Recognition and Alleviation of Pain in Laboratory Animals (2009) / Chapter Skim
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Appendix A: Models of Pain
Appendix A: Models of Pain
Pages 143-158
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From page 143... ...
Numerous animal models exist for the exploration of mechanism(s) and mediators of persistent pain in particular.
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2004 Neuropathic pain models Central nervous system spinal cord trauma (blunt) Young 2002 spinal cord insult (chemical)
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2005 review of animal models Pacharinsak and Beitz 2008 aMost of these models are provided here for completeness and are not discussed further in this report. bMany of these models are inflammatory in nature, but response measures differ significantly from nonvisceral inflammatory models.
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From page 146... ...
. Post-treatment response measures are hyperalgesic, meaning that response latency to heat is faster and mechanical withdrawal thresholds (typically assessed using von Frey-like nylon monofilaments, each of which has a different bending force)
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From page 147... ...
. In general, pain associated with inflammatory joint models is assessed by documenting changes in body weight, joint circumference, joint mobility, degree of weight bearing, soft tissue swelling, general activity, and gait.
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Blood pressure and heart rate measurement require either surgical implantation of an arterial catheter, which can be difficult to keep patent in rodents, or expensive telemetric methods for long-term recording of these measures. These responses to organ distension are organized in the brainstem (and thus are not simple nociceptive reflexes)
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From page 149... ...
Pain Models Models of postoperative pain have revealed that the mechanisms and subsequent control of postoperative pain differ significantly from those of inflammatory pain. These models involve an incision of glabrous or hairy skin of controlled length and depth to determine the relative contributions of skin, fascia, and underlying muscle to postoperative pain.
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From page 150... ...
. Neuropathic Pain Models Of the two major classes of clinical pain conditions -- those produced by tissue injury and those produced by nerve injury -- the latter for many years were very difficult to model in animals.
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to model the different clinical conditions, most studies have built on the principle that neuropathic pain arises from partial nerve injury (e.g., of a peripheral nerve) or abnormal neuronal activity.
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As noted above, one of the problematic adverse side effects of chemotherapy treatment for cancer pain is the development of a profound peripheral neuropathy with mechanical allodynia, thermal hypersensitivity, and ongoing, often burning pain. In recent years several laboratories have developed neuropathic pain models based on treatment with vincristine or taxol; the treatment typically involves weeks of drug administration to gradually produce in the animals a significant mechanical and thermal hypersensitivity to both warm and cold stimuli (the hypersensitivity disappears when the drug treatment ends)
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From page 153... ...
It was originally assumed that such cancer pains are largely inflammatory in nature, but animal studies indicate that there is a nerve injury-associated component as well. The peripheral nerve endings of fibers that innervate bone are unquestionably involved and these likely contribute to the mechanical hypersensitivity and ongoing pain that develop.
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From page 154... ...
In analogous inflammatory and postsurgical circumstances in humans, pain at rest is either minimal or acceptable, but, as in these animal models, hypersensitivity and pain can be easily provoked by certain stimuli (e.g., forced movement, application of noxious stimuli)
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2000. Spared nerve injury: An animal model of persistent peripheral neuropathic pain.
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1995. Artificial ureteral calculosis in rats: Behavioural characterization of visceral pain episodes and their relationship with referred lumbar muscle hyperalgesia.
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1990. A novel behavioral model of neuropathic pain disorders produced in rats by partial sciatic nerve injury.
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1994. Behavioral evidence of trigeminal neuropathic pain following chronic constriction injury to the rat's infraorbital nerve.
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