Abstract
Purpose:
To measure the expresssion of the enzyme Arylalkylamine N-acetyltransferase (AANAT) which is a key step in the biosynthesis of melatonin. To measure melatonin production levels in aqueous humor of glaucomatous mice compared to control mice,and the corresdonding in human non pigmented ciliary epithelium cells.
Methods:
Animals: Mice, normotensive model C57BL/6J and glaucomatous model DBA/2J. All animals were kept with free access to food and water; they were submitted to controlled 12h/12h light/dark cycle.<br /> Cellular studies: These studies were conducted using immortalized human non-pigmented ciliary epithelial cells (59HCEsv).<br /> The expression of AANAT was measured by western blot using a primary antibody at concentration (1:500). Melatonin levels were measured by HPLC using a mobile phase consisting of 40% methanol and 60% ultrapure water and detection was performed at 244nm.
Results:
Melatonin levels have shown an increment in glaucomatous mice compared to the control. aqueous humor melatonin concentration in glaucomatous mice before developing glacoma was 218 ±20 nM while when the pathology was fully developed (15 months of age) melatonin concentration was 500±10nM.Non glaucomatous mice did not significantly change thier melatonin concentration with age, the value been 229 ±27nM these results were similar when measuring melatonin production in human non pigmented cilary epithelial cells. under normal conditions, presented extracellular melatonin concentration 17.1±0.6nM. when tried to mimic a glaucomatous condition by means of a TRPV4 agonist (GSK1016790a) the concentration was 52.7 ±2.1nM.<br /> AANAT expression was demonstrated in the human non pigmented ciliary cells and the expression was increased roughly 30% when applying GSK1016790a.
Conclusions:
Melatonin production as well as the expression of the enzyme synthesising melation is increased under ocular hypertension.