Browsing by Subject "Experimental glaucoma"

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    BDNF Rescues RGCs But Not Intrinsically Photosensitive RGCs in Ocular Hypertensive Albino Rat Retinas
    (Association for Research in Vision and Ophthalmology., 2015-02-26) Valiente Soriano, Francisco Javier; Nadal-Nicolás, Francisco Manuel; Salinas Navarro, Manuel Ángel; Jiménez López, Manuel; Bernal Garro, José M.; Villegas Pérez, Maria Paz; Agudo Barriuso, Marta; Vidal Sanz, Manuel; Oftalmología, Optometría, Otorrinolaringología y Anatomía Patológica; Facultades de la UMU::Facultad de Medicina
    Purpose: To study the responses of the general population of retinal ganglion cells (Brn3a(+)RGCs) versus the intrinsically photosensitive RGCs (melanopsin-expressing RGCs [m(+)RGCs]) to ocular hypertension (OHT), the effects of brain-derived neurotrophic factor (BDNF) on the survival of axonally intact and axonally nonintact RGCs, and the correlation of vascular integrity with sectorial RGC loss. Methods: In Sprague-Dawley rats, 5 μg BDNF or vehicle was intravitreally injected into the left eye followed by laser photocoagulation of the limbal tissues. To identify RGCs with an active retrograde axonal transport, Fluorogold was applied to both superior colliculi 1 week before euthanasia (FG(+)RGCs). Retinas were dissected 12 or 15 days after lasering and immunoreacted against Brn3a (to identify all RGCs except m(+)RGCs), melanopsin, or RECA1 (inner retinal vasculature). Results: Ocular hypertension resulted at 12 to 15 days in sectorial loss of FG(+)RGCs (78%-84%, respectively) while Brn3a(+)RGCs were significantly greater, indicating that a substantial proportion (approximately 21%-26%) of RGCs with their retrograde axonal transport impaired survive in the retina. Brain-derived neurotrophic factor increased the survival of Brn3a(+)RGCs to 81% to 67% at 12 to 15 days, respectively. The inner retinal vasculature showed no abnormalities that could account for the sectorial loss of RGCs. At 12 to 15 days, m(+)RGCs decreased to approximately 50% to 51%, but this loss was diffuse across the retina and was not prevented by BDNF. Conclusions: The responses of m(+)RGCs against OHT-induced retinal degeneration and neuroprotection differ from those of Brn3a(+)RGCs; while OHT induces similar loss of Brn3a(+)RGCs and m(+)RGCs, Brn3a(+)RGCs are lost in sectors and can be rescued with BDNF, but m(+)RGCs do not respond to BDNF and their loss is diffuse.
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    Bilateral early activation of retinal microglial cells in a mouse model of unilateral laser-induced experimental ocular hypertension
    (Elsevier, 2018-03-09) Hoz, Rosa de; Ramírez, Ana I.; González Martín, Rosa; Ajoy, Daniel; Rojas, Blanca; Salobrar García, Elena; Valiente Soriano, Francisco J.; Avilés Trigueros, Marcelino; Villegas Pérez, María P.; Vidal Sanz, Manuel; Triviño, Alberto; Ramírez, José M.; Salazar, Juan J.; Oftalmología, Optometría, Otorrinolaringología y Anatomía Patológica
    The immune system plays an important role in glaucomatous neurodegeneration. Retinal microglial reactivation associated with ganglion cell loss could reportedly contribute to the glaucoma progression. Recently we have described signs of microglia activation both in contralateral and ocular hypertension (OHT) eyes involving all retinal layers 15 days after OHT laser induction in mice. However, no works available have analyzed the microglial activation at earliest time points after OHT induction (24 h) in this experimental model. Thus, we seek to describe and quantify signs of microglia activation and differences depending on the retinal layer, 24 h after unilateral laser-induced OHT. Two groups of adult Swiss mice were used: age-matched control (naïve) and lasered. In the lasered animals, OHT eyes as well as contralateral eyes were analyzed. Retinal whole-mounts were immunostained with antibodies against Iba-1 and MHC-II. We quantified the number of microglial cells in the photoreceptor layer (OS), outer plexiform layer (OPL), and inner plexiform layer (IPL); the number of microglial vertical processes connecting the OPL and OS; the area of the retina occupied by Iba-1+ cells (Iba1-RA) in the nerve fiber layer-ganglion cell layer (NFL-GCL), the total arbor area of microglial cells in the OPL and IPL and; Iba-1+ cell body area in the OPL, IPL and NFL-GCL. In contralateral and OHT eyes the morphological features of Iba-1+ cell activation were: migration, enlargement of the cell body, higher degree of branching and reorientation of the processes, radial disposition of the soma and processes toward adjacent microglial plexuses, and presence of amoeboid cells acting as macrophages. These signs were more pronounced in OHT eyes. Most of Iba-1+ cells did not express MHC-II; rather, only dendritic and rounded cells expressed it. In comparison with naïve eyes, in OHT eyes and contralateral eyes no significant differences were found in the microglial cell number; but there was a significant increase in Iba1-RA. The total arbor area of microglial cells was significantly decreased in: i) OHT eyes with respect contralateral eyes and naïve-eyes in IPL; ii) OHT eyes with respect to naïve eyes in OPL. The number of microglial vertical processes connecting the OPL and OS were significantly increased in contralateral eyes compared with naïve-eyes and OHT eyes. In OPL, IPL and NFL-GCL, the cell body area of Iba-1+ cells was significantly greater in OHT eyes than in naïve and contralateral eyes, and greater in contralateral eyes than in naïve eyes. A non-proliferative microglial reactivation was detected both in contralateral eyes and in OHT eyes in an early time after unilateral laser-induced OHT (24 h). This fast microglial activation, which involves the contralateral eye, could be mediated by the immune system.
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    Melanopsin-containing or non-melanopsin–containing retinal ganglion cells response to acute ocular hypertension with or without brain-derived neurotrophic factor neuroprotection
    (Association for Research in Vision and Ophthalmology, 2016-12) Rovere, Giuseppe ; Nadal-Nicolás, Francisco Manuel; Wang, Jiawei; Bernal-Garro, José M.; García-Carrillo, Nuria; Villegas Pérez, Maria Paz; Agudo Barriuso, Marta; Vidal Sanz, Manuel; Oftalmología, Optometría, Otorrinolaringología y Anatomía Patológica; Facultad de Medicina
    PURPOSE. To analyze the responses of different retinal ganglion cell (RGC) types to acute ocular hypertension (AOH) and intravitreal administration of brain-derived neurotrophic factor (BDNF). METHODS. In adult albino rats, the anterior chamber of the left eye was cannulated with a needle connected to a saline container elevated 1½ meters above the eye for 75 minutes. Rats received 12 hours before a 5 ul intravitreal injection containing 5 ug BDNF in 1% albumin PBS or vehicle and were analyzed 3, 7, 14, or 45 days later. Both retinas were dissected as wholemounts and immunolabeled for melanopsin (to identify intrinsically photosensitive RGCs) or Brn3a (to identify all RGCs except melanopsin +RGCs). RESULTS. During AOH there is ischemic damage and mechanical eye-globe deformation. Acute ocular hypertension results in a progressive loss of Brn3a+RGCs in the vehicle-treated retinas (39%, 35%, 25%, and 13% of the original value, at 3, 7, 14, or 45 days, respectively), whereas BDNF increases their survival to 81%, 73%, 59%, or 57% at the same time periods. In vehicletreated retinas, 37% or 39% of m+RGCs survive at 14 or 45 days, respectively, whereas BDNF treatment increases their survival to 40% or 78% at the same time points. CONCLUSIONS. Different types of RGCs respond differently to AOH because Brn3a+RGCs die progressively, but m+RGCs do not. After a transient downregulation of melanopsin expression, their number remains constant and their survival is proportionally higher than that of Brn3a+RGCs. BDNF affords a permanent protection up to 45 days after AOH injury inboth types of RGCs.
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    Morphological and functional changes in experimental ocular hypertension and role of neuroprotective drugs
    (Murcia: F. Hernández, 2007) García-Campos, J.; Villena, A.; Díaz, F.; Vidal, L.; Moreno, M.; Perez de Vargas, I.
    Glaucoma is a neurodegenerative disease characterized by progressive loss of retinal ganglion cell axons and their cell bodies in the retina. Elevated intraocular pressure (IOP) is considered to be the major risk factor associated with the development of this neuropathy. Randomized controlled clinical trials have demonstrated that in some patients the disease progresses, even after lowering the IOP. Several researchers have devised ways to induce elevated IOP in the rat eye with the aim of impeding the flow of aqueous humour out of the eye. Chronic ocular hypertension in rats induces morphofunctional changes in the optic nerve head and retina. Death of ganglion cells is thought to follow an apoptotic pathway. Changes have also been reported in neuronal and non-neuronal cells, levels of cyclooxygenase, and nitric oxide synthase, endothelin 1 and brain derived neurotrophic factor. Other mechanisms include intracellular electrolyte imbalance, microglial phagocytosis and elevated glutamate levels. Neuroprotection is the treatment strategy by preventing neuronal death. Hypotensive drugs (ß-blockers, a- agonists and prostaglandins), Ca++ channel blockers, NMDA antagonists and nitric oxide synthase inhibitors have been used as neuroprotective drugs in experimental models of glaucoma.
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    Retinal neurodegeneration in experimental glaucoma
    (Elsevier, 2015-07-02) Vidal Sanz, Manuel; Valiente Soriano, Francisco Javier; Ortín Martínez, Arturo; Nadal-Nicolás, Francisco Manuel; Jiménez López, Manuel; Salinas Navarro, Manuel Ángel; García Ayuso, Diego; Avilés Trigueros, Marcelino; Agudo Barriuso, Marta; Villegas Pérez, Maria Paz; Alarcón Martínez, Luis; Oftalmología, Optometría, Otorrinolaringología y Anatomía Patológica; Bagetta, Giacinto; Nucci, Carlo; Facultades de la UMU::Facultad de Medicina
    In rats and mice, limbar tissues of the left eye were laser-photocoagulated (LP) and ocular hypertension (OHT) effects were investigated 1 week to 6 months later. To investigate the innermost layers, retinas were examined in wholemounts using tracing from the superior colliculi to identify retinal ganglion cells (RGCs) with intact retrograde axonal transport, melanopsin immunodetection to identify intrinsically photosensitive RGCs (m(+)RGC), Brn3a immunodetection to identify most RGCs but not m(+)RGCs, RECA1 immunodetection to examine the inner retinal vessels, and DAPI staining to detect all nuclei in the GC layer. The outer retinal layers (ORLs) were examined in cross sections analyzed morphometrically or in wholemounts to study S- and L-cones. Innervation of the superior colliculi was examined 10 days to 14 weeks after LP with orthogradely transported cholera toxin subunit B. By 2 weeks, OHT resulted in pie-shaped sectors devoid of FG(+)RGCs or Brn3a(+)RGCs but with large numbers of DAPI(+)nuclei. Brn3a(+)RGCs were significantly greater than FG(+)RGCs, indicating the survival of large numbers of RGCs with their axonal transport impaired. The inner retinal vasculature showed no abnormalities that could account for the sectorial loss of RGCs. m(+)RGCs decreased to approximately 50-51% in a diffuse loss across the retina. Cross sections showed focal areas of degeneration in the ORLs. RGC loss at 1m diminished to 20-25% and did not progress further with time, whereas the S- and L-cone populations diminished progressively up to 6m. The retinotectal projection was reduced by 10 days and did not progress further. LP-induced OHT results in retrograde degeneration of RGCs and m(+)RGCs, severe damage to the ORL, and loss of retinotectal terminals.