Effects of vasoactive intestinal peptide on human sperm motility

Loss of Function of Vasoactive-intestinal Peptide Alters Sex Ratio and Reduces Male Reproductive Fitness in Zebrafish

Vasoactive-intestinal peptide (Vip) is a pleiotropic peptide with a wide range of distribution and functions. Zebrafish possess 2 isoforms of Vip (a and b), in which Vipa is most homologous to the mammalian form. In female zebrafish, Vipa can stimulate LH secretion from the pituitary but is not essential for female reproduction, as vipa-/- females display normal reproduction. In contrast, we have found that vipa-/- males are severely subfertile and sex ratio of offspring is female-biased. By analyzing all aspects of male reproduction with wild-type (WT) males, we show that the testes of vipa-/- are underdeveloped and contain ∼70% less spermatids compared to WT counterparts. The sperm of vipa-/- males displayed reduced potency in terms of fertilization (by ∼80%) and motility span and duration (by ∼50%). In addition, vipa-/- male attraction to WT females was largely nonexistent, indicating decreased sexual motivation. We show that vipa mRNA and protein is present in Leydig cells and in developing germ cells in the testis of WT, raising the possibility that endogenous Vipa contributes to testicular function. Absence of Vipa in vipa-/- males resulted in downregulation of 3 key genes in the androgen synthesis chain in the testis, 3β-hsd, 17β-hsd1, and cyp11c1 (11β-hydrogenase), associated with a pronounced decrease in 11-ketotestosterone production and, in turn, compromised reproductive fitness. Altogether, this study establishes a crucial role for Vipa in the regulation of male reproduction in zebrafish, like in mammals, with the exception that Vipa is also expressed in zebrafish testis.

Seasonal differences in seminal plasma proteins from two bovine breeds adapted to a subtropical climate

This study was designed to evaluate the seasonal expression of seminal plasma proteins from two bovine breeds adapted to a subtropical climate and their associations with post-thawing sperm and environmental characteristics. Semen samples were obtained three times in summer and three times in winter from four Crioulo Lageano and four Angus bulls. Seminal plasma was obtained by centrifugation, and the other portion of the semen was cryopreserved. Seminal plasma proteins were identified by 2D-nanoUPLC-MS^E. Post-thawing assessments of sperm kinetics, morphology and membrane integrity were performed. Environmental data such as air temperature, air humidity and black globe temperature (BGT) were recorded, and the temperature-humidity index (THI) was calculated in summer and winter. Results showed that the climate varied significantly between seasons. Although no statistical differences were observed in semen quality between breeds, the protein profiles varied within and between seasons. We suggest that the most critical proteins in summer affecting sperm characteristics were TIMP-2, DNase, Clusterin, CFAH and GPx6. TIMP-2 and DNase showed a higher abundance in Crioulo Lageano in comparison with Angus, while Clusterin, CFAH and GPx6 presented a lower abundance. To the best of our knowledge, this is the first report of a recently evolved type of glutathione peroxidase, GPx6, in seminal plasma of bovines. In winter, five proteins were considered to be more critical: BSP1, BSP3, CCL2, Sulfhydryl oxidase and TIMP-2. BSP1 and TIMP-2 showed a lower abundance while BSP3, CCL2 and Sulfhydryl oxidase presented a higher abundance in this season in Crioulo Lageano in comparison with Angus.

Characteristics of human prostasomes isolated from three different sources

BACKGROUND

Prostasomes are organelles secreted by human prostate epithelial cells and appear freely in semen. Most prostasomal functional and biochemical characteristics have been settled on basis of seminal prostasomes (SP).

METHODS

Three types of prostasomes, viz., from seminal plasma, prostate gland (native), and prostate cancer bone metastasis, were isolated and compared for their biochemical and functional characteristics.

RESULTS

Flow cytometry showed that all three types of prostasomes had a similar size distribution and electrophoresis revealed close similarities in banding pattern. Also, a high cholesterol/phospholipid ratio and some marker enzymes were distinctive common features. The unusual chromogranin B (CgB)/chromogranin A (CgA) ratio with CgB in abundance over CgA, previously found only in SP, was also valid for the native (NP) and metastasis-derived prostasomes (MP). The latter prostasome type contained a 10-fold higher amount of CgA compared to the others. SP and MP showed the same promotive effect on sperm forward motility, whereas NP did not. All three prostasome types exhibited an antibacterial activity against Bacillus megaterium.

CONCLUSIONS

Since the three prostasome types were isolated from different environments, our data support the view that the common characteristics were prostasome-genuine.