The cumulative evidence suggests that oxytocin is involved in the male sexual behaviors. However, no significant sexual impairments were observed in oxytocin gene knock-out (KO) mice, suggesting that oxytocin is not necessary for sexual behavior in male mice. To better understand the role of oxytocin in male erection, two types of oxytocin gene KO mice were created. In the first type, the oxytocin gene was deleted in the zygote, while in the second type, the oxytocin gene was mutated in adulthood by injecting the CRISPR/Cas9 AAVs. The results showed that disrupting the oxytocin gene at either the embryonic or adult stage did not affect erection, indicating that oxytocin is not necessary for penile erection. Pharmacologically, injecting oxytocin receptor agonist Carbetocin into the VTA of the oxytocin gene KO mice still evoked penile erection. By employing the Oxt-Ires-Cre mice, we found that specifically activating oxytocinergic neurons through chemogenetics strongly induced penile erection, while inhibiting these neurons blocked the erection responses. Furthermore, ablating PVN oxytocinergic neurons abolished the male erection response. In conclusion, although the neuropeptide oxytocin is not essential for male erection, the activity of oxytocinergic neurons is required. Our results might reflect the redundancy in the central nerve system in the sense that many signals contribute to the activation of oxytocinergic neurons to evoke penile erection during sexual behaviors.

MicroRNAs (miRNAs), a class of small non-coding RNAs, are important regulators on a post-transcriptional level. As a classical non-coding RNA, miRNAs are expressed in various tissue and are involved in many biological processes. More recently, increasing evidence has confirmed the existence of the secreted miRNAs in follicular fluid, which shed a light on the local intercellular communication. Interestingly, the miRNA profile of follicular fluids is different temporally, suggesting that miRNA secretion is finely controlled during times of development and aging. The secretion of miRNAs by somatic cells in the ovary follicle is an important resource of follicular fluid miRNAs. Comparing the miRNAs profile between follicular fluid and plasma could reveal critical miRNAs that come from circulation. The physiological functions of miRNAs in follicular fluid are believed to be a versatile message carrier for cell communications, however, due to the lack of cell-type-specific labeling methods, the route of information transmission remains elusive. It is well known that miRNA expression changes in different disease state, so it might be suitable as a biomarker. Further investigating the regulatory mechanisms mediated by these secreted miRNAs can help to understand the molecular mechanisms of oocyte maturation, early embryo development, and implantation. Therefore, this review summarizes the functions of extracellular follicular fluid miRNAs, and discusses recent progress on the potential of secreted miRNA as a biomarker in reproductive diseases.

Epilepsy is accompanied by abnormal neurotransmission, and microRNAs, as versatile players in the modulation of gene expression, are important in epilepsy pathology. Here, we found that miR-128 expression was elevated in the acute seizure phase and decreased during the recurrent seizure phase after status epilepticus in mice. Both SNAP-25 and SYT1 are regulated by miR-128 in vitro and in vivo. Overexpressing miR-128 in cultured neurons decreased neurotransmitter released by suppressing SNAP-25 and SYT1 expression. Anti-miR-128 injection before kainic acid (KA) injection increased the sensitivity of mice to KA-induced seizures, while overexpressing miR-128 at the latent and recurrent phases had a neuroprotective effect in KA-induced seizures. Our study shows for the first time that miR-128, a key regulator of neurotransmission, plays an important role in epilepsy pathology and that miR-128 might be a potential candidate molecular target for epilepsy therapy.