Pinealectomy exaggerates and melatonin treatment suppresses neuroma formation of transected sciatic nerve in rats: gross morphological, histological and stereological analysis

Abstract

At present, an intensive effort for prevention of neuroma formation following peripheral nerve section continues. It has been recently suggested that surgical pinealectomy (Px) induces elevation of the collagen content in the granulation tissue of a wound, while melatonin application after Px suppresses elevation of the collagen accumulation in the tissue. The aim of the present study was to assess whether melatonin had the ability to suppress collagen production and neuroma formation following peripheral nerve transection. A total of 40 male rats (four groups of 10) were left intact (intact controls) or sham operated (sham group), were Px, or were Px and given melatonin (Px + melatonin group). All animals underwent a surgical intervention consisting of right sciatic nerve neurectomy. After 4 wk, the animals were killed following intracardiac perfusion. Gross morphology of neuroma formation in the proximal nerve segment was examined and proximal neuroma evaluated. Macroscopic and microscopic findings revealed that Px caused a proliferation of connective tissue and large neuroma formation at the proximal ends of transected nerves. Stereological analysis showed that there was a statistically significant reduction in connective tissue content of the same region in Px animals treated with melatonin (P < 0.005). The results achieved in a rodent model of sciatic nerve neuroma formation showed that there was a positive correlation between macroscopic and microscopic observations, and that melatonin enhanced axonal regeneration presumably due to its inhibitory effect on neuroma formation.

İyonize Radyasyon Uygulaması Yapılmış Rat Pineal Bezi Üzerinde Melatoninin Koruyucu Etkisi Var mıdır? Kronobiyolojik ve Elektron Mikroskobik Çalışma

“…Organizmanın bu süreçle savaşta, antioksidan sistemleri devreye soktuğu bilinmektedir 9 . Yapılan araştırmalar melatoninin, antioksidan defans sistemlerinden biri olduğunu göstermektedir [10][11][12] . Diğer yandan, organizmadaki birçok fonksiyon düzenli olarak tekrarlayan bir organizasyon içinde olup, bu değişikler "biyolojik ritimler" olarak adlandırılmaktadır.…”

The Effect of Intrauterine Acute Ethanol Exposure on Developing Sciatic Nerves and Their Myelination: A Stereological Study

“…It has the ability to protect DNA against oxidative damage and may also have strong antiinflammatory effects (Genovese et al, 2005). In recent years, MLT has been indicated as having a neuroprotective effect upon a variety of neuropathological events such as ischemia, infarction, and edema formation (Pei et al, 2002;Reiter et al, 2001;Turgut et al, 2005a;Turgut et al, 2005b). Based on these data, it was expected that MLT, given during the prenatal period, may ameliorate the developmental damage to the PNS, and the disruption of nerve myelination, caused by ETH toxicity.…”

The Role of Pharmacological Agents in Nerve Regeneration after Peripheral Nerve Repair

“…The functional recovery of damaged nerves was estimated by the amount of Schwann cells and the number of re-innervated muscle motor end-plate targets [117]. Furthermore, it is worth mentioning that Turgut et al have experimentally demonstrated in rats that melatonin prevents neuroma formation after transacting the sciatic nerve by enhancing axonal regeneration [118]. Recently, some studies have shown the positive effect of melatonin on preventing scar formation, increasing nerve regeneration and improving functional recovery [119,120].…”

“…Turgut et al examined the gross morphology of neuroma formation in the proximal nerve segment via macroscopic and microscopic findings, and the surgical pinealectomy group without application of melatonin caused a proliferation of connective tissue and large neuroma formation at the proximal ends of transacted nerves compared with the surgical pinealectomy group and the group given melatonin (P < 0.005) [118]. In addition, Kaya et al demonstrated a beneficial effect on axonal regeneration and functional recovery in the experimental group in which melatonin was applied after stripping of the epineurial vessels compared with other groups without melatonin application [119].…”

“…Chang et al [115] Limits fibrosis and neuroma formation Through promoting Schwann cell proliferation Chang et al [117] Exact mechanisms through which melatonin imparts these effects are currently unclear Turgut et al [118] Peripheral Nerve Regeneration -From Surgery to New Therapeutic Approaches Including Biomaterials and Cell-Based Therapies Development…”