Effects of Obesity and Diabetes on Sperm Cell Proteomics in Rats

Abstract

Infertility caused by male factors is potentially associated with metabolic disorders such as obesity and/or diabetes. This experimental study was conducted in a male rodent model to assess the effects of different diseases on semen quality and sperm proteomics. Ten Wistar rats were used for each treatment. Rats were fed commercial food provided controllably to the control group and the diabetic group, and a hypercaloric diet supplemented with 5% sucrose in water was provided ad libitum to the obese group for 38 weeks. Diabetes was induced with 35 mg/kg streptozotocin. After euthanasia, testicles, spermatozoa, fat, and blood (serum) samples were collected. Spermatozoa were evaluated for quality and subjected to proteomics analyses. Histology and cytology of the testis, and serum leptin, adiponectin, interleukin 8 (IL-8), blood glucose, and testosterone levels, were also assessed. Body weight, retroperitoneal and testicular fat, and the Lee index were also measured. Obesity and diabetes were induced. The diabetic group showed noticeable changes in spermatogenesis and sperm quality. The mass spectrometry proteomics data have been deposited in Mendeley Data (doi: 10.17632/rfp7kfjcsd.5). Fifteen proteins varied in abundance between groups, especially proteins related to energy production and structural function of the spermatozoa, suggesting disturbances in energy production with a subsequent alteration in sperm motility in both groups, but with a compensatory response in the obese group.

Influence of Risk Factors for Male Infertility on Sperm Protein Composition

“…Different samples can be used to investigate sperm proteins: the seminal plasma or the complete set of cells in the semen, recovered as the supernatant and the pellet after centrifugation of sperm (e.g., [ 31 , 32 ]), respectively; or purified spermatozoa, isolated by swim-up (e.g., [ 39 ]) or density gradient (e.g., [ 33 ]) ( Figure 1 ). The purpose of this purification is to eliminate contaminating cells such as epithelial cells, leukocytes, and cells from early stages of spermatogenesis, whose protein content could decrease the capacity to discriminate deregulated proteins in spermatozoa [ 20 , 46 ].…”

“…The composition of the lysis buffer depends on the technique used to process the extracted proteins. Usually, it contains chaotropic agents (e.g., urea), reducing agents (e.g., dithiotreitol—DTT), and detergents, which can be ionic (e.g., sodium dodecyl sulphate—SDS), non-ionic (e.g., Triton-X-100), or zwitterionic (e.g., 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate—CHAPS) (e.g., [ 32 , 34 , 39 ]). Although SDS is a highly effective solubilising agent, this ionic detergent causes a background signal in MS analyses, leading to the suppression of the peptide signal [ 49 ].…”

“…After this step, proteins are submitted to enzymatic digestion, often by trypsin, to generate peptides that will be analysed by MS. Protein digestion can be performed directly on the proteins (“in-solution digestion”), on the filter in the case of FASP, or after protein separation by one- or two-dimensional polyacrylamide gel electrophoresis (1D- or 2D-PAGE) (e.g., [ 32 , 34 , 41 ]) ( Figure 1 ). In the latter case, to allow for protein quantification, the gels are scanned with a biomolecular imager, either directly in the case of Difference Gel Electrophoresis (DIGE) of fluorescently labelled proteins (e.g., [ 33 ]), or after staining for conventional PAGE (e.g., [ 41 ]).…”

“…An abundance ratio, also called fold-change, is then calculated based on the differential intensity of the protein spots between the groups. In the case of in-solution digestion, fold changes are calculated based on the detection of the tags added to the proteins (e.g., iTRAQ) or inferred from MS or MS/MS-derived signals (e.g., [ 31 , 32 , 35 ]). Replicated experiments allow statistical analyses of the data to establish a p -value associated with the calculated fold change.…”

Effect of Spermidine on Ameliorating Spermatogenic Disorders in Diabetic Mice Via Regulating Glycolysis Pathway.

“…It's worth noting that male reproductive disorder is becoming one of the common complications of DM recently, such as hyposexuality, impotency and decreased fertility [5]. In particular, it can cause testicular spermatogenic dysfunction, which include damaged testicular normal structural, impaired structural and functional of SCs, decreased sperm number and motility as well increased abnormal sperm numbers [6,7]. However, the molecular mechanisms underlying DM-induced male reproductive dysfunction is not clear.…”