The perivascular neuron type and the blood brain barrier

Abstract

The blood brain barrier (BBB) is involved in the transport mechanisms between the blood and the central nervous system (CNS). The BBB protect the CNS from injurious agents and modulates selectively the passage of pharmacological agents. The BBB is composed by a layer of endothelial cells, incompletely covered by pericytes surrounded by the extracellular matrix sheathed by endfeet astrocyte processes. The endfeet astrocytes are the mainly target of neu- ronal processes, the exact neuronal control on the BBB and the neuronal role in the neurovas- cular unit it is not completely know [1]. Studies revealed the presence of perivascular neuronal processes involved in the modulation of the BBB and few studies demonstrate in the CNS the presence of neuronal cell bodies in close relationship with the wall of vessels [2-6]. The goal of this study of chemical neuroanatomy is to investigate on the presence of monoaminergic and peptidergic perivascular neuronal elements in the human cerebellum.

The study was carried out on autoptic fragments of human cerebellum fixed in an aldehyde picric acid solution, embedded in paraffin, cut into 5μm sections and subjected to light micro- scopic immunohistochemistry with rabbit polyclonal antibodies for serotonin (5-HT), dopaminetransporter (DAT), dopamine type 2 receptor (DRD2), neurotensin (NT), neurotensin receptor type 1 (NTR1). The immunoreaction revealed in the molecular layer, in the three zones of the granular layer of the cerebellar cortex, in the dentate nucleus the presence of neuronal cell bod- ies and processes in close relationship with the wall of microvessels positive for 5-HT, DAT, DRD2, NT and NTR1.

Although, this data provides further insights, we suggest that the perivascular neuron may be considered a new specific neuron type of the neurovascular unit involved in the permeabil- ity control mechanisms of the BBB.