Mouse Behavior in the Open-field Test after Meloxicam Administration

Abstract

Several analgesics are suggested for pain management in mice. Nonsteroidal antiinflammatories (NSAIDs), such as meloxicam can be administered for the treatment of inflammation and acute pain; however, several side effects can occur which include gastrointestinal ulceration and renal and hepatic toxicity. We previously performed a pilot study to test the antinociceptive activity of meloxicam in mice, but we observed behavioral changes in unoperated control mice. These observations spurred further investigation. One hypothesis for the result was potential differences in formulation between commercial brands of meloxicam. Thus, this current study aimed to evaluate the effects of 3 different commercial brands of meloxicam (20 mg/kg) in the general activity of mice using the open field test. Our results showed that meloxicam had several effects on mouse behavior and caused the formation of skin lesions at the injection site, depending on the brand of the drug. The most significant adverse effect observed was decreased exploratory activity. Grooming frequency was reduced in all groups. These adverse effects might be related to the quality of the drugs because meloxicam formulations can contain crystal polymorphisms that affect drug quality and efficacy. This study points out the importance of drug quality variation that can affect the outcome of behavioral studies in mice.

Figure 1.

Assessment of general activity of C57BL/6J mice in the open field test (OFT) after meloxicam administration. Distance traveled (cm) (A); average speed (cm/s) (B); time spent in the peripheral zone of the arena (C); time spent in the center zone of the arena (s) (D); time moving (s) (E); rearing frequency (counts) (F); grooming frequency (counts) (G). Data are presented as the means ± SEM. ANOVA followed by Tukey’s multiple comparisons test was used to compare differences between groups. M1_SC (n = 7); CTR, M1_IP, M2_SC, M2_IP, M3_SC, and M3_IP (n = 8/group). IP, intraperitoneal; SC, subcutaneous. ***P < 0.001(extremely significant).

Figure 2.

Photographs of mice after subcutaneous injection of M1_SC sample. Mice showed alopecia and scratching on the skin at the injection site after subcutaneous injection (arrows).