Cyclic adenosine monophosphate, inositol 1,4,5-trisphosphate, calcium, and phosphorylated myosin light chain regulation through m2 and m3 muscarinic receptors of scleral fibroblast cells in rat myopia model

AIM: This study aims to investigate the concentration of cyclic adenosine monophosphate (cAMP), inositol 1,4,5-trisphosphate (IP3), calcium (Ca²⁺), and the expression phosphorylated myosin light chain (MLC) in Rattus norvegicus scleral fibroblast cells. METHODOLOGY: This study utilized an in vitro experimental study by applying Rattus norvegicus scleral fibroblast cell culture. The cultured cells were divided into control and lens-induced myopia (LIM) groups. The control and LIM culture groups were each divided into five groups, namely, negative control, 0.1 µM acetylcholine, 0.1 µM himbacine, 0.1 µM methoctramine, and 0.1 µM 4-DAMP group. The cAMP, IP3, and Ca²⁺ concentration were analyzed in the 0^th, 5^th, 10^th, 20^th, and 30^th. The phosphorylated MLC expression was analyzed using confocal microscope. RESULTS: In the LIM group, the highest cAMP concentration is visible at the 10^th min on the himbacine group (0.304 ± 0; p = 0.043) and on the 4-DAMP group (0.346 ± 0; p = 0.043). The highest IP3 concentration is found on the LIM group at the 20^th min in comparison to the control group (2503.6 ± 11 vs. 2039.2 ± 2.1; p = 0.046). The highest Ca²⁺ concentration belongs to the 4-DAMP treatment group from the 5^th to the 30^th min. The highest average phosphorylated MLC expression value in the LIM group is shown by the 0.1µM 4-DAMP treatment (184.2 ± 37.9c au). CONCLUSION: The regulation of cAMP, IP3, Ca²⁺, and phosphorylated MLC on the M2 and M3 muscarinic receptor of the scleral fibroblast cells of myopia animal models differs from normal animal models which may be due to interactions of M2 and M3 muscarinic receptor as compensation reaction or crosstalk on myopia induction.