[Neuroexcitotoxic action of db-cAMP: lesioning of neuronal cell bodies while sparing fibers of passage].

In our previous study, we have demonstrated that intra-amygdaloid injection of dibutyryl-cAMP causes neuronal damage in the injected AM and the CA 1-3 subfields of the ipsilateral hippocampus in addition to epileptic seizures. This result suggested that db-cAMP is a new neuroexcitotoxin. In this study, we examined comparative morphological effect on acetylcholinesterase (AChE) following intra-amygdaloid injection of db-cAMP or, kainate. In Expt. 1, twenty rats received 100 micrograms db-cAMP (N = 10), 0.5 micrograms kainate (N = 4), or saline as a vehicle (N = 6), through the implanted cannula under non-anesthesia. Either kainate or db-cAMP produced epileptic seizures, while saline induced no electroclinical ictal response. Following db-cAMP or kainate injection, neuronal loss was observed in the injected AM, but AChE positive fibers were intact. In the hippocampus ipsilateral to the injected AM, the loss of pyramidal cells was also noted in accordance with the severity of seizure intensity. In the piriform cortex ipsilateral to the injected AM, the loss of AChE-positive fibers were seen, but sparing neuronal cell bodies. In Expt. 2, nineteen rats were injected with 100 micrograms db-cAMP (N = 7), 0.5 micrograms kainate (N = 7), or saline as a vehicle (N = 5) under pentobarbital anesthesia. Kainate or db-cAMP produced few sporadic spikes.(ABSTRACT TRUNCATED AT 250 WORDS)