Ultrastructural changes of cornea after ethanol ingestion in Otsuka Long-Evans Tokushima fatty (OLETF) and Long-Evans Tokushima Otsuka (LETO) rats

Purpose: To compare ethanol-induced ultrastructural changes in corneas of Otsuka Long-Evans Tokushima fatty (OLETF) rats and Long-Evans Tokushima Otsuka (LETO) rats. Methods: Forty, five-week-old male LETO and OLETF rats were fed an ethanol-containing liquid diet (LETO alc and OLETF alc) for 11 weeks, and another forty OLETF and LETO rats were put on a pair-fed control diet (LETO con and OLETF con) for 11 weeks. The body weight and fasting blood glucose levels, and 2-hour blood glucose levels after glucose tolerance test (GTT) were checked every week. Central corneal thickness (CCT) was measured with an ultrasound pachymeter after 11 weeks. After corneal buttons were excised, transmission electron microscopy (TEM) examination was performed. Results: The CCTs in groups LETO-alc (179.39∈±∈28.64 μm) and OLETF-alc (189.46∈±∈44.44 μm) were significantly thicker than those in groups LETO-con (168.07∈±∈15.57 μm) and OLETF-con (179.28∈±∈14.68 μm) respectively (P∈<∈0.05). The percentage of basement membrane occupied by hemidesmosome (HD/BM) in the LETO-alc (43.2∈±∈3.7%) and OLETF-alc (35. 3∈±∈4.1%) was lower than that in the LETO-con (51.5∈±∈2.6%) and OLETF-con (41.6∈±∈3.5%) group respectively (P∈<∈0.05). Descemet's membrane thickness of the LETO-alc (4.45∈±∈0.3 μm) and OLETF-alc (4. 98∈±∈0.5 μm) was greater than that of the LETO-con (4.11∈±∈0.2 μm) and and OLETF-con (4. 57∈±∈0.3 μm) group respectively (P∈<∈0.05). In the OLETF group, the hemidesmosomes and endothelial tight junctions were less electron-dense; interstromal edema was more prominent than that in the LETO group. Conclusions: Corneal ultrastructural damage can develop in the pre-diabetic stage and when alcohol is ingested chronically in rats.