R De Hoz

The influence of ocular hypertension on retinal glial cells

We describe the effects of unilateral laser‐induced ocular hypertension (OHT) in the macroglia and microglia of eyes with OHT and their contralateral normotensive untreated eyes. In both eyes, the glia was reactive even though, contrary to OHT‐eyes, no retinal ganglion cell loss or abnormalities in the electroretinogram were found in contralateral eyes. With respect GFAP immunostaining there were differences between contralateral and OHT‐eye. Signs of microglial activation in contralateral and in OHT‐eyes affected all retinal layers, including: morphological changes, migration, increased cell number, upregulation of activation markers and quantification of the area occupied by Iba‐1+ cells and of the arbor area of Iba‐1+ cells. In microglia, MHC‐II upregulation in contralateral eyes was similar to that in OHT‐eyes. By contrast, MHC‐II upregulation in macroglia was observed mainly in astrocytes in contralateral eyes and in Müller cells in OHT‐eyes. Only eyes with OHT had rod‐like microglia and rounded Iba‐1+ CD68+ CD86+ cells. Glial differences between contralateral and OHT‐eyes could help us to understand glaucoma pathophysiology and develop new strategies for treatment.

The human choroid posseses substance P and calcitonine gene-related peptide intrinsic neurons

Purpose To determine the presence of substance P (SP)-and calcitonine gene-related peptide (CGRP) positive intrinsic choroidal neurons (ICNs) in human Methods Nineteen choroidal whole-mounts were processed for indirect immunofluorescence. Antibody to a component of the neuronal cytoskeleton, neurofilament 200 kDa (NF-200), was combined with antibodies to SP and to CGRP (neuropeptides proper to the sensory nervous system). Results The human choroid possesses numerous SP(+) and CGRP(+) ICNs. These neurons were observed in the suprachoroid, both in isolation and forming microganglia. For both types of ICNs studied, neurons were more numerous in the temporal than in the nasal regions. In both locations, SP(+) and CGRP(+) ICNs were more abundant in the central choroid (the choroid underneath the macular area of the retina), with cell density diminishing outwards to the choroidal periphery. There were no appreciable differences between the two populations of ICNs studied in terms of size, morphology or immunostaining characteristics. Conclusion The human choroid contains an abundant population of SP(+) and CGRP(+) ICNs. Given that peripheral sensory innervation could be involved in the regulation of both choroidal blood flow and vascular architecture, the SP(+) and CGRP(+) ICNs described for first time in the present work may be implicated in these mechanisms of vascular regulation

Estudio comparativo de la inervación coroidea en el hombre y en el conejo (oryctolagus cuniculus)

OBJECTIVE To analyze morphological differences between the choroidal innervation of the human and the rabbit, the latter being a species frequently used as an experimental model of human ocular diseases. METHODS Twelve human and 12 rabbit choroidal whole mounts were processed using an indirect immunohistochemical technique, peroxidase-anti-peroxidase and antibodies against 200 kD neurofilament. RESULTS Choroidal nerve fibers were perivascular and intervascular. Perivascular fibers surrounded all arteries forming a network that was more developed in the rabbit. In humans, intervascular fibers were mainly concentrated at the posterior pole where they formed a denser and more highly organized plexus than in the rabbit, which did not exhibit a preferential location for these fibers. Human choroidal ganglion cells were far more numerous than in the rabbit and were concentrated in a circumferential area corresponding to the entrance of the short posterior ciliary arteries of the submacular area. In the rabbit, these cells were restricted to the peripheral choroid. CONCLUSIONS Some differences were observed between human and rabbit choroidal innervation. The abundance of ganglion cells and their preferential distribution could be necessary to maintain a constant blood flow in the central area of the human choroid. The lack of organization of rabbit choroidal innervation at the posterior pole could be associated with an absence of the macula. These differences, along with peculiarities of retinal vascularization, should be taken into consideration when using the rabbit as an experimental model to study human eye diseases in which regulation of choroidal blood flow is involved.