K+ currents fail to change in reactive retinal glial cells in a mouse model of glaucoma

Purpose To investigate the membrane physiology of Muller glial cells from retinae of DBA/2J mice (which develop ocular hypertension) and of C57BL/6 control mice of different ages. Methods Retinae were obtained at the ages of 3, 6, and 12 months from DBA/2J mice and from C57BL/6 controls. Immunohistochemistry was performed using antibodies against glial fibrillary acidic protein (GFAP). Whole-cell membrane currents, membrane potentials and capacitances were recorded from freshly isolated Muller cells. Results Strong immunostaining for GFAP was found in Muller cells of 12-month-old DBA/2J mice, whereas only astrocytes were immunopositive in C57BL/6 retinae. No significant alterations of membrane currents or potentials of Muller cells from DBA/2J mice as compared to controls were observed at any age; however, the membrane capacitance was increased in Muller cells from DBA/2J mice at the age of 6 months. Conclusions Although Muller cells of DBA/2J mice display some symptoms of reactive gliosis, the lack of significant alterations of the membrane physiology confirm previous data demonstrating that these cells undergo a nonproliferative gliosis.