Rajasekaran Karthik, Kapur Jaideep, Bertram Edward H
Department of Neurology, University of Virginia, Health Sciences Center, Charlottesville, VA 22908, USA.
J Neurophysiol. 2007 Nov;98(5):2501-8. doi: 10.1152/jn.00139.2007. Epub 2007 Sep 12.
There is evidence that the dorsal midline thalamus is involved in the seizures of limbic epilepsy. However, little is known about the inhibitory synaptic function in this region. In the present study, inhibitory postsynaptic currents (IPSCs) mediated by GABA(A) receptors were recorded from the mediodorsal (MD) and paraventricular (PV) nuclei from control and epileptic animals. In the MD, the spontaneous (s)IPSCs for epileptic animals had a lower frequency, prolonged rise time, prolonged decay, but unaltered net charge transfer compared with controls. The miniature (m)IPSC parameters were unaltered in the epileptic animals. In contrast, in the PV, both sIPSCs and mIPSCs in the epileptic animals were more frequent with larger amplitudes and there was an increase in the net charge transfer compared with controls. The rise times of the sIPSCs of the PV neurons were significantly prolonged, whereas the weighted decay time of the mIPSC was significantly shortened in epileptic animals. These findings suggest that the changes associated with inhibitory synaptic transmission in limbic epilepsy are not uniform across regions in the thalamus that are part of the seizure circuit.
有证据表明，丘脑背侧中线参与边缘性癫痫发作。然而，关于该区域的抑制性突触功能却知之甚少。在本研究中，从对照动物和癫痫动物的背内侧（MD）核和室旁（PV）核记录了由GABA(A)受体介导的抑制性突触后电流（IPSC）。在MD核中，与对照相比，癫痫动物的自发性（s）IPSC频率较低、上升时间延长、衰减延长，但净电荷转移未改变。癫痫动物的微小（m）IPSC参数未改变。相比之下，在PV核中，癫痫动物的sIPSC和mIPSC频率更高、幅度更大，与对照相比净电荷转移增加。癫痫动物PV神经元的sIPSC上升时间显著延长，而mIPSC的加权衰减时间显著缩短。这些发现表明，边缘性癫痫中与抑制性突触传递相关的变化在作为癫痫发作环路一部分的丘脑各区域并不一致。
