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E. Beit-Yannai, A. Shmulevich; Aqueous Humor Has a Role in Signaling via the MAPK Pathway in Normal and Elevated IOP Rat Model. Invest. Ophthalmol. Vis. Sci. 2007;48(13):5903.
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To investigate the expression of the activated mitogen-activated protein kinases (MAPK), extracellular-regulated kinase (ERK), c-jun N-terminal kinase (JNK) and p38, in the aqueous humor of control and induced elevated IOP rats.
SD rats weighting 160-180g were injected into the anterior chamber of the right eye, under general & local anesthesia, a 2% Hyaluronic acid solution (HA), once a week. IOP was measured by Tonopen-XL. At different time point Aqueous humor sample were taken from the treated eye and evaluated for MAPK protein expression by western blot analysis. Saline injected eyes and untreated eyes served as control sham.
phosphorylated-ERK (pERK) and total-ERK (tERK) changes in rat's aqueous humor following HA injection. In tErk1&2 analyses, we were able to show that Erk1&2 are definitively presented at the aqueous humor from control and HA injected rats. The mean levels of Erk2 was higher at the aqueous humor drained from rats eyes with elevated IOP after HA injections. pERK 1&2 were found at the aqueous humor of HA injected and control rats. The mean levels of pErk2 was significantly (p<0.05) higher in rats injected HA more than two weeks versus control. Two bands corresponding to total-JNK were found in the control & elevated IOP groups. Only the phosphorylated-JNK2 (pJNK) was found in elevated IOP rats and control groups. pJNK2 expression was significantly (p<0.05) higher in rats injected HA more than two weeks versus control. p-38 total form can be detected only at the elevated IOP rat’s aqueous humor. Phosphorylated-p38 was detected in elevated IOP and control.
In this study we were able to show the presence of several members of the MAPK signaling pathway, in rat’s aqueous humor, an extra-cellular environment. The response of the extra cellular aqueous humor to the continuously elevated IOP resulted in changes in MAPK expression. We suggest the MAPK in the aqueous humor as new target for modifying IOP and trabecular meshwork resistance to flow.
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