Eur J Anat, 3 (2): 87-92 (1999)

Forebrain and brainstem perivascular neurons projecting to the thalamus (An anatomical explanation of the pathophysiology of fatal familial insomnia)

Velayos J.L., Alfageme F.

Dpto. de Morfologia, Facultad de Medicina, Universidad Autonoma de Madrid, C/ Arzobispo Morcillo s/n, 28029 Madrid, Spain

ABSTRACT Afferent projections to the mediodorsal and anterior nuclei of the cat thalamus were studied by means of stereotaxic injections of neuronal tracers (horseradish peroxidase, HRP, and fluorochromes). The co-location of HRP and NADPH-diaphorase in neuronal bodies sending projections to the mediodorsal and anterior nuclei of the thalamus was studied. The differences in connectivity between the mediodorsal nucleus and the anterior nuclei of the thalamus are discussed. The possibility that prion agents responsible for fatal familial insomnia could spread from the mediodorsal and anterior nuclei of the thalamus (mainly the intermediate band of the mediodorsal nucleus and the anteroventral nucleus of the anterior complex) through a retrograde pathway is discussed. Retrograde-labelled neuronal cell bodies around vessels in the basal prosencephalon and brainstem were mainly observed after tracer injections in the intermediate band of the mediodorsal nucleus and in the anteroventral nucleus of the anterior complex of the thalamus. This finding, along with the observation of the colocation of HRP and NADPH-diaphorase in this type of neurons in the cases of mediodorsal and anterior nuclei tracer injections leads us to propose a possible pathophysiological involvement of nitrergic systems in fatal familial insomnia.

Keywords: horseradish peroxidase, reduced nicotinamide adenine dinucleotide phosphate, animal experiment, animal model, animal tissue, article, brain stem, cat, controlled study, familial disease, forebrain, insomnia, neuroanatomy, nonhuman, pathological anatomy, pathophysiology, perikaryon, thalamus