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Comparative Study
. 2011 May;50(3):355-60.

Analgesic effects of meloxicam, morphine sulfate, flunixin meglumine, and xylazine hydrochloride in African-clawed frogs (Xenopus laevis)

Dondrae J Coble  1 , Douglas K Taylor, Deborah M Mook
Affiliations
Comparative Study

Analgesic effects of meloxicam, morphine sulfate, flunixin meglumine, and xylazine hydrochloride in African-clawed frogs (Xenopus laevis)

Dondrae J Coble et al. J Am Assoc Lab Anim Sci. 2011 May.

Abstract

We evaluated analgesic use and analgesiometry in aquatic African-clawed frogs (Xenopus laevis). We used the acetic acid test (AAT) to assess the analgesic potential of systemic xylazine hydrochloride, meloxicam, flunixin meglumine, and morphine sulfate after injection into the dorsal lymph sac. Flunixin meglumine provided better analgesia than did the other drugs, most evident at 5 and 9 h after administration. Because the AAT was associated with the development of dermal lesions, we discontinued use of this assay and chose the Hargreaves test as an alternative method of measuring nociception in Xenopus. This assay is commonly performed in rodents, but its efficacy in an aquatic species such as Xenopus was unknown prior to this study. We found that the Hargreaves test was an effective measure of nociception in Xenopus, and we used it to evaluate the effectiveness of the nonopiod agents xylazine hydrochloride, meloxicam, and flunixin meglumine both in the absence of surgery and after surgical oocyte harvest. Similar to findings from the AAT, flunixin meglumine provided better analgesia in the Hargreaves test than did the other agents when analyzed in the absence of surgical intervention. Results were equivocal after oocyte harvest. Although surgical oocyte harvest is a common procedure in Xenopus, and currently there are no published recommendations for analgesia after this invasive surgery. Future studies are needed to clarify the efficacy of nonsteroidal antiinflammatory drugs for that purpose.

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Figures

Figure 1.
Figure 1.
Photograph of the testing mechanism, including the Hargreaves apparatus, glass chamber, and Xenopus laevis.
Figure 2.
Figure 2.
Nociceptive threshold (mean ± SEM) as determined by using the AAT in Xenopus laevis after systemic injection of xylazine hydrochloride (10 mg/kg), meloxicam (0.2 mg/kg), morphine sulfate (40 mg/kg), and flunixin meglumine (25 mg/kg).
Figure 3.
Figure 3.
Nociceptive threshold (mean ± SEM) as determined by using the Hargreaves test in Xenopus laevis after systemic injection of xylazine hydrochloride (10 mg/kg), meloxicam (0.2 mg/kg), and flunixin meglumine (25 mg/kg).
Figure 4.
Figure 4.
Perioperative nociceptive threshold (mean ± SEM) as determined by using the Hargreaves test in Xenopus laevis after systemic injection of xylazine hydrochloride (10 mg/kg), meloxicam (0.2 mg/kg), and flunixin meglumine (25 mg/kg).
See this image and copyright information in PMC

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