The effects of melatonin and octreotide on peridural fibrosis after laminectomy: An experimental study

2. ABSRACTPeridural fibrosis, which may develop after lumbar spinal surgery is fibroblasticinvasion of nerve roots into the peridural space opened during operations. It is afrequently seen complication. Formation of dense fibrous tissue in such cases causeslumbar and radicular pain in patients. In addition to radicular symptoms, scar tissuedeveloped in peridural area may cause problems during dissection of intraspinalstructures in case of a re-operation needed later.Several experimental and clinical studies using histopathological,immunohistochemical and electron microscopic approaches have shown in the recentyears that the pineal gland hormone (melatonin) may have beneficial effects againstfibrosis at tissue level. Anti-oxidant, anti-proliferative, anti-edema, anti-adhesive andfree radical scavenging effects of octreotide, a somatostatin analogue have also beenreported. It is known that octreotide inhibits transforming growth factor- β1 (TGF-β1)which plays an important role in formation of fibrosis. It also affects levels ofhidroxyprolin which is used to diagnose fibrosis.In view of the studies outlined above, we aimed to comparatively investigateeffects of melatonin and octreotide in prevention of fibrosis in an experimental ratmodel. Histopathological and biochemical parameters were examined to compare theeffects of two agents.A total of 36 adult male Wistar rats were used in this study. They were dividedinto three groups: Group I was laminectomized and not given any treatment. The rats inGroup II received a single intraperitoneally (ip) dose of octreotide (30 µg/kg) just afterthe injury and then 30 µg/kg/day divided into three equal doses for six weeks. Group IIIwere ip injected with melatonin 7.5 mg/kg as a single dose just after laminectomy andthen 7.5 mg/kg/day divided into three equal doses for six weeks. At the end of sixweeks, serum TGF-β1 levels and peridural fibrous tissue hidroxyprolin concentrationswere determined and histopathological examinations was performed.In conclusion, positive effects of melatonin and octreotide were observed inprevention of fibrosis developed after laminectomy. They both significantly decreasedserum levels of TGF-β1 (p<0.05). When histopathological scores and tissuehidroxyprolin levels were examined, it was seen that melatonin?s preventive effectswere statistically significant. Octreotide-induced effects were beneficial but notsignificant compared to the laminectomy group.Key words: melatonin, octreotide, peridural fibrosis, transforming growthfactor, hidroxyprolin