Journal
EXPERIMENTAL GERONTOLOGY
Volume 42, Issue 8, Pages 745-752Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.exger.2007.04.007
Keywords
tyrosine hydroxylase; dopamine beta hydroxylase; angiotensin II; aging; exercise; caloric restriction
Categories
Funding
- NIA NIH HHS [R01 AG021042, R01 AG017994-07, R01 AG017994, R01 AG 17994, AG 21042] Funding Source: Medline
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We examined if life-long mild caloric restriction (CR) alone or with voluntary exercise prevents the age-related changes in catecholamine biosynthetic enzyme levels in the adrenal medulla and hypothalamus. Ten-week-old Fisher-344 rats were assigned to: sedentary; sedentary + 8% CR; or 8% CR + wheel running. Rats were euthanized at 6 or 24 months of age. Tyrosine hydroxylase (TH) mRNA expression was 4.4-fold higher in the adrenal medullae and 60% lower in the hypothalamus of old sedentary rats compared to young (p < 0.01). Life-long CR reduced the age-related increase in adrenomedullary TH by 50% (p < 0.05), and completely reversed the changes in hypothalamic TH. Voluntary exercise, however, had no additional effect over CR. Since angiotensin II is involved in the regulation of catccholamine biosynthesis, we examined the expressions of angiotensin II receptor subtypes in the adrenal medulla. AT, protein levels were 2.8-fold higher in the old animals compared to young (p < 0.01), and while AT, levels were unaffected by CR alone, CR + wheel running decreased AT, levels by 50%) < 0.01). AT(2) levels did not change with age, however CR + wheel running increased its level by 42% (p < 0.05). These data indicate that a small decrease in daily food intake can avert age-related changes in catecholamine biosynthetic enzyme levels in the adrenal medulla and hypothalamus, possibly through affecting angiotensin II signaling. (c) 2007 Elsevier Inc. All rights reserved.
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