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    Constructive effect of exogenous melatonin against osteoporosis after ovariectorny in rats
    (Sci Printers & Publ Inc, 2007) Uslu, Serap; Uysal, Ayseguel; Oektem, Guelperi; Yurtseven, Mine; Tanyalcin, Tijen; Basdemir, Guelcin
    OBJECTIVE: To analyze histomorphometric, densitometric and biochemical effects of melatonin on osteoporosis in ovariectomized rats. STUDY DESIGN: Wistar rats were divided into 6 groups. Group C: control; Group I: bilateral ovariectomy (OVX); Group II. OVX + vehicle; Group III: OVX + 10 mg/kg/day melatonin WLT); Group IV. OVX + 30 mg/kg/day MLT; Group V. sham + 10 mg/kg/day MLT. Cortex, trabecula, osteoblast and osteoclast numbers were evaluated on vertebra and femur histomorphometrically. Hydroxyproline analysis was used to determine collagen content of femur and vertebrae. Bone mineral density and bone mineral content were measured. RESULTS: Trabecular thickness and trabecular area of vertebra and femur and cortical thickness of femur showed remarkable decrease after OVX, but increased after MLT treatment in the OVX+MLT groups. Following OVX, no statistically significant difference was found in number of osteoblasts or osteoclasts, trabecular number or levels of hydroxyproline after treatment with MLT. OVX caused significant decrease in bone mineral density, but treatment with MLT was unable to reverse this effect. CONCLUSION: MLT may trigger microscopic changes in bone, and time of application is critical for clinical recovery. It can be effective in helping treat postmenopausal osteoporosis. However, it is contraindicated in women who have normal-functioning ovaries.
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    Immunohistochemical profile of transforming growth factor-beta 1 and basic fibroblast growth factor in sciatic nerve anastomosis following pinealectomy and exogenous melatonin administration in rats
    (Churchill Livingstone, 2006) Turgut, Mehmet; Oektem, Guelperi; Uysal, Ayseguel; Yurtseven, Mine Ertem
    Collagen sear formation at the cut end of a peripheral nerve, an important problem in clinical practice for neurosurgeons, obstructs sprouting of axons into appropriate distal fascicles, and thereby limits the regeneration process. Researchers have attempted to control collagen accumulation and neuroma formation with various physical and chemical methods, but with limited functional success. Recently, it has been demonstrated that transforming growth factor (TGF)-beta and basic fibroblast growth factor (bFGF) play an important role in collagen production by fibroblasts and in Schwann cell activity. In our study, rats were divided into a control group, a melatonin-treated group, a surgical pinealectomy group, and a group treated with melatonin following pinealectomy. They then underwent a surgical sciatic nerve transection and primary suture anastomosis. At 2 months after anastomosis, the animals were sacrificed and unilateral sciatic nerve specimens, including the anastomotic region, were removed and processed for immunohistochemical study from two animals in each group. For each antibody, immunoreactivity was assessed using a semiquantitative scoring system. Strong TGF-beta 1 and/ or bFGF expression was observed in the epineurium of animals that underwent pinealectomy, but no or weak staining was observed in animals in the control and melatonin treatment groups. Based on these data, we suggest that both TGF-beta 1 and bFGF have important roles in control of collagen accumulation and neuroma formation at the anastomotic site, and that the pineal neurohormone melatonin has a beneficial effect on nerve regeneration. (C) 2006 Elsevier Ltd. All rights reserved.