ARA290 in a Rat Model of In fl ammatory Pain - Tissue-Protective Cytokines: Methods and Protocols - page 215

Following neuritis, there were signs of mechanical allodynia on
the ipsilateral side that peaked on day 4, which was indicated by a
decrease in monofilament threshold (Fig. 2a , vehicle group). By
day 7 mechanical allodynia had partly recovered. Treatment with
120 g/kg ARA290 significantly reduced the development of

mechanical allodynia on day 4 (Fig. 2a ). Heat hyperalgesia peaked
by day 3 following neuritis (Fig. 2b , vehicle group), which was
indicated by a reduction in withdrawal latency. Similar to mechani-
cal allodynia, almost complete reversal had occurred by day 7.
Treatment with 120

μ

g/kg ARA290 caused a notable reduction in
heat hyperalgesia on day 3 (Fig. 2b ). These data clearly demon-
strate the positive effects of ARA290 in the treatment of neuritis-
induced pain where there is no frank nerve injury.

μ

4 Notes

1. There has been much discussion regarding a suitable negative
control for the neuritis. Previous studies have performed the
same surgery but replaced the complete Freund's adjuvant
with saline. However, it should be noted that surgery alone is
sufficient to cause low grade inflammation around the nerve.
2. It is important to monitor anesthesia depth during surgery.
For example, the pedal withdrawal reflex should be absent.
Visual inspection of chest wall movements will indicate changes
in the rate, depth, and pattern of breathing. Respiratory rate
should fall during anesthesia.
3. To blunt dissect, insert the scissors (or forceps) closed into the
tissue plane that you are trying to separate. Partly open the
scissors and slowly remove. Repeat until all tissue has been
separated.
4. Make sure you always have a good visual of the surgical site.
Never cut through tissue that you cannot see.
5. The surgery is best performed under a dissection microscope
with a good light.
6. The complete Freund's adjuvant solution tends to separate.
Therefore, it is important to shake the Eppendorf prior to use,
between animals.
7. Always feed the Gelfoam under the nerve with both sets of
angled forceps. Pulling the Gelfoam with one set of forceps
will cause it to break up or stretch/twist the nerve.
8. To reduce the risk of animals chewing stitches, bury the knot
below skin. This is best achieved by performing inside-out stitches,
whereby the knot will be on the inside of the surgical side.
9. Behavioral testing should always be performed at the same
time of each day.