Effects of life-long caloric restriction and voluntary exercise on age-related changes in levels of catecholamine biosynthetic enzymes and angiotensin II receptors in the rat adrenal medulla and hypothalamus

Abstract

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 decline 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 catecholamine biosynthesis, we examined the expressions of angiotensin II receptor subtypes in the adrenal medulla. AT 1 protein levels were 2.8-fold higher in the old animals compared to young (p<0.01), and while AT 1 levels were unaffected by CR alone, CR+wheel running decreased AT 1 levels by 50% (p<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.

Caloric restriction reduces IgA levels and modifies cytokine mRNA expression in mouse small intestine

“…The higher expression of the gene for pIgR under conditions of CR could be due in part to the effect of glucocorticoids and catecholamines [40][41][42][43][44]. However, we did not find any change in the levels of corticosterone and norepinephrine in CR mice, and therefore the changes that occurred in the synthesis of α-chain and pIgR in the present study cannot associated with those hormones.…”

Treadmill exercise does not change gene expression of adrenal catecholamine biosynthetic enzymes in chronically stressed rats

“…Treadmill exercise did not result in further modulation of gene expression of catecholamine synthesizing enzymes in the adrenal medulla of chronically psychosocially stressed adult rats. In the adrenal medulla, the DNAbinding activities of AP-1 and CREB play a major role in regulating the expression of TH and DBH genes during forced exercise (Erdös et al 2007). Transcription factor CREB may be important in establishing the stress-induced patterns of gene expression.…”

Effect of high-fat diet feeding on hypothalamic redox signaling and central blood pressure regulation

“…18 Briefly, total cellular RNA was extracted using Trireagent (Sigma, St Louis, MO, USA), and the isolated RNA was quantified by spectrophotometry. Membranes were hybridized with 32 P random primergenerated probes.…”

“…18 Briefly, an equal amount of protein for each sample was separated by 12.5% SDS-PAGE, transferred onto a nitrocellulose membrane and blocked with 5% skimmed milk in Tris-buffered saline containing 0.1% Tween 20. Blots were incubated overnight at 4 1C with anti-TH (Pel-Freez Biologicals, Rogers, AR, USA), anti-AT 1 (Fitzgerald Industries, Concord, MA, USA), anti-gp91/NOX2 (BD Transduction Labs, San Diego, CA, USA), and anti-p47 phox and anti-p67 phox (Upstate, Temecula, CA, USA) antibodies.…”