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. These results strongly suggest that striatal NPY interneurones are not under the direct influence of the main component of the thalamo-striatal system.