Relationship between intracellular calcium, energy metabolism, and motility of ram sperm

Is lithium essential for epididymal sperm maturation?

A wider biological role of ultratrace element lithium in the mammalian reproduction has been reported, however, presence of lithium in the epididymal luminal fluid (ELF) and its influence on sperm during maturation events in the epididymal regions are still unknown. A pilot study was carried out in Jamunapari buck which revealed that levels of lithium in the ELF diminished gradually and significantly (P<0.01) from caput to cauda epididymis, concomitantly, a distinct increase (P<0.01) in the spermatozoan motility, viability and hypo-osmotic reactive sperm were observed, except spermatozoan motility that was found absent in the caput epididymis. Therefore, we hypothesize that levels of lithium in the epididymal regions is one of the motility initiation and/or regulatory factor for epididymal sperm maturation essential for acquiring fertilizing competence of sperm cells, hence, lithium could also be considered as one of the biomarker of sperm maturation in any species.

Helium-neon laser irradiation of cryopreserved ram sperm enhances cytochrome c oxidase activity and ATP levels improving semen quality

This study examines whether and how helium-neon laser irradiation (at fluences of 3.96-9 J/cm(2)) of cryopreserved ram sperm helps improve semen quality. Pools (n = 7) of cryopreserved ram sperm were divided into four aliquots and subjected to the treatments: no irradiation (control) or irradiation with three different energy doses. After treatment, the thawed sperm samples were compared in terms of viability, mass and progressive sperm motility, osmotic resistance, as well as DNA and acrosome integrity. In response to irradiation at 6.12 J/cm(2), mass sperm motility, progressive motility and viability increased (P < 0.05), with no significant changes observed in the other investigated properties. In parallel, an increase (P < 0.05) in ATP content was detected in the 6.12 J/cm(2)-irradiated semen samples. Because mitochondria are the main cell photoreceptors with a major role played by cytochrome c oxidase (COX), the COX reaction was monitored using cytochrome c as a substrate in both control and irradiated samples. Laser treatment resulted in a general increase in COX affinity for its substrate as well as an increase in COX activity (Vmax values), the highest activity obtained for sperm samples irradiated at 6.12 J/cm(2) (P < 0.05). Interestingly, in these irradiated sperm samples, COX activity and ATP contents were positively correlated, and, more importantly, they also showed positive correlation with motility, suggesting that the improved sperm quality observed was related to mitochondria-laser light interactions.

Hyaluronic acid increases motility/intracellular CA2+ concentration in human sperm in vitro

This study investigated the mechanisms of the stimulatory effect of hyaluronic acid on motility in human sperm in vitro. A method, involving the measurement of forward progression through an agarose gel. was used to measure sperm motility quantitatively. Changes in intracellular Ca2+ concentrations in sperm were detected using the fluorescent dye Fluo-3. The effects of hyaluronic acid (6.5, 65, 650 ng/mL) and nifedipine (32 nM) on sperm motility were investigated. The effects of hyaluronic acid, nifedipine (32 nM), A23187 (32 microM), and a monoclonal antibody to human CD44 (1 microg/mL) on changes in intracellular CA2+ concentrations were investigated. Hyaluronic acid significantly (p < .008) stimulated sperm motility and this was partially inhibited by nifedipine. A23187 significantly (p < .005) increased intracellular CA2+ concentrations. Hyaluronic acid significantly (p < .04) increased intracellular Ca2+ concentrations and this was inhibited by nifedipine and a monoclonal antibody to human CD44. Hyaluronic acid stimulated human sperm motility by increasing intracellular Ca2+ concentration, partially via an influx of extracellular Ca2+.