Lateral geniculate nucleus: Histological and cytochemical changes following afferent denervation and visual deprivation

Abstract

The histology and cytochemistry of neurons in the lateral geniculate nucleus of kittens was compared following unilateral afferent denervation (enucleation) and unilateral visual deprivation (lid closure). Afferent denervation at 5 weeks of age resulted in a rapid and severe transneuronal atrophy of the neurons in the appropriate geniculate laminae. There was a concomitant decrease in the activity of TPN-diaphorase, DPN-diaphorase, cholinesterase and the dehydrogenases of 6-phosphogluconate, succinate and lactate-DPN in the atrophied laminae as compared with the adjacent normal laminae. Although visual deprivation at 5 weeks of age resulted in a decrease in size of the geniculate neurons in those laminae receiving input from the closed eye, the smaller neuron had an appearance which was normal for neurons from a 5-week old kitten, i.e., when the eye was closed. In addition, cytochemical studies indicated no difference in enzyme activity between the smaller neurons and adjacent neurons of normal size. Since the normal geniculate neuron increased in cross-sectional area about 50–60% from birth to 15 weeks of age, this suggests that visual deprivation arrests normal growth of the neuron without significantly altering its metabolic activity.