The Potential Role of Circulating MicroRNAs in Male Rat Infertility Treated with Kaempferia parviflora

BACKGROUND

Therapeutic strategies based on herbal plants and diets containing sufficient amounts of antioxidants and essential vitamins are very important factors in treating reproduction and male infertility worldwide. Thus, the aim of this study was to investigate the potential effects of Kaempferia parviflora (KP) on the role of some microRNAs in treated and nontreated infertile rats. In addition, the correlation of expressed microRNAs with sperm count, sperm motility, and sperm viability was identified. The probable use of these microRNAs as a diagnostic marker for predicting the clinical response of infertility to the treatment with KP was also achieved.

METHODS

In the present study, the potential effects of Kaempferia parviflora (KP) at different doses (140, 280, and 420 mg/kg) for six weeks on male rats with subinfertility were explored. In addition, the effect of KP on the expression of circulating microRNAs and its correlation with the parameters of sexual infertility was identified by performing both in vitro and in vivo assays. In vitro antioxidant activity, sperm functional analysis, serum testosterone, and expression of circulating microRNAs were conducted using colorimetric, ELISA, and real-time RT-PCR analysis, respectively.

RESULTS

Kaempferia parviflora (KP) at nontoxic doses of 140-420 mg/kg/day for six weeks significantly improved serum testosterone and epididymal sperm parameters (sperm count, motility, and sperm viability), increased testicular weight, and provided a reduction in the percentage of abnormal spermatozoon in infertile male rats. The expression of miR-328 and miR-19b significantly decreased, and miR-34 significantly increased in infertile rats treated with KP compared to infertile nontreated rats. After six weeks of KP therapy, the change in the expression levels of miRNAs was correlated positively with higher levels of serum testosterone and the measures of epididymal sperm parameters. The respective area under the receiver operating characteristic curve (AUC-ROC) was applied to predict the potential use of miR-328, miR-19b, and miR-34 in the diagnosis of male infertility in treated and nontreated infertile male rats. The data showed that AUC cutoff values of 0.91 for miR-328, 0.89 for miR-19b, and 0.86 for miR34 were the best estimated values for the clinical diagnosis of male rats with infertility. In rats treated with KP for six weeks, AUC cutoff values of 0.76 for miR-328, 0.79 for miR-19b, and 0.81 for miR-34 were the best cutoff values reported for the clinical response of infertility to KP therapy after six weeks.

CONCLUSIONS

In this study, the improvement of male infertility might proceed via antioxidant and antiapoptotic pathways, which significantly improve spermatogenesis and aphrodisiac properties of males. In addition, the expression of miRNAs, miR-328, miR-34, and miR-19b, in KP-treated and nontreated infertile rats significantly correlated with increased serum testosterone levels and epididymal sperm parameters as well. MicroRNAs, miR-328, miR-34, and miR-19b, might be related to oxidative and apoptotic pathways that proceeded in spermatogenesis. Thus, the use of miRNAs could have a role as diagnostic, therapeutic, and predictive markers for assessing the clinical response of Kaempferia parviflora treatment for six weeks. This may have potential applications in the therapeutic strategies based on herbal plants for male infertility. However, in subsequent studies, the genetic regulatory mechanisms of the expressed miRNAs should be fully characterized.

Kaempferia parviflora and Its Methoxyflavones: Chemistry and Biological Activities

Kaempferia parviflora (KP), a health-promoting herb, has been traditionally used for treating a variety of diseases. Pharmacological studies have claimed the various benefits from KP and its main effective methoxyflavones, including cellular metabolism-regulating activity, anticancer activity, vascular relaxation and cardioprotective activity, sexual enhancing activity, neuroprotective activity, antiallergic, anti-inflammatory, and antioxidative activity, antiosteoarthritis activity, antimicroorganism activity, and transdermal permeable activity. These might be associated with increased mitochondrial functions and activated cGMP-NO signaling pathway. However, the underlying molecular mechanisms of KP and its methoxyflavones are still under investigation. The clinical applications of KP and its methoxyflavones may be limited due to their low bioavailability. But promising strategies are on the way. This review will comprehensively discuss the biological activities of KP and its methoxyflavones.

Effect of Kaempferia parviflora on sexual performance in streptozotocin-induced diabetic male rats

Kaempferia parviflora Wall. Ex.Baker or Krachidum (KP) has been used locally in medicine and food. It has been claimed that KP has aphrodisia properties; however, no scientific data in support of this function in diabetic model have been reported. This study aimed to investigate the efficacy of KP on sexual behaviour and sperm parameter in streptozotocin (STZ)-induced diabetic male rats. Diabetes was induced in twenty male rats by STZ and divided into four groups: diabetic control group, and 3 treatment groups where KP was dose at 140, 280 and 420 mg/kg orally once a day for 6 weeks. Five normal control rats were treated with vehicle. The body weight, blood glucose, food intake, epididymal sperm parameter, sexual behaviour and serum testosterone level were evaluated. The results showed that KP treatment has no effect on the body weight, blood glucose and food intake in diabetic rats. A significant increase in sperm density in diabetic rats was observed (p < .05) at highest dose of KP. Furthermore, KP treatment demonstrated a significant recovery of sexual behaviour and serum testosterone levels in diabetic rats. These results confirm that KP exhibits aphrodisiac properties that improve the sperm density, testosterone level and sexual performance of STZ-induced diabetic rats.