S-090 | Evaluation of a mouse model of chronic muscular pain induced by acidic saline injections

Disorders of the Nervous System
Author: Martina Poodts | Email: Mpoodts@mail.austral.edu.ar

Martina Poodts^1°, Benjamín Zylberberg^2°, Violeta Klimek^1°,  M. Clara Rodríguez^1°, Alejandro Montaner^3°, M. Florencia Coronel^1°2°, Graciela L. Mazzone^1°2°

^1° Facultad de Ciencias Biomédicas, Universidad Austral, Av. Pte. Perón 1500, B1629AHJ, Pilar, Buenos Aires, Argentina.
^2° Instituto de Investigaciones en Medicina Traslacional (IIMT), CONICET-Universidad Austral, Av. Pte. Perón 1500, B1629AHJ, Pilar, Buenos Aires, Argentina.
^3° Instituto de Ciencia y Tecnología “Dr. César Milstein”, CONICET, Fundación Pablo Cassará, Pilar, Buenos Aires, Argentina

Fibromyalgia (FM) is a widespread chronic pain condition with unclear etiology and limited therapeutic strategies. In the present study, we aimed to test a model of chronic muscular hyperalgesia that mimics FM-syndrome to investigate underlying mechanisms and develop novel treatments. To induce FM-like syndrome two acidic saline (pH 4.0) injections were administrated four days apart into the left gastrocnemius muscle of male and female Balb/C mice. Based on our findings from the Von Frey and Choi tests, we observed increased sensitivity to both mechanical and thermal stimuli, indicating a decrease in mechanical pain threshold and higher number of cold-induced responses. This hypersensitivity was particularly pronounced bilaterally with a significantly greater impact being observed in females. No differences were observed in the locomotor patterns studied, including distance travelled and immobility time. The expression of GFAP in the spinal cord remained unchanged. However, females showed a significant decrease in the size of the gastrocnemius endplates when analyzing images stained with the postsynaptic marker α-bungarotoxin. According to our data, repeated injections of acid saline into the muscles of rodents seems to be relevant for studying a condition involving widespread, long-lasting pain, such as FM, and could potentially be used to develop new treatment approaches. Supported by Universidad Austral, CONICET and FONCYT.