QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: jpet.104.077792v1 313/1/449    most recent Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Cook, C. D. Articles by Nickerson, M. D. Search for Related Content PubMed PubMed Citation Articles by Cook, C. D. Articles by Nickerson, M. D.

BEHAVIORAL PHARMACOLOGY

Nociceptive Sensitivity and Opioid Antinociception and Antihyperalgesia in Freund's Adjuvant-Induced Arthritic Male and Female Rats

Department of Pharmacology and Toxicology and Institute for Drug and Alcohol Studies, Virginia Commonwealth University, Richmond, Virginia

The present study was designed to examine sex differences in complete Freund's adjuvant (CFA)-induced mechanical hyperalgesia and sex differences in opioid antinociception and anti-hyperalgesia. Female rats developed inflammation and hyperalgesia faster and exhibited greater peak hyperalgesia than male rats. In arthritic (CFA-treated) rats, lower thresholds were observed during estrus and proestrus, and in nonarthritic (vehicle-treated) rats, lower thresholds were observed during proestrus. Morphine and oxycodone were more potent in male than female arthritic rats, and butorphanol was more potent and effective in male than female arthritic rats. The potency of morphine was increased in arthritic rats, although to a greater magnitude in males. The potency of oxycodone was increased in male but not female arthritic rats. The potency of butorphanol was increased in arthritic male rats and the maximal antinociceptive effect of butorphanol was increased in arthritic female rats, but it did not result in greater than 20% antinociception. Morphine, oxycodone, and butorphanol all produced antihyperalgesic effects (returning thresholds of arthritic rats to the thresholds of nonarthritic rats) with greater potency in males than females. The peripherally acting opioid agonist loperamide produced intermediate levels of antinociception in male and female arthritic rats and no antinociception in nonarthritic rats. Loperamide was more potent in male than female arthritic rats at producing antihyperalgesia. These data demonstrate sex differences in arthritis-induced hyperalgesia and responsiveness to opioid analgesics. In arthritic rats, the antinociceptive effects of opioid agonists are most probably mediated by both central and peripheral opioid receptors, whereas their antihyperalgesic effects are mediated primarily by actions at peripheral opioid receptors.

Address correspondence to: Dr. Charles D. Cook, Department of Pharmacology and Toxicology and Institute for Drug and Alcohol Studies, Virginia Commonwealth University, 410 North 12th St., P.O. Box 980613, Richmond, VA 23298-0613. E-mail: ccook{at}hsc.vcu.edu

This article has been cited by other articles:

				D. R. Loyd, X. Wang, and A. Z. Murphy Sex Differences in {micro}-Opioid Receptor Expression in the Rat Midbrain Periaqueductal Gray Are Essential for Eliciting Sex Differences in Morphine Analgesia J. Neurosci., December 24, 2008; 28(52): 14007 - 14017. [Abstract] [Full Text] [PDF]

				R. W. Hurley and M. C. B. Adams Sex, Gender, and Pain: An Overview of a Complex Field Anesth. Analg., July 1, 2008; 107(1): 309 - 317. [Abstract] [Full Text] [PDF]

				K. K. Lemberg, A. O. Siiskonen, V. K. Kontinen, J. T. Yli-Kauhaluoma, and E. A. Kalso Pharmacological Characterization of Noroxymorphone as a New Opioid for Spinal Analgesia Anesth. Analg., February 1, 2008; 106(2): 463 - 470. [Abstract] [Full Text] [PDF]

				N. M. Flake, T. O. Hermanstyne, and M. S. Gold Testosterone and estrogen have opposing actions on inflammation-induced plasma extravasation in the rat temporomandibular joint Am J Physiol Regulatory Integrative Comp Physiol, August 1, 2006; 291(2): R343 - R348. [Abstract] [Full Text] [PDF]

				X. Wang, R. J. Traub, and A. Z. Murphy Persistent pain model reveals sex difference in morphine potency Am J Physiol Regulatory Integrative Comp Physiol, August 1, 2006; 291(2): R300 - R306. [Abstract] [Full Text] [PDF]

				Y. Ji, A. Z. Murphy, and R. J. Traub Sex differences in morphine-induced analgesia of visceral pain are supraspinally and peripherally mediated Am J Physiol Regulatory Integrative Comp Physiol, August 1, 2006; 291(2): R307 - R314. [Abstract] [Full Text] [PDF]

				K. J. Berkley, S. S. Zalcman, and V. R. Simon Sex and gender differences in pain and inflammation: a rapidly maturing field Am J Physiol Regulatory Integrative Comp Physiol, August 1, 2006; 291(2): R241 - R244. [Full Text] [PDF]