COMPARTMENTALIZATION OF CALBINDIN AND PARVALBUMIN IN DIFFERENT PARTS OF RAT RUBROSPINAL NEURONS

The distribution of calbindin-immunoreactive neurons in the red nucleu s and the subcellular distribution of the calbindin and parvalbumin in tracer-identified rubrospinal neurons of the rat were studied. Only a fraction of the retrogradely labelled rubrospinal neurons was found t o contain calbindin. These neurons filled the caudal part of the red n ucleus and also appeared sporadically along the ventromedial border of the middle segment of the red nucleus. In addition to the somata, cal bindin was found in the dendritic arbors of tracer-identified rubrospi nal neurons, revealed by injecting the fluorescent dye Lucifer Yellow into their cell bodies. The axons of rubrospinal neurons located in th e caudal red nucleus were marked by performing anterograde tracing wit h fluorescent dextran tracer in freshly prepared brainstem slices. Par valbumin was found to locate in swellings along these tracer-identifie d axons as well as at their cut ends. The results indicate that calbin din and parvalbumin are segregated to the somadendritic and axonal com partments of the rat rubrospinal neurons, respectively. This anatomica l segregation suggests that they may have different Functions in neuro ns. Copyright (C) 1996 IBRO. Published by Elsevier Science Ltd.