Chronic Osteoporotic Pain in Mice: Cutaneous and Deep Musculoskeletal Pain Are Partially Independent of Bone Resorption and Differentially Sensitive to Pharmacological Interventions

Figure 2

Effects of ovariectomy on behavioral indices of cutaneous and deep musculoskeletal pain and physical function. Hypersensitivity to cutaneous plantar mechanical stimuli (von Frey assay) (a), cold (acetone test) (b) and cold plate tests (c), and heat (radiant heat hindpaw withdrawal assay) (d) develops by 8 weeks and persists for 6 months after ovariectomy. Using the grip force strength assay as a behavioral index of deep musculoskeletal pain, reduced strength is observed at 8 weeks and 6 months, after surgery (e). The total exploration distance during 5-minute exposures to an open field test was used as a behavioral index of physical function; a significant difference is not evident between OVX and sham-operated mice at either time-point (f). Data are expressed as means ± standard error of the mean. OVX: ovariectomized; NS: not significant; ; ; and OVX versus sham-operated, two-way repeated measures analysis of variance (factors = group time) followed by Tukey’s test for multiple comparisons.

(a) Mechanical: von Frey

(b) Cold: acetone

(c) Cold plate

(d) Heat: paw withdrawal

(e) Grip strength

(f) Open field