Skin and brain age together: The role of hormones in the ageing process

Abstract

The importance of the endocrine environment in the initiation of the ageing process has been elucidated in several in vivo an in vitro studies. Changes in endocrine pathways accompany healthy ageing, these include the growth hormone /insulin like growth factor-I axis (somatopause) and that of sexual hormones, namely estradiol (menopause), testosterone (andropause), and dehydroepiandrosterone and its sulphate (adrenopause). The clinical significance of these changes is variable and results in morphological and functional alterations of all organ systems including the skin and the central nervous system. Moreover, the pathogenesis of age-associated diseases such as epithelial skin cancer and neurodegenerative diseases has been partly attributed to the lack of hormones. Several studies have been conducted in an attempt to reverse the ageing process and clinical signs by substitution of the serum hormone levels in older individuals, however the benefits of hormone replacement therapy, if any, are still controversial. On the other hand, recent data suggest that skin is a window to the human organism and represents an adequate model for ageing research, also implying the use of skin samples for evaluating the ageing status of the central nervous system.

Functional magnetic resonance imaging in dermatology: The skin, the brain and the invisible

“…[6,[25][26][27][28][29] Furthermore, the skin and brain age together as their intrinsic ageing strongly depends on a similar endocrine environment leading to the suggestion that skin ageing models represent an effective tool for understanding molecular ageing mechanisms of the brain. [30] The notion that skin may reflect a "diagnostic window into the brain" is tempting and the use of alpha-synuclein in skin nerve fibres biopsies to support diagnoses of Parkinson's disease [31,32] and fibroblast-based tests for Alzheimer's disease [33] is currently under investigation.…”

Intracrine sex steroid synthesis and signaling in human epidermal keratinocytes and dermal fibroblasts

“…Estrogens and their receptors are directly involved in various age-related diseases and the impact of estrogen deficiency in accelerating skin aging is well documented (3,5,(64)(65)(66). Furthermore, recent studies have suggested that human skin cells provide a useful in vitro model that will allow us to gain a better understanding of the global pathogenesis of human hormonal aging, particularly in tissues that share the same embryonic origin (66).…”

“…Menopause highlights 3 important features that distinguish humans from lower mammals [i.e., termination of ovarian function and estrogen secretion, secretion of DHEA by the adrenal cortex, and the presence of intracrine enzymes in peripheral tissues that convert DHEA into active sex steroids, as reviewed by Labrie and Labrie (63)]. Estrogens and their receptors are directly involved in various age-related diseases and the impact of estrogen deficiency in accelerating skin aging is well documented (3,5,(64)(65)(66). Furthermore, recent studies have suggested that human skin cells provide a useful in vitro model that will allow us to gain a better understanding of the global pathogenesis of human hormonal aging, particularly in tissues that share the same embryonic origin (66).…”

Physiological effect of olfactory stimuli inhalation in humans: an overview

“…Hormones, playing an important role in physiological human system, have the ability of regulating various pathways, including skin and hair functions [58,59].…”