[Ultrastructure of the frontal cortex in response to leponex]

Following a single or 3-week administration of leponex (clozapine) (in a dose of 10 mg/kg) to rats their brain prefrontal cortices were studied by electron microscopy. Layers III and IV showed hyperchromic pyramidal neurons in different phases of hyperchromia and activation of glial cells. Membranous structures were disclosed in cell somata of individual neurons, dendrites and astrocyte processes. Leponex increased the size of mitochondria and the osmiophilia of their matrix and caused swelling of the cristae in the dendrites near the zone of synaptic contacts. The number of synaptic vesicles, the thickness of the postsynaptic membrane and the size of mitochondria were increased in individual axo-spie and axodendritic synapses. These changes may be secondary to the leponex-induced blockade of postsynaptic receptors.