The Mechanistic Pathway and Target of Action of Naltrexone in the Enhancement of Full-thickness Wound Closure and Healing in Type 1 Diabetic Rats
Open Access
- Author:
- Immonen, Jessica Ann
- Graduate Program:
- Anatomy
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- March 25, 2011
- Committee Members:
- Dr Patricia Mc Laughlin, Thesis Advisor/Co-Advisor
Patricia J Mc Laughlin, Thesis Advisor/Co-Advisor - Keywords:
- Type 1 diabetes
wound healing - Abstract:
- [Met5]- enkephalin, also known as opioid growth factor (OGF), interacts with the opioid growth factor receptor (OGFr) to depress DNA synthesis and therefore, cell replication during wound healing, angiogenesis and other developmental activities. In this study, an opioid antagonist, naltrexone, is shown to inhibit the receptor-endogenous opioid interaction to increase cell proliferation and wound closure in healing full-thickness wounds. Sprague Dawley rats were rendered diabetic using streptozotocin (STZ) and were given 7 weeks to maintain hyperglycemia. The wounding surgery was performed on 23 normal and 25 diabetic animals. There were 4 full-thickness wounds made with a 6mm biopsy punch on the dorsum of each rat. Three times a day at 0800 h, 1200 h and 1600 h, 3 of the 4 wounds were treated with topical 10-5M Naltrexone (NTX), an opioid antagonist which blocks the interactions between OGF and OGFr to increase cellular proliferation. One wound per animal was chosen at random and was treated with only vehicle. Four diabetic and four normal animals were euthanized at days 3, 5, 8, 10, 15 and 20 post-wounding. Wound closure rates were determined by areal analysis of wounds using Optimas62 computer software. Histological analysis was done to determine the mechanistic pathway by which naltrexone accelerates the particular phases of wound healing in normal and diabetic animals. For inflammation, mast cells were quantified using a Toluidine Blue stain. H&E was implemented to visualize the proliferative phase of wound healing by quantifying epithelial thickness. Granulation tissue formation and angiogenesis was quantified using VEGF and α-SMA as markers in a standard immunohistochemistry protocol. Immunohistochemistry was also performed to analyze the remodeling phase using an MMP-9 primary antibody. Sirius Red stain was also used to document collagen maturation during the remodeling phase.