)mm Hg versus(130.4±7.9)mm Hg(t=14.96,P＜0.01).(2)MPO activity of cortex,striatum,and cerebellum were markedly higher in SHR than in Wistar-Kyoto rats.Carbonyl protein levels of cortex,striatum,and cerebellum in Wistar-Kyoto rats and SHR were(3.27±0.43)nmol/mg versus(11.87±1.11)nmol/mg,(4.02±1.04)nmol/mg versus(14.06±1.36)nmol/mg,(5.94±0.71)nmol/mg versus(14.95±1.82)nmol/mg,indicating significantly higher levels of protein oxidation in SHR than Wistar-Kyoto rats(t=17.70,14.36,11.30,P＜0.05).Consistently,the expression of pro-inflammatory mediators(IL-1β,TNFα,ICAM-1,and iNOS)was upregulated when compared with Wistar-Kyoto rats.The difference between SHR and control Wistar-Kyoto rats was statistically significant except the mRNA expression of IL-1β in striatum,cerebellum and TNFα in cerebellum of SHR.All the above experimental data indicated the occurrence of inflammatory status in the brain tissue of hypertension.(3)mRNA and protein levels of brain PPAR isoforms(PPARα,PPARβ/δ,and PPARγ)of SHR increased significantly when compared with Wistar-Kyoto rats.Specifically.protein levels of PPARα in cortex.striatum,and cerebellum of SHR increased by 644.78%,791.95%,and 42.85%;PPARβ/δ increased by 106.72%,94.12%,and 161.44%;PPARγ was up-regulated by 2700.16%,790.81%,and 875.00%compared with that of Wistar-Kyoto rats,respectively.Conclusions The brain(cortex,striatum,and cerebellum)from SHR shows marked inflammatory status and increased expression of all PPAR isoforms.Increases in PPARs expression may play a compensatory role in the inflammatory response of the brain in SHR.