Diabetic Retinopathy Is Associated with Decreased Tyrosine Nitrosylation of Vitreous Interleukins IL-1α, IL-1ß, and IL-7.

OBJECTIVE: To simultaneously evaluate tyrosine nitrosylation and phosphorylation levels of vitreous interleukins of patients with diabetic retinopathy, in which abnormal tyrosine phosphorylation has been previously described. RESEARCH DESIGN AND METHODS: Specific immunoprecipitation of interleukins IL-1α, IL-1ß, IL-2 and IL-7 was carried out in samples obtained during vitrectomy performed for proliferative diabetic retinopathy in patients (n=12) and for macular hole in controls (n=12). Tyrosine nitrosylation and phosphorylation levels of the immunoprecipitated interleukins were analysed by Western blot with the respective specific antibodies and correlated. The results were also correlated with the total amount of immunoprecipitated interleukin protein. The mean phosphorylation/nitrosylation ratios of these proteins in vitreous humour of both the control group and diabetic patients were determined. RESULTS: Diabetes was associated with decreased tyrosine nitrosylation of IL-1α, IL-1ß and IL-7 and an increased tyrosine phosphorylation/nitrosylation ratio with respect to controls in IL-1α (1.58±0.22 vs. 2.74±0.39, respectively; p<0.05) and IL-7 (2.15±0.01 vs. 3.26±0.57, respectively; p<0.05). No significant changes were observed in nitrotyrosine or in the tyrosine phosphorylation/nitrosylation ratio of IL-2. CONCLUSIONS: Proliferative diabetic retinopathy is associated with concomitant and simultaneous changes in both tyrosine phosphorylation and tyrosine nitrosylation status of specific pro-inflammatory interleukins present in the vitreous fluid such as IL-1α, IL-1ß and IL-7. These changes could be related to the increase in pro-inflammatory activity detected in diabetes-induced retinopathy.

Natural Mediterranean photoperiod does not affect the main parameters of boar-semen quality analysis.

Photoperiod is an important factor in the modulation of male reproduction in mammals. In boars, however, it is a controversial factor. The main aim of this work is to determine the precise effect of the natural, Mediterranean photoperiod on boar-semen quality. To do this, boars were housekept in strictly controlled temperature and humidity conditions, whereas light periods were also strictly adjusted to obtain a light-cycle in the farm. The work was performed over a period of one year, thus allowing for the determination of the putative yearly oscillations of boar-semen quality. Variations of the natural Mediterranean photoperiod do not induce substantial changes in overall semen-quality parameters like the percentages of viability, morphological abnormalities and total motility, the response to the osmotic resistance test and sperm motion characteristics. Only the motile-sperm subpopulation structure was significantly (P<0.05) changed depending on the variations of the natural photoperiod. Furthermore, the boar-semen ability for storage at 15-17 degrees C in a commercial extender was not modified by photoperiod changes. Our results indicate that the natural Mediterranean photoperiod does not induce strong changes in boar-semen characteristics, probably due to boar sperm having a strong capability of adaptation to the light variations of this photoperiod.

The presence and function of dopamine type 2 receptors in boar sperm: a possible role for dopamine in viability, capacitation, and modulation of sperm motility.

Several studies have shown that dopamine and other catecholamines are present in oviduct luminal fluid. We recently reported that dopamine type 2 receptors (DRD2) are present in a wide range of mammalian sperm, suggesting a role for dopaminergic signaling in events such as fertilization, capacitation, and sperm motility. In the present study, we used Western blot analysis to show that boar sperm express DRD2 and that their activation with dopamine (100 nM) has a positive effect on cell viability that can be correlated with AKT/PKB phosphorylation. Bromocriptine (100 nM) and dopamine (100 nM and 10 muM) increased tyrosine phosphorylation during the capacitation period. Immunofluorescence analysis indicated that DRD2 localization is dynamic and depends on the capacitation stage, colocalizing with tyrosine phosphorylated proteins in the acrosome and midpiece region of capacitated boar sperm. This association was confirmed by coimmunoprecipitation analysis. We also showed that bromocriptine (100 nM) and low-concentration dopamine (100 nM and 10 muM) increased total and progressive motility of sperm. However, high concentrations of dopamine (1 mM) decreased tyrosine phosphorylation and motility in in vitro sperm capacitation assays. This can be explained by the presence of the dopamine transporters (DAT, official symbol SLC6A3) in sperm, as demonstrated by Western blot analysis and immunocytochemistry. Taken together, our results support the idea that dopamine may have a fundamental role during sperm capacitation and motility in situ in the female upper reproductive tract.