| INTRODUCTIONUncoupling proteins ( UCPs) are proton transporters of the inner mitochondria! membrane. They dissipate the proton electrochemical gradient, uncouple mitochondria! electron transport from oxidative phospharylation and release stored energy as heat without enhancing a-denosine triphosphate ( ATP) production. The change of UCPs, gene and its expression can affect the efficiency of metabolism, so UCPs has been proposed to play a role in the maintenance and regulation of body temperature.The expression of uncoupling protein 2(UCP2) is the most ubiquitous in the UCPs family. It was expressed in many organs such as heart, lung, liver and so on. Liver is one of important organs for ther-mogenesis, which take part in thermoregulation.Injection of lipopolysacchride ( LPS) intraperitoneally induces a febrile response in mice. The fever response caused by LPS and the cytokines induced by LPS, such as tumor necrosis factor -a (TNF -a) can be mediated by prostaglandin E (PGE). Giving indometha-cin, a cyclooxygenase inhibitor, can reduce the production of PGE, and thus decrease the body temperature .Since UCP2 is involved in thermogenesis and liver is an importantthermogenic organ, whether or not, the expression of UCP2mRNA in liver has some relationship with the change of body temperature of mice during the fever response caused by LPS and the antipyrogenic effect of indomethacin? There is no report has been seen about this aspect .The current research intends to use the method of in - situ hybridization to study the expression of UCP2mRNA in the livers of mice. The method not only enables us to locate the expression of UCP2mRNA in the level of cell, in quantity, but also enables us to observe the regulation of UCP2mRNA expression during the fever response caused by LPS and the antipyretic effect of indomethacin. In this study HE ?stained and electromicroscopic technique are also used to observe the change of mitochondria structure and the degenerative alteration of hepatocytes following with the rise of UCP2mRNA expression. The results are expected to help us go further into the possible mechanism underlying the increment of energy expenditure seen during fever response.MATERIALS AND METHODSMaterial; thirty three healthy female C57BL/6 mice, weighting 18~22g, at4~6 weeks age, were used. The mice were divided into 3 groups; LPS - treated groups, which were further divided into five subgroups. The mice were injected intraperitoneally (i. p. ) with LPS in a dose of 5mg/kg. We recorded the rectal temperature and measured the quantity of UCP2mRNA respectively at 0,6,12,16 and 24 hour after injection; saline - treated groups, which also included 0,6, 12,16 and 24 hour subgroups, were injected intraperitoneally with thesame volume of sterile, pyrogen - free saline. The same indices as that of LPS - treated groups were tested at each time point; combination-treated group, i. e. ,11th subgroup: indomethacin( lOmg/kg, ip)was administered immediately before LPS(5mg/kg,ip) injection. The above indices were measured at 12h after treatment.The mice in all groups were housed in a sound - proof room illuminated daily from 8:00 - 20:00 ( a 12:12h light - dark cycle) with environment temperature at ( 20 ?1) Tl and humility at ( 45 ?5 ) % for 2 weeks. The mice were allowed free access to standard powered mice chow and tap water. To exclude the difference in chow consumption between groups, food was withdrawn from both control and treated animals 6 hours before the measurement of temperature and drawing materials.Method: A thermistor probe was inserted approximately 3cm into the rectum to record the body temperature of mice. The method of in - situ hybridization was used to measure the UCP2mRNA positive product and the data was analyzed by microscopic image quantitative analysis technique to determine the mean gray value, % thretholded area and integrated optical density of UCP2mRNA; Electron microscopic and HE - stained technique were used to observe the change of mitochondria and hepatocytes.
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