Impaired hormonal regulation of enzyme activity during aging

Abstract

A general feature of all aging populations is the progressively impaired ability to adapt to changes in the surrounding environment. Biochemical expressions of adaptive response include modifications in the rates of enzyme synthesis and degradation, as well as alterations in physiological activity. Therefore, the effects of aging on enzyme adaptation were surveyed in an attempt to explore fundamental biochemical mechanisms in the deterioration of responsiveness. The ability to stimulate adaptive increases in the activity of a large number of enzymes is impaired during aging in a variety of tissues from several different species. The impaired capability for liver enzyme adaptation in a rigorously controlled colony of aging male Sprague-Dawley rats probably reflects alterations in hormonal control mechanisms. The present article reviews and evaluates our interest in understanding the effects of aging on regulation of liver enzyme activity by the hormones, insulin and corticosterone. Specific areas currently under investigation include: 1) the regulation of their concentrations in blood; 2) the integrity of their receptor systems in liver; and 3) effectiveness of the endogenous hormone pools from the viewpoints of the availability of physiological antagonists and the potential for alterations in molecular structure.—Adelman, R. C. Impaired hormonal regulation of enzyme activity during aging. Federation Proc. 34: 179–182, 1975.

From Session VI, Development and Aging at the Molecular Level, of the FASEB Conference on Biology of Development and Aging, presented at the 58th Annual Meeting of the Federation of American Societies for Experimental Biology, Atlantic City, N.J., April 11, 1974.

Preparation of this manuscript, as well as related experimentation, is supported by research grants HD-04382, HD-05874, CA-12227 and RR-05417 from the National Institutes of Health and IN-88-D from the American Cancer Society.