NOS-positive Neurons In The Gray Matter Around The Central Canal And In The Shallow Lamina Of Dorsal Horn In The Lumbar And Sacral Segments Of The Spinal Cord And Antinociception Produced By Acupuncture

Nitric oxide was first identified as endothelium-derived relaxing factor(EDRF) by Professor Furchgott in the early eighties in the 20th century. In recent years, it was found out that NO plays a great role on the forming of nociception. The shallow lamina of dorsal horn is an important structure in the passing of nociception, while the function of the gray matter around the central canal is not clear up till now. So it is of certain significance to analyze the relationship between NOS-positive neurons in the gray matter around the central canal and in the shallow lamina of dorsal horn in the spinal cord and antinociception produced by acupuncture. In the present study, using the method of NADPH-d ,we observed NOS-positive neurons in the gray matter around the central canal and in the shallow lamina of dorsal horn in the lumbar and sacral segments of spinal cord when animal is normal, pain stimulated, electroacupuncture stimulated, or pain and electroacupuncturestimulated. We also count the number of NOS-positive neurons in the four conditions above in order to analyze the relationship between NOS-positive neurons in the gray matter around the central canal and in the shallow lamina of dorsal horn in the spinal cord and antinociception produced by acupuncture.Twenty healthy adult rats (250~300g in weight) were divided randomly into four groups: a) Normal group, b) Pain stimulated group: inject 200ul formaldehyde (5%) in the right hind paw of the rats as models, c) Electroacupuncture stimulated group: stimulate acupuncture point "Zu san li" of the rats (3V, 8Hz, 0.5h) with electroacupuncture as models. d)Pain and electroacupuncture stimulated group: after the injection of 200ul formaldehyde (5%) in the right hind paw, the rats are stimulated with electroacupuncture immediately; The four groups of rats were perfused. Sections were cut at 40um for the method of NADPH-d. All the results are observed with the microscope made in the Japanese company of Olympus. NOS-positive neurons in the gray matter around the central canal and in the shallow lamina of dorsal horn in the lumbar and sacral segments of the spinal cord are counted. The number of NOS-positive neurons in the gray matter around the central canal of each animal is the average number of NOS-positive neurons in the gray matter around the central canal of twenty pieces of sections of that animal. The number of NOS-positive neurons in the shallow lamina of dorsal horn of each animal is the average number of NOS-positive neurons in the shallow lamina of dorsal horn on the stimulated side of twenty pieces of sections of that animal. The number of NOS-positive neurons of each group is the average number of NOS-positive neurons of every animal in that group. The experimental data were presented as mean 1 standard deviation (x眘).The results are as follows:1. In normal conditions, there are a few NOS-positive neurons in the gray matter around the central canal(2.9110.83) and in the shallow lamina of dorsal horn(2.06+1.03).2. After pain stimulated, compared with normal group, the number of NOS-positive neurons in the gray matter around the central canal(8.54?.12) and in the shallow lamina of dorsal horn(3.97?.40) increased significantly (PO.01).3. After electroacupuncture stimulated, compared with normal group, the number of NOS-positive neurons in the gray matter around the central canal (2.7310.65) and in the shallow lamina of dorsal horn (2.0110.86) did not change greatly (P>Q.Q5).4. After pain and electroacupuncture stimulated, compared with normal group, the number of NOS-positive neurons in the gray matter around the central canal (2.8710.88) and in the shallow lamina of dorsal horn (2.2011.08) did not change greatly (P>0.05). However, compared with pain stimulated group, the number of NOS-positive neurons in the two area above decreased significantly (PO.01).The results suggest that:1. In normal conditions, there are a few NOS-positive neurons in the gray matter around the central canal and in the...