An Update of Sperm Preparation : A Review of Supplementation Substances to Improve Sperm Quality

One etiology of the unsuccesful intra uterine insemination (IUI) is sperm preparation. There are some limitations of sperm preparation utilization which may decrease fertilization rates leading to IUI failure. Nevertheless, there are some substances which suggested could improve the outcome of sperm preparation. This review aimed to summarize the substances that could improve the sperm quality, thus increasing success rate of IUI, as an update of sperm preparation. Several researches which have developed agreed that the supplementation of antioxidant, hormone and drugs could improve the quality of sperm. The addition of dithiothreitol and superoxide dismutase during centrifugation could prevent some harmful effects such as membrane plasma disruption caused by lipid peroxidation process. The supplementation of myoinositol before and after capacitation increased total and progressive motile sperm significantly. Astaxanthin decreased the generation of ROS in sperm. Furthermore, LH could increased intracellular Ca2+ as a second messenger of signal transduction pathways during sperm capacitation, whereas prolactine prolonged human sperm motility and prevent caspase activation. In addition, the supplementation of pentoxifylline could enhance the motility of post-thaw sperm and its longevity in vitro.


INTRODUCTION
It is have known that the success rate of Intrauterine Insemination (IUI) remains low, ranging about 10 to 20%. 1 Sperm preparation should be standardized in order to achieve an enormous success rate of a program.In sperm preparation, there are two methods that frequently performe, namely Swim-up (SU) and Density-gradient Centrifugation (DGC). 2 Nevertheless, there are some controversies related to the deterioration of the SU and the DGC methods such as non-optimal progressive motile sperm which may decrease of fertilization rates leading to IUI failure.][5] The most important part of the semen is the sperm, and the quality of semen involves either quantity or quality of sperm.Mostly, the decreased sperm quality play role more in causing male infertility, compared to sperm quantity.There were many researches accomplished in order to increase the success rate of IUI through sperm preparation manipulation.This review aimed to summarize the substances that could increase the sperm quality in sperm preparation as an update to increase the success rate of IUI.These researches provided several substances such as antioxidant, hormones and drugs that could increase the sperm quality in sperm preparation could increase the sperm motility as demonstrated in table 1. (Table 1) 6,7

Substances Supplementation of Sperm Preparation in Improving Sperm Quality Antioxidant Supplementation
During sperm preparation, sperm undergo a complex series of centrifugation affecting deleterious effects on sperm movement parameters, motility and acrosome reaction.The side effect induced by centrifugation could be prevented by addition of antioxidants prior to sperm preparation.DTT and SOD supplementation as potent antioxidant in the preparation medium improved both the level of hyperactivated sperm and velocity of the sperm significantly and maintained levels of induced acrosome reaction. 7,8 ithiothreitol (DTT) could prevent membrane plasma disruption caused by lipid peroxidation process which generated from reactive oxygen species (ROS). 7In addition, DTT as an of potent antioxidant could induce chromatin destabilization and sperm nuclear stability.
The total and progressivity of sperm motility was increased significant after the addition of myoinositol before and after capacitation.Previously research in agreement observed that myoinositol have antioxidant properties and present in huge concentrations particularly in seminal liquid. 9Myoinositol, sugar like molecule, could increase cytosolic Ca 2+ and inner mitochondrial Ca 2+ thus enhance sperm motility and increase the number of spermatozoa with high inner mitochondrial membrane potential (MMP).The molecular mechanism of myoinositol is suggested by having a role in the chemiotaxis and human sperm thermotaxis through phospholipase C activation, leading to the origination of inositol triphosphate and calcium channels initiating. 9e v e r a l r e s e a r c h e s d e v e l o p e d i n agreement said that myoinositol increase the number of spermatozoa with progressive motility in vary of semen analyses result. 9,10 almier et al., 11 studied in vitro myoinositol effect on sperm quality, findings showed that the reducing motility caused by the freezing-thawing process was diminishing the sperm quality and fertilization rate.By the treatment of myoinositol to the thawed samples were proved more efficacious and showed a significant difference in improvement of sperm progressive motility.[12] Astaxanthin is recognized not only for having anti-cancer, anti-diabetic and anti-inflammatory properties but also antioxidant activity that could improve sperm quality.Astaxanthin acts by inhibiting intracellular radical generation thus induce low ROS production by improving tyrosine phosphorylation of sperm head and acrosome-reacted cells values.Findings showed that astaxanthin incubation during sperm preparation could generate the enormous number of spermatozoa undergo capacitation-like membrane which allow the phosphorylation of tyrosine on sperm head. 13

Hormone Supplementation
Luteinizing hormone (LH), a heterodimeric glycoprotein, secreted by the anterior pituitary has a crucial role in inducing ovulation.It is suggested that spermatozoa undergo capacitation through female reproductive tract may be exposed to LH promoting protein kinase A (PKA) activity in this cell.The molecular mechanism of LH in regulating sperm function one of which is by increasing the concentration of Ca 2+ .Ca 2+ is a second messenger that has a role in sperm signal transduction pathways including changes in sperm capacitation such as sperm motility and acrosomal reaction.LH binds to LH/hCG receptors located in sperm thus stimulate G-protein (Gs) and Gq proteins in activating adenylate cyclase thus leading to activation cascade of signal transduction which regulating sperm capacitation. 14Prolactin receptor (PRLR) is identified in human sperm and located in the neck, midpiece, and principal piece of the sperm. 15Thereby it is suggested that there was an essential function of prolactin hormone on human sperm.Findings said that prolactin is a pro-survival factor for human sperm that act through stimulation of Akt phosphorylation, and inhibit phosphatidylinositol-3-OH kinase.Prolactin avoids the human sperm from apoptosis through intrinsic pathway related to cell senescence. 15

Drug Supplementation
Pentoxifylline is a phosphodiesterase inhibitor which could be utilized to encourage motility and fertilizing capacity of sperm. 16Pentoxifylline performances by preventing the production of cyclic adenosine monophosphate (cAMP) phosphodiesterase, intensifying intracellular cAMP concentration and tyrosine-phosphorylation.Previously research showed that after 1-hour incubation with pentoxifylline improved the total motility of sperm after the freeze-thaw process.Pentoxifylline could improve post thaw sperm fertilizing ability by reducing acrosome loss during the freeze-thaw process and rises the post-thaw agonist-induced acrosome reaction rate.7][18] The author assessed that pentoxifylline may be utilized as a supplement to the cryomedia but in higher concentrations may be detrimental to membrane integrity.

CONCLUSION
The findings in unison performed that the supplementation substances such as antioxidants, hormones, and drugs as explained above could be used in sperm preparation in order to increase sperm qualities.The mechanism of these substances in increasing sperm qualities were vary such as the lipid peroxidation that generated by ROS, regulating Ca 2+ as a second messenger in sperm capacitation, and also maintaining the cAMP level in sperm motility.In conclusion, these supplementation substances could be use to increase the sperm quality which leading to the improvement of IUI success rate.

Table 1 :
Substances and the role in increasing sperm spermatozoa with high MMP in OAT, but not in normozoospermic men •Further studies are required to clarify if the specific effect on sperm fertilization ability is indeed dose movement without any harmful effects on sperm DNA integrity