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Updated: Aug 16, 2026

Assessment of Morphine-induced Hyperalgesia and Analgesic Tolerance in Mice Using Thermal and Mechanical Nociceptive Modalities
Published on: July 29, 2014
Dose-dependent analgesic and hyperalgesic effects of systemic naloxone in arthritic rats
Abstract:
The effects of various i.v. naloxone doses (10 microgram, 300 microgram, 600 microgram, 1 mg/kg) were studied upon vocalization threshold to foot-pressure in 30 normal rats and 70 rats with Freund's adjuvant-induced arthritis. In arthritic rats, the lowest naloxone doses yielded a clear increase in pressure required to trigger vocalization (i.e. were analgesic) while the highest dose (1 mg/kg) was hyperalgesic. In normal rats, naloxone never induced significant changes in the vocalization threshold.
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