Ishizu Hidenori, Sekiguchi Toshio, Ikari Takahiro, Kitamura Kei-Ichiro, Kitani Yoichiro, Endo Masato, Urata Makoto, Kinoshita Yasuko, Hattori Atsuhiko, Srivastav Ajai K, Mishima Hiroyuki, Mizusawa Kanta, Takahashi Akiyoshi, Suzuki Nobuo
Noto Marine Laboratory, Institute of Nature and Environmental Technology, Division of Marine Environmental Studies, Kanazawa University, Noto-cho, Ishikawa 927-0553, Japan.
Department of Clinical Laboratory Science, Division of Health Sciences, Graduate School of Medical Science, Kanazawa University, Kodatsuno, Ishikawa 920-0942, Japan.
Gen Comp Endocrinol. 2018 Jun 1;262:99-105. doi: 10.1016/j.ygcen.2018.03.020. Epub 2018 Mar 22.
We examined the effects of α-melanocyte-stimulating hormone (α-MSH) on bone metabolism using regenerating goldfish scales. Normally developed scales on the bodies of goldfish were removed to allow the regeneration of scales under anesthesia. Thereafter, the influence of α-MSH on the regeneration of goldfish scales was investigated in vivo. In brief, α-MSH was injected at a low dose (0.1 μg/g body weight) or a high dose (1 μg/g body weight) into goldfish every other day. Ten days after removing the scales, we collected regenerating scales and analyzed osteoblastic and osteoclastic activities as respective marker enzyme (alkaline phosphatase for osteoblasts, tartrate-resistant acid phosphatase for osteoclasts) activity in the regenerating scales as well as plasma calcium levels. At both doses, osteoblastic and osteoclastic activities in the regenerating scales increased significantly. Plasma calcium concentrations in the α-MSH-treated group (high doses) were significantly higher than those in the control group. Next, in vitro experiments were performed to confirm the results of in vivo experiments. In the cultured regenerating scales, osteoblastic and osteoclastic activities significantly increased with α-MSH (10 and 10 M) treatment. In addition, real-time PCR analysis indicated that osteoclastogenesis in α-MSH-treated scales was induced by the receptor activator of the NF-κB/receptor activator of the NF-κB ligand/osteoprotegerin pathway. Furthermore, we found that α-MSH receptors (melanocortin receptors 4 and 5) were detected in the regenerating scales. Thus, in teleosts, we are the first to demonstrate that α-MSH functions in bone metabolism and promotes bone resorption via melatonin receptors 4 and/or 5.
我们使用再生的金鱼鳞片研究了α-黑素细胞刺激素（α-MSH）对骨代谢的影响。去除金鱼身上正常发育的鳞片，以便在麻醉状态下让鳞片再生。此后，在体内研究了α-MSH对金鱼鳞片再生的影响。简而言之，每隔一天以低剂量（0.1μg/g体重）或高剂量（1μg/g体重）向金鱼注射α-MSH。去除鳞片10天后，我们收集再生鳞片，并分析再生鳞片中作为各自标记酶（成骨细胞为碱性磷酸酶，破骨细胞为抗酒石酸酸性磷酸酶）的活性以及血浆钙水平。在两个剂量下，再生鳞片中的成骨细胞和破骨细胞活性均显著增加。α-MSH处理组（高剂量）的血浆钙浓度显著高于对照组。接下来，进行体外实验以证实体内实验的结果。在培养的再生鳞片中，α-MSH（10和10μM）处理后成骨细胞和破骨细胞活性显著增加。此外，实时PCR分析表明，α-MSH处理的鳞片中的破骨细胞生成是由NF-κB受体激活剂/NF-κB配体受体激活剂/骨保护素途径诱导的。此外，我们发现再生鳞片中检测到α-MSH受体（黑皮质素受体4和5）。因此，在硬骨鱼中，我们首次证明α-MSH在骨代谢中起作用，并通过褪黑素受体4和/或5促进骨吸收。
