Role of cholinergic systems in pain modulation: I. Impact of scopolamine on environmentally induced hypoalgesia and pain reactivity.
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Scopolamine was found to block both brief shock-induced (3 0.75-s, 1.0-mA shocks) and conditioned hypoalgesia on the tail-flick test in rats. The drug also produced a general increase in pain reactivity as measured by both the tail-flick test and shock-induced vocalization. It was shown that this hyperalgesia cannot account for the effect of the drug on brief-shock or conditioned hypoalgesia. Scopolamine did not block the nonopioid analgesia observed after long shock (3 25-s, 1.0-mA shocks). When the effect of the drug on baseline levels of pain reactivity was controlled, it potentiated long shock-induced hypoalgesia. Scopolamine also increased reactivity to tactile stimulation, which suggests the hyperalgesia reflects a general increase in arousal. None of these effects were observed with methylscopolamine, which suggests they are not peripherally mediated.
author list (cited authors)
Grau, J. W., Illich, P. A., Chen, P. S., & Meagher, M. W.
complete list of authors
Grau, JW||Illich, PA||Chen, PS||Meagher, MW