Type 1 diabetes impairs the activity of rat testicular somatic and germ cells through NRF2/NLRP3 pathway-mediated oxidative stress

Front Endocrinol (Lausanne). 2024 May 16:15:1399256. doi: 10.3389/fendo.2024.1399256. eCollection 2024.

Abstract

Background: It is well known that metabolic disorders, including type 1 diabetes (T1D), are often associated with reduced male fertility, mainly increasing oxidative stress and impairing the hypothalamus-pituitary-testis (HPT) axis, with consequently altered spermatogenesis and reduced sperm parameters. Herein, using a rat model of T1D obtained by treatment with streptozotocin (STZ), we analyzed several parameters of testicular activity.

Methods: A total of 10 adult male Wistar rats were divided into two groups of five: control and T1D, obtained with a single intraperitoneal injection of STZ. After 3 months, the rats were anesthetized and sacrificed; one testis was stored at -80°C for biochemical analysis, and the other was fixed for histological and immunofluorescence analysis.

Results: The data confirmed that T1D induced oxidative stress and, consequently, alterations in both testicular somatic and germ cells. This aspect was highlighted by enhanced apoptosis, altered steroidogenesis and Leydig cell maturity, and impaired spermatogenesis. In addition, the blood-testis barrier integrity was compromised, as shown by the reduced levels of structural proteins (N-cadherin, ZO-1, occludin, connexin 43, and VANGL2) and the phosphorylation status of regulative kinases (Src and FAK). Mechanistically, the dysregulation of the SIRT1/NRF2/MAPKs signaling pathways was proven, particularly the reduced nuclear translocation of NRF2, affecting its ability to induce the transcription of genes encoding for antioxidant enzymes. Finally, the stimulation of testicular inflammation and pyroptosis was also confirmed, as highlighted by the increased levels of some markers, such as NF-κB and NLRP3.

Conclusion: The combined data allowed us to confirm that T1D has detrimental effects on rat testicular activity. Moreover, a better comprehension of the molecular mechanisms underlying the association between metabolic disorders and male fertility could help to identify novel targets to prevent and treat fertility disorders related to T1D.

Keywords: INSL3; RXFP2; SIRT1; apoptosis; blood-testis barrier; inflammasome; spermatogenesis; steroidogenesis.

MeSH terms

  • Animals
  • Diabetes Mellitus, Experimental* / metabolism
  • Diabetes Mellitus, Experimental* / pathology
  • Diabetes Mellitus, Type 1* / metabolism
  • Diabetes Mellitus, Type 1* / pathology
  • Germ Cells / metabolism
  • Male
  • NF-E2-Related Factor 2* / metabolism
  • NLR Family, Pyrin Domain-Containing 3 Protein* / metabolism
  • Oxidative Stress*
  • Rats
  • Rats, Wistar
  • Signal Transduction
  • Spermatogenesis
  • Spermatozoa / metabolism
  • Testis* / metabolism
  • Testis* / pathology

Substances

  • NF-E2-Related Factor 2
  • Nfe2l2 protein, rat
  • NLR Family, Pyrin Domain-Containing 3 Protein
  • Nlrp3 protein, rat

Grants and funding

The author(s) declare financial support was received for the research, authorship, and/or publication of this article. This work was supported by the Italian Ministry of University and Research (Grant No. PRIN to M.V., 2022, CUP B53D23011470006). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.