Large diameter primary afferent input is required for expression of the Cat-301 proteoglycan on the surface of motor neurons

Monoclonal antibody Cat-301 identifies Y-cells in the dorsal lateral geniculate nucleus of the cat

In mammalian visual pathways, information is carried in parallel channels from the retina through the visual thalamus to visual cortex. The cat's visual pathway comprises at least three major channels that begin with the X, Y, and W ganglion cells in the retina. In the dorsal lateral geniculate nucleus (LGN) of the thalamus, neurons in the X, Y, and W channels receive input from their retinal counterparts and can be discriminated from one another on the basis of their anatomical and physiological properties. The search for molecular properties that might correlate with anatomically or physiologically defined classes of neuron has been a major area of research in recent years. Monoclonal antibody Cat-301 recognizes a neuronal surface-associated proteoglycan in many areas of the mammalian central nervous system. In the cat LGN Cat-301 immunoreactivity is restricted to a subset of neurons. We show here that the distribution, size, morphology, and cortical projection pattern of Cat-301-positive LGN neurons match those previously described for Y-cells. Taken together with our previous studies of the development of immunoreactivity and the sensitivity of Cat-301 staining to visual deprivation, these studies suggest that Cat-301 specifically recognizes Y-cells in the cat LGN. These results indicate that neurons within a physiologically and anatomically defined cell class share a molecular property. They further suggest that differences in molecular traits may reflect, and possibly subserve, differences in anatomical and physiological characteristics.

Induction of a neuronal proteoglycan by the NMDA receptor in the developing spinal cord

Activation of the N-methyl-D-aspartate (NMDA) subclass of glutamate receptors is a critical step in the selection of appropriate synaptic connections in the developing visual systems of cat and frog. Activity-dependent development of mammalian motor neurons was shown to be similarly mediated by activation of the NMDA receptor. The expression of the Cat-301 proteoglycan on motor neurons was developmentally regulated and could be specifically inhibited by blockade of the NMDA receptor at the spinal segmental level. In the adult, Cat-301 immunoreactivity on motor neurons was not diminished by NMDA receptor blockade. The NMDA receptor may regulate the expression of a class of neuronal proteins (of which Cat-301 is one example) that underlie the morphological and physiological features of activity-dependent development.