Deep prepyriform cortex kindling and its relation to amygdala kindling in the rat.
Kindling of the deep prepyriform cortex (DPC), a recently identified sensitive site to chemoconvulsants, was compared to kindling of the amygdala in rats. Although the two kindled sites were very similar in their initial responses, electroencephalographic changes during kindling stimulation, kindling seizure development, and growth of afterdischarge, they differed in that the deep prepyriform cortex showed a significantly lower final threshold, a significantly higher frequency of afterdischarge and a significantly shorter latency to bilateral forelimb clonus than the amygdala. Significant bidirectional transfer was found during secondary kindling of either of the two sites, suggesting a close interrelation between them. Rhythmic synchronous discharge was directly induced in the deep prepyriform cortex by ipsilateral amygdala stimulation, but not in the amygdala by ipsilateral cortical stimulation. Local application of both muscimol (0.45 nM) and 2-amino-5-phosphonovaleric acid (25 nM) into the cortical site reduced the afterdischarge duration of amygdala-kindled seizures by approximately 20% without changing the type or duration of the motor seizure. We suggest that the deep prepyriform cortex is "downstream" from the amygdala in the preferential routes of afterdischarge propagation, and that, although the deep prepyriform cortical neurocircuits of GABA and excitatory amino acids may be involved in the maintenance of amygdala-kindled, self-sustained afterdischarge, they are not essential in the expression of amygdala-kindled motor convulsions.
D015763:2-Amino-5-phosphonovalerate; D000200:Action Potentials / Q000187:drug effects; D000679:Amygdala / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000502:physiology; D002540:Cerebral Cortex / Q000187:drug effects / Q000502:physiology*; D004569:Electroencephalography; D007696:Kindling, Neurologic / Q000187:drug effects; D008297:Male; D009118:Muscimol / Q000494:pharmacology; D016202:N-Methylaspartate; D051381:Rats; D014633:Valine / Q000031:analogs & derivatives / Q000494:pharmacology; D005680:gamma-Aminobutyric Acid / Q000502:physiology
D009118:Muscimol; D001224:Aspartic Acid; D005680:gamma-Aminobutyric Acid; D016202:N-Methylaspartate; D015763:2-Amino-5-phosphonovalerate; D014633:Valine