| Background and Aim:The chronic prostatitis is a very common urological disease of young and mid-age men and the pain is the main syndrome of which despite of many kinds of etiological factors. The past research has only focused on the pathological changes of prostate, however, the neurological transduction pathway and regulation mechanism of chronic prostatitis pain has not been noticed completely. The recent research has identified the chronic prostatitis pain is often a persistent L5-S2 visceral referred pain and companioned with the dysfunction of the pelvic base muscle.Recently, the activation of the astrocyte and strong immune activity of P substance(SP) in spinal cord have been found in some kinds of chronic pain models. With the development of the research in central nervous system, it has been found the transduction and regulation of pain in not only the function of neurocyte, but is firmly correlated with the astrocyte. It has been observed by further research that the astrocyte can excrete the inflammation factors such as TNF,IL-1,NGF and NO, et al on some conditions, which may lead to the injury of neurocyte and chronic pain. Moreover, SP is a very important transmitter to transduct pain and has been identified that the level of SP has been enhanced in many kinds of chronic pain.Accordingly, it is interesting to investigate the concrete cellular and molecular mechanism of the astrocyte how to be activated and to regulate pain in chronic prostatitis pain and the relationship between the astrocyte activation and SP, so the main object of the study is to investigate the cellular and molecular mechanism of activation of astrocyte and the role of SP in the chronic prostatitis pain and to explore the new therapeutic way for which.Methods: We made the rat prostatitis pian model and observered the alteration of the express of SP mRNA in DRG neurocyte and NK-1R, GFAP, iNOS and TNF-αin posterior horn with Real-time RT-PCR and Western-blot respectively(L5-S2), then the astrocyte of spinal cord has been cultured in vitro to investigate the effect of SP on which, including the excretion of IL-1β, TNF-α, NO, NOS obsevered with ELISA, nitrate reductase and colorimetric methods, moreover, the excretion of these inflammation factors investigated after P38MAKP blocked by SB203580, the phosphorylation of P38MAKP and express of C-fos with Western-blot and RT-PCR, glutamate intake with 3H-Glutamate incorporation and express of GFAP and GLT-1 with RT-PCR.Main results:1. The express of SP mRNA in DRG neurocyte and NK-1R express in posterior horn of L5-S2 spinal cord of the rat prostatitis pain model was obviously higher than the control at 6d, 12d (P<0.01) and the experimental at 6d , 12d were higher than 0d (P<0.01).2. The express of GFAP, TNF-αand iNOS in posterior horn of the L5-S2 spinal cord of the rat prostatitis pain model was obviously higher than the control at 6d, 12d and the experimental at 6d , 12d were higher than 0d (P<0.01), moreover, the express of GFAP at 6d was lower than 12d (P<0.05) and the peak value of iNOS express was at 6d in experimental groups(P<0.01).3. The astrocyte of spinal cord of rats was cultured and purified to more than 95% yield (confirmed with GFAP immunofiuorescence cytochemistry).4. SP caused a concentration-dependent(10-9-10-6mol/L,12h) increase of TNF-α, IL-1β, NO excretion and NOS activity with marked difference between every experimental group and control (P<0.01, P<0.05), except in 10-6mol/L, there is no obvious difference of the excretion of IL-1βbetween the experimental and control.5. SP(10-7mol/L)could promote the express of GFAP in astrocyte gradually on the time range of 0-72h and with marked difference between every experimental group and control (P<0.01).6. 3H-Glutamate incorporation of the gruoups stimulated by SP decreased gradually at the concentration of SP 10-9 -10-6 mol/L and had obvious difference with the control(P<0.05, P<0.01).7. No obvious difference of the express of GLT-1 had been found between the groups stimulated by SP(10-9-10-8mol/L) and control (p>0.05), but the groups stimulated by SP (10-7-10-6mol/L) is lower than the control (P<0.05, P<0.01).8. Enhanced P38MAPK activity was found at 15,30,45,60min in the groups stimulated by SP with the obvious difference compared with the control(P<0.05, P<0.01), and which reached the highest level at 45min.9. The express of C-fos in 0.5h, 1h, 3h, 6h is obviously higher than the control (P<0.05, P<0.01), and which reached the highest level at 3h.10. SP(10-7mol/L,12h) caused a increase of IL-1β, NO and TNF-αexcretion with marked difference between every experimental group and control (P<0.01). SB203580 could obviously inhibit the increase of excretion of NO and TNF-α(P<0.01) and had no obvious effect on IL-1β(P>0.05).There was no significant difference between only blocked by SB203580 and the control(P>0.05).Conclusoions:1. The chronic prostatitis pain model of rat had been made successfully and more effect of excitatory transmitter SP than normal in L5-S2 spinal cord had been observed.2. In the chronic prostatitis pain model of rat, the express of GFAP, TNF-αand iNOS had been up-regulated in posterior horn of L5-S2 spinal cord, whcih indicated that the chronic prostatitis pain could result in the activation of astrocyte and inflammation of L5-S2 spinal cord.3. Furthermore, stimulated by SP, the cultured astrocyte of spinal cord of rat had been activated and synthesized more GFAP, excreted more inflammation factors, such as TNF-α,IL-1βand NO, moreover, the express of GLT-1 and 3H-Glu incorporation could be affected by SP and too high concentration SP could lead to the reduction of the intake of glutamate in astrocyte, and over-concentration glutamate would result in the more serious injury of neurocyte.4. So the result of rat prostatitis pain model and cultured astrocyte all indicated that chronic prostatitis pain might lead to the the secondary inflammation of L5-S2 spinal cord by activation and glutamate intake reduction of astrocyte stimulated by SP, which was probably correlated with the maintenance and enlargement of chronic prostatitis pain.5. It also has been identified the P38MAPK and C-fos could be activated by SP in astrocyte of spinal cord, which indicated P38MAPK and C-fos are important signal pathway in neurogenic inflammation of L5-S2 spinal cord of chronic prostatitis pain model of rat .
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