Departamento de Neurofisiología Celular y Molecular, Instituto de Investigaciones Biológicas Clemente Estable (IIBCE), Av. Italia 3318, 11600, Montevideo, Uruguay.
Neuroscience. 2011 Aug 25;189:12-24. doi: 10.1016/j.neuroscience.2011.05.063. Epub 2011 Jun 6.
In contrast with mammals, adult fish brains exhibit an enormous potential to produce new cells. Proliferation zones, however, have been described in only a few species, hindering comparisons among genuses and orders. Here we analyzed brain cell proliferation in annual teleostean fishes Austrolebias (Cyprinodontiform: Rivulidae). Immunocytochemistry against 5-bromo-2'-deoxyuridine (BrdU) was quantitated and mapped 24 h after injection in three species with different phylogenetic positions or habitats. All species had similar brain anatomy and total volume, but olfactory bulbs, torus longitudinalis and cerebellum were of different sizes in different species. Cell proliferation was found throughout the brain. Three-D reconstructions provided evidence for contiguity along the rostro-caudal axis and concentration in the vicinity of the ventricles. Brain regions analyzed exhibited high mitotic activity, and the torus longitudinalis had the highest volume-normalized proliferation index. A. affinis exhibited the highest normalized proliferation indexes in visual regions but the lowest in olfactory bulb. A. reicherti showed an inverse pattern, suggesting that these species have a different hierarchy of sensorial modalities that could be related to phylogeny or habitat. Double immunostaining against BrdU and cell-type specific markers was performed to determine the fate of proliferating cells. A widespread gliogenesis was evidenced. Few cells positive for both BrdU and the neuronal marker HuC/D were found in the brain of the three species, demonstrating neurogenesis in the adult Austrolebias brain. Summarizing, adult members of the three species showed similar brain anatomy and cell proliferation patterns. Among species, volume-normalized proliferation indexes varied in regions involved in different sensory modalities. To our knowledge, this is the first report showing proliferating cells with neuronal markers as earlier as 24 h after BrdU injection.
与哺乳动物相比，成年鱼类的大脑具有产生新细胞的巨大潜力。然而，只有少数几种鱼类中描述了增殖区，这阻碍了属和目之间的比较。在这里，我们分析了年度硬骨鱼类 Austrolebias（鲤形目：Rivulidae）的脑细胞增殖。在三个具有不同系统发育位置或栖息地的物种中，在注射后 24 小时对 5-溴-2'-脱氧尿苷（BrdU）进行免疫细胞化学定量和定位。所有物种的大脑解剖结构和总体积相似，但嗅球、长环和小脑在不同物种中大小不同。细胞增殖发生在整个大脑中。三维重建提供了沿头尾部轴连续性和靠近脑室集中的证据。分析的脑区显示出高有丝分裂活性，长环具有最高的体积归一化增殖指数。A. affinis 在视觉区域表现出最高的归一化增殖指数，但在嗅球中最低。A. reicherti 表现出相反的模式，这表明这些物种具有不同的感官模态层次结构，这可能与系统发育或栖息地有关。对 BrdU 和细胞类型特异性标志物进行双重免疫染色，以确定增殖细胞的命运。广泛的神经胶质发生得到了证明。在三个物种的大脑中，只有少数 BrdU 和神经元标志物 HuC/D 均为阳性的细胞，这表明成年 Austrolebias 大脑中存在神经发生。综上所述，三个物种的成年成员表现出相似的大脑解剖结构和细胞增殖模式。在物种之间，参与不同感觉模态的区域的体积归一化增殖指数有所不同。据我们所知，这是第一个在 BrdU 注射后 24 小时内显示具有神经元标志物的增殖细胞的报告。
