Abstract
Purpose::
Naltrexone (NTX) is an opioid antagonist that accelerates wound healing of corneal epithelium in normal and diabetic animals. Junctional complexes (hemidesmosomes) are responsible for the adhesion of the corneal epithelium to the stroma in rats. This study was designed to examine whether NTX influences the appearance and/or number of hemidesmosomes in Normal, diabetic (DB) (hyperglycemic), and DB animals receiving insulin (DB-IN) (normoglycemic), and treated topically with NTX or sterile vehicle (SV) for 7 days.
Methods::
Type 1 DB (glucose levels >400 mg/dl) was induced with streptozotocin; in some animals glycemic levels were controlled with insulin minipumps (DB-IN). Eight weeks after induction of diabetes, a 5 mm diameter abrasion was created in the center of the cornea in one eye of each rat. Eye drops of NTX (10-4 M) dissolved in Vigamox (Alcon Laboratories, TX), or SV were given 4 times daily for 7 days. One week after termination of treatment (i.e., 2 weeks after abrasion), the corneas were fixed and prepared for electron microscopic analysis.
Results::
Electron microscopic analysis of the repaired cornea revealed no ultrastructural differences in morphology in the basal or suprabasal regions for Normal, DB, or DB-IN groups of animals exposed to SV, or those treated with NTX. Four types of hemidesmosomes were identified. Neither the structure nor the number of junctional complexes differed between Normal, DB, or DB-IN groups subjected to SV. Moreover, Normal, DB, or DB-IN animals receiving topical treatment with 10-4 M NTX for 7 days exhibited the same types and number of adhesion complexes as respective groups receiving SV.
Conclusions::
Animals with controlled and uncontrolled DB do not have alterations in corneal adhesion complexes two weeks following abrasion. Moreover, topical application of NTX to Normal or diabetic animals (controlled or uncontrolled), which accelerates healing, does not influence the hemidesmosome number or type.
Keywords: diabetes • wound healing • microscopy: electron microscopy