Figure 5: Contribution of the cAMP/PKA pathway to PACAP-induced tear secretion.
From: PACAP suppresses dry eye signs by stimulating tear secretion
(a) cAMP content in infraorbital lacrimal gland extracts after application of 10−10 M PACAP eye drops (n=8 per group). *P<0.05 versus 0 min. (b) Phosphorylated PKA (pPKA) levels in the mouse infraorbital lacrimal gland after PACAP eye drop application (n=6 per group). *P<0.05 versus 0 min. (c) Pre-treatment with the adenylate cyclase inhibitor SQ22536 or the PACAP receptor antagonist PACAP6–38 suppressed PKA phosphorylation 30 min after PACAP eye drop administration (n=6 per group). *P<0.05. (d) Effect of SQ22536 pre-treatment on PACAP-induced tear secretion in male mice (n=10 per group). A single drop of test solution was applied to each ocular surface. The sum of the wet lengths of thread from both eyes is shown. *P<0.05, **P<0.01 versus saline+PACAP group.
