The lesion of CSF contacting neurons in rat brain parenchyma inhibits the development of morphine dependence and withdrawal / 中国应用生理学杂志

<p><b>AIM</b>To investigate the effect of CSF contacting neurons (CSF-CNs) lesion in rat dorsal raphe nucleus (DRN) on the scores of morphine withdrawal symptoms precipitated by naloxone and the nNOS expression in dorsal horn of spinal cord, and study the relationship between the distal CSF-CNs in rat brain parenchyma and the development of morphine dependence and withdrawal.</p><p><b>METHODS</b>Chemical lesion of neurons the injection of cholera toxin subunit B with horseradish peroxidase (CB-HRP) into one of the rats lateral ventricles, TMBST reaction, nNOS immunohistochemistry and Western blot were used in this study.</p><p><b>RESULTS</b>The withdrawal symptoms by the naloxone precipitated attenuated obviously after the lesion of CSF-CNs in rat DRN, scores of all signs were significantly decreased about 38% compared to that of withdrawal group without lesion (P < 0.05). The withdrawal symptoms scores of vehicle withdrawal group and side lesion withdrawal group were not changed significantly (P > 0.05). Neurons in the location of CSF-CNs concentrated in the rat brain slices of lesion group were damaged obviously, there were only few CB-HRP positive neurons around the lesion location. But the location and the quantity of the CB-HRP positive neurons in the brain slices of the group without lesion was stable relatively, and their appearance was very clear. After the lesion, the nNOS expression and the quantity of the nNOS positive neurons in dorsal horn of spinal cord decreased significantly compared to that of withdrawal group without lesion (P < 0.05), but it also increased significantly compared to that of normal group and dependence group (P < 0.01).</p><p><b>CONCLUSION</b>The lesion of distal CSF contacting neurons attenuated the scores of morphine withdrawal symptoms precipitated by naloxone and the nNOS expression in dorsal horn of spinal cord. The distal CSF contacting neurons in rat brain parenchyma partly participated in the development of morphine dependence and naloxone precipitated withdrawal possibly by the modulation of NO (nitric oxide).</p>

Distribution and expression of p38 MAPK in the distal cerebrospinal fluid contacting neurons in brain of rat by noise stress / 中国应用生理学杂志

<p><b>AIM</b>To observe the distribution and expression of p-p38MAPK in the distal cerebrospinal fluid contacting neurons in brain of rat by noise stress.</p><p><b>METHODS</b>By a double-labelled method combing the tracing of CB-HRP and the immunohistochemical technique p-p38MAPK, the distribution and expression of p-p38MAPK in the distal cerebrospinal fluid contacting neurons(csf cn) were observed following noise stress. Expression of p-p38MAPK and double-labelled of CB-HRP/p-p38MAPK were also observed in rat brain after noise stress.</p><p><b>RESULTS</b>Two groups of CB-HRP labeled neuron clusters consistently appeared in certain regions of the brainstem but none in other regions of the brain. Without noise stress exposure, only a few neurons were found double-labeled by CB-HRP/p-p38MAPK. After 1 day noise stress exposure, only few neurons double-labeled by CB-HRP/p-p38MAPK were observed in the above-mentioned regions. After 5 days, the number of neurons double-labeled by CB-HRP/p-p38MAPK increased significantly compared with the control group (P < 0.05). After 10 days, the number of neurons double-labeled by CB-HRP/p-p38MAPK increased significantly compared with the control group (P < 0.05). After 20 days, both of the numbers of neurons double-labeled by CB-HRP/p-p38MAPK increased significantly compared with that of the control group (P < 0.01).</p><p><b>CONCLUSION</b>Two groups of distal cerebrospinal fluid contacting neuron clusters consistently existed in certain regions of the brain parenchyma, and in these clusters only a few neurons con rained p-p38MAPK. After noise stress exposure of different durations (days 1, 5, 10, 20), the number of distal cerebrospinal fluid contacting neurons with p-p38MAPK increased significantly with increasing days. The results indicate that distal cerebrospinal fluid contacting neurons are special neurons existing consistently in brain, including distal cerebrospinal fluid contacting neurons with p-p38MAPK which may participate in the whole procedure of signal transduction or central modulation in noise stress response and play greater roles with increasing days.</p>