Anesth Analg 1999;89:428
© 1999 International Anesthesia Research Society
REGIONAL ANESTHESIA AND PAIN MANAGEMENT
Systemic Physostigmine Shows Antiallodynic Effects in Neuropathic Rats
R. Pöyhiä, MD, PhD*, ,
M. Xu, MD, ,
V. K. Kontinen, MD, PhD,,
S. Paananen, MD,, and
E. Kalso, MD, PhD
*Department of Anesthesia, McGill University, Montréal, Quebec, Canada; and Departments of
Anaesthesia and
Pharmacology and Toxicology, Institute of Biomedicine, University of Helsinki, Helsinki, Finland
Address correspondence and reprint requests to Reino Pöyhiä, MD, PhD, Department of Anesthesia, McGill University, Royal Victoria Hospital, 687 Pine Ave. West, Room F9.12, Montreal, Quebec, Canada H3A 1A1. Address e-mail to mbd2{at}musica.mcgill.ca
The aim of this study was to examine the antiallodynic and antinociceptive effects of subcutaneously administered physostigmine (50, 100, 200 µg/kg), compared with morphine (2.5, 5, 10 mg/kg) and NaCl after spinal nerve ligation in rats. The following stimuli were used: acetone (cold allodynia), von Frey hairs (mechanical allodynia), and paw flick test (thermal nociception). Motility boxes were used to investigate the effects of the drugs on motor performance. Physostigmine attenuated both mechanical and cold allodynia dose-dependently but had no effect on the paw flick test. The effect was antagonized by atropine (muscarinic receptor antagonist) but not by mecamylamine (nicotinic receptor antagonist) or naloxone (opioid receptor antagonist). Morphine produced dose-dependent antiallodynic and antinociceptive effects. In the antiallodynic doses, morphine caused severe rigidity. Physostigmine 200 µg/kg impaired locomotor activity, but no rigidity was observed.
Implications: Physostigmine has different effects on allodynia and nociception, which suggests that different cholinergic (muscarinic) mechanisms may be involved in neuropathic and nociceptive pain.
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