UC San Diego

Following vaginal delivery, the most common treatment is ibuprofen, a non-steroidal anti-inflammatory drug (NSAID) that helps alleviate postpartum pain. In the limb muscles, NSAIDs have been observed to interfere with the immune and myogenic events associated with skeletal muscle regeneration, leading to impaired muscle regeneration. However, the effect of NSAIDs on the pelvic floor muscles (PFMs) injured during parturition has never been evaluated. Thus, we aimed to elucidate: 1) the impact of birth injury on PFM micromorphological properties and 2) the effect of NSAIDs on the cellular events associated with PFM regeneration following birth injury. Utilizing an established rat model of simulated birth injury (SBI), we performed histological analysis of the temporal cellular events in the PFMs along the biologically relevant continuum following SBI. Our data demonstrate a profound negative impact of SBI on the functionally relevant morphological PFMs’ properties. NSAIDs do not impact the overall immune infiltrate following SBI but appear to delay muscle resident stem cells (MuSC) differentiation and decrease MuSC pool. In addition to these alterations in the acute recovery period, our analyses demonstrate a statistically significant reduction in the PFM myofiber size 28 days post-SBI in the group exposed to NSAIDs relative to the animals who did not receive NSAIDs following birth injury. The studies presented here are the first step in the continuum of the novel research evaluating the impact of postpartum NSAIDs on functional PFM properties.