Neuroscience letters
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Neuroscience letters · Jun 2010
Sex and hormonal variations in the development of at-level allodynia in a rat chronic spinal cord injury model.
The development of central neuropathic pain varies among patients with spinal cord injury (SCI). The factors contributing to the development and perpetuation of segmental pain (at-level allodynia) has been the focus of ongoing experiments in our laboratory. One such factor is hormonal status. ⋯ The proportion of ovx SCI female rats and placebo-treated SCI males displaying pain-like behaviors to touch/pressure of at-level dermatomes up to 6 weeks post-injury (67% and 75%, respectively) was similar to our previous studies on SCI males (69%). In contrast, significantly fewer cycling SCI female rats and 17beta-estradiol treated SCI male rats showed sensitivity to touch at-level (26% and 30%, respectively). These results implicate 17beta-estradiol as a potential target that can readily be modulated to prevent segmental pain following SCI.
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Neuroscience letters · Jun 2010
Effect of analgesic standards on persistent postoperative pain evoked by skin/muscle incision and retraction (SMIR).
Various common surgeries such as thoracotomy and inguinal hernia repair involve essential prolonged tissue retraction, often causing persistent postoperative pain. A new model was developed to mimic this clinical scenario, whereby skin/muscle incision and retraction (SMIR) in the medial thigh evoked persistent postoperative pain (Flatters (2008) [Pain 135:119-130]). This study examines the response of SMIR-evoked mechanical hypersensitivity to analgesic standards commonly used as positive controls in behavioural pain studies. ⋯ In conclusion, the SMIR model displays persistent mechanical hypersensitivity that is reversible by morphine or gabapentin treatment. As previously demonstrated, SMIR-evoked pain is not driven by neuronal damage and these data show that NMDA receptor activation does not play a role in the maintenance of SMIR-evoked pain. This study further demonstrates the value of the SMIR model as a tool to understand persistent postoperative/postsurgical pain mechanisms and evaluate potential treatments.