AB024. Safety evaluation of low-energy extracorporeal shock wave therapy to rat testes

Background: The purpose of the study is to determine the optimal energy frequency of LESWT to rat testes by comparing three different shock wave frequencies.

Methods: A total of 40 healthy Sprague-Dawley (SD) rats were randomly assigned to a blank group (C group) in which 5 rats received no treatment, a sham group (B group) in which 5 rats only exposed to shockwave, and LESWT groups (A group) in which 30 rats separately exposed to 0.02 mJ/mm² (A1 group), 0.04 mJ/mm² (A2 group), and 0.06 mJ/mm² (A3 group). The changes of rat weight among these five groups were compared. Eenzyme-linked immunosorbent assay (ELISA) was performed to measure the concentrations of testosterone (T), luteinizing hormone (LH), and follicle-stimulating hormone (FSH). Testicular mass index (TMI) of rat bilateral testes was compared. A transmission electron microscopy (TEM) was used to observe the microstructure of testes in rats among five groups.

Results: After a 2-week period of low-energy extracorporeal shock wave therapy (LESWT), the rat weight changed significantly between A1 and A3 groups but did not differ among A1, A2, B, and C groups (P=0.09, 0.31, 0.47); no significant difference in T, LH, and FSH concentrations was observed when the A1 group was respectively compared with other four groups (P=0.11, 0.33, 0.19, 0.47); the TMI of rat testes in the A1 group was significantly different from that in the A3 group (P=0.04). Observations from the TEM showed that rats exhibited normal microstructure of testes in A1, B, and C groups. Mitochondrial swelling, dissolution of cristae, and dilated intercellular space occurred in the A2 group. Mitochondrial vacuolization, nuclear perturbations, cytoplasmic segregation, and necrotic cells were observed in the A3 group.

Conclusions: Taken together, we conclude that 0.02 mJ/mm² LESWT exerts no significant influence on rat weight, T, LH, FSH, TMI of testes, and microstructure, which may be regarded as the safe frequency for rat testes undergoing LESWT. Furthermore, our study demonstrates that TEM is one of the most reliable methods for evaluating the effect of LESWT on microstructures of rat testes.

Keywords: Low-energy extracorporeal shock wave therapy (LESWT); testes; safety evaluation