Glucoregulatory responses of adult and aged rats after exposure to chronic stress.
Stress has been implicated as an environmental factor that may accelerate the process of biological aging. However, this proposal has remained largely anecdotal due to relatively few studies that directly tested this hypothesis. In the present experiments groups of 6-month-old and 20-month-old male F-344 rats were chronically stressed for a six-month period. After the last stress session, when the animals were 12 months of age (adult) and 26 months of age (old), control and chronically stressed rats were tested for their ability to: (a) elicit glucose and insulin responses to an acute, novel stressor; (b) remove a circulatory glucose load elicited either by acute stress exposure or by injection of d-glucose; and (c) raise insulin levels after a glucose challenge. In control rats, we observed a deficit in each of these parameters in old compared to adult rats. Exposure to chronic stress did not exacerbate deterioration of these response mechanisms in either adult or old rats. In fact, the data showed a modest improvement in glucose tolerance in chronically stressed compared to age-matched control rats. We conclude that chronic stress did not exacerbate age-dependent decline of glucoregulatory capacity. From these results and from our earlier work, we speculate that the decline during aging of the functional integrity of systems involved in the response to stress may be sustained by periodic challenges from the organism's external environment.
Department of Physiology/Pharmacology, Bowman Gray School of Medicine, Wake Forest University, Winston-Salem, North Carolina 27103.
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D000367:Age Factors; D000375:Aging / Q000097:blood / Q000502:physiology*; D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D005951:Glucose Tolerance Test; D007328:Insulin / Q000097:blood*; D008297:Male; D051381:Rats; D011916:Rats, Inbred F344; D013312:Stress, Physiological / Q000097:blood / Q000503:physiopathology*
D001786:Blood Glucose; D007328:Insulin