Science Links Japan | Effects of naloxone, buprenorphine, pentazocine, ketamine and benzodiazepins on pain threshold and pain tolerance level in mice.

Effects of naloxone, buprenorphine, pentazocine, ketamine and benzodiazepins on pain threshold and pain tolerance level in mice.

Accession number;02A0305820

Title;Effects of naloxone, buprenorphine, pentazocine, ketamine and benzodiazepins on pain threshold and pain tolerance level in mice.

Author; UCHIDA K (St. Marianna Univ. School Of Medicine) TATEDA T (St. Marianna Univ. School Of Medicine) NAGANO K (St. Marianna Univ. School Of Medicine) SUGIHARA H (St. Marianna Univ. School Of Medicine)

Journal Title;Prog Med

Journal Code:F0664B

ISSN:0287-3648

VOL.22;NO.2;PAGE.423-427(2002)

Figure&Table&Reference;FIG.1, TBL.2, REF.12

Pub. Country;Japan

Language;English

Abstract;Purpose: In a previous paper, two patterns of pain behavior, forepaw licking and jumping, were recommended as indexes for pain threshold and pain tolerance level, respectively, during the hot-plate test in mice. The aim of the present study was to investigate the effects of naloxone, buprenorphine, pentazocine, ketamine and bezodiazepins (midazolam, diazepam and flunitrazepam) on pain threshold and pain tolerance level using these indexes. Methods: The latency periods until forepaw licking and jumping were measured in each mouse using the hot-plate test (55.0.+-.0.2.DEG.C.) between the hours of 10:00-12:30. The mice were intraperitoneally injected with 0.5mL/kg of body weight of isotonic saline (control) or one of the seven drugs. The latency periods for each of the seven drugs were then compared to the latency periods of the control. Measurement of the latency period was started 10 minutes after the injection. Results: Although naloxone decreased the pain tolerance level in a dose-dependent manner, the drug did not decrease the pain threshold. Buprenorphine had a larger effect on the pain threshold than on the pain tolerance level. Pentazocine was equally effective for both the pain threshold and the pain tolerance level. Higher doses of ketamine shortened the licking latency period but prolonged the jumping latency period. Highest doses of midazolam and diazepam prolonged the jumping latency period but flunitrazepam was inactive. Conclusion: Naloxone, buprenorphine, pentazocine and ketamine have different effects on pain threshold and pain tolerance level in mice. The benzodiazepins have weak effects on pain sensitivity or are ineffective. (author abst.)

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