(063) Effect of Phosphodiesterase Type 4 Inhibitor on Erectile Function Recovery and Nerve Regeneration After Cavernous Nerve Injury in Rats

Abstract Introduction There is no consensus on the best treatment regimen for recovery of erectile function (EF) after radical prostatectomy (RP). Although many pharmacological interventions can improve EF in rats, there is still a lack of studies evaluating strategies that promote nerve regeneration of the cavernous nerve (CN). Phosphodiesterase type 4 inhibitors (PDE4Is), such as rolipram, have shown a neuroprotective effect after spinal cord injury in mice, facilitating functional recovery. It has also been suggested that the neuroprotective property of sildenafil is probably attributed to its effect on phosphodiesterase type 4. Objective Our aim was to evaluate the role of rolipram and its association with tadalafil in EF recovery and nerve regeneration after bilateral CN crush injury (BCNI) in rats. Methods Thirty-five male Wistar rats were randomly divided into four groups: (i) sham (no CN lesion); (ii) control (no treatment after BCNI); (iii) BCNI + tadalafil; (iv) BCNI + rolipram and (v) BCNI + tadalafil + rolipram. The initial laparotomy was performed and the CN were crushed with a hemostatic clamp. The animals in groups (iii) and (iv) received tadalafil (5mg/kg/d) or rolipram (1mg/kg/d) orally for 14 days, respectively. The animals in group (v) received tadalafil + rolipram at the same doses. Then, the animals were submitted to CN stimulation at frequencies 4, 8 and 16 Hz, with recording of mean arterial pressure (MAP) and intracavernosal pressure (ICP). EF was represented by the measurement of maximum ICP normalized to MAP (ICP/MAP ratio) and total normalized area under the curve (AUC) of ICP. The penises and CN of the animals were sent for structural evaluation with the immunohistochemical markers S100 and Ki-67. Results In the functional analysis, BCNI resulted in worse EF when compared to sham. This was observed when considering the maximum ICP/MAP and when analyzing normalized AUC of ICP for 4Hz and 8Hz. The different treatments were able to increase the ICP/MAP ratio after stimulation with 4Hz (p = 0.04) and 8Hz (p = 0.01). When considering normalized AUC of ICP, the different drugs (tadalafil, rolipram or tadalafil + rolipram) showed a significant improvement in EF in two of the three frequencies analyzed (4Hz and 8Hz) (figure 1). For 16hz, although it did not reach a statistical difference, a trend of improvement was observed after the different treatments (p = 0.08). With regard to immunohistochemical analysis, the tadalafil group had a higher expression of S100 in the dorsal penile nerve compared to the control group (p = 0.01). The rolipram group had a lower expression of Ki-67 in the CN compared to the control group (p = 0.03). Conclusions The combination of tadalafil and rolipram was associated with a functional improvement in EF in the experimental model with rats. The present study also suggests that rolipram may have a neuroprotective effect according to the structural evaluation of the CN. Disclosure No.