Original Contribution AN ANTEROGRADE TRACER STUDY OF A DIRECT TRIGEMINO- NIGRAL PROJECTION IN THE RAT BRAIN USING BIOTINYLATED

The mesencephalic trigeminal nucleus (MTN) is a unique structure in the central nervous system (CNS). It is composed of primary sensory neurons, which are mainly typical of dorsal root ganglia. The afferent projections of the MTN neurons are relatively well studied, although the data about the efferents are still controversial. The goal of the present study was to verify the MTN projections to the substantia nigra (SN) in the rat brain via anterograde tracing using the marker BDA. Anterograde tracing experiments showed the presence of a direct projection arising from the MTN neurons, located in the caudal portion of the nucleus, to the SN. Single ipsilateral projection fibres were found in the SN pars compacta dorsal part, and then penetrated its pars reticulata. It can be inferred from the study results that the MTN is bi-directionally linked with the SN, which probably in a way determines the mandibular motor activity and oro-facial dyskinesias