We have used the model of four soft knots on the sciatic nerve and the model of four soft knots on the saphenous nerve, but were unable to generate the expected hyperalgesia. Animals exhibited no significant changes and sometimes presented hypoesthesia.
Dear Pablo,
It looks that you tried a model of Chronic Constriction Injury (CCI) described by Bennet and Xie (1988). What method did you use to assess the pain response, and did you use any molecular markers? This model might be little problematic, since is hard to define what does it means exactly that the applied ligature should be “soft”. I used this model with a good result by applying the ligatures and constricting them slightly (a space remained to put the tip of the watchmaker forceps underneath), and you could observed a twitch in the rat's hind limb after the knot was done. However, there is a modification of this model where instead of silk ligatures you can use a cuff made of polyethylene tubing (Pitcher GM et al. Pain 1999), which might be more repeatable model. Another model that you can consider is Partial Sciatic Nerve Transection (PST) where you need to transect the peroneal, inferior part of the sciatic nerve (Lindenlaub and Sommer, 2000). There is also a Paclitaxel induced pain model. It is hard to say which one is the best. It all depends of your experiment design.
Maybe this paper will help you to select a suitable model (Wang LX 2003 - Animal and cellular models of chronic pain)
Dear Michal,
Thank you, I think we had problem to define what is "soft" ligature. Maybe our ligature was "very soft". Pain measured by hot plate test.
We have been using sciatic nerve crush injury model. With regards to hot plate test, results are not consistent and highly variable. Just wonder if hot plate test is still acceptable by most of the researchers in this field nowadays.
It depends upon what you want to investigate and your expertise. Several "good" models of sicatic nerve lesions have been used to study neuropathic pain, and most are useful. Particularly the spared nerve injury is probably the most consistent in terms of results. What is also very important is to use adequate methods for evaluation. I would not recommend the hot plate. Algesimetry tests for mechanical (Von Frey) and thermal (plantar) focal stimulation are adequate. However, you have to be aware of the innervation territories of the limbs and which areas are denervated or innervated in the surgical model you use. You may take a look at our recent article Cobianchi et al Exp Neurol 2014, 255:1-11.
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