Objective To investigate the regulatory effects of nerve growth factor （NGF） on basal and capsaicin-induced release of neuropeptide substance P （SP） in primary cultured embryonic rat dorsal root ganglion （DRG） n...Objective To investigate the regulatory effects of nerve growth factor （NGF） on basal and capsaicin-induced release of neuropeptide substance P （SP） in primary cultured embryonic rat dorsal root ganglion （DRG） neurons. Methods DRGs were dissected from 15-day-old embryonic Wistar rats. DRG neurons were dissociated and cultured, and then exposed to different concentrations of NGF （10 ng/mL, 30 ng/mL, or 100 ng/mL） for 72 h. The neurons cultured in media without NGF served as control. RT-PCR were used for detecting the mRNAs of SP and vanilloid receptor 1 （VR1） in the DRG neurons. The SP basal and capsaicin （100 nmol/L）-induced release in the culture were measured by radioimmunoassay （RIA）. Results SP mRNA and VR1 mRNA expression increased in primary cultured DRG neurons in a dose-dependent manner of NGF. Both basal release and capsaicin-evoked release of SP increased in NGF-treated DRG neurons compared with in control group. The capsaicin-evoked release of SP also increased in a dose-dependent manner of NGF. Conclusion NGF may promote both basal release and capsaicin-evoked release of SP. NGF might increase the sensitivity of nociceptors by increasing the SP mRNA or VR1 mRNA.展开更多
Objective To investigate the involvement of transient receptor potential vanilloid receptor 1 （TRPV1） in the facial inflammatory pain in relation to thermal hyperalgesia and cold pain sensation. Methods Facial infla...Objective To investigate the involvement of transient receptor potential vanilloid receptor 1 （TRPV1） in the facial inflammatory pain in relation to thermal hyperalgesia and cold pain sensation. Methods Facial inflammatory pain model was developed by subcutaneous injection of turpentine oil （TO） into rat facial area. Head withdrawal thermal latency （HWTL） and head withdrawal cold latency （HWCL） were measured once a day for 21 d after TO treatment using thermal and cold measurement apparatus. The immunohistochemical staining, cell-size frequency analysis and the survey of average optical density （OD） value were used to observe the changes of TRPV1 expression in the neurons of the trigeminal ganglion （TG）, peripheral nerve fibers in the vibrissal pad, and central projection processes in the trigeminal sensory nuclei caudalis （Vc） on day 3, 5, 7, 14, and 21 after TO injection. Results HWTL and HWCL decreased significantly from day 1 to day 14 after TO injection with the lowest value on day 5 and day 3, respectively, and both recovered on day 21. The number of TRPV1-labeled neurons increased remarkably from day 1 to day 14 with a peak on day 7, and returned back to the normal level on day 21. In control rats, only small and medium-sized TG neurons were immunoreactive （IR） to TRPV1, and the TRPV1-IR terminals were abundant in both the vibrissal pad and the Vc. Within 2 weeks of inflammation, the expression of TRPV1 in small and medium-sized TG neurons increased obviously. Also the TRPV1 stained terminals and fibers appeared more frequent and denser in both the vibrissal pad skin and throughout laminae Ⅰ and the outer zone of laminae Ⅱ （Ⅱo） of Vc. Conclusion Facial inflammatory pain could induce hyperalgesia to noxious heat and cold stimuli, and result in increase of the numbers of TRPV1 positive TG neurons and the peripheral and central terminals of TG. These results suggest that the phenotypic changes of TRPV1 expression in small and medium-sized TG neurons and terminals might play an important role in the development and maintenance of TO-induced inflammatory thermal hyperalgesia and cold pain sensation.展开更多
文摘Objective To investigate the regulatory effects of nerve growth factor （NGF） on basal and capsaicin-induced release of neuropeptide substance P （SP） in primary cultured embryonic rat dorsal root ganglion （DRG） neurons. Methods DRGs were dissected from 15-day-old embryonic Wistar rats. DRG neurons were dissociated and cultured, and then exposed to different concentrations of NGF （10 ng/mL, 30 ng/mL, or 100 ng/mL） for 72 h. The neurons cultured in media without NGF served as control. RT-PCR were used for detecting the mRNAs of SP and vanilloid receptor 1 （VR1） in the DRG neurons. The SP basal and capsaicin （100 nmol/L）-induced release in the culture were measured by radioimmunoassay （RIA）. Results SP mRNA and VR1 mRNA expression increased in primary cultured DRG neurons in a dose-dependent manner of NGF. Both basal release and capsaicin-evoked release of SP increased in NGF-treated DRG neurons compared with in control group. The capsaicin-evoked release of SP also increased in a dose-dependent manner of NGF. Conclusion NGF may promote both basal release and capsaicin-evoked release of SP. NGF might increase the sensitivity of nociceptors by increasing the SP mRNA or VR1 mRNA.
基金supported by the National Natural Science Foundation of China(No.30570629)China-Dutch Joint Research Project(No.05CDP030)
文摘Objective To investigate the involvement of transient receptor potential vanilloid receptor 1 （TRPV1） in the facial inflammatory pain in relation to thermal hyperalgesia and cold pain sensation. Methods Facial inflammatory pain model was developed by subcutaneous injection of turpentine oil （TO） into rat facial area. Head withdrawal thermal latency （HWTL） and head withdrawal cold latency （HWCL） were measured once a day for 21 d after TO treatment using thermal and cold measurement apparatus. The immunohistochemical staining, cell-size frequency analysis and the survey of average optical density （OD） value were used to observe the changes of TRPV1 expression in the neurons of the trigeminal ganglion （TG）, peripheral nerve fibers in the vibrissal pad, and central projection processes in the trigeminal sensory nuclei caudalis （Vc） on day 3, 5, 7, 14, and 21 after TO injection. Results HWTL and HWCL decreased significantly from day 1 to day 14 after TO injection with the lowest value on day 5 and day 3, respectively, and both recovered on day 21. The number of TRPV1-labeled neurons increased remarkably from day 1 to day 14 with a peak on day 7, and returned back to the normal level on day 21. In control rats, only small and medium-sized TG neurons were immunoreactive （IR） to TRPV1, and the TRPV1-IR terminals were abundant in both the vibrissal pad and the Vc. Within 2 weeks of inflammation, the expression of TRPV1 in small and medium-sized TG neurons increased obviously. Also the TRPV1 stained terminals and fibers appeared more frequent and denser in both the vibrissal pad skin and throughout laminae Ⅰ and the outer zone of laminae Ⅱ （Ⅱo） of Vc. Conclusion Facial inflammatory pain could induce hyperalgesia to noxious heat and cold stimuli, and result in increase of the numbers of TRPV1 positive TG neurons and the peripheral and central terminals of TG. These results suggest that the phenotypic changes of TRPV1 expression in small and medium-sized TG neurons and terminals might play an important role in the development and maintenance of TO-induced inflammatory thermal hyperalgesia and cold pain sensation.
