MOSSY FIBER SPROUTING - EVIDENCE AGAINST A FACILITATORY ROLE IN EPILEPTOGENESIS

SPROUTING of messy fibres from dentate granule cells occurs in several animal models of epilepsy and in epileptic humans. Messy fibre sprout ing might contribute to epileptogenesis but also could be a compensato ry, inhibitory response. We analysed messy fibre sprouting in the supr agranular zone of the dentate gyrus using Timm's histochemical method in genetically fast and slow kindling rats. Before the start of amygda la kindling, the slow rats showed higher Timm's staining scores than d id the fast kindlers. No increase of messy fibre density was observed when the animals were stimulated until either the fast or the slow rat s had reached the fully kindled state. Our data argue against the hypo thesis that messy fibre sprouting facilitates epileptogenesis.