A novel role for involvement of N-methyl-D-aspartate (NMDA) glutamate receptors in sperm acrosome reaction.

Ionotropic glutamate receptors are expressed in mouse and human spermatozoa. However, the possible role of these receptors has not been reported in the sperm acrosome reaction. This study was conducted to demonstrate the function of N-methyl-D-aspartate (NMDA) glutamate receptors in the acrosome reaction of mouse spermatozoa. Epididymal spermatozoa from adult mice were release in a culture medium. The sperm suspension was then divided into six groups: (1) spermatozoa at 0 min, (2) spermatozoa at 60 min (control), (3) spermatozoa treated with NMDA glutamate receptor agonist (L-glutamate, LG), (4) spermatozoa treated with α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA)/kainite glutamate receptor agonist (kainic acid), (5) spermatozoa treated with NMDA glutamate receptor antagonist (MK-801)+LG and (6) spermatozoa treated with ethylene glycol tetraacetic acid (EGTA, as a calcium chelator)+ LG. The sperm samples were examined for the acrosome reaction and intracellular calcium concentration. After 60 min, LG but not kainic acid significantly increased both the acrosome reaction and intracellular calcium levels in the spermatozoa compared with the control group. Co-administration of MK-801 or EGTA+LG could significantly reverse the effect of LG in the acrosome reaction and the level of intracellular calcium as compared to the LG group. The possibility that LG induced the acrosome reaction and elevated inter-cellular calcium concentration in mouse spermatozoa and that MK-801 could reverse the effects of LG, may suggest the involvement of NMDA glutamate receptors, at least in the initiation of the acrosome reaction in vitro.

The P53/microRNA network: A potential tumor suppressor with a role in anticancer therapy.

MicroRNAs (miRNAs) are endogenous and small non-coding RNAs that have been identified as mediators of tumor suppression as well as stress responses mediated by p53 suppressors. MiRNAs may act as tumor suppressors under certain conditions. MiRNAs regulated by p53 may control the expression of processes such as cell cycle progression, cell survival, and angiogenesis. P53 activity and expression are also controlled by miRNA; consequently alterations in the p53-miRNA network may be essential for tumor initiation and progression. Future studies on the p53-miRNA network presumably would find it helpful in diagnostic and therapeutic approaches or as tools for various cancers.

Aquaporin3 expression and the potential role of aquaporins in motility and mitochondrial membrane potential in human spermatozoa.

Aquaporins are water selective channels which play important roles in cell volume regulation during the transmission of spermatozoa to female tract. This study investigated the expression of aquaporin3 and determined the role of aquaporins in human sperm motility and mitochondrial membrane potential (MMP). RT-PCR and flow cytometry analysis were done to investigate aquaporin3 expression levels, and immunolocalisation of aquaporin3 in the spermatozoa was detected using immunocytochemical analysis. The sperm suspension was divided into four groups of spermatozoa: (a) Spermatozoa at 0 hr, (b) spermatozoa in control group, (c) spermatozoa treated with HgCl2 (as an aquaporin inhibitor) and (d) spermatozoa treated with HgCl2 + and 2-mercaptoethanol. The sperm samples were examined in terms of sperm motility and mitochondrial membrane potential. Results confirmed aquaporin3 expression in human spermatozoa and immunocytochemistry results showed an intense immunoreactivity in whole sperm tail. After 60 min, HgCl2 showed a significant decrease in motility and MMP compared to the control group. At this time point, 2-mercaptoethanol in the HgCl2 + 2-mercaptoethanol group reversed the effects of HgCl2 as compared to the HgCl2 group. Present study showed the expression and immunolocalisation of AQP3 in human spermatozoa and the potential role of AQPs in the sperm motility and MMP.

Asthenozoospermia: Cellular and molecular contributing factors and treatment strategies.

Semen sample with poor sperm motility, which called asthenozoospermia, is considered as one of the main factors contributing to male infertility. Recognition of the cellular and molecular pathways contributing to sperm motility reduction may lead to applying novel treatment strategies for overcoming low sperm motility in asthenozoospermia individuals. In this review, we intend to discuss the main causes of sperm motility reduction in asthenozoospermia and some treatment strategies used to overcome low sperm motility.