Figure 3
NPSR antagonist blocks NPS effects on vocalizations. Audible (A) and ultrasonic (B) vocalizations were evoked by brief (15 s) innocuous (300 g/30 mm2, A, C) and noxious (1200 g/30 mm2, B, D) stimulation of the knee joint in arthritic rats (4 days postinudction). Duration of vocalizations during a 1 min period was measured during stereotaxic application of an NPS receptor antagonist (SHA68, 50 μM, concentration in microdialysis probe, 20 min; n = 6 rats) or ACSF (vehicle control; n = 6 rats) following nasal application of NPS. Stereotaxic applications started 25 min after NPS and behavioral measurements were made 45 min after NPS. Compared to NPS coapplied with ACSF, vocalizations were significantly increased when NPS was coapplied with the antagonist. *,** P < 0.05, 0.01, unpaired t-test.