Mechanisms of Tyrosine Hydroxylase Regulation with Age
The incidence of cardiovascular disease increases in the elderly. In particular, the elderly do not regulate blood pressure as well as young people.1 Plasma catecholamines (CAs) and CA biosynthesis in the adrenal medulla increase with age and may be contributing to the prevalence of hypertension in the elderly1. Tyrosine hydroxylase (TH) is the rate-limiting enzyme in catecholamine biosynthesis. TH gene expression and TH activity are elevated in the adrenal medulla of senescent rats. An elevated sympathoadrenal activity with age might play an important role in the pathogenesis of genetically determined blood pressure elevation2. The sustained elevation of catecholaminergic activity most likely requires increases in TH gene expression to maintain the augmented CAs. The failure of homeostatic regulation may be contributing to this autonomic dysfunction in the elderly. Autonomic dysfunction not only contributes to medical problems in the elderly, but strongly affects the quality of life in relatively healthy individuals.
KeywordsExercise Training Tyrosine Hydroxylase Adrenal Medulla Tyrosine Hydroxylase Gene Catecholamine Biosynthesis
Unable to display preview. Download preview PDF.
- 1.M. L. Tuck, in: Endocrinology of Aging, edited by JA. Armbrecht, R. Coe, and N. Wongsurawat (Springer-Verlag, 1989) pp. 147–160.Google Scholar
- 3.T. Nagatsu., M. Levitt. and S. Udenfriend, Tyrosine hydroxylase: The initial step in norepinephrine biosynthesis. J. Biol. Chem. 238: 2910–2917 (1964).Google Scholar
- 13.L. I. Serova, B.B. Nankova, K. Pacak, O. Tjurmina, E. L. Sabban, and R. Kvetnansky Age and stress: differential effect on neurotransmitter gene expression in adrenal medulla and dopaminergic neurons, in Stress: Neural, Endocrine and Molecular Studies, edited by R. McCarty, G. Aguilera, E.L. Sabban, and R. Kvetnansky (Harwood Academic Publishers, London, in Press).Google Scholar