Laboratory of Fish Biology and Pollution, Zoology Department, Faculty of Science, Assiut University, 71516, Assiut, Egypt.
Zoology Department, Faculty of Science, Sohag University, 8562 Sohag, Egypt.
Photochem Photobiol Sci. 2019 Jan 1;18(1):71-79. doi: 10.1039/c8pp00169c. Epub 2018 Oct 11.
Ultraviolet radiation-induced neurodegeneration has been studied in the early stages of development in fish, but not extensively in the adult stage. The present study aimed at investigating the effects of ultraviolet radiation-A (UVA) in adult Japanese medaka (Oryzias latipes). The brain, spinal cord, and retina were examined histopathologically as nervous system target organs. Japanese medaka fish were exposed to 15, 30, and 60 min day UVA for 3 days, and samples were obtained 24 h and 14 days after UVA exposure. Neurohistopathological alterations in brain tissue included vacuoles, blood congestion, degeneration of neuropils, and pyknotic nuclei in neurons. Alterations in the spinal cord included neuronal cell degeneration, reduction in the spinal cord area, and degeneration of Mauthner cells. Retinal tissue showed vacuolation in the nerve fiber layer (NFL), pyknotic nuclei in the ganglion cell layer (GCL), and decreased cell populations particularly in the inner nuclear layer (INL) and GCL. The degree of degeneration was dependent on the duration of UVA exposure. The signs of degeneration decreased gradually and disappeared completely after the 14-day recovery period. In addition, p53-deficient medaka fish were more tolerant than were wild-type (Hd-rR) Japanese medaka. In conclusion, UV radiation induced neurodegeneration in the brain, spinal cord, and retina of adult Japanese medaka (Oryzias latipes) but their normal histological architecture reappeared in these tissues after 14 days.
紫外线辐射诱导的神经退行性变在鱼类的早期发育阶段已有研究，但在成年阶段尚未广泛研究。本研究旨在研究紫外线 A（UVA）对成年日本青鳉（Oryzias latipes）的影响。将大脑、脊髓和视网膜作为神经系统靶器官进行组织病理学检查。日本青鳉鱼接受 15、30 和 60 分钟/天的 UVA 照射 3 天，在 UVA 照射后 24 小时和 14 天采集样本。脑组织的神经组织病理学改变包括空泡、血液充血、神经原纤维变性和神经元固缩核。脊髓的改变包括神经元细胞变性、脊髓面积减少和 Mauthner 细胞变性。视网膜组织的神经纤维层（NFL）有空泡形成，神经节细胞层（GCL）有固缩核，特别是内核层（INL）和 GCL 的细胞数量减少。退行性变的程度取决于 UVA 暴露的持续时间。退行性变的迹象在 14 天的恢复期后逐渐减轻并完全消失。此外，p53 缺陷型青鳉鱼比野生型（Hd-rR）日本青鳉鱼更耐受。总之，紫外线辐射诱导成年日本青鳉（Oryzias latipes）的脑、脊髓和视网膜发生神经退行性变，但在 14 天后这些组织的正常组织学结构再次出现。
