Cremer H, Chazal G, Carleton A, Goridis C, Vincent J D, Lledo P M
Developmental Biology Institute of Marsaille, Centre National de la Recherche Scientifique, Marseille Cedex 9, France.
Proc Natl Acad Sci U S A. 1998 Oct 27;95(22):13242-7. doi: 10.1073/pnas.95.22.13242.
Cell adhesion molecules (CAMs) are known to be involved in a variety of developmental processes that play key roles in the establishment of synaptic connectivity during embryonic development, but recent evidence implicates the same molecules in synaptic plasticity of the adult. In the present study, we have used neural CAM (NCAM)-deficient mice, which have learning and behavioral deficits, to evaluate NCAM function in the hippocampal mossy fiber system. Morphological studies demonstrated that fasciculation and laminar growth of mossy fibers were strongly affected, leading to innervation of CA3 pyramidal cells at ectopic sites, whereas individual mossy fiber boutons appeared normal. Electrophysiological recordings performed in hippocampal slice preparations revealed that both basal synaptic transmission and two forms of short-term plasticity, i.e., paired-pulse facilitation and frequency facilitation, were normal in mice lacking all forms of NCAM. However, long-term potentiation of glutamatergic excitatory synapses after brief trains of repetitive stimulation was abolished. Taken together, these results strongly suggest that in the hippocampal mossy fiber system, NCAM is essential both for correct axonal growth and synaptogenesis and for long-term changes in synaptic strength.
细胞黏附分子（CAMs）已知参与多种发育过程，这些过程在胚胎发育期间突触连接的建立中起关键作用，但最近的证据表明，相同的分子也参与成体的突触可塑性。在本研究中，我们使用了存在学习和行为缺陷的神经细胞黏附分子（NCAM）缺陷小鼠，以评估海马苔藓纤维系统中的NCAM功能。形态学研究表明，苔藓纤维的成束和分层生长受到强烈影响，导致CA3锥体细胞在异位部位受到神经支配，而单个苔藓纤维终扣看起来正常。在海马脑片标本上进行的电生理记录显示，在缺乏所有形式NCAM的小鼠中，基础突触传递以及两种形式的短期可塑性，即双脉冲易化和频率易化，均正常。然而，短暂的重复刺激序列后谷氨酸能兴奋性突触的长时程增强被消除。综上所述，这些结果强烈表明，在海马苔藓纤维系统中，NCAM对于正确的轴突生长和突触形成以及突触强度的长期变化都是必不可少的。
