N-Methyl-d-Aspartate Injection Into the Massa Intermedia Facilitates Development of Limbic Kindling in Rats

Summary The effect on limbic kindling of N-methyl-D- aspartate (NMDA) injection into the midline thalamus of rats was investigated. Repeated injection of 25 nmol/0.5 pl NMDA (experimental group) into the massa intermedia (MI), particularly into the reuniens nucleus, caused tonic and/or clonic generalized convulsion associated with temporal limbic EEG seizure discharge. This did not occur after injection of phosphate-buffered saline (PBS, control group). When the animals were subjected to sub-sequent kindling at either the hippocampus (HP) or the amygdala (AM), only the experimental group showed a significant facilitation of kindling rate. The results suggest that an NMDA receptor in the reuniens nucleus participates in modulation of temporal limbic excitability and seizure development.