SYNAPTIC DEGENERATION AND REMODELING AFTER FAST KINDLING OF THE OLFACTORY-BULB

Kindling of the olfactory bulb using a novel fast protocol (within 24 h) was studied in rats. In target brain regions, the effects of kindli ng were measured on the concentration of glial fibrillary acidic prote in (GFAP) by dot-blot and on the concentrations of neural cell adhesio n molecule (NCAM) and the 25 kDa synaptosomal associated protein of th e D3 immunoprecipitate (D3(SNAP-25)) by crossed immunoelectrophoresis. Bilateral increases in the levels of GFAP, indicating activation of a strocytes, were detected in primary olfactory cortical projection area s, including the piriform cortex, and also in the basolateral amygdala and dentate gyrus, suggesting that these regions may be functionally altered during the kindling process. In the piriform cortex and dentat e gyrus increased NCAM/D3(SNAP-25) ratios found ipsilaterally at seven days after kindling probably reflect an elevated rate of synaptic rem odelling. At this time, however, an overall pattern of ipsilateral dec reases in the synaptic marker proteins NCAM and D3(SNAP-25) indicated that this remodelling occurred on a background of synaptic degeneratio n. These results confirm previous studies showing that kindling is ass ociated with synaptic remodelling and neuronal degeneration in the hip pocampal formation and extends the area of plasticity to include the p iriform cortex which is believed to be central to the kindling process .