Effect of vasoactive intestinal peptide on the wound healing of alkali-burned corneas

AIM: To study the effect of vasoactive intestinal peptide (VIP) on wound healing in experimental alkali burns of the cornea.METHODS: Twenty-seven albino rabbits, weighing 3.2±0.75 kg were used. Alkali burns were induced on corneas by applying 10 mm Whatman paper No:50 soaked in 1 mol/L NaOH. They have further classified into 5 groups as follows: 1) control group given no treatment (n=5); 2) VIP given subconjunctivally (n=6); 3) VIP injected into anterior chamber (n=6); 4) NaCl 0.9% given subconjunctivally (n=5); 5) NaCl 0.9% given into the anterior chamber (n=5). All treatment protocols except control group were followed by topical eye drops composed of VIP at two hourly intervals for one week from 8 a.m. to 6 p.m.RESULTS: VIP treated groups of rabbits with alkali burns were found to have better wound healing findings histo-pathologically when compared to those of control group who have received no treatment on day 30. No differences were observed between groups in respect to degree of polymorphonuclear leukocytes (PMNL) infiltration and degree of loss of amorphous substrate on day 15. However, PMNL infiltration and degree of loss of amorphous substrate were lower in Groups 2 and 3 when compared to that of control group on day 30 (P(0.05).CONCLUSION: We have shown that VIP has positive effects on alkali induced corneal burns. VIP may inhibit PMNL migration to cornea through an immunomodulatory effect. Inhibition of PMNL migration might reduce the release of collagenases and this might prevent the extracellular amorphous substance loss.