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Query: UMLS:C0424790 (rigors)
 822 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Adipocytes isolated from the epididymal fat of hypophysectomized rats by digestion with collagenase failed to respond to insulin with an increase in glucose utilization. These cells also exhibited an anomalous response to insulin when added in the presence of epinephrine. While insulin antagonized the lipolytic actions of epinephrine in normal adipocytes or in segments of epididymal fat from normal or hypophysectomized rats, it potentiated lipolysis in adipocytes isolated from hypophysectomized rats. This anomalous effect was also evident when isoproterenol, ACTH, or glucagon was used as the lipolytic agent, but the expected antilipolytic response was obtained when theophylline served as the lipolytic agonist. The lipolytic effects of insulin were not seen until 4-7 days after hypophysectomy. Treatment of hypophysectomized rats with a combination of GH (100 micrograms/rat . day), cortisone acetate (1 mg/rat . day), and T3 (1 micrograms/rat . day) for 5 days restored the antilipolytic response to insulin in cells of hypophysectomized rats, but no one hormone alone was effective. The data indicate that adipocytes of hypophysectomized rats retain their ability to recognize and response to insulin, but the ability of insulin to stimulate glucose oxidation or antagonize epinephrine-induced lipolysis is abolished by the cell isolation procedure. The findings underscore the need to consider the impact of hormonal status on the ability of cells to retain normal responsiveness during the rigors of the cell isolation procedure and suggest that failure to do so might lead to erroneous interpretations of the physiological actions of hormones.
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PMID:Lipolytic effects of insulin in adipocytes isolated from hypophysectomized rats. 627 27

A hormonal-challenge protocol was used to compare the stress response of males of Arctic ground squirrels and red squirrels during the breeding season (May). These squirrels live in the same boreal forest of the Yukon, but have very different life histories and utilize the forest in markedly different ways. Red squirrels had levels of total cortisol, maximum corticosteroid-binding capacity, and free cortisol that were 5, 7, and 2 times, respectively, those of Arctic ground squirrels. Red squirrels were resistant to suppression by an artificial glucocorticoid, dexamethasone (DEX); Arctic ground squirrels were not. Cortisol levels in red squirrels responded slowly but continuously to the ACTH injection; Arctic ground squirrels responded rapidly and then stabilized. Testosterone levels in red squirrels were extremely sensitive to the challenge, being suppressed by both DEX and ACTH; levels in Arctic ground squirrels were resistant to the challenge, being modestly suppressed by DEX and stimulated by ACTH. Energy mobilization, as measured by glucose and free fatty acid responses, was not affected. Red squirrels had four times the levels of white blood cells and higher proportions of lymphocytes and lower proportions of eosinophils than Arctic ground squirrels, indicating that the latter were in worse condition immunologically. Our evidence suggests that the functions associated with the hypothalamic-pituitary-adrenal axis are compromised in breeding male Arctic ground squirrels, but not in red squirrels. We propose that in male red squirrels this axis has evolved in the context of a stable social system based on long-lived animals with individual territories which are needed to deal with unpredictable winter food supplies. In contrast, Arctic ground squirrels escape the rigors of winter by hibernation and this hormonal axis has evolved in short-lived males in the context of intense intra-sexual competition in a social system based on female kin groups and regular male dispersal to avoid inbreeding. J. Exp. Zool. 286:390-404, 2000.
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PMID:Contrasting stress response of male arctic ground squirrels and red squirrels. 1068 62