Localization of adrenergic neurons in human and cat meninges

In human and cat meninges the presence of adrenergic neurons was studied. The human meninges were obtained from 10 adult individuals 1-3 hours postmortem and the 6 cats meninges, one pretreated 7 days before the experiment with 5 mg of 6-OHDopamine intracisternally. In human and cat meninges, adrenergic granulations, located in fibers that form a reticulum around the arterial, arteriolar and small vein vessels were observed. These adrenergic fibers appeared forming a very dense reticulum in the adventitia of the small calibre arteries and in arterioles. In addition, in some vascular sectors, a considerable number of triangular or elongated cells, whose cytoplasm is full of adrenergic granulations can be observed isolated or in close vicinity to the adrenergic reticulum. In the meninges of the cat treated with 6-OH-Dopamine there was no adrenergic granulation. Furthermore, the radioenzymatic determination of noradrenaline content in 3 human meninges shows the existence of this amine. The number of cellular elements with adrenergic granulations is notable and permits one to suspect that this cellular system can play an important role in the autoregulation on the cerebral circulation together with the perivascular adrenergic reticulum.