Homovanillic acid in different regions of the human brain: attempt at localizing central dopamine fibres

Abstract

The distribution of HVA in various regions of the grey and white matter of the human brain has been examined. HVA was found to occur in appreciable amounts in the following regions: (a) Grey matter - putamen, caudate nucleus, globus pallidus, substantia nigra, red nucleus, subthalamic nucleus, thalamus, lamina quadrigemina; (b) White matter - all components of the internal capsule (anterior limb, genu, posterior limb, supralenticular part), pes pedunculi, white matter of the cortex. From the characteristics distribution pattern of HVA within the internal capsule (lowest concentrations in the caudal parts of the posterior limb, highest values in the anterior limb), and from the results obtained in parkinsonian brains, it is concluded that dopamine-containing fibres are present in the internal capsule running in rostral direction to reach the striatum. These dopamine fibres are assumed to originate in the substantia nigra. Contrary to this, the biochemical source and significance of the HVA found in other brain regions than the striatum, the substantia nigra and the internal capsule ( i.e. globus pallidus, red and subthalamic nuclei, thalamus, lamina quadrigemina, and possibly also pes pedunculi and white matter of the cortex) remain unexplained as yet.