[Effect of epidural capsaicin on substance P in the dorsal horn in adult rats using epidural tubing].
Male Sprague-Dawley rats weighing 280-300g were used. To achieve the long-term administration of drugs into the epidural space without anesthesia, a new method of epidural tubing was used. A polyethylene catheter was inserted for 1.5cm into the epidural space through a slit made in the ligamentum flavum of L2-L3 intervertebral space. When 0.1ml of contrast media was injected through this catheter, the media spread from lumbar to upper thoracic vertebral region, as demonstrated with X-ray pictures. The rats with an epidural catheter were injected with 0.1ml of 2% capsaicin solution into the epidural space once a day for 4 days. Control rats were administered with the same volume of capsaicin-free vehicle. The depression of substance P at the dorsal horn (C6, Th7, L1) was investigated by the indirect immunofluorescence technique of Coons. One day after the end of capsaicin administration the depression of substance P was remarkable at laminae I-II in dorsal horn. But 14 days after the end of administration, substance P content at laminae I-II returned to the level of control rats. It was concluded that the depression of substance P by consecutive epidural capsaicin is reversible.
Matsumoto
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D000818:Animals; D002211:Capsaicin / Q000008:administration & dosage / Q000494:pharmacology*; D003864:Depression, Chemical; D004824:Epidural Space; D007440:Intubation; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D013116:Spinal Cord / Q000187:drug effects* / Q000378:metabolism; D013373:Substance P / Q000378:metabolism*
D013373:Substance P; D002211:Capsaicin