Garant D S, Xu S G, Sperber E F, Moshé S L
Department of Neurology, Albert Einstein College of Medicine, Bronx, NY 10461.
Epilepsy Res. 1993 Jul;15(3):185-92. doi: 10.1016/0920-1211(93)90055-c.
There is considerable evidence that thalamic nuclei are involved in the propagation and regulation of seizures. In the present study, we investigated the possible role in seizure mechanisms of GABAergic transmission in two thalamic nuclei, the posterior nucleus (PO) and the ventromedial nucleus (VM). Several GABAergic drugs were bilaterally microinfused into PO or VM of adult rats via chronically implanted cannulae, before testing the rats' susceptibility to seizures induced by flurothyl. In PO, infusions of the GABA elevating agent gamma-vinyl-GABA (20 micrograms) or of the GABAA receptor agonist muscimol (100 ng) suppressed both clonic and tonic seizures. Infusions into PO of the GABAA receptor antagonist bicuculline (100 ng) facilitated both these seizure types. Administration of the GABAB receptor agonist baclofen (200 ng) also suppressed clonic seizure susceptibility. Drug infusions into VM, however, did not significantly modify the susceptibility to seizures. These findings lead us to conclude that GABAergic transmission in the vicinity of the PO, but perhaps not in VM, affects flurothyl seizure susceptibility. We hypothesize that GABA synapses in PO may be part of a seizure propagation or control circuit including striatum, substantia nigra, and superior colliculus.
有大量证据表明丘脑核参与癫痫发作的传播和调节。在本研究中，我们调查了γ-氨基丁酸（GABA）能传递在两个丘脑核团，即后核（PO）和腹内侧核（VM）的癫痫发作机制中可能发挥的作用。在测试成年大鼠对氟烷诱发癫痫发作的易感性之前，通过长期植入的套管将几种GABA能药物双侧微量注入成年大鼠的PO或VM。在PO中，注入GABA增强剂γ-乙烯基-GABA（20微克）或GABAA受体激动剂蝇蕈醇（100纳克）可抑制阵挛性和强直性癫痫发作。向PO中注入GABAA受体拮抗剂荷包牡丹碱（100纳克）会促进这两种癫痫发作类型。给予GABAB受体激动剂巴氯芬（200纳克）也可抑制阵挛性癫痫发作的易感性。然而，向VM中注入药物并未显著改变癫痫发作的易感性。这些发现使我们得出结论，PO附近的GABA能传递，但可能不是VM中的，会影响氟烷癫痫发作的易感性。我们推测PO中的GABA突触可能是包括纹状体、黑质和上丘在内的癫痫发作传播或控制回路的一部分。
