Impact of carbohydrate-rich meals on plasma epinephrine levels: dysregulation with aging

Context: Plasma norepinephrine (NE) and epinephrine (E) levels are indicators of peripheral sympathetic and adrenomedullary activities, respectively. The sympathoadrenomedullary system is involved in the metabolic response to carbohydrate intake and is affected by aging; however, the relationship between glucose metabolism and adrenomedullary activity in older adults remains poorly defined. Objective: The objective of this study was to examine the changes in the impact of carbohydrate-rich meals on circulating catecholamines with aging. Design: After iv glucose tolerance testing and 1 d of habituation, blood samples were collected every 10-30 min for 24 h. Daytime hours were spent at bed rest. Sleep was scheduled between 2300 and 0700 h with polygraphic monitoring. Setting: The study was performed at a general clinical research center. Participants: Nine young (age, 20-28 yr) and eight older (age, 50-69 yr) healthy men participated in this study. Intervention: Identical mixed meals (62% carbohydrate) were given at 0900, 1400, and 1900 h. Main Outcome Measures: The main outcome measures were 24-h plasma E and NE measurements. Results: The profiles of E and NE were characterized by clear daynight differences, which were preserved in the older group. Young subjects showed a clear dissociation between postprandial adrenomedullary and sympathetic activities characterized by a rapid decline in plasma E and increased NE levels. There was an overall increase in NE levels and markedly dampened postprandial variation in plasma E in the older men. Conclusions: In young adults, postprandial E levels follow a biphasic pattern that is inversely related to that of glucose and insulin. Aging is associated with a dysregulation of this response. Copyright © 2005 by The Endocrine Society.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

The metabolic consequences of sleep deprivation

The prevalence of diabetes and obesity is increasing at an alarming rate worldwide, and the causes of this pandemic are not fully understood. Chronic sleep curtailment is a behavior that has developed over the past 2-3 decades. Laboratory and epidemiological studies suggest that sleep loss may play a role in the increased prevalence of diabetes and/or obesity. Current data suggest the relationship between sleep restriction, weight gain and diabetes risk may involve at least three pathways: (1) alterations in glucose metabolism; (2) upregulation of appetite; and (3) decreased energy expenditure. The present article reviews the current evidence in support of these three mechanisms that might link short sleep and increased obesity and diabetes risk. © 2007 Elsevier Ltd. All rights reserved.SCOPUS: re.jinfo:eu-repo/semantics/publishe

Sleep curtailment results in decreased leptin levels and increased hunger and appetite

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Sleep duration is a major determinant of leptin levels, hunger and appetite

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Effects of age on the circadian system.

While aging has been associated with changes in the period and amplitude of circadian rhythms, little is known about how aging influences the response of the circadian clock to environmental stimuli. In this paper, we report on recent studies designed to determine the effects of advanced age on the response of the circadian clock to both photic and nonphotic stimuli in old hamsters (e.g. over 16 mo of age). Among the most pronounced age-related changes in the circadian rhythm of locomotor activity are: (a) alterations in the phase-angle of entrainment to the light-dark cycle; (b) an increase in the magnitude of phase shifts induced by pulses of light presented at specific circadian times; and (c) a loss of responsiveness to the phase shifting or entraining effects of stimuli which induce an acute increase of activity. Depletion of brain monoamine levels in young animals can induce changes in the responsiveness of the circadian clock to environmental stimuli which are similar to those which occur spontaneously in old animals, suggesting that aging alters monoaminergic inputs to the clock. Some of the age-related changes in the response of the clock to an activity-inducing stimulus can be reversed by implanting old animals with fetal SCN tissue. Determining the physiological basis for age related changes in the responsiveness of the clock to both internal and external stimuli, and the mechanisms by which normal circadian function can be restored, should lead to new insight into the functioning of the circadian clock and may lead to new approaches for normalizing disturbed circadian rhythms.Journal ArticleResearch Support, U.S. Gov't, Non-P.H.S.Research Support, U.S. Gov't, P.H.S.Reviewinfo:eu-repo/semantics/publishe

Relationship between REM sleep and testosterone secretion in older men

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Heart rate and heart rate variability monitoring reveals activation of the sympathetic nervous system during sleep restriction

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