When western blot evaluation of ASMA expression in homogenates of penile shaft tissue(bottom, B)was performed, it paralleled the immunohistochemical measurements. neuronal NOS(nNOS),endothelial NOS(eNOS),proliferating cell nuclear antigen(PCNA), and TUNEL. Quantitative western blot analysis was carried out in homogenates. == Main outcome steps == Time course on the development of fibrosis and CVOD == Results == Following BCNR, CVOD was detectable 30 days later and it became more pronounced by 45 days. In contrast, the SMC/collagen ratio in the BCNR corpora was reduced at 7 days and bottomed at 30 and 45 days, due in part to the reduction of SMC, presumably caused by an increase in apoptosis peaking at 3 days. PCNA also peaked at 3 days but then decayed. nNOS was reduced early (3-7 days) and disappeared at 30 days, whereas eNOS was not affected. iNOS was induced at day 3, and continuously increased peaking at 30 days. == Conclusions == CVOD evolves in the BCNR rat as a result of the early loss of corporal SMC by the neuropraxia-induced apoptosis, which the initial cell replication response cannot counteract, followed by fibrosis. The time course of iNOS induction supports the antifibrotic role of iNOS. Keywords:fibrosis; erectile dysfunction, easy muscle mass, nerve sparing, radical prostatectomy, penis, nitric oxide; cGMP, collagen, inducible nitric oxide synthase, apoptosis == INTRODUCTION == Despite the use of nerve-sparing surgical techniques during radical pelvic surgery in men, the cavernosal nerves still appear to be somewhat susceptible to injury during the surgical procedure as evidenced by prolonged and relatively high rates of erectile dysfunction in the immediate post operative period following such nerve sparing techniques (1-4). The primary reason for this surgically induced impotence is usually corporal veno-occlusive dysfunction(CVOD)or venous leakage (5-8) which becomes manifest whenever there is a decrease in the content of corporal easy muscle mass cells(SMC)(9). When this occurs, the remaining corporal easy muscle mass is unable to accomplish sufficient relaxation to attain CCT251236 the high intracorporeal pressures which are necessary for the passive Rabbit polyclonal to HSD17B13 occlusion of the veins that egress the corporal body as they traverse underneath and through the tunica albuginea of the penis. We have previously exhibited in the rat, in a model of cavernosal nerve resection, that CVOD is usually apparent at 45 days after the neural injury (10-13). This functional impairment was associated with a decrease in the SMC mass and an increase in collagen content in the corporal tissue. In addition, we also observed a concomitant increase CCT251236 in the expression of the inducible nitric oxide synthase(iNOS)following bilateral cavernosal nerve resection(BCNR).Since we have shown in other experimental injury models that this upregulation of iNOS post-injury, presumably via the synthesis of NO, can act as an anti-fibrotic defense mechanism against the development of CCT251236 fibrosis, we then hypothesized that this iNOS may be acting in a similar manner around the corporal tissue in this BCNR model. The evidence to support this hypothesis comes from our finding that the long-term continuous oral administration of a PDE5 inhibitor, which is known to upregulate the action of nitric oxide, not only prevented both the BCNR-induced CVOD and the loss of the corporal SMC mass (10,11,12) normally seen following this type of injury, but there was the unexpected finding that the PDE5 inhibitors also enhanced replication of the corporal SMC themselves. However, even though it has been well established that CVOD evolves after BCNR and that iNOS expression is CCT251236 usually increased in the corporal tissue, the temporal relationship between these processes have never been fully elucidated. CCT251236 The aim of this study was to determine: a) whether the development of the histological and biochemical changes that occur after BCNR precedes the onset of the CVOD, and b) when and how long does iNOS induction occur following such a neural injury. These observations would help establish the time frame of when to initiate treatment with PDE5 inhibitors following cavernosal nerve damage in order to accomplish the optimum anti-apoptotic and anti-fibrotic effect of these drugs. == MATERIALS AND METHODS == == Animal treatments == Five month-old male Fisher 344 rats (Harlan Sprague-Dawley, San Diego, CA) were randomly divided into sham operated and BCNR groups. Animals were sacrificed at 1, 3, 7, 15, 30 and 45 days after surgery (n=8 each group). BCNR was performed as previously explained (9-12). Animals were operated under aseptic conditions and isoflurane anesthesia. In supine position, a midline incision was carried out, the pelvic cavity was opened, and the bladder and prostate were.