Degeneration of interneurons in the lateral geniculate nucleus after 5,6-dihydroxytryptamine treatment.

Intraventricular administration of the cytotoxic compound 5,6-dihydroxytryptamine produces extensive damage in a small population of neurons in the lateral geniculate nucleus of the cat. The observed changes are characterized by osmiophilic deposits in the cytoplasm and an overall increase in the electrodensity of the matrix. No alterations in the relay cells nor in synaptic endings were observed. The cells affected by 5,6-dihydroxytryptamine, most probably tryptaminergic in nature, belong to the class of interneurons and may correspond to local inhibitory cells described in neurophysiological studies.