M5 muscarinic receptor activation decreases proliferation through modulation of p21 levels in neonatal rat retinal cells.

Retinal cells from neonatal rats still exhibit intense proliferation as many of its cell subtypes have not exit the cell cycle to differentiate. The distinct phases of cell cycle (G1, S, G2, M) are controlled by proteins as cyclins dependent kinases (CDK). p21 is a cell cycle inhibitor capable of stopping progression at G1/S and G2/M transitions, by inhibiting CDK4.6/cyclin-D and CDK2/cyclin-E, respectively. P21 expression can be induced in a P53 dependent or in independent way. Our previous results have shown that treatment with Vu0238429 (Vu), a selective agonist of M5 muscarinic acetylcholine receptor for 48h, decreases retinal cells proliferation measured by [3H]-thymidine incorporation.