Yanovsky Y, Sergeeva O A, Freund T F, Haas H L
Institute of Physiology II, Heinrich-Heine-Univerisity, Düsseldorf, Germany.
Neuroscience. 1997 Mar;77(1):87-96. doi: 10.1016/s0306-4522(96)00461-7.
The consequences of activation or inactivation of interneurons at the CA1 stratum oriens/ alveus border for signal transmission at the apical dendritic region of pyramidal cells were investigated in slices from mice submerged in a perfusion chamber. A characteristic subpopulation of interneurons with a horizontal dendritic tree in this region, which sends a GABAergic projection to the apical dendrites of CA1 pyramidal cells is strongly excited by metabotropic glutamate receptor activation and receives GABAergic input from vasoactive intestinal polypeptide-containing interneurons. Pressure ejection of glutamate or the metabotropic agonist 1s,3r-aminocyclopentane dicarboxylic acid from micropipettes onto the stratum oriens/alveus border caused a long lasting (more than 90 min) decrease of field-excitatory postsynaptic potentials in the strata radiatum and lacunosum-moleculare. The GABAB antagonist CGP 35348 (100 microM in the perfusion fluid) partially and reversibly blocked this effect. Vasoactive intestinal polypeptide- (0.1 microM in the bath) excited neurons with response and firing properties characteristic for interneurons at the oriens/alveus border. Local pressure application of vasoactive intestinal polypeptide (10 microM) to the alveus region led, after a brief (2 min) and small (10%) increase, to a longer lasting (30-50 min) decrease (by 20-30%) in the slope of the field-excitatory postsynaptic potential in strata radiatum and lacunosum-moleculare. This action was completely blocked by bath application of CGP 35348. Local application of tetrodotoxin in the stratum oriens/alveus region markedly increased the slope of evoked dendritic excitatory postsynaptic potentials, and caused multiple firing of pyramidal cells. Thus, stratum oriens/alveus interneurons have a profound inhibitory effect on signal transmission in the apical dendritic area of CA1, which is, at least in part, mediated by GABAB receptors. It appears that the GABAB receptor-mediated effect in stratum lacunosum-moleculare is produced by vasoactive intestinal polypeptide-sensitive interneurons.
在浸没于灌注室的小鼠脑片中，研究了CA1海马下托/肺泡边界处中间神经元的激活或失活对锥体细胞顶端树突区域信号传递的影响。该区域有一特征性中间神经元亚群，其树突呈水平状，向CA1锥体细胞的顶端树突发出GABA能投射，该亚群被代谢型谷氨酸受体激活强烈兴奋，并接受来自含血管活性肠肽中间神经元的GABA能输入。用微量移液器将谷氨酸或代谢型激动剂1s,3r -氨基环戊烷二羧酸压力喷射到海马下托/肺泡边界，可导致辐射层和分子层的场兴奋性突触后电位持续长时间（超过90分钟）降低。GABAB拮抗剂CGP 35348（灌注液中浓度为100微摩尔）可部分且可逆地阻断这种效应。血管活性肠肽（浴液中浓度为0.1微摩尔）可兴奋具有海马下托/肺泡边界处中间神经元特征性反应和放电特性的神经元。将血管活性肠肽（10微摩尔）局部压力施加于肺泡区域，在短暂（2分钟）且小幅（10%）增加后，可导致辐射层和分子层中场兴奋性突触后电位斜率出现更持久（30 - 50分钟）的降低（降低20 - 30%）。这种作用可被浴液中加入CGP 35348完全阻断。在海马下托/肺泡区域局部应用河豚毒素可显著增加诱发的树突兴奋性突触后电位斜率，并导致锥体细胞多次放电。因此，海马下托/肺泡中间神经元对CA1顶端树突区域的信号传递具有深远的抑制作用，这至少部分是由GABAB受体介导的。似乎分子层中GABAB受体介导的效应是由对血管活性肠肽敏感的中间神经元产生的。
