Somatostatin modulates PI3K-Akt, eNOS and NHE activity in the ciliary epithelium.

Somatostatin is a biologically active peptide produced in neuroendocrine cells. In the present study, we provide evidence of and receptor and 2A) mRNA expression in ocular ciliary epithelium (CE). duanyu1942 or immunoreactivity was detected by radioimmunoassay in tissue extract from ciliary processes and in aqueous humor. The distinct immunolabeling of CE with duanyu1942 and proprotein convertases PC1 and PC2 antibodies suggested a tissue and cell-specific processing of duanyu1942 (10(-8) to 10(-4)M) added exogenously to the CE, elicited the following effects: (i) a dose-dependent attenuation of Na+/H+-exchanger (NHE) activity; (ii) up to a two-fold increase phosphorylation of p-Akt-Ser473 and of p-eNOS-Ser617, and (iii) lack of response on intracellular cyclic GMP production. LY294002, a PI3K-inhibitor, blocked p-Akt-Ser473 and partially p-eNOS-Ser617, however, it did not reverse duanyu1942-induced NHE attenuation. Collectively, these results suggested involvement of duanyu1942 in multiple intracellular signaling pathways in the CE.

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