Protective effects of melatonin and aminoguanidine on the cornea in streptozotocin-induced diabetic rats.
OBJECTIVE
This study was designed to investigate the protective effect of aminoguanidine (AG) and melatonin (M) on the cornea in a streptozotocin-induced diabetic rat model.


METHODS
Twenty-eight Sprague-Dawley rats were used in this study. Animals were divided into 4 groups: control (C), diabetes (D), diabetes + AG (D+AG), and diabetes + M (D+M). Diabetes was induced by 1 intraperitoneal dose of 45 mg/kg of streptozotocin (STZ). In the treatment groups, the D + AG group received AG in their water (1 g/L), and D + M rats were injected with M (10 mg/kg/d) intraperitoneally. One of the groups remained an untreated diabetic group (D group). All animals were euthanized at the end of 8 weeks. After enucleation, eyes were fixed in 10% phosphate-buffered formalin and embedded in paraffin wax. Histochemical stains were applied, and specimens were examined under a light microscope.


RESULTS
After 8 weeks, the rats in the diabetes group had significantly lower body weight and significantly higher blood glucose levels than those of the control, D + AG, and D + M groups. Diabetes resulted in prominent edema in the stroma with interruptions in the subepithelial basement membrane. These alterations were not prominent or were absent in the D + AG and D + M groups. The mean thicknesses of the cornea, corneal epithelium, and stroma were statistically significantly different between the C and D, and D and D + AG and D + M groups (P < 0.05).


CONCLUSIONS
Long-term administration of AG and M reduced corneal injury in an STZ-induced diabetic rat model. AG and M may be potential candidates in the treatment of diabetic keratopathies. However, further studies are needed to elucidate the mechanisms of the protective effect of both molecules on diabetic corneal complications.
Gül
Mehmet
M
Department of Histology and Embryology, Faculty of Medicine, Inonu University, Malatya, Turkey.
Emre
Sinan
S
Eşrefoğlu
Mukaddes
M
Vard
Nigar
N
D000284:Administration, Oral; D000818:Animals; D000975:Antioxidants / Q000008:administration & dosage*; D001786:Blood Glucose / Q000032:analysis; D001835:Body Weight; D003316:Corneal Diseases / Q000209:etiology / Q000473:pathology / Q000517:prevention & control*; D003921:Diabetes Mellitus, Experimental / Q000209:etiology / Q000473:pathology / Q000517:prevention & control*; D004791:Enzyme Inhibitors / Q000008:administration & dosage*; D005260:Female; D006146:Guanidines / Q000008:administration & dosage*; D007274:Injections, Intraperitoneal; D008550:Melatonin / Q000008:administration & dosage*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D051381:Rats; D017207:Rats, Sprague-Dawley
D000975:Antioxidants; D001786:Blood Glucose; D004791:Enzyme Inhibitors; D006146:Guanidines; D019001:Nitric Oxide Synthase; D008550:Melatonin; C004479:pimagedine