Figure 3

Increased audible and ultrasonic vocalizations in the K/C model of arthritic pain. (A, B) Original recordings of ultrasonic vocalizations evoked by innocuous (upper trace) and noxious (lower trace) stimulation of the knee joint in a rat before (A) and after (B) induction of arthritis with intraarticular kaolin and carrageenan injections. Mechanical stimuli were applied for 15 s; duration of the recording period was 1 min. Vocalizations during and after stimulation (VDS and VAD, respectively) were analyzed separately. (C) Duration of audible and ultrasonic VDS increased significantly 6 h after induction of arthritis compared to the values measured in the same animals before arthritis (n = 16). Stimuli of innocuous (left side) and noxious (right side) intensities evoked VDS of longer duration in arthritic animals compared to controls. (D) Duration of ultrasonic, but not audible, VAD following innocuous (left) and noxious (right) stimuli increased significantly in the arthritis pain model (6 h postinduction; n = 16). Symbols and error bars represent mean ± SE. ** P < 0.01, *** P < 0.001. Reprinted from Han JS & Neugebauer V [54]. PAIN 2005;113-211-222. Used with permission from the International Association for the Study of Pain^®.