Numerous adrenal chromaffin cell preparations fail to produce analgesic effects in the formalin test or in tests of acute pain even with nicotine stimulation.
Previous studies have reported that intrathecal implants of a variety of adrenal chromaffin cell preparations all produce analgesic effects in rodents. The major objective of the present study was to determine if any adrenal chromaffin cell preparations produce more robust analgesic effects than other cell preparations. The present study included adult rat adrenal chromaffin tissue allografts, purified adult bovine chromaffin cells, and polymer-encapsulated calf adrenal chromaffin cells, all prepared according to previously published procedures, as well as purified calf adrenal chromaffin cells. Previous studies have also suggested that immunosuppression may play a role in graft survival, and potentially increase the magnitude of analgesic effects, so the present study included both immunosuppressed and non-immunosuppressed groups (cyclosporin A, 10 mg/kg per day). Behavioral tests included the formalin test; and a dorsal tail-flick, hot-plate, and paw-pinch test, conducted sequentially 2 min after systemic nicotine (0.1 mg/kg) to evoke release from the chromaffin cells, as previously reported. Analgesic effects related to morphine and nicotine were detected, and consistent differences in performance could be detected between individual animals. Surprisingly, no analgesic effects were detectable with any of the four chromaffin cell preparations, with or without immunosuppression, in the formalin test or with nicotine stimulation in tests of acute pain.
Lindner
Mark D
MD
CytoTherapeutics, Inc., Two Richmond Square, Providence, RI 02906, USA.
Francis
Jonathan M
JM
McDermott
Patricia E
PE
Bell
William J
WJ
Blaney
Thomas J
TJ
Sherman
Sandy S
SS
Saydoff
Joel A
JA
D000208:Acute Disease; D000311:Adrenal Glands / Q000166:cytology / Q000502:physiology*; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D002417:Cattle; D017690:Cell Transplantation / Q000502:physiology*; D019439:Chromaffin Cells / Q000502:physiology*; D016572:Cyclosporine / Q000494:pharmacology; D005557:Formaldehyde; D007166:Immunosuppressive Agents / Q000494:pharmacology; D008297:Male; D009538:Nicotine / Q000494:pharmacology*; D018722:Nicotinic Agonists / Q000494:pharmacology*; D010147:Pain Measurement / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013268:Stimulation, Chemical; D014183:Transplantation, Heterologous
D007166:Immunosuppressive Agents; D018722:Nicotinic Agonists; D005557:Formaldehyde; D009538:Nicotine; D016572:Cyclosporine