Proteômica do plasma seminal e expressão gênica e localização da ngf e seus receptores (TRK1 e NGFR) no sistema genital de coelhos

Abstract

The aim this study were (i) to map and identify proteins in seminal plasma of New Zealand white rabbits strain, using the techniques of two-dimensional electrophoresis coupled to mass spectrometry and to estimate associations between these proteins with sperm parameters and (ii) characterize expression of the nerve growth factor polypeptide beta ( -NGF) and its cognate neurotrophic receptor tyrosine kinase type 1 (NTRK1), and nerve growth factor receptor (NGFR) at gonads and sex glands in adult New Zealand white rabbits as well as the NGF concentration in seminal plasma of sexually mature animals, using RT - PCR and immunohistochemistry. Also was measured the NGF concentration in the blood and seminal plasma by ELISA. Study 1 was performed at Federal University of Ceará, in Fortaleza-Ce. Semen samples were collected from 18 adult rabbits, using an artificial vagina. After collecting proceeded to the evaluation of semen quality parameters: total motility, individual progressive motility, sperm concentration, sperm morphology and functional tests: membrane integrity (HOST), acrosomal integrity and vitality. The seminal plasma was obtained by centrifugation of semen, and subjected to two-dimensional electrophoresis. Gels were stained with colloidal Coomassie, scanned and analyzed in PDQuest application. The individual spots were excised from the gels, digested with trypsin, and submitted to mass spectrometry (ESI-QUAD-TOF) to identification. The results were subjected to statistical analysis to verify the existence of associations between the presence and / or intensity of the spots present in the protein maps of seminal plasma with the semen quality parameters. The associations between the parameters of ejaculated sperm and the expression of seminal plasma proteins of rabbits were estimated by multiple regression models using the REG procedure of SAS statistical application (v.9.0, 2002) with STEPWISE selection. 232 ± 69.5 spots/gel were detected with 34 spots consistently present in all gels. These 34 spots corresponded to 15% of the total number of spots, representing 32% of the optical intensity of all the spots. Mass spectrometry identified approximately 95% of the detected spots (identified: 220 spots; analyzed: 232 spots), which corresponded to 87 different proteins. The most abundant proteins were the annexins, zeta-globin, lipocalin, FAM 115 protein and a serpins cluster. Other proteins also have been identified, such as transferrin, heat shock protein, glutathione transferase and others. The NGF (protein nerve growth factor) presence also has been identified which has been reported in other species such as ovulation induction factor. This 87 proteins identified in seminal plasma of rabbits participate mainly of biological processes associated with cellular processes (65.25%), regulation (64.25%) and response to stimuli (22.9%). Significant associations were observed between the proteins identified in seminal plasma of rabbits with sperm evaluated parameters such as individual progressive motility, sperm viability, cells with morphology and functional membranes have been associated with specific proteins. Associations were observed for several proteins with the same sperm parameter. According to literature, this is first report about the proteome of seminal plasma of rabbits and its role on the seminal parameters. Knowledge of these proteins contributes to a better understanding of the regulatory mechanisms of seminal plasma on sperm function in rabbits. Study 2 was conducted at Università Degli Studi di Perugia in the city of Perugia-Pe, Italy. It was evaluated the expression of NGF protein that was previously identified during study 1. The immunoreactivity and gene expression of NGF and cognate receptors were detected in testis, prostate and seminal vesicle. The highest levels of NGF and NTRK1 transcripts were found in prostate, while intermediate expressions were found in testis. NGFR transcripts were expressed at the same level on both the testis and prostate, and were more abundant than in seminal vesicles. The widespread distribution of NGF in all glandular cells of the prostate, coupled with its high abundance of mRNA on confirm that the prostate is a major source of this neurotrophin in rabbits. In conclusion, the present data suggest that NGF is involved in developmental system and spermatogenesis of testis rabbits and that NGF can act as a potential factor for induction of ovulation, being abundantly present in seminal plasma.