Type 1 diabetes (T1D) is a chronic metabolic disease defined by sustained hyperglycemia, leading to oxidative stress (OS) and systemic complications, including male subfertility. This study investigates the potential impact of T1D-induced OS on microtubule (MTs) dynamics and microtubule-associated proteins (MAPs) in the testis and spermatozoa (SPZ). Using a streptozotocin-induced T1D rat model, we examined the expression and localization of key MAPs, including Microtubule Affinity-Regulating Kinase 4 (MARK4), Microtubule-Associated Protein 1A (MAP1A), Dynein Light Chain LC8-Type 1 (DYNLL1), Prolyl Endopeptidase (PREP), and Radial Spoke Head 6 Homolog A (RSPH6A), alongside sperm functional parameters. Our findings showed that T1D significantly impaired the expression and distribution of these proteins, which may affect MTs organization and be associated with cytoskeletal disorganization, and impaired germ cell differentiation. Moreover, T1D rats exhibited reduced sperm count, viability, and motility, accompanied by increased DNA fragmentation and chromatin defects. Elevated levels of 4-hydroxy-2-nonenal (4-HNE), a marker of OS, were detected in SPZ, particularly in the acrosome and flagellum, correlating with mitochondrial dysfunction and ATP depletion. Additionally, decreased intracellular Ca²⁺ levels, downregulation of Cation Channel of Sperm (CATSPER) and Voltage-Dependent Anion Channel 3 (VDAC3), and altered tubulin acetylation, possibly due to imbalanced Alpha-Tubulin N-Acetyltransferase 1 (ATAT1) and Histone Deacetylase 6 (HDAC6) expression, were also associated with impaired sperm motility. The combined data suggest that T1D-induced OS is linked to disrupted MTs dynamics, which may contribute to testicular dysfunction and reduced sperm quality, potentially affecting male fertility. A better understanding of these associations may support the development of therapeutic strategies to mitigate the reproductive consequences of T1D and improve male fertility outcomes.

Polystyrene Microplastics (PS-MPs) affect testicular activity, as evidenced by increased oxidative stress, apoptosis, and autophagy activation, impairing steroidogenesis and spermatogenesis. The present study investigates, for the first time in vivo, the potential protective effect of D-aspartate (D-Asp) against PS-MPs-induced damage on the testicular function of adult rats. D-Asp, well-known stimulator of testosterone biosynthesis and spermatogenesis progression, possesses pharmacological properties, including antioxidant and anti-apoptotic ones. The results showed that PS-MP’s adverse effects on testicular activity were reversed by D-Asp treatment. Mechanistically, D-Asp inhibited testicular oxidative stress by modulating the protein levels of CAT, SOD1, SOD2, and 4-HNE; affecting TBARS levels; and reducing apoptosis, as suggested by CYT C analysis and a TUNEL assay. Furthermore, D-Asp administration mitigated PS-MPs-induced autophagy activation by modulating the expression of LC3BI, LC3BII, and p62 proteins. Finally, the amino acid counteracts PS-MPs damage on steroidogenesis and spermatogenesis by restoring normal levels of steroidogenic (StAR, 3β-HSD, and 17β-HSD) and spermatogenic (PCNA and SYCP3) markers. This study encourages further research to understand the potential value of the amino acid in improving human testicular health and male fertility.

Type 1 diabetes (T1D) is a systemic metabolic disorder associated with male reproductive dysfunction. Given the pivotal role of actin cytoskeleton remodeling in spermatogenesis and sperm function, this study investigated the effects of T1D on actin-regulating pathways in rat testis and spermatozoa (SPZ). Adult Wistar rats were rendered diabetic by streptozotocin administration (65 mg/kg, i.p.). Testicular analysis revealed a reduced F-/G-actin ratio together with marked F-actin disorganization, consistent with altered actin cytoskeleton remodeling. To investigate the molecular mechanisms underlying these alterations, key regulators of actin dynamics were examined. Diabetic animals displayed impaired expression of EPS8, Fascin, N-WASP, and the ARP2/3 complex, suggesting altered regulation of actin assembly, bundling, and branching. Further analyses demonstrated dysregulation of signaling pathways governing cytoskeletal organization. Reduced levels of phosphorylated Disheveled-2, DAAM1, RhoA-GTP, and ROCK1 indicated impairment of the planar cell polarity pathway. In parallel, changes in LIMK1/cofilin phosphorylation supported abnormal regulation of actin filament turnover. Alterations in the RICTOR/PKC/MARCKS signaling pathway further highlighted defects in cytoskeletal control. Similar abnormalities were observed in mature SPZ, where altered F-actin distribution and DAAM1 localization suggested persistent cytoskeletal defects. Moreover, diabetic SPZ exhibited a reduced ability to undergo acrosome reaction, accompanied by altered MARCKS phosphorylation, highlighting defects in actin-dependent processes essential for sperm function and fertilizing capacity. These findings indicate that disruption of actin cytoskeleton dynamics may represent a major mechanism contributing to testicular and sperm abnormalities in T1D, providing new insights into the mechanisms underlying diabetes-associated male reproductive dysfunction.