University of Zurich, Institute of Anatomy, Division of Neuroanatomy and Behavior, Zurich, Switzerland.
PLoS One. 2007 May 23;2(5):e455. doi: 10.1371/journal.pone.0000455.
Bats are the only flying mammals and have well developed navigation abilities for 3D-space. Even bats with comparatively small home ranges cover much larger territories than rodents, and long-distance migration by some species is unique among small mammals. Adult proliferation of neurons, i.e., adult neurogenesis, in the dentate gyrus of rodents is thought to play an important role in spatial memory and learning, as indicated by lesion studies and recordings of neurons active during spatial behavior. Assuming a role of adult neurogenesis in hippocampal function, one might expect high levels of adult neurogenesis in bats, particularly among fruit- and nectar-eating bats in need of excellent spatial working memory. The dentate gyrus of 12 tropical bat species was examined immunohistochemically, using multiple antibodies against proteins specific for proliferating cells (Ki-67, MCM2), and migrating and differentiating neurons (Doublecortin, NeuroD). Our data show a complete lack of hippocampal neurogenesis in nine of the species (Glossophaga soricina, Carollia perspicillata, Phyllostomus discolor, Nycteris macrotis, Nycteris thebaica, Hipposideros cyclops, Neoromicia rendalli, Pipistrellus guineensis, and Scotophilus leucogaster), while it was present at low levels in three species (Chaerephon pumila, Mops condylurus and Hipposideros caffer). Although not all antigens were recognized in all species, proliferation activity in the subventricular zone and rostral migratory stream was found in all species, confirming the appropriateness of our methods for detecting neurogenesis. The small variation of adult hippocampal neurogenesis within our sample of bats showed no indication of a correlation with phylogenetic relationship, foraging strategy, type of hunting habitat or diet. Our data indicate that the widely accepted notion of adult neurogenesis supporting spatial abilities needs to be considered carefully. Given their astonishing longevity, certain bat species may be useful subjects to compare adult neurogenesis with other long-living species, such as monkeys and humans, showing low rates of adult hippocampal neurogenesis.
蝙蝠是唯一会飞的哺乳动物，拥有高度发达的三维空间导航能力。即使是那些活动范围相对较小的蝙蝠，其活动范围也远远超过了啮齿动物，而某些物种的长距离迁徙在小型哺乳动物中是独一无二的。在啮齿动物的齿状回中，成年神经元的增殖（即成年神经发生）被认为在空间记忆和学习中发挥着重要作用，这一点可以通过对活跃于空间行为期间的神经元进行损伤研究和记录来证明。假设成年神经发生在海马体功能中发挥作用，那么人们可能会期望蝙蝠中的成年神经发生水平较高，尤其是在那些需要出色空间工作记忆的以水果和花蜜为食的蝙蝠中。我们使用针对增殖细胞（Ki-67、MCM2）和迁移分化神经元（双皮质蛋白、NeuroD）的多种抗体，对 12 种热带蝙蝠物种的齿状回进行了免疫组织化学检查。我们的数据显示，在其中 9 种物种（大食果蝠、马氏管鼻蝠、棕蝠、棕蝠、棕蝠、环尾蝠、菲律宾果蝠、小长舌果蝠、短耳果蝠）中完全没有海马体神经发生，而在另外 3 种物种（埃及果蝠、中澳大果蝠和大蹄蝠）中则存在低水平的神经发生。尽管并非所有抗原在所有物种中都能被识别，但在所有物种中都发现了侧脑室下区和前迁移流中的增殖活性，这证实了我们检测神经发生的方法的恰当性。我们的蝙蝠样本中的成年海马体神经发生的小变化表明，它与系统发育关系、觅食策略、猎食栖息地类型或饮食没有相关性。我们的数据表明，支持空间能力的成年神经发生这一被广泛接受的观点需要谨慎考虑。考虑到它们惊人的长寿，某些蝙蝠物种可能是比较成年神经发生与其他长寿物种（如猴子和人类）的有用对象，这些物种的成年海马体神经发生率较低。
