Role of cholinergic systems in pain modulation: I. Impact of scopolamine on environmentally induced hypoalgesia and pain reactivity. Academic Article uri icon


  • 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.

published proceedings

  • Behav Neurosci

author list (cited authors)

  • Grau, J. W., Illich, P. A., Chen, P. S., & Meagher, M. W.

citation count

  • 17

complete list of authors

  • Grau, JW||Illich, PA||Chen, PS||Meagher, MW

publication date

  • February 1991