UC San Diego

Peripheral neuropathy is a complication of diabetes commonly associated with pain and decline in motor compound action potential, leading to alterations in plantar pressure during gait. We identified motor impairments in streptozotocin (STZ)-induced diabetic neuropathic rats and correlated with mechanical withdrawal thresholds, establishing this correlation as a complementary method to investigate the development of chronic hyperalgesia in diabetic neuropathy.

Methods

UNICAMP's Ethics Committee (protocol number 3902-1) approved all experiments. Male Lewis rats (200-250 g) received a STZ-low-dose (25 mg/kg/day) (STZ group) or 0.1 M sodium citrate buffer (SCB, control group) once a day, during five consecutive days. Diabetic rats (250 mg/dL blood glucose) were submitted to electronic von Frey and CatWalk tests at 0, 7, 14, 21, and 28 days after treatment.

Results

STZ, but not SCB, induced diabetes. After the 14^th day (STZ)-induced diabetic rats showed mechanical hyperalgesia and a reduction in the hind limbs footprint intensities. At the 28^th day, rats presented alterations in spatial parameters (Maximum Contact Area; Stride Length; Print Area), which showed a strong correlation with mechanical withdrawal thresholds (r² = 0.97; 0.99, and 0.93, respectively).

Conclusions

Correlation between gait parameters and mechanical withdrawal thresholds enables a better experimental approach to evaluate the development of chronic hyperalgesia in the STZ-induced diabetes model. It allows a concise crosstalk of motor and sensorial functions, which are usually analyzed individually. CatWalk gait parameters can be used as a complementary tool to investigate the development of hyperalgesia in STZ-induced diabetic neuropathic rats.