Abstract
Purpose: :
To evaluate the effect of hyperbaric pressure on purified retinal ganglion cells (RGCs), and also its additive effect on glutamate–induced neurotoxicity in RGCs using a high pressure incubation chamber.
Methods: :
RGC cultures were obtained from retina of 6– to 8–day–old rats utilizing the two–step immunopanning procedure. The RGCs were cultured in serum–free medium. After 3–day incubation, the culture medium was changed to B27 neurobasal medium with or without glutamate (25µM) and the culture was moved to a special incubator in which constant high pressures can be maintained. The RGCs were divided into the following groups: (1) normobaric group, 1.0 ATA (atmosphere absolute), (2) hyperbaric group, 30mmHg + 1.0 ATA, (3) hyperbaric group, 90mmHg +1.0 ATA. After 72 hours, using the calcein–AM assay, the percentage of surviving RGCs was determined by comparison with the control group (normobaric group without glutamate).
Results: :
Without glutamate, the viability percentage was 92.9% in 30mmHg group and 96.0% in 90mmHg group. There was no meaningful difference of cell viabilities between the normobaric group and the hyperbaric groups. However, with the addition of glutamate, the viability was 79.6% in normobaric group, 63.7% in 30mmHg group and 62.9% in 90mmHg group, compared with the control group. Under the glutamate–induced neurotoxicity, the viabilities of RGCs in pressure loading groups are lower than that in normobaric group. (n=12)
Conclusions: :
Hyperbaric pressure loading alone could not induce cell death but exacerbated glutamate–induced neurotoxicity in purified RGCs.
Keywords: neuroprotection • apoptosis/cell death • intraocular pressure