Ultrastructural and metabolic changes in the neuropeptide Y-containing striatal neuronal network after thermocoagulatory cortical lesion in adult rat.

This study examined the effects of unilateral thermocoagulatory cortical lesion on the pattern of neuropeptide Y immunostaining in the rat ipsilateral striatum at 4 and 21 days post-lesion. Light microscopic analysis showed a significant increase in the number of neuropeptide Y-positive neurons vs. control at both time points; paradoxically, the intraneuronal level of labelling significantly decreased at 4 days post-lesion but increased at 21 days post-lesion.

Relationships between striatin-containing neurons and cortical or thalamic afferent fibres in the rat striatum. An ultrastructural study by dual labelling.

Striatin, a recently isolated rat brain calmodulin-binding protein belonging to the WD-repeat protein family, is thought to be part of a calcium signal transduction pathway presumably specific to excitatory synapses, at least in the striatum. This study was aimed to specify the cellular and subcellular localization of striatin, and to determine the possible synaptic relationships between the two main excitatory afferent pathways, arising from the cerebral cortex and the thalamus, and the striatin-containing elements, in the rat striatum. Anterograde tract-tracing by means of biotinylated dextran amine injection in the frontoparietal cerebral cortex or the parafascicular nucleus of the thalamus was combined with immunogold detection of striatin.

Striatal neuropeptide Y neurones are not a target for thalamic afferent fibres.

This study examined at the ultrastructural level the putative relationships between afferent fibres coming from the parafascicular nucleus of the thalamus and neuropeptide Y (NPY)-containing neurones in the rat striatum. Experiments used a combination of anterograde transport of the biotin dextran amine to label the thalamo-striatal pathway and immunogold labelling to reveal the NPY-containing neurones at the electron microscopic level. Examination of sections from three animals failed to demonstrate thalamic terminals in synaptic contact with NPY-immunoreactive dendrites or cell bodies, although both types of labelled elements were frequently involved in synaptic complex with unlabelled profiles.

Emergence of a synaptic neuronal network within primary striatal cultures seeded in serum-free medium.

In order to investigate the basic cellular mechanisms involved in neuronal interactions within the striatum, we prepared a primary striatal cell culture from rat fetal brain in chemically defined medium. Using morphological and whole-cell recording methods, we observed that an intensive neuritic elongation with a progressive build up of a sodium-dependent electrogenesis occurred during the first week of culture. Morphologically mature synapses began to develop after 10 days in vitro.

Ultrastructural analysis of graft-to-host connections, with special reference to dopamine-neuropeptide Y interactions in the rat striatum, after transplantation of fetal mesencephalon cells.

In a previous study we demonstrated that grafted dopamine (DA) neurons are able to induce an early and widespread normalization of DA-neuropeptide Y (NPY) interactions in the host striatum previously deprived of its DA input. Since similar recoveries were found to occur in striatal areas densely or poorly reinnervated by the graft, the question was raised as to what mechanisms (synaptic or volumic release) were involved in these functional effects. Ultrastructural analysis of graft-to-host relationships was performed using single--and double--immunolabelling techniques to detect neurons containing tyrosine hydroxylase (TH) and NPY, with a view to analysing the early establishment of synaptic connectivity in various areas of the host striatum.