Neuropeptide Y-evoked proliferation of retinal glial (Müller) cells (original) (raw)
Related papers
Glia, 2002
The Y1 receptor of neuropeptide Y (NPY) has been demonstrated in glial cells of astrocytic lineage in vitro. We have studied the immunohistochemical expression of Y1 receptors in the glia of the diseased human retina, in tissue samples obtained after surgery for proliferative vitreoretinopathy. In this condition, glia and other cell types migrate and form epi-or subretinal membranes. Both diseased retinas (n ϭ 8) and PVR membranes (n ϭ 43) contained numerous Y1-immunoreactive cells. In the diseased retina, the Y1 antiserum labeled cells with the morphological radial pattern characteristic of Mü ller cells, whereas in the membranes, label appeared in a large population of elongate cells, measuring up to 250 m. In both retina and membranes, double labeling demonstrated that the vast majority of Y1-immunoreactive cells were also labeled by a glial fibrillary acidic protein (GFAP) antibody, indicating their glial origin. Retinal regions devoid of GFAP immunoreactivity also lacked the Y1 label. None of these markers was detected in Mü ller cells of normal retina. Y1 immunoreactivity did not co-localize with smooth muscle actin immunoreactivity, a marker of myofibroblasts. Expression of Y1 receptors would characterize reactive and proliferating glial cells of the diseased retina and could perhaps be involved in the proliferation of injured glial cells causing regrowth of PVR membranes and the consequent secondary retinal detachments. GLIA 39: 320 -324, 2002.
Investigative Ophthalmology & Visual Science, 2005
To determine whether activation of receptor tyrosine kinases enhances the responsiveness of purinergic P2Y receptors in Müller glial cells, known to induce Müller cell proliferation. METHODS. The P2Y receptors of primary cultured Müller cells of the guinea pig were desensitized by short (30 seconds to 10 minutes)-and long (24 or 48 hours)-term application of adenosine 5Ј-triphosphate (ATP). Recordings of ATP-evoked intracellular calcium responses showed whether short-term application of different growth factors evoke a resensitization of the receptors. Coapplication of pharmacologic inhibitors showed whether activation of protein kinases is involved in receptor resensitization. RESULTS. Both short-and long-term incubation with ATP induced a significant P2Y receptor desensitization, which was indicated by a strongly reduced intracellular calcium mobilization and which lasted for at least 48 hours. However, the receptors were significantly resensitized after short-term application of platelet-derived, epidermal, or nerve growth factors. The growth factor-mediated resensitization was dependent on an intact cytoskeleton and on the activation of protein phosphatases and of the phosphatidylinositol-3 kinase (PI3K), but was independent of the activation of protein kinase C, src kinases, or extracellular signal-regulated kinases. CONCLUSIONS. The results show that activation of receptor tyrosine kinases causes, via activation of PI3K and protein phosphatases, a resensitization of P2Y receptors formerly desensitized by agonist application. The growth factor-mediated resensitization may underlie the previously observed enhanced responsiveness of P2Y receptors in retinal glial cells in experimental retinal detachment and proliferative vitreoretinopathy and may contribute to the induction of reactive gliosis and Müller cell proliferation. (Invest Ophthalmol Vis Sci. 2005;46: 1525-1532
Neurochemistry international, 2007
NPY is present in the retina of different species but its role is not elucidated yet. In this work, using different rat retina in vitro models (whole retina, retinal cells in culture, microglial cell cultures, rat Müller cell line and retina endothelial cell line), we demonstrated that NPY staining is present in the retina in different cell types: neurons, macroglial, microglial and endothelial cells. Retinal cells in culture express NPY Y 1 , Y 2 , Y 4 and Y 5 receptors. Retina endothelial cells express all NPY receptors except NPY Y 5 receptor. Moreover, NPY is released from retinal cells in culture upon depolarization. In this study we showed for the first time that NPY is present in rat retina microglial cells and also in rat Müller cells. These in vitro models may open new perspectives to study the physiology and the potential pathophysiological role of NPY in the retina. #
Neuropeptide Y suppresses the neurogenic inflammatory response in the rabbit eye; mode of action
Regulatory Peptides, 1993
Ocular injury in the rabbit causes miosis and breakdown of the blood aqueous barrier (aqueous flare response, AFR), reflecting a sensory nerve-mediated inflammatory response, elicited by the release of tachykinins and calcitonin gene-related peptide (CGRP) from C-fibers. Neuropeptide Y (NPY) occurs in sympathetic fibers in the eye. The study was designed to examine whether NPY and related peptides interfere with the inflammatory response to ocular injury in the rabbit in vivo. The isolated rabbit iris was studied with respect to NPY binding sites and second messenger coupling. The AFR and the miotic response to a standardized injury (infrared irradiation (IR) of the iris) were suppressed dose-dependently by NPY (0.01-1.0 nmol) injected intravitreally 30 min prior the trauma. The treated eye was compared with the contralateral eye, which received 0.9?0 saline and IR. The Y1 receptor agonist [Pro34]NpY, the Y2 receptor agonist NPY 13-36 and the structurally related peptide YY (1 nmol each) suppressed the AFR in response to IR. Injection of either NPY or the Y1 and Y2 receptor agonists (0.3 nmol each) suppressed the AFR evoked by exogenously applied CGRP (0.15 nmol). Saturation studies with x2SI-NPY revealed both high and 'moderate' affinity binding sites in the iris. The Bma x values were 26 and 321 fmol/mg protein, respectively. NPY suppressed the forskolin-stimulated adenylate cyclase activity (ICs0 value 19 nM). NPY did not affect basal or noradrenaline-induced accumulation ofinositol phosphates in the iris. In conclusion, the rabbit iris seems to be rich in NPY receptors linked to inhibition of adenylate cyclase activity. NPY and related peptides effectively suppress the sensory nerve-mediated inflammatory response in the rabbit eye. Conceivably, NPY acts to suppress the impulse flow in C-fibers and, in addition, counteracts the vasodilation and the leakage of proteins in response to CGRP by acting as a potent vasoconstrictor. Both Y1 and Y2 receptors seem to be involved in mediating these responses.
Acta Ophthalmologica, 2018
To investigate the effects of intravitreal neuropeptide Y (NPY) treatment following acute retinal ischaemia in an in vivo porcine model. In addition, we evaluated the vasoconstrictive potential of NPY on porcine retinal arteries ex vivo. Methods: Twelve pigs underwent induced retinal ischaemia by elevated intraocular pressure clamping the ocular perfusion pressure at 5 mmHg for 2 hr followed by intravitreal injection of NPY or vehicle. After 4 weeks, retinas were evaluated functionally by standard and global-flash multifocal electroretinogram (mfERG) and histologically by thickness of retinal layers and number of ganglion cells. Additionally, the vasoconstrictive effects of NPY and its involved receptors were tested using wire myographs and NPY receptor antagonists on porcine retinal arteries. Results: Intravitreal injection of NPY after induced ischaemia caused a significant reduction in the mean induced component (IC) amplitude ratio (treated/normal eye) compared to vehicle-treated eyes. This reduction was accompanied by histological damage, where NPY treatment reduced the mean thickness of inner retinal layers and number of ganglion cells. In retinal arteries, NPY-induced vasoconstriction to a plateau of approximately 65% of potassium-induced constriction. This effect appeared to be mediated via Y1 and Y2, but not Y5. Conclusion: In seeming contrast to previous in vitro studies, intravitreal NPY treatment caused functional and histological damage compared to vehicle after a retinal ischaemic insult. Furthermore, we showed for the first time that NPY induces Y1-and Y2-but not Y5-mediated vasoconstriction in retinal arteries. This constriction could explain the worsening in vivo effect induced by NPY treatment following an ischaemic insult and suggests that future studies on exploring the neuroprotective effects of NPY might focus on other receptors than Y1 and Y2.
ASN neuro, 2015
Neuropeptide Y (NPY) is expressed in mammalian retina but the location and potential modulatory effects of NPY receptor activation remain largely unknown. Retinal ganglion cell (RGC) death is a hallmark of several retinal degenerative diseases, particularly glaucoma. Using purified RGCs and ex vivo rat retinal preparations, we have measured RGC intracellular free calcium concentration ([Ca(2+)]i) and RGC spiking activity, respectively. We found that NPY attenuated the increase in the [Ca(2+)]i triggered by glutamate mainly via Y1 receptor activation. Moreover, (Leu(31), Pro(34))-NPY, a Y1/Y5 receptor agonist, increased the initial burst response of OFF-type RGCs, although no effect was observed on RGC spontaneous spiking activity. The Y1 receptor activation was also able to directly modulate RGC responses by attenuating the NMDA-induced increase in RGC spiking activity. These results suggest that Y1 receptor activation, at the level of inner or outer plexiform layers, leads to modul...
Investigative Ophthalmology & Visual Science, 2005
PURPOSE. Retinal Müller glial cells are known to express metabotropic P2Y receptors. The present study was conducted to identify certain subtypes of P2Y receptors in human Müller cells. METHODS. The patch-clamp technique was used to measure increases of Ca 2ϩ-dependent K ϩ currents mediated by the activation of P2Y receptors in freshly isolated human Müller cells. Several P2 agonists were used. Subsequently, the cells were harvested into the patch pipette and a single cell RT-PCR was performed. Moreover, retinal tissue from organ donors was used for immunohistochemistry. RESULTS. The electrophysiological data were consistent with the expression of P2Y 1 , P2Y 2 , P2Y 4 , and P2Y 6 receptor subtypes. RT-PCR revealed that mRNA for all these subtypes was present in Müller cells. However, the incidence of P2Y 2 receptor mRNA was significantly lower than that of the other subtypes. Immunoreactivity for all four subtypes was found in retinal tissue, partly colocalized with immunoreactivity for vimentin. CONCLUSIONS. The presented data obtained by different techniques revealed that human Müller cells express P2Y 1 , P2Y 2 , P2Y 4 , and P2Y 6 receptors. The specific roles of these receptor subtypes in retinal physiology and/or pathophysiology remain to be investigated in future studies.
Ophthalmic Research, 2003
During proliferative vitreoretinopathy (PVR) Müller glial cells show an up-regulation of their responsiveness to extracellular adenosine 5)-triphosphate (ATP). In the present study, we investigated if such a glial cell response is also a feature for other retinopathies besides PVR. To this aim, the proteolytic enzyme, dispase (0.1 U), was injected into the vitreous of rabbit eyes. After 3 weeks, a distinct retinopathy had developed which showed no signs of PVR. The retinopathy was characterized by strong alterations of the retinal vasculature in the medullary rays, by photoreceptor degeneration, retinal atrophy, and activation of microglial cells. Müller cells became reactive, as indicated by up-regulation of glial fibrillary acidic protein immunoreactivity and by hypertrophy involving subretinal fibrosis. Müller cell reactivity was also evidenced electrophysiologically by a downregulation of their inwardly rectifying potassium currents and by an up-regulation of their responsiveness to extracellular ATP. Significantly more Müller cells from dispase-treated eyes showed ATP-evoked calcium (83%) and current responses (69%) when compared with cells from control eyes (13 and 9%, respectively). The results indicate that increased responsiveness to extracellular ATP may be a more general feature of Müller cell gliosis, and is also observed in retinopathies besides PVR.
Neuropeptide Y inhibits [Ca2+]i changes in rat retinal neurons through NPY Y1, Y4, and Y5 receptors
Journal of neurochemistry, 2009
Neuropeptide Y (NPY) and NPY receptors are widely distributed in the CNS, including the retina, but the role of NPY in the retina is largely unknown. The aim of this study was to investigate whether NPY modulates intracellular calcium concentration ([Ca 2+ ] i ) changes in retinal neurons and identify the NPY receptors involved. As NPY decreased the [Ca 2+ ] i amplitudes evoked by 30 mM KCl in only 50% of neurons analyzed, we divided them in two populations: NPY-nonresponsive neurons (D2/D1 ‡ 0.80) and NPY-responsive neurons (D2/D1 < 0.80), being the D2/D1 the ratio between the amplitude of [Ca 2+ ] i increase evoked by the second (D2) and the first (D1) stimuli of KCl. The NPY Y 1 /Y 5 , Y 4 , and Y 5 receptor agonists (100 nM), but not the Y 2 receptor agonist (300 nM), inhibited the [Ca 2+ ] i increase induced by KCl. In addition, the inhibitory effect of NPY on evoked-[Ca 2+ ] i changes was reduced in the presence of the Y 1 or the Y 5 receptor antagonists. In conclusion, NPY inhibits KCl-evoked [Ca 2+ ] i increase in retinal neurons through the activation of NPY Y 1 , Y 4 , and Y 5 receptors. This effect may be viewed as a potential neuroprotective mechanism of NPY against retinal neurodegeneration.