Pain
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In the study of neuropathic pain, the reduction of spinal neuronal activity by an analgesic drug can inform about site and mechanistic aspects of action. Animal experiments such as in vivo electrophysiological recordings from spinal neurons, however, largely require anesthesia. The impact of the anesthesia on the interpretation of the experimental result has been mostly disregarded. ⋯ A marked inhibitory effect of gabapentin can be revealed by isoflurane anesthesia. It could be expected that drug profiles of clinically active agents are similar across neuropathic pain models. Instead, our results suggest that the choice of the anesthetic influences electrophysiological results to a greater extent than the surgical protocol used to induce nerve injury in an animal model of neuropathic pain.
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Fast Conducting Mechanoreceptors Contribute to Withdrawal Behavior in Normal and Nerve Injured Rats.
Fast-conducting myelinated high-threshold mechanoreceptors (AHTMR) are largely thought to transmit acute nociception from the periphery. However, their roles in normal withdrawal and in nerve injury-induced hyperalgesia are less well accepted. Modulation of this subpopulation of peripheral neurons would help define their roles in withdrawal behaviors. ⋯ This suggests that AHTMR neurons play a role not only in threshold-related withdrawal behavior in the normal animal, but also in sensitized states after nerve injury. This is the first time this subpopulation of neurons has been reversibly modulated to test their contribution to withdrawal-related behaviors before and after nerve injury. This technique may prove useful to define the role of selective neuronal populations in different pain states.
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Editorial Comment
Does cold hypersensitivity increase with age in sickle cell disease?