Abstract
Abstract: :
Purpose:To investigate whether P38 mitogen–activated protein (MAP) kinase is activated in rat eyes with experimental glaucoma. Methods:Glaucoma was induced unilaterally in 8 adult Wister rats using two treatments of translimbal argon laser photocoagulation to the trabecular meshwork, 7 days apart. Rats were sacrificed 8 days after the first laser treatment and eyes were immediately enucleated and cryopreserved. The activation of the P38 member of the MAP kinase intracellular signal transduction pathway in retinal ganglion cells (RGCs) was studied using immunohistochemistry. Treated and control eyes were introduced to P38 MAP kinase antibody and to the activated form antibody phospho–P38 MAP kinase (Cell Signaling Technology Inc. Beverly, MA, USA). Their expression was compared between glaucomatous and control eyes in a masked way by two investigators. The significance of this assessment was determined using the t–test. Results:There was statistically significant increase in immunolabeling for P38 MAP kinase and phospho–P38 MAP kinase in RGCs at 8 days after intra ocular pressure (IOP) elevation. Eight glaucomatous eyes and 7 control eyes were tested. At day 8 after the first laser treatment, a mean of 21±3 RGCs per section were positive to phopho–P38 MAP kinase (n= 8) compared to 3±1RGCs (n=7, p=0.0001, t–test) in the control eyes. Labeling for P38 MAP kinase was positive at a mean of 7±1 (n=8) RGCs per section, versus 3±1 RGCs (n=7, p=0.03, t–test) in the control. IOP was elevated in all laser treated eyes. Conclusions:Eight days after induction of experimental glaucoma in rats, there was significant positive reaction of P38 and phospho–P38 MAP kinase pathway among retinal ganglion cells.
Keywords: immunohistochemistry • ganglion cells • apoptosis/cell death