Abstract
Arginine vasopressin (VP) is neurohypophysial hormone has been implicated in stimulating contractile activity of the male reproductive tract in the testis. Higher levels of VP decrease sperm count and motility. However, very little is known about the involvement of VP in controlling mammalian reproductive process. The goal of this study was to confirm that effect of VP receptor (AVPR2) on sperm function in capacitation condition. Deamino [Cys 1, D-ArgS] vasopressin (dDAVP), an AVPR2 agonist that operates only on AVPR2, was used. Also, Mouse spermatozoa were incubated with various concentrations of dDAVP (10−11–10−5 M) and sperm motility, capacitation status, Protein Kinase A activity (PKA), tyrosine phosphorylation, fertilization, and embryo development were assessed using computer-assisted sperm analysis, Combined Hoechst 33258/chlortetracycline fluorescence, Western blotting, and in vitro fertilization, respectively. AVPR2 was placed on the acrosome region and mid-piece in cauda epididymal spermatozoa, but the caput epididymal spermatozoa was mid-piece only. The high dDAVP treatment (10−8 and 10−5 M) significantly decreased sperm motility, intracellular pH and PKA substrates (approximately 55 and 22 kDa) and increased Ca2+ concentration. The highest concentration treatment significantly decreased PKA substrate (approximately 23 kDa) and tyrosine phosphorylation (approximately 30 kDa). VP detrimentally affected capacitation, acrosome reaction, and embryo development. Treatment with the lowest concentration (10−11 M) was not significantly different. Our data have shown that VP stimulates ion transport across sperm membrane through interactions with AVPR2. VP has a detrimental effect in sperm function, fertilization, and embryonic development, suggesting its critical role in the acquisition of fertilizing ability of mouse spermatozoa. These research findings will enable further study to determine molecular mechanism associated with fertility in capacitation and fertilization. It is also an important pivotal precondition to the progress of diagnostic test to identify infertility and to apply male contraception.
Highlights
Arginine vasopressin, which is found in most mammals including humans, is essential for cardiovascular homeostasis [1]
This neurohypophysial hormone has been implicated in stimulating contractile activity of the male reproductive tract, with each including dose-dependent seminiferous tubule contraction in the testis [2,3]
VP increases the accumulation of cytosolic cAMP in vas deferens epithelial cells and can modulate ion transport across vas deferens epithelia by independent mechanisms [8]
Summary
Arginine vasopressin (hereafter referred to as vasopressin, VP, and known as antidiuretic hormone), which is found in most mammals including humans, is essential for cardiovascular homeostasis (i.e., survival) [1]. This neurohypophysial hormone has been implicated in stimulating contractile activity of the male reproductive tract, with each including dose-dependent seminiferous tubule contraction in the testis [2,3]. Puri and Puri [9] discovered that a higher level of VP decreases the sperm count and motility in healthy human but infertile men. Oh [11] discovered that VP receptor 2 (arginine vasopressin receptor 2; AVPR2) was differentially expressed between small and large litter size group spermatozoa in porcine. AVPR2 from small litter size group spermatozoa was increased more so than the expression level of the large one. The association between VP and fertility is a continuing source of concern
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