Abstract
Neuronal stimulation was induced in rats by systemic administration of kainic acid (KA) to determine if such stimulation is responsible for changes in the expression patterns of cβKit and stem cell factor (SCF) in cerebellar synapses between inhibitory interneurons and Purkinje cells. Using immunocytochemistry and immunoblotting analyses, we demonstrate that cβKit receptor tyrosine kinase and its ligand SCF are present on the preβ and postsynaptic sides of inhibitory synapses on Purkinje cells. These proteins are upregulated during the first 48 hr after KA treatment, whereas their levels fall below that of the control by 1 week and remain as such thereafter. Expression of both cβKit and SCF are significantly elevated in the Purkinje cell layer 24 hr after KA administration, and the Purkinje cell layer exhibits a loss of calbindin Dβ28K immunoreactivity. Expression of cβKit in basket cell axon terminals is activated until 48 hr after KA treatment, suggesting the transient participation of cβKit receptor tyrosine kinase in the maintenance of these axonal terminals. Also during the first 48 hr after KA treatment, SCF levels increase in axonal processes of Purkinje cells, and these SCFβpositive axons correlate with cβKitβpositive pinceau structures. The increased expression of cβKit and SCF in response to KAβinduced neuronal stimulation may indicate that cβKit receptor tyrosine kinase and its ligand SCF function in the inhibitory synapse between cerebellar interneurons and Purkinje cells, and that this role is most pronounced during the first 48 hr after KA treatment. Β© 2002 WileyβLiss, Inc.