Abstract
Bilateral cavernous nerve injury-related erectile dysfunction (BCNI-ED) shows a limited response to type 5 phosphodiesterase inhibitors. Furthermore, lacosamide (LCM) can alleviate peripheral neuropathy. To explore whether LCM can improve the erectile response after BCNI, we randomly divided 30 young Sprague-Dawley rats into three groups (n = 10 per group), namely, the sham operation, 0.9% normal saline-treated (BCNI + 0.9% NS), and LCM-treated BCNI (BCNI + LCM) groups. LCM was injected intraperitoneally at a dose of 90 mg/kg/day for 7 consecutive days. Erectile function was assessed by measuring the ratio of peak intracavernous pressure (ICP) to mean arterial pressure (MAP), and tissues were harvested for transmission electron microscopy, immunofluorescence, Masson's trichrome staining, TUNEL staining, and Western blot analysis. The BCNI + 0.9% NS group showed reduced ICP/MAP ratio (0.93 ± 0.04 vs. 0.44 ± 0.05, P < 0.0001). An increased proportion of TUNEL-positive cells (0.04 ± 0.01 vs 0.87 ± 0.03, P < 0.0001) and a decreased smooth muscle/collagen ratio (0.44 ± 0.01 vs. 0.33 ± 0.01, P < 0.001) were observed in the BCNI + 0.9% NS compared with the sham group. Administration of LCM significantly restored the ICP/MAP ratio (0.44 ± 0.05 vs. 0.74 ± 0.05, P < 0.001) and decreased the proportion of TUNEL positive cells (0.87 ± 0.03 vs. 0.60 ± 0.04, P < 0.0001) in the corpus cavernosum following BCNI. The ratio of smooth muscle to collagen (0.43 ± 0.01vs. 0.33 ± 0.01, P < 0.01) and expression of α-SMA (P < 0.0001) in the BCNI + LCM group significantly increased compared with BCNI + 0.9% NS group, indicating alleviation of fibrosis. Apoptotic markers, including Bax/Bcl-2 (P < 0.01) and Caspase-3 (P < 0.0001) in the BCNI + LCM group was significantly lower than that in the BCNI + 0.9% NS group. LCM treatment partially upregulated the expression of vWF and eNOS in cavernous tissue in rats subjected to BCNI (P < 0.05). Increases in S100-β and nNOS expression in the major pelvic ganglion (MPG) were observed after LCM administration. In summary, LCM can recover erectile function in BCNI-ED rat model by suppressing corporal apoptosis and fibrosis, and protecting the cavernous nerve.