Endocrine Abstracts

Cimetidine, an antagonist of histamine H2-receptors used for treatment of gastric ulcers, exerts antiandrogenic effect. In testes, cimetidine causes histopathological disorders in the seminiferous tubules and impairs spermatogenesis. Additionally to testosterone, Leydig cells (LC) produce several paracrine factors, including EG–VEGF (endocrine gland-derived vascular endothelial growth factor) which participates in the testicular microvasculature control. Regarding the importance of histamine and androgens for the blood vessels maintenance, we purposed to evaluate whether cimetidine impairs testicular microvasculature and/or structural and functional integrity of LC. Adult rats received 100 mg/kg BW of cimetidine (CMTG) and saline solution (CG) for 50 days. The testes were fixed in buffered 4% formaldehyde and embedded in historesin and paraffin. Some testicular fragments were embedded in Araldite for analysis under transmission electron microscopy. The serum levels of testosterone were also evaluated. In the PAS-stained historesin sections, the microvascular density (MVD) was obtained. Paraffin sections were submitted to the following reactions: TUNEL method; 17β-HSD6 (for LC quantification); 17β-HSD6+TUNEL (for detection of LC undergoing cell death); and Prokineticin-1 (for detection of EG–VEGF expression). The semiquantitative score (1+, 2+, 3+) of EG–VEGF-immunolabeled LC was obtained. Statistical analyses were performed (P≤0.05). In CMTG, a significant decrease (17%) in the MVD was observed. The presence of 17β-HSD6+TUNEL positive LC and the typical ultrastructural features of apoptosis confirm the harmful effect of cimetidine in LC. This is reinforced by the significant reduction in the number of LC and in the serum levels of testosterone (42%). The immunoexpression of EG–VEGF in LC was also reduced in CMTG. The results indicate that cimetidine induces LC apoptosis. As vascular cells express ARs and VEGF receptors, the testicular microvasculature impairment may be caused by the interference of cimetidine treatment in the Leydig cell-microvasculature paracrine control due to LC death.

Financial support: FAPESP (2010/02409–5), CNPq (Brazil).

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This work was supported, however funding details unavailable.