angiotensin-i and Infertility--Male

Do angiotensin (Ang)-(1-7) levels in human ovarian follicular fluid (FF) correlate with the number and proportion of mature oocytes obtained for IVF?. The present study shows for the first time that Ang-(1-7) levels in human FF correlate with the proportion of mature oocytes collected upon ovarian stimulation for IVF.. Ang-(1-7) is an active peptide of the renin-angiotensin system that stimulates oocyte maturation in isolated rabbit and rat ovaries. However, its role in human ovulation remains unexplored.. This was a prospective cohort study including 64 participants from a single IVF center. Sample size was calculated to achieve a statistical power of 80% in detecting 20% differences in the proportion of mature oocytes between groups. The participants were enrolled in the study during six consecutive months.. Plasma samples were obtained from all subjects at Day 21 of the last menstrual cycle before starting pituitary blockade and controlled ovarian stimulation (COS). Plasma and FF samples were quickly mixed with a protease inhibitor cocktail and stored at -80°C. Ang-(1-7) was quantified in plasma and FF samples by a highly sensitive and specific radioimmunoassay, which was preceded by solid phase extraction, speed vacuum concentration and sample reconstitution in assay buffer. FF Ang-(1-7) levels were stratified into tertiles and the patients of each tertile were compared for COS/IVF outcomes using Kruskal-Wallis ANOVA. Multiple regression analysis was used to adjust correlations for potential confounders. The mRNA encoding for Mas, a receptor for Ang-(1-7), was investigated by real-time PCR in luteinized granulosa cells purified from the FF.. There was a four-fold increase in plasma Ang-(1-7) after ovulation induction (median 160.9 vs 41.4 pg/ml, P < 0.0001). FF Ang-(1-7) levels were similar to (169.9 pg/ml) but did not correlate with plasma Ang-(1-7) levels (r = -0.05, P = 0.665). Patients at the highest FF Ang-(1-7) tertile had a higher proportion of mature oocytes compared to patients at the lower FF Ang-(1-7) tertile (median 100% vs 70%, P < 0.01). There was a linear correlation between FF Ang-(1-7) and the proportion of mature oocytes (r = 0.380, P < 0.01), which remained significant after adjustment for age and duration of infertility (r = 0.447, P < 0.001). The luteinized granulosa cells expressed Mas receptor mRNA, which was positively correlated to the number of mature oocytes in women with more than three mature oocytes retrieved (r = 0.42, P < 0.01).. This is an observational study, therefore, no causal relationship can be established between Ang-(1-7) and human oocyte maturation. Mas protein expression was not quantified due to limited availability of granulosa cells.. Since this peptide promotes oocyte maturation in other species, it deserves further investigation as a potential maturation factor to human oocytes.. Research supported by Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) and Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG). The authors have nothing to disclose.

Topics: Adult; Angiotensin I; Blastocyst; Cohort Studies; Family Characteristics; Female; Fertility Agents, Female; Fertilization in Vitro; Follicular Fluid; Humans; Infertility, Female; Infertility, Male; Male; Oocyte Retrieval; Oogenesis; Ovulation Induction; Peptide Fragments; Prospective Studies; Radioimmunoassay; Solid Phase Extraction; Up-Regulation

The presence of classical components of the renin-angiotensin system has been demonstrated in the male reproductive tract, mainly in the testes and epididymis. The objective of this study was to verify the localization of angiotensin (Ang)-(1-7) and its receptor Mas in human testis. The study included 12 men with previously proven fertility submitted to orchiectomy for prostate cancer and 20 infertile men submitted to testicular biopsy for infertility work-up, comprising a subgroup with obstructive azoospermia/normal spermatogenesis (n = 8) and another with non-obstructive azoospermia and severely impaired spermatogenesis (n = 12). Testicular tissue samples were processed by immunohistochemistry and real time polymerase chain reaction. Ang-(1-7) was strongly expressed in the interstitial compartment, mainly in Leydig cells, with similar intensity in all groups evaluated. The peptide was also detected in the seminiferous tubules, but with much less intensity compared to interstitial cells. The receptor Mas was equally distributed between interstitial and tubular compartments and was found in all layers of the normal seminiferous epithelium. However, neither Ang-(1-7) nor Mas were detected in the seminiferous tubules of samples with impaired spermatogenesis. The testicular samples of infertile men with impaired spermatogenesis (non-obstructive azoospermia) expressed Mas and ACE2 mRNA at lower concentrations (fold change = 0.06 and 0.04, respectively, P < 0.05) than samples with full spermatogenesis (obstructive azoospermia). This shows, for the first time, the immunolocalization of Ang-(1-7) and its receptor Mas in testes of fertile and infertile men, and suggests that this system may be altered when spermatogenesis is severely impaired.

Topics: Adult; Aged; Aged, 80 and over; Angiotensin I; Angiotensin-Converting Enzyme 2; Azoospermia; Biopsy; Gene Expression Regulation; Humans; Infertility, Male; Male; Middle Aged; Peptide Fragments; Peptidyl-Dipeptidase A; Protein Transport; Proto-Oncogene Mas; Proto-Oncogene Proteins; Receptors, G-Protein-Coupled; RNA, Messenger; Testis; Young Adult

Angiotensin-converting enzyme (ACE) is expressed in many tissues, including vasculature and renal proximal tubules, and its genetic ablation in mice causes abnormal renal structure and functions, hypotension, and male sterility. To test the hypothesis that specific physiological functions of ACE are mediated by its expression in specific tissues, we generated different mouse strains, each expressing ACE in only one tissue. Here, we report the properties of two such strains of mice that express ACE either in vascular endothelial cells or in renal proximal tubules. Because of the natural cleavage secretion process, both groups also have ACE in the serum. Both groups were as healthy as wild-type mice, having normal kidney structure and fluid homeostasis, though males remained sterile, because they lack ACE expression in sperm. Despite equivalent serum ACE and angiotensin II levels and renal functions, only the group that expressed ACE in vascular endothelial cells had normal blood pressure. Expression of ACE, either in renal proximal tubules or in vasculature, is sufficient for maintaining normal kidney functions. However, for maintaining blood pressure, ACE must be expressed in vascular endothelial cells. These results also demonstrate that ACE-mediated blood pressure maintenance can be dissociated from its role in maintaining renal structure and functions.

Topics: Angiotensin I; Angiotensin II; Animals; Blood Pressure; Endothelium, Vascular; Female; Gene Expression Regulation, Enzymologic; Infertility, Male; Kidney Diseases; Kidney Tubules, Proximal; Male; Mice; Mice, Inbred Strains; Mice, Knockout; Peptidyl-Dipeptidase A; Pregnancy; Transgenes

There are potent kinin degrading activities in seminal plasma and testis of various mammals. The activities in boar and human seminal plasma, and testis extracts from boar, rat, guinea pig and rabbit were eluted out at a similar position as a single peak in column chromatography with Sephadex G-200 or DEAE Sephadex A-50. These enzymes degraded synthetic bradykinin and yielded angiotensin II from angiotensin I by cleaving the second peptide bond from the carboxytermini of the substrate, and it was concluded that these enzymes were dipeptidyl carboxypeptidases like kininase II or angiotensin I converting enzyme. The enzymes in male genital organs of these mammals were found to be identical with further investigation on the enzymic properties of them. The enzyme in rat testis increased significantly in accordance with sexual maturation, and the increase was suppressed by injection of danazol or diethylstilbesterol to rats. Furthermore, the dipeptidyl carboxypeptidase content in human seminal plasma was positively correlated to the semen qualities, i.e. sperm density and motility. From these results it is supposed that dipeptidyl carboxypeptidase in male genital organ and its secretion seem to be related to the male reproductive functions.

Topics: Angiotensin I; Animals; Bradykinin; Danazol; Diethylstilbestrol; Endopeptidases; Guinea Pigs; Humans; Infertility, Male; Male; Rabbits; Rats; Semen; Substrate Specificity; Swine; Testis