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 their axonal terminals were GABA- and GAD-positive; (2) in both stellate and basket cells, the cell bodies and terminals were GABA- and GAD-positive but Gly-negative; (3) the Golgi cells were GABA-, GAD- and Gly-positive; (4) the granule cells were negative with all antibodies. Based on the populations of each type of neuron, identified by the properties mentioned above, the reeler cerebellum was divided into four regions, namely, (1) the molecular and Purkinje cell layers covering the surface of the cerebellum, where the stellate and basket cells were present as in normal mouse, (2) the granule cell layer, where the heterotopic Purkinje and stellate-type cells (including both stellate and basket cells) were present together with the granule and Golgi cells, (3) the region beneath the granule cell layer where Purkinje cells were present as clusters of several neurons, and in addition, the superficial zone 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 central cell mass, where the Golgi cells were exclusively present among the Purkinje cells. The heterologous synapses originating from inhibitory interneurons were formed on the Purkinje cells closely related to the distribution of these neurons.