ALTERED DISTRIBUTION OF INHIBITORY SYNAPTIC TERMINALS IN REELER CEREBELLUM WITH SPECIAL REFERENCE TO MALPOSITION OF GABAERGIC NEURONS

In immunohistochemical reactions against glutamic acid decarboxylase ( GAD), gamma-aminobutyric acid (GABA) and glycine (Gly), neurons in the mouse cerebellum showed the following reactivities: (1) the dendrites and cell bodies of the Purkinje cells were only GAD-positive, but the ir axonal terminals were GABA- and GAD-positive; (2) in both stellate and basket cells, the cell bodies and terminals were GABA- and GAD-pos itive but Gly-negative; (3) the Golgi cells were GABA-, GAD- and Gly-p ositive; (4) the granule cells were negative with all antibodies. Base d on the populations of each type of neuron, identified by the propert ies mentioned above, the reeler cerebellum was divided into four regio ns, namely, 1) the molecular and Purkinje cell layers covering the sur face of the cerebellum, where the stellate and basket cells were prese nt as in normal mouse, (2) the granule cell layer, where the heterotop ic Purkinje and stellate-type cells (including both stellate and baske t cells) were present together with the granule and Golgi cells, 3) th e region beneath the granule cell layer where Purkinje cells were pres ent as clusters of several neurons, and in addition, the superficial z one of the central cell mass, where the stellate-type and Golgi cells were present among the Purkinje cells, and (4) the deep zone of the ce ntral cell mass, where the Golgi cells were exclusively present among the Purkinje cells. The heterologous synapses originating from inhibit ory interneurons were formed on the Purkinje cells closely related to the distribution of these neurons.