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Abstract #20517 Published in IGR 10-1
Effect of ocular hypertension on retinal GABAergic activity
Moreno MC; de Zavalia N; Sande P; Jaliffa CO; Fernandez DC; Keller Sarmiento MI; Rosenstein RENeurochemistry International 2008; 52: 675-682
See also comment(s) by Felipe Medeiros •
Glutamate and (gamma)-aminobutyric acid (GABA) are major excitatory and inhibitory retinal neurotransmitters. The balance between these signals is a key principle of organization at retinal level. Although glutamate-induced excitotoxicity could mediate retinal ganglion cell death in glaucoma, the GABAergic system was not previously examined in this disease. The aim of this work was to study the retinal GABAergic activity in eyes with ocular hypertension induced by hyaluronic acid (HA). For this purpose, weekly injections of HA were performed unilaterally in the rat anterior chamber, whereas the contralateral eye was injected with saline solution. At 3 weeks of treatment with HA, GABA turnover rate, glutamic acid decarboxylase activity, and both glutamate- and high K+-induced GABA release significantly decreased, whereas GABA uptake increased in HA-treated eyes. The binding of t-butylbicyclophosphorothionate (TBPS) to GABA(A)/benzodiazepine Cl+ channels significantly increased in eyes injected with HA as compared with vehicle-injected eyes. Changes in GABA uptake and TBPS binding persisted at 6 weeks of treatment with HA. These results indicate a dysfunction of the retinal GABAergic activity in hypertensive eyes, which could suggest the involvement of GABA in glaucomatous neuropathy.
Dr. R.E. Rosenstein, Laboratorio de Neuroquimica Retiniana y Oftalmologia Experimental, Departamento de Bioquimica Humana, Facultad de Medicina, Buenos Aires, Argentina. ruthr@fmed.uba.ar
Classification:
2.13 Retina and retinal nerve fibre layer (Part of: 2 Anatomical structures in glaucoma)
3.6 Cellular biology (Part of: 3 Laboratory methods)
5.1 Rodent (Part of: 5 Experimental glaucoma; animal models)
11.8 Neuroprotection (Part of: 11 Medical treatment)