Peters Bethlehem, Powers Shelby A, Burleson Lindsey K, Odom Michael R, Pak Elena S, Turner Alexander C, Sivanesan Nethusan, Koontz Bridget F, Hannan Johanna L
Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, USA.
Department of Psychiatry and Behavioral Sciences, Duke University School of Medicine, Durham, USA.
Cureus. 2024 Aug 7;16(8):e66374. doi: 10.7759/cureus.66374. eCollection 2024 Aug.
Introduction Radiation therapy (RT) is the gold standard for many pelvic cancers and improves overall patient survival. However, pelvic RT is associated with increased sexual dysfunction and urinary incontinence. Although the side effects of pelvic RT are well-documented, the pathological mechanisms leading to pelvic organ dysfunction are unknown, and a preclinical model has not been established. This study characterized the impact of pelvic RT at early and late timepoints on female rat bladder, vaginal, and urethral physiology and morphology. Methods Adult female Sprague-Dawley rats were divided into three groups (n = 8/group): (I) Sham, (II) four weeks RT (4wk RT), and (III) nine weeks RT (9wk RT). The RT groups received a single dose of 20 Gy external beam radiation, and experiments were conducted at 4wk and 9wk post-RT. Nerve-mediated vaginal blood flow was measured via laser Doppler. Tissue bath studies assessed vaginal contractility to electric field stimulation (EFS), adrenergic and cholinergic agonists, and relaxation to a nitric oxide donor. Bladder and urethral sphincters were evaluated for cholinergic, caffeine, and EFS-mediated contractility. Quantitative polymerase chain reaction (qPCR) measured gene expression of markers of oxidative stress. Vaginal, bladder, and urethral fibrosis were assessed with Masson's trichrome staining. Results At 4wk post-RT, total vaginal blood flow decreased, and at 9wk post-RT, returned to baseline levels. At 9wk post-RT, vaginal neurogenic and adrenergic-mediated contractile responses increased significantly. Vaginal epithelial thickness decreased post-RT and correlated with an acute rise in vaginal inflammatory gene expression. At 4wk post-RT, bladder neurogenic contractions decreased and remained lowered. Internal urethral contractions increased at 4wk post-RT and returned to Sham levels after 9wk post-RT. Pelvic RT increased external urethral neurogenic contractions, which remained elevated. Conclusion This novel preclinical model provides valuable insights into the temporal pathophysiology of pelvic RT-induced sexual and urinary dysfunction. The establishment of this model is crucial for understanding the underlying mechanisms involved in RT-induced pelvic injury. A reliable, clinically relevant model will allow for the testing of therapeutic strategies to prevent adverse effects with RT in pelvic cancer survivors.
引言 放射治疗（RT）是许多盆腔癌症的金标准，可提高患者的总体生存率。然而，盆腔放疗会导致性功能障碍和尿失禁增加。尽管盆腔放疗的副作用已有充分记录，但导致盆腔器官功能障碍的病理机制尚不清楚，且尚未建立临床前模型。本研究描述了盆腔放疗在早期和晚期对雌性大鼠膀胱、阴道和尿道生理及形态的影响。方法 将成年雌性Sprague-Dawley大鼠分为三组（每组n = 8）：（I）假手术组，（II）四周放疗组（4wk RT），（III）九周放疗组（9wk RT）。放疗组接受单次20 Gy外照射，实验在放疗后4周和9周进行。通过激光多普勒测量神经介导的阴道血流。组织浴研究评估阴道对电场刺激（EFS）、肾上腺素能和胆碱能激动剂的收缩性以及对一氧化氮供体的舒张性。评估膀胱和尿道括约肌的胆碱能、咖啡因和EFS介导的收缩性。定量聚合酶链反应（qPCR）测量氧化应激标志物的基因表达。用Masson三色染色评估阴道、膀胱和尿道纤维化。结果 放疗后4周，阴道总血流量减少，放疗后9周恢复至基线水平。放疗后9周，阴道神经源性和肾上腺素能介导的收缩反应显著增加。放疗后阴道上皮厚度降低，并与阴道炎症基因表达的急性升高相关。放疗后4周，膀胱神经源性收缩减少并持续降低。放疗后4周内尿道收缩增加，放疗后9周恢复至假手术组水平。盆腔放疗增加了尿道外神经源性收缩，且持续升高。结论 这种新型临床前模型为盆腔放疗引起的性和泌尿功能障碍的时间病理生理学提供了有价值的见解。该模型的建立对于理解放疗引起盆腔损伤的潜在机制至关重要。一个可靠的、与临床相关的模型将有助于测试预防盆腔癌症幸存者放疗不良反应的治疗策略。
