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Oral Biology Program
BDS, Liaquat University of Medical and Health Sciences, Pakistan
MSD, UMDNJ, New Jersey Dental School
Thesis Advisor: Eli Eliav, Ph.D.
Department of Diagnostic Sciences, Dental School
Wednesday, July 31, 2013
1:00 PM., D-987, RSDM
There is growing evidence in literature looking at the role of pain modulation systems in acute and chronic pain conditions. Recent studies also suggest an association between pre-operative pain modulation patterns and post-operative pain development. Despite the mention, pain modulation have not been studied extensively in the laboratory setting. One of the limitations is the lack of validated animal models. We established a rat model for Temporal Summation (TS) and Exercise Induced Analgesia (EIA) to study pain modulation systems. Repetitive tactile stimuli were applied to the hind paw of a rat before and after 180 seconds on a rota-rod device. The difference between the percent stimuli response, before and after exercise presented the EIA score. The change in response 1 minute post exercise from baseline was used to categorized the rats into low, medium and high EIA groups. The difference between the last and first 10 stimuli percentage response was considered as the TS score, that was used to categorize the rats into high, medium and low TS groups.
In the first phase of the study TS did not predict pain severity in acute and chronic stages of neuropathic pain. However, EIA was able to predict pain severity in acute and chronic phases of neuropathic pain. In the acute phase EIA profile predicted heat, cold and mechanical hyperalgesia, whereas in the chronic stage EIA predicted tactile allodynia only.
The second phase of the study focused on the effect of low and high doses of medication commonly used for the treatment of neuropathic pain as diclofenac, duloxetine and pregabalin on the pain modulation systems. We found that high dose diclofenac had an immediate short lasting effect in reducing neuropathic pain in High TS and low EIA groups. Duloxetine was effective in the acute phase of neuropathic pain for groups with high TS. In the chronic phase of neuropathic pain both high doses of duloxetine and pregabalin reduced pain significantly in high TS and low EIA groups.
In conclusion, pain modulation profile may help identifying subjects at risk to develop chronic pain condition following injury.
The findings from this study may serve as a basis for more efficient pharmacotherapy for chronic pain conditions, based on the patientís pain modulation profile.