Downregulation of the expression of galanin impairs erectile function in hypoandrogenic rats

BACKGROUND: The relationship between galanin and erectile function under low androgen levels is still unclear. AIM: To explore whether a low testosterone level damages the erection of a rat by regulating the expression of galanin and GalR in penile cavernous tissue. METHODS: Thirty-six male Sprague-Dawley rats, 8 weeks of age, were randomly grouped as follows (n = 6): control, castration, castration + testosterone replacement, control + transfection, castration + transfection, and castration + empty transfection. At 4 weeks after castration, rats in the transfection group were injected with lentivirus carrying the targeting galanin gene (2 × 10(8) TU/mL, 10 μL) in the corpus cavernosum. After 1 week of injection, the intracavernosal pressure (ICP), mean arterial blood pressure (MAP), nitric oxide (NO), serum testosterone concentration, galanin, GalR1-3, ROCK1, ROCK2, and p-eNOS/eNOS in the rat penile tissues were evaluated. OUTCOMES: ICPmax/MAP and the expression of galanin in the corpus cavernosum in castrated rats were obviously decreased as compared with those in the control rats. RESULTS: The castrated rats showed remarkably lower ICPmax/MAP, galanin, GalR1-3, p-eNOS/eNOS, and NO content and markedly higher ROCK1 and ROCK2 in penile tissues than the control group (P < .05). The transfected rats administrated with LV Gal had obviously higher ICPmax/MAP, p-eNOS/eNOS, and NO content and less ROCK1 and ROCK2 protein expression in the corpus cavernosum when compared with the castration group (P < .05). CLINICAL TRANSLATION: Upregulating the expression of galanin in the penile corpus cavernosum might be a novel method of treating erectile dysfunction caused by a low androgen level. STRENGTHS AND LIMITATIONS: The conclusions obtained in the animal experiments need to be confirmed in human data. CONCLUSION: The erectile function of hypoandrogen rats might be inhibited by downregulating the level of galanin and GalR1-3, upregulating ROCK1 and ROCK2 levels, and inhibiting the eNOS/NO signaling pathway in penile corpus cavernosum.