Neuroactive amino acids in the area postrema. An immunocytochemical investigation in rat with some observations in cat and monkey (Macaca fascicularis).

The localization of five neuroactive amino acids in the rat area postrema was studied by postembedding immunocytochemistry in semithin and ultrathin sections. Antisera to GABA, glycine, glutamate and aspartate produced labelling of cells that were identified as neurons in the electron microscope. GABA-like and glycine-like immunoreactivities occurred in about 20% and 60% of the neurons, respectively, and a minor proportion of the cells displayed both immunoreactivities, suggesting a cellular colocalization of GABA and glycine.

Metabolic compartmentation of glutamate and glutamine: morphological evidence obtained by quantitative immunocytochemistry in rat cerebellum.

An electron microscopic, double-labelling immunocytochemical procedure was used to assess the level of fixed glutamate and glutamine in different cell profiles in ultrathin sections of rat cerebellar cortex. The procedure was based on sequential immunolabelling with two rabbit antisera, using gold particles of different sizes as markers and formaldehyde vapour as a means to avoid interference between the two incubations. Model sections containing a series of known concentrations of the respective amino acids (aldehyde--fixed to rat brain protein) were incubated together with the tissue material.

An electron microscopic, immunogold analysis of glutamate and glutamine in terminals of rat spinocerebellar fibers.

A semiquantitative, electron microscopic immunocytochemical procedure based on the use of colloidal gold particles as markers was employed to analyze the subcellular distribution of glutamate and glutamine, a major glutamate precursor, in a subpopulation of spinocerebellar mossy fiber terminals. These terminals were identified by anterograde transport of a horseradish peroxidase-wheat germ agglutinin conjugate, injected in the thoracic spinal cord. Gold particles signalling glutamate-like immunoreactivity were enriched over clusters of synaptic vesicles relative to organelle-free cytoplasmic matrix, and there was a strong positive correlation between gold particle and synaptic vesicle densities (correlation coefficient 0.

Afferent connections to the abducent nucleus in the cat.

The afferent connections to the abducent nucleus in the cat were studied by means of retrograde transport of WGA-HRP after implantations of the tracer in crystalline form. Retrogradely labelled cells were found bilaterally in the medial and descending vestibular nuclei, mainly in their ventral and medial portions, in the rostral part of the ipsilateral gigantocellular reticular nucleus, in the medial part of the contralateral caudal pontine reticular nucleus and bilaterally in the oculomotor nucleus, mainly in its dorsolateral division. Some labelled cells were also found bilaterally in the mesencephalic reticular formation, the periaqueductal grey and the nucleus of the trapezoid body.

The olivocerebellar projection to lobules I and II.

The olivocerebellar projection to lobules I and II was studied by means of retrograde transport from implants of the crystalline WGA-HRP complex. Retrogradely labelled neurons were found in the medial and dorsal accessory olives. Judged from the distribution of labelled cells, we conclude that parasagittally the olivocerebellar terminal zones A and B (i.