Effects of phonophoresis with diclofenac linked gold nanoparticles in model of traumatic muscle injury

The use of nanotechnology for administering drugs is a recent development that presents promising results. Therapeutic Pulsed Ultrasound (TPU) is one such therapeutic option and is widely used for treating soft tissue lesions. Thus, the objective of this study was to investigate the therapeutic effect of phonophoresis using diclofenac (DC) linked to gold nanoparticles (GNPs) in the skeletal muscle of rats used as a model of traumatic muscular injury. Wistar rats were divided into eight groups (N = 10): Sham, Muscle injury (MI), MI + TPU, MI + DC, MI + GNPs, MI + TPU + DC, MI + TPU + GNPs, and MI + TPU + DC-GNPs. The traumatic injury was performed in the gastrocnemius with a single direct traumatic impact via an injuring press. The animals received daily treatment for 5 consecutive days with TPU and gel with DC and/or GNPs. Two hours after the last treatment session, animals were euthanized and the gastrocnemius muscle surgically removed for histological and biochemical analysis. The groups exposed to some therapies (MI + TPU + DC, MI + TPU + GNPs and MI + TPU + DC-GNPs) showed reduced levels of pro-inflammatory cytokines, whereas an increase in anti-inflammatory cytokine levels was observed in the group exposed to all therapies combined (MI + TPU + DC-GNPs). Reactive species production and protein damage resulting from oxidative damage was lower for the group exposed to all tested therapies had lower production. Lower protein damage was also observed in the TPU + GNPs group. The group that underwent all tested therapies combined showed a significant increase in antioxidants compared to the MI group. During histological analysis, the MI group showed large amounts of cell infiltration and centralized nuclei, whereas the MI + TPU + DC-GNPs group showed structural improvements. Pain levels in the MI + TPU + DC-GNPs group were lower than those of the MI group. We believe that the association of TPU with DC linked to GNPs decreases the inflammation caused by traumatic muscle injury and accelerates tissue repair.