The effect of long-term oral tadalafil treatment on corpus cavernosum function in an experimental spinal cord transection rat model.

OBJECTIVES: The aim of this study was to investigate the pharmacological effects of long-term oral tadalafil treatment on the corpus cavernosum function in rats subjected to experimental spinal cord transection (SCT).

METHODS: Thirty young adult, male Sprague–Dawley rats were randomly divided into five groups (n¼ 6, each), as follows: (1) Control,(2) Control surgery (Sham), (3) Tadalafil (Td), (4) Experimental SCT, and (5) SCT + Tadalafil (SCT + Td). SCT rat model: after removal of T8-T9 spinal processes and laminates, a full-thickness scalpel incision was made in the spinal cord. SCT + Td rat model:rats subjected to SCT were given tadalafil (5mg kg(-1), p.o.) for 4 weeks. Next, the penile cavernous tissues obtained by en blocexcision were trimmed free of the surrounding tissue to isolate cavernosal smooth muscle strips, which were then transferred into the isolated organ baths to investigate isometric tension changes in response to various bioactive agents and electrical field stimulation (EFS).

RESULTS: The relaxation response to acetylcholine at 0.01 mM concentration was significantly less in the SCT group compared with other groups. EFS-induced relaxation in the basal and precontracted cavernous tissue preparations was greater in the SCT + Td group than in the SCT group.

CONCLUSION: This study demonstrated that long-term tadalafil administration preserves relaxation responses probably by affecting through the nitric oxide (NO)/cyclic guanosine monophosphate (cGMP) pathway in SCT-applied rats. This treatment strategy might preserve the erectile process and prevent the SCT-induced permanent damage in the cavernosal tissue.