Abstract
Purpose: :
The aim of this study is to know the role of Melatonin, the MT3 agonist 5-MCA-NAT and MT2 agonist IIK7, have in the rate of re-epithelization after corneal wound healing as well as what melatonin receptor is involved in such process.
Methods: :
In wounded SIRC monolayers (establish rabbit corneal epithelial cell line) we studied the estimated migration rate (EMR) and estimated healing time (EHT) after treatment of wounds with melatonin, 5-MCA-NAT and IIK7 100 µM (n = 8). In the presence of melatonin 100 µM, we also assayed the effect the antagonists Luzindole (non-selective), DH97 (MT2) and Prazosin (MT3) (n = 8) had on the migration rate. A control wound was performed in each experiment, this being treated with buffer.
Results: :
When we assayed both melatonin and IIK7 100 µM, the EMR was increased (6.65 ± 0.27 and 8.22 ± 0.39, respectively) in relation to the control (5.61 ± 0.54). This result was in accordance with a decrease in EHT in 5 and 10 hours for melatonin and IIK7, respectively. The MT3 selective agonist 5-MCA-NAT (100 µM) had no effect in migration rate (5.76 ± 0.16). In the presence of melatonin 100 µM, Luzindole 100µM, DH97 100 µM and Prazosin 1 µM produced a reduction in EMR (5.37 ± 1.09, 0.82 ± 0.45 and 2.73 ± 0.37 respectively) with an increase in EHT (9 hours, no apparent healing and 32 hours respectively). In the presence of 5-MCA-NAT 100 µM, DH97 100 µM and Corynanthine 25 µM produced a delay in EMR with an increased in EHT (2.93 ±0.85 and 70 hours for DH97 100 µM and 1.89 ± 0.38 and 60 hours for Corynanthine 25 µM), while Prazosin 1 µM had no effect on EMR (5.20 ± 0.30).
Conclusions: :
The increase of rate that melatonin exerts in corneal epithelial cell migration is due mainly to the activation of a MT2 receptor melatonin receptor.
Keywords: cornea: epithelium • wound healing • receptors: pharmacology/physiology