PATTERNS OF TRANSMITTER LABELING AND CONNECTIVITY OF THE CATS NUCLEUSOF DARKSCHEWITSCH - A WHEAT-GERM AGGLUTININ-HORSERADISH PEROXIDASE AND IMMUNOCYTOCHEMICAL STUDY AT LIGHT AND ELECTRON-MICROSCOPIC LEVELS

Immunocytochemical studies using antibodies raised against a number of probable synaptic transmitters of the mesodiencephalic area, and fibr e-tracing studies using wheat germ agglutinin-horseradish peroxidase ( WGA-HRP), have been performed in adult cats. Glutamate and aspartate i mmunoreactivity produced a strong labelling of many cell bodies and te rminals in the nucleus of Darkschewitsch (ND). gamma-Aminobutyrate (GA BA) immunoreactivity in the ND appeared as a moderate label in some sm all neurones, and as a strong label in a few glial-like cells, in addi tion to being present in high levels to produce strong labelling in ma ny GABA-immunopositive terminals that possessed pleomorphic vesicles. Some choline acetyltransferase-positive terminals and dendrites and a few substance P-positive fine fibres possessing varicosities also were observed in the ND. Following WGA-HRP injection in the ND, dense term inal labelling was seen ipsilaterally in the rostral half of the media l accessory olive, suggesting that there may be a certain degree of me diolateral and dorsoventral topographic correspondance within the ND-o live projection. In the same cases, many cell bodies containing HRP re action product also were found 1) ipsilaterally in the motor cortex, a nterior pretectal nucleus, and a restricted area of the caudal part of the substantia nigra pars reticulata; 2) contralaterally in the anter ior and posterior interposed cerebellar nuclei as well as in a portion of the lateral cerebellar nucleus; and 3) bilaterally in the zona inc erta, the posterior pretectal nucleus, the pedunculopontine tegmental nuclei, the spinal trigeminal nucleus, the dorsal column nuclei, and t he spinal cord. Details of the interrelationships and functional consi derations amongst the ND, adjacent nuclei, and longitudinal zones of t he cerebellum are discussed. (C) 1995 Wiley-Liss, Inc.