Improving Sexual Dysfunction with Cinnamon Leaf Extract and Nanoemulsion by Using a Rat Model

Background/Objectives: Taiwan cinnamon leaves have been reported to be effective in improving chronic diseases. Herein, cinnamon leaf extract (CLE) and nanoemulsion (CLEN) were prepared to explore their effects in improving sexual dysfunction in rats. Methods: Following extraction with 80% ethanol and analysis by UPLC-MS/MS, CLEN was prepared using an optimal ratio of soybean oil, lecithin, Tween 80, deionized water, and CLE. A total of 48 male rats and 48 female rats were used, with the former being induced with erectile dysfunction, followed by treatment with CLEN or CLE at two doses (100 mg/kg and 50 mg/kg) for 4 weeks. After conducting the penile reflex test, male rats were paired with female rats for measurement of sexual behavior and ICP/MAP. Following sacrifice, α-SMA, nNOS, and β-III tubulin expression areas were measured by histochemical analyses; SMC/collagen ratio by Masson's trichrome staining; and NO, cGMP, and PDE5 levels by ELISA kits. Results: CLEN was more effective than CLE in increasing intromission frequency, decreasing intromission and ejaculation latency, and recovering erectile response for improving copulatory and ejaculatory performances. A higher maximum ICP/MAP ratio was shown for CLEN through elevation of neurovascular function and erectile capacity. Additionally, CLEN efficiently reduced fibrosis, enhanced neuronal marker expression, and increased the SMC/collagen ratio, leading to penile tissue protection and neural regeneration. Both treatments showed elevated levels of NO and cGMP with a reduction in PDE5, probably through modulation of the NO-cGMP signaling pathway. Conclusions: CLEN was more effective than CLE in restoring erectile function in rats. Some more clinical trials are needed to verify this finding.