Pang K, Rose G M
Department of Pharmacology, University of Colorado Medical Center, Denver 80262.
Brain Res. 1987 Nov 3;425(1):146-58. doi: 10.1016/0006-8993(87)90493-8.
The central noradrenergic system has long been postulated to modulate learning and memory. A brain structure known to be important in these functions is the hippocampus. Since the hippocampus receives a noradrenergic projection from the locus coeruleus, knowledge of norepinephrine's actions in the hippocampus may help determine its role in learning and memory. In the present study, the effects of norepinephrine were examined on two hippocampal cell types: complex-spike and theta-neurons. In the hippocampus, there is good evidence that complex-spike cells are pyramidal neurons, while theta-neurons are interneurons. Extracellular action potentials from hippocampal neurons were recorded using multibarrel glass micropipettes. Drugs were locally applied using pressure micro-ejection. Norepinephrine inhibited the spontaneous firing of complex-spike cells, while theta-neurons were excited. The inhibitory response of complex-spike neurons was mediated by an alpha 1-receptor. However, selective agonists for the alpha 2- and beta-noradrenergic receptors excited the complex-spike cells. The noradrenergic-induced excitatory response of theta-neurons was also mediated by alpha 2- and beta-receptors. This study provides evidence that locally applied norepinephrine produces different responses on two types of hippocampal neurons. Furthermore, these differential responses arise primarily from the activation of distinct populations of noradrenergic receptors.
长期以来，人们一直假定中枢去甲肾上腺素能系统调节学习和记忆。海马体是已知在这些功能中起重要作用的脑结构。由于海马体接受来自蓝斑核的去甲肾上腺素能投射，了解去甲肾上腺素在海马体中的作用可能有助于确定其在学习和记忆中的作用。在本研究中，研究了去甲肾上腺素对两种海马体细胞类型的影响：复合棘波细胞和θ神经元。在海马体中，有充分证据表明复合棘波细胞是锥体神经元，而θ神经元是中间神经元。使用多管玻璃微电极记录海马神经元的细胞外动作电位。通过压力微喷射局部施加药物。去甲肾上腺素抑制复合棘波细胞的自发放电，而θ神经元则被兴奋。复合棘波神经元的抑制反应由α1受体介导。然而，α2和β去甲肾上腺素能受体的选择性激动剂兴奋复合棘波细胞。去甲肾上腺素诱导的θ神经元兴奋反应也由α2和β受体介导。本研究提供了证据，表明局部应用去甲肾上腺素对两种海马神经元产生不同反应。此外，这些差异反应主要源于不同群体的去甲肾上腺素能受体的激活。
