Artificial cold exposure induced stroke in renovascular hypertensive rats and its association with cold-inducible RNA binding protein mRNA expression in brain tissue and blood pressure

BACKGROUND： High incidence of stroke at interchange period of autumn and winter was demonstrated by epidemiological survey, and the specific causes should be further investigated. OBJECTIVE： To investigate the influence of artificial cold exposure on the incidence of stroke in renovascular hypertensive rats （RHR）, and analyze the association with blood pressure and cold-inducible RNA binding protein （CIRP） mRNA expression in brain tissue. DESIGN： A completely randomized grouping design, a randomized control animal trial. SETTINGS： Lab of Neurology, the First Affiliated Hospital of Sun Yat-sen University; Department of Chemistry, Open laboratory of Chemical Biology, Institute of Molecular Technology for Drug Discovery and Synthesis, University of Hong Kong. MATERIALS： Male SD rats （n=460）, weighing 80 - 100 g were obtained from Guangdong Province Health Animal Unit. A modified RXZ-300A intelligent artificial climate cabinet （Ningbo Jiangnan Instrument Co. ,Ltd., China）. METHODS： The experiment were processed in the Lab of Neurology, the First Affiliated Hospital of Sun Yat-sen University and the Open Laboratory of Chemical Biology, Institute of Molecular Technology for Drug Discovery and Synthesis, University of Hong Kong from October 2004 to November 2005. Rats （n = 400） were operated to establish 2-kidney 2-clip RHR model as described previously. The sham-operated rats （n =60） served as normotensive controls. Eight weeks later, 300 of RHR were randomly selected according to their systolic blood pressure （SBP） and divided into 3 sub-groups （n =100 per group）： mild hypertensive group （SBP of 160 - 200 mm Hg）, moderate hypertensive group （SBP of 200 - 220 mm Hg） and severe hypertensive group （SBP 〉 220 mm Hg）. Each group was further divided into two groups （n =50） under ACE and non-ACE. Normal sham-operated SD rats （n =60）, SBP 〈 140 mm Hg, were randomly divided into two groups： Sham-operated control group （n =30） under ACE and non-ACE. To establish the ACE and non-ACE treatment, rats were housed individually in artificial climate cabinet, and ACE was designed as three cycles of 12-hour light of 22℃ （7 ： 00 - 19 ： 00） and 12-hour dark of 4℃（19 ： 00 - 7 ： 00）. The non-ACE group was kept at 22℃ throughout the experiment. MAIN OUTCOME MEASURES： Blood Pressure changes were measured and stroke symptom were observed; Expression of the CIRP were examined by reverse transcription-polymerase chain reaction. RESULTS： Finally 360 rats were involved in the analysis of results. ①Incidence of stroke： The incidence of stroke in 2k2c RHR was significantly higher after a three-day intermittent （12-hour） ACE （29.3%） as compared with that in non-ACE （17.3%） （P 〈 0.05）. Furthermore, the severe hypertensive 2k2c RHR （BP 〉 220 mm Hg） was found to have much higher incidence of stroke （66%, 33/50） than the mild （8%, 4/50） and moderate （18%） hypertensive 2k2c RHR. ②CIRP mRNA in brain tissue： ACE treatment stimulated the mRNA expression of CIRP in non-stroke 2k2c RHR but not in stroke 2k2c RHR （P 〈 0.05）. CONCLUSION： High blood pressure and low expression of CIRP are associated with ACE induced stroke.

Anti-hypertensive effects of rosiglitazone on renovascular hypertensive rats:role of oxidative stress and lipid metabolism

This study investigated the anti-hypertensive mechanismof rosiglitazone in renovascular hypertensive rats,and examined its relationship to oxidative stress and lipid metabolism. The renovascular hypertension was induced by stenosis of the left renal artery. Four groups of rats were selected： control,induced untreated,rosiglitazone（ 20 mg / kg） and captopril（ 10 mg / kg）. After 14 d of administration,compared with induced untreated group,rosiglitazone group reduced the renovascular hypertensive rats ＇ systolic blood pressure and diastolic blood pressure,and decreased total cholesterol（TCH）,triglyceride（TG）,angiotensin II（ Ang II） and angiotensin receptor（ AT1） levels（ P ＆lt; 0. 05）. Meanwhile,rosiglitazone remarkably decreased the levels of malondialdehyde（ MDA） and hydrogen peroxide（ H2O2） while improved the levels of supperoxide dismutase（ SOD） and reduced glutathione（ GSH）. These results suggested that rosiglitazone could effectively decreased the blood pressure in renovascular hypertensive rats,and this might be performed by regulating the activity of angiotensin and the lipid metabolismand improving the oxidative stress.

Gene expression profiles in the peri-infarct brain cortex in a rat model of stroke-prone renovascular hypertension

BACKGROUND： Previous studies have focused on gene expression acutely following stroke onset. However, there have been a few reports of gene expression during later stages of cerebral infarction. OBJECTIVE： To determine gene expression profiling in the peri-infarct brain cortex 7 days after ischemia in a rat model of cerebral infarction in renovascular hypertensive rats. DESIGN, TIME AND SETTING： An in vivo, molecular experiment was performed at the Experimental Animal Center of Sun Yat-sen University and CapitalBio, Beijing, China between February 2004 and August 2005. MATERIALS： A 70-mer oligo chip containing 5 705 rat genes was supplied by CapitalBio, Beijing, China; and the Oligo rat gene bank was provided by Qiagen, the Netherlands. METHODS： Six Sprague Dawiey rats were utilized to establish a stroke-prone renovascular hypertensive model using the two-kidney and two-clip method. The rats were subsequently randomly assigned to two groups： middle cerebral artery occlusion and sham-operation, with three rats in each group. The middle cerebral artery occlusion model was induced by intraluminal suture method. Incisions were sutured following isolation of carotid arteries in the sham-operation group. MAIN OUTCOME MEASURES： Total RNA was extracted from the peri-infarct cerebral cortex 7 days after surgery. Following fluorescent labeling, RNA was hybridized to an Oligo chip containing 5 705 genes and was then scanned. Images were collected and the differentially expressed genes （number and category） were selected by data analysis. RESULTS： A total of 174 genes were upregulated, and 23 were downregulated, in the peri-infarct cerebral cortex 7 days after ischemia. The upregulated genes were distributed among 12 functional categories, and the downregulated genes belonged to categories of transport, transcription regulators, signals, response to stress, metabolism, and cell adhesion. The expression of some cytoskeletal genes was upregulated, including VIM, A2M, B2M, ACTR3, and ARPClB. Expression of a few cell adhesion-related genes （such as NLGN1, LGALS1, LGALS3, COLIA1, COL2A1, and SPP1） and other inflammation-related genes （such as CIQB, ClS, C4, C5R1, CFH, CD14, CD164, CD47, CD48, CD53, CD8B, IFNGR, and TFITM2） were upregulated. The glutamate-receptor gene GRIK5 was downregulated, which is related to the excitatory neurotransmitter glutamate. However, expression of the inhibitory neurotransmitter GABA-related genes was bidirectional - namely, GABRA5 downregulation and GABARAP upregulation. CONCLUSION： Upregulation of many cell adhesion and inflammation related genes and downregulation of excitatory glutamate-related receptor genes revealed active gene expression during later stages of cerebral infarction, which suggested molecular mechanisms of injury or repair.