Nerve vasculature changes induced by serotonin - under chronic cauda eauina compression-

2002 Fiscal Year Final Research Report Summary

• Project/Area Number: 13671527
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Orthopaedic surgery
• Research Institution: Fukushima Medical University
• Principal Investigator: NAGAOSA Yoshihiro Fukushima Medical University, school of medicine, Assistant, 医学部, 助手 (40295415)
• Co-Investigator(Kenkyū-buntansha): KONNO Shinichi Fukushima Medical University, school of medicine, Assistant Professor, 医学部, 助教授 (70254018) ; KIKUCHI Shinichi Fukushima Medical University, school of medicine, Professor, 医学部, 教授 (80045773)
• Project Period (FY): 2001 – 2002
• Keywords: cauda equina / blood flow / blood vessels / serotonin / serotonin receptor

Research Abstract

This study was to analyze the changes of nerve vascular reaction and blood flow in nerve roots to serotonin following chronic compression.
Methods : A total of 35 dogs were used. Seven experimental groups were used : no operation (Group A), the balloon was placed under the lamina but not inflated (Group B), the balloon was inflated and the pressure was released just before the measurement (Group C), and the balloon was inflated and maintained during the measurements (Group D, E, F, G). Diameters of the blood vessels and blood flow of the second or 3rd sacral nerve were measured using a specially designed operation microscope equipped with a video camera. In Group A, B, C and D, 0.5μM serotonin was injected. In Group E and D, Sarpogrelate hydrochloride (5-HT_<2A> receptor antagonist : 5-HTRA) was injected before administration of serotonin. In Group G, 5HTRA was injected after administration of serotonin. Cauda equina tissues were used for electron microscopic analysis. Results : [Diameter of blood vessels] In Group A and B, the diameter of blood vessels and blood flow increased. In Group C and D, the diameter of blood vessels contracted and blood flow decreased after injecting serotonin. In Group E and F, 5-HTRA inhibited vasoconstrictive effects and reduction of blood flow before injecting serotonin. In Group G, 5-HTRA inhibited the reduction of blood flow but not vasoconstrictive. In an electron microscopic observation, tight junction of endothelial cells was destroyed in chronically compressed nerve roots. Discussion : This study showed that serotonin had a vasodilative effect on the intact nerve roots, while it caused vasoconstriction and reduction of blood flow in the chronically compressed nerve roots. 5HTRA inhibited vasoconstrictive effects and reduction of blood flow induced by serotonin. 5HTRA might improve intermittent claudication in the spinal canal stenosis.