1: Spine. 2003 Aug 1;28(15):1635-41.  

Changes in Spontaneous Behavior in Rats Exposed to Experimental Disc Herniation
are Blocked by Selective TNF-Alpha Inhibition.

Olmarker K, Nutu M, Storkson R.

*Department of Orthopaedics, Goteborg University, Sahlgrenska University
Hospital, Gothenburg, Sweden, and the.

STUDY DESIGN Study of pain behavior in animals by observation of changes in
spontaneous behavior.OBJECTIVES To assess if selective inhibition of tumor
necrosis factor alpha may reduce changes in spontaneous behavior induced by
experimental disc herniation in the rat as previously reported.SUMMARY OF
BACKGROUND DATA It is known that the proinflammatory cytokine tumor necrosis
factor alpha may play a key role for the nucleus pulposus-induced nerve
dysfunction seen in experimental set ups. However, it is not known if tumor
necrosis factor alpha is also involved in pain production induced by the same
procedure.METHODS Thirty-two rats were used for the study. Twenty-two rats had
an L4-L5 disc incision combined with a displacement of the L4 dorsal root
ganglion. Twelve of these rats received an intraperitoneal injection of 0.125 mL
of 10 mg/mL Remicade(R), and the remaining 10 were left untreated. Ten rats only
had the L4-L5 disc exposed and formed the control group. The day before surgery
and days 1, 3, 7, 14, and 21 after surgery, the rats were videotaped from below
during a 20-minute period. The duration of four specific behaviors were
determined and compared between the three experimental groups at each time
point.RESULTS Similar to a previous study, the nontreated showed increased signs
of focal pain behavior (rotation of the head towards the operated leg and
lifting of the operated leg) during the first 7 postoperative days. Treatment
with the tumor necrosis factor alpha-inhibitor infliximab significantly reduced
this behavior. At day 14, there were no differences between the groups, and at
day 21, the nontreated group displayed reduced locomotion and increased
immobility, similar to previous observations. Tumor necrosis factor alpha
inhibition also seemed to reduce these behaviors.CONCLUSIONS The data of the
study clearly indicate a role for tumor necrosis factor alpha in the studied
behavior changes after experimental disc herniation in the rat. Clinical trials
must be performed in order to assess if there may be a clinical use for tumor
necrosis factor alpha inhibition in the treatment of sciatica due to disc
herniation.

PMID: 12897484 [PubMed - in process]