| INTRODUCTIONNonsteroidal anti - inflammatory drugs ( NSAIDS ) , a group of structurally unrelated compounds, are commonly prescribed to relieve inflammation, pain and fever. The pharmacologic target of NSAIDS is cyclooxygenase (COX) ,a critical enzyme in the biosynthetic pathway of prostaglandins( PGS) . PGS, particularly PGE2, are considered to be mediators of inflammation and immunomodulators. COX exists as two isoforms encoded by two different genes: COX- 1 which is constitu-tively and ubiquitously expressed, and COX - 2 which can be induced only in certain cells by inflammatory stimulation and cytokines etc. The COX isoforms are pharmacologically distinct according to their sensitivity to inhibition by NSAIDS. This finding has renewed interest in designing drugs that highly selective for inhibition of COX - 2 activity and to date several new compounds are under study. However,there is a controversy regarding the effect of NSAIDS on expression of COX mRNA and protein. In human osteoblastic cells stimulated with inter-leukin -1 (IL - 1) it has been showed that indomethacin( INDO) , pi-roxicam and flurbiprofen can partially inhibit the expression of COX mRNA induced by serum. On the contrary, in rabbit alveolar macro-phage aspirin ( ASA) and naproxen has no effect with the expression of COX - 2 induced by LPS at the levels of transcription and translation.We observed if the Meloxicam, a selective COX - 2 inhibitor would effect the COX -2 protein expressin caused by LPS in rats train and further discussed the frondose mechanism of specific COX - 2 inhibitor.MATERIALS AND METHODSMaterials: Male Wister rats, 180 -220g,were used in this study. They were assigned into two big groups of ten animals each at random and then every big ones were divided into two small groups. The time course of rectal temperature ( T.J, ) change was studied in 10 LPS - injected rats(100g/kg) , 10 saline - injected rats ( with the same volume of LPS) , 10 Meloxicam (0. 5mg/kg)3h taken orally pretreated and LPS - injectioned rats, 10 distilled water(with the same volume of Meloxicam) taken orally pretreated and LPS - injected rats by insec-ting the sensory of the digital thermometer into the rectum for 6cm. Methods: (1) Insecting the sensory of the digital thermometer into the rectum for 6cm. and the Tab of each was measured every 30 min from 1h before and 8h after the injection. (2 ) Iirnninuhistochemistry: (1)Ani-mal perfusion and histology: The rats were anesthetized with chloral hydrate at 2.5h after the LPS injection and perfused via the left ventricle with 0.9% saline for 20 minutes,followed by 250ml 4% paraform-aldehyde solution(PH6.5) containing 8% sucrose at 4 C. The brains were removed, stored in the 2% parafonnaldehyde fixative with 8% sucrose for 24h until immunohistochemistry staining was intitiated. Meloxicam - pretreated + LI'S - injected rats, distilled water - pretreated + LPS - injected rats were killed at 2. 5h after the injection. For each time point,5 rat brains were studied. (2)Immnuohistochemis-try:The tissue was stained using S - P. Tissue sections were rinsedwith 0.1M PBS (initially and between incubation steps) and then sequentially incubated in 3% hydrogen peroxide in PBS for 30 minutes at room temperature and 3% normal goat serum . Sections were then in-curated in rabbit COX -2 primary antiserum( 1:100 in PBS diluent) for 12h at room temperature. Sections were washed in PBS and incubated in peroxidase - conjugated goat anti - rabbits IgG( 1:100 in PBS diluent)for 30 minutes at room temperature. After rinsing,the sections were incubated in 0. 01% hydrogen peroxide dissolved in PBS. The section was terminated after 6 - 10 minutes with two successive rinses in PBS. Then we used the DAB as the staining material. (3)The sections were analyzed by using microscopic image quantitative analysis technique. (4)The statistic analysis used the Student t test.REDULTS1. The Tab of the UPS - injected rats, but not that of the saline -injected rats, started to rise again between 70 min and 90 m...
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