Age-related changes of dopamine, noradrenaline and adrenaline in adrenal glands of mice

Aim: Catecholamines, which are physiologically important neurotransmitters and hormones, apparently decrease in the brain and plasma as some species age. Because this observation has engendered controversy, we used mice to investigate whether age-related changes occur in adrenal catecholamine levels and in the expression of catecholamine synthetic enzymes. Methods: Adrenal glands were collected from male C57BL/6NCr mice at the ages of 6, 12 and 24months. Catecholamines, such as dopamine (DA), noradrenaline (NA) and adrenaline (AD) from those glands, were measured by using a highly sensitive liquid chromatographic method with peroxyoxalate chemiluminescence reaction detection. Tyrosine hydroxylase (TH), dopa decarboxylase, dopamine beta hydroxylase (DBH) and phenylethanolamine N-methyltransferase (PNMT) mRNA expression levels were measured by quantitative real-time polymerase chain reaction. Results: Although DA levels in the adrenals of 24-month-old mice were higher than in 6- and 12-month-old mice, the AD content decreased with age. In such mice, the ratio of DA to NA at 24months was lower than at 12months, and the ratio of NA to AD content at 24months was significantly lower than at 6months. The mRNA expression ratios in TH, DBH and PNMT in 24-month-old mice were all lower than in 12-month-old mice. Conclusions: These results strongly suggest that catecholamine synthesis, in general, declines with aging in the adrenal glands of mice and that AD, in particular, undergoes a significant decrease with advancing age. Geriatr Gerontol Int 2013; 13: 490496.