Abstract
Purpose::
To test the glutamate sensitivity in retinal bipolar cells of the rd10 mouse model of retinal degeneration. It has been recently shown that the rd10 model of retinal dystrophy experiences a more delayed rod degeneration than rd1 animals (Cassani et al. J. Comp. Neurol. 500:222, 2007). Since the rd10 mouse seems to be a good model for rescue experiments, it should be necessary to address the functional state of those cells postsynaptic to degenerated photoreceptors.
Methods::
Ionic currents induced by glutamate were studied by the patch clamp technique in the whole cell configuration on rod and cone bipolar cells in the slice preparation of the mouse retina. The data obtained from the rd10 mice were compared with those from control animals (C57Bl/6). All animals were tested at 60 days of postnatal age. Recorded cells were recognized by cell dying with alexa 488. L-Glutamate (100 µM) were applied from a puff pipette in the near proximity of recorded cell and their evoked currents were studied. Changes in membrane conductances induced by glutamate were averaged from different cell groups (ON and OFF cells).
Results::
From a total of 84 bipolar cells recorded in the retina of the control animals, a total of 35 cells responded to local application of glutamate with conductance decrease; 27 bipolar cells responded with a conductance increase and just 22 cells did not show significant response. Similar experiments performed in a total of 66 bipolar cells from the rd10 mice showed that 33 bipolar cells still responded with a conductance decrease and 16 cells witht conductance increase. In these animals, glutamate application did not induce any significant response in 14 bipolar cells. Membrane conductance measured under the effect of glutamate in bipolar cells of the rd10 retinas did not show significant differences with those from the bipolar cells of the control animals.
Conclusions::
Bipolar cells of the retina of rd10 mouse model of retinal degeneration maintain their glutamate responses similarly to control animals at 60 days of postnatal age.
Keywords: retina: proximal (bipolar, amacrine, and ganglion cells) • retinal degenerations: cell biology • bipolar cells