Effect of exercise on mRNA expression of select adrenal medullary catecholamine biosynthetic enzymes

Abstract

The effect of submaximal endurance training (SET) on sympathoadrenal activity is not clear. We tested the hypothesis that SET (90 min/day, 5 days/wk, for 12 wk) elevates mRNA expression of catecholamine (CA) biosynthetic enzymes, tyrosine hydroxylase (TH) and dopamine-beta-hydroxylase (DbetaH) in the adrenal medullae of adult, female Sprague-Dawley rats. SET increased TH protein level by 35%, TH activity by 62%, TH mRNA expression by 40%, and DbetaH mRNA expression by 67%. In addition, we examined the effect of SET on Fos-related antigens (FRAs), FRA-2 immunoreactivity, and activator protein (AP)-1 binding activity. SET increased AP-1 binding activity by 78%; however, it did not affect late FRAs and FRA-2 immunoreactivity. Because the regulation of neuropeptide Y (NPY) often parallels that of CAs, we also examined the effect of SET on NPY mRNA expression. Indeed, SET elevated NPY mRNA expression as well. We conclude that 1) SET elicits a pretranslational stimulatory effect on adrenomedullary CA biosynthetic enzymes, 2) another immediate early mRNA product, rather than FRA-2, may contribute to the increase in AP-1 binding activity in response to SET, and 3) SET increases NPY mRNA expression.

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

“…To reveal the detailed mechanisms underlying age-and CR-related changes in adrenomedullary TH and DβH, we measured the binding activities of AP-1 and CREB transcription factors in nuclear extracts from adrenal medulla, since AP-1 and CREB play a central role in the regulation of TH and DβH expression during stress (Sabban et al, 2004a(Sabban et al, , 2004bSabban and Kvetnansky, 2001) and forced exercise training (Erdem et al, 2002b;Tumer et al, 2001). However, in the present study, we found that neither of these transcription factors is responsible for the observed changes in adrenomedullary TH and DβH levels with age or in response to CR.…”

“…TH and DβH mRNA levels were determined using Northern blot analysis as previously described (Tumer and Larochelle, 1995;Erdem et al, 2002b). Briefly, total cellular RNA was extracted using Tri-reagent (Sigma, St. Louis, MO), and the isolated RNA was quantified by spectrophotometry.…”

“…TH, AT 1 and AT 2 protein levels were determined using Western blot as previously described (Tumer et al, 1992, Erdem et al, 2002b. Briefly, an equal amount of protein for each sample was separated by 10 % SDS-PAGE, transferred onto a polyvinylidine difluoride membrane and blocked with 5% skimmed milk in Tris-buffered saline containing 0.1% Tween 20.…”

“…The AP-1 and CREB sequences (25 oligomers) from Promega (Madison, WI) were 32 P 3' end labeled using the End Labeling System (Promega) as previously described (Tumer et al, 1997b, Erdem et al, 2002b. Probe (3.5 pg, 10 000 cpm) was incubated in 10 µL of 4% glycerol, 1 mM MgCl 2 , 0.5 mM DTT, 50 mM NaCl, 10 mM Tris -HCl, pH 7.5, 0.05 mg/mL poly(dIdC) and 20 µg of nuclear protein extract for 20 min at room temperature.…”

“…We assessed TH and DβH expressions in the adrenal medulla and hypothalamus. The DNA-binding activities of activating protein-1 (AP-1) and cAMP-response element binding protein (CREB) transcription factors, which have a major role in the control of TH expression in stress (Sabban et al, 2004a(Sabban et al, , 2004bSabban and Kvetnansky, 2001) and exercise (Erdem et al, 2002b;Tumer et al, 2001) were measured in the adrenal medulla. In addition, changes in adrenomedullary angiotensin II (Ang II) AT 1 and AT 2 receptor subtype protein levels were also analyzed, since expressions and activities of TH and DβH are greatly influenced by Ang II (Jezova et al, 2003;Stachowiak et al, 1990;Takekoshi et al, 2000;Wong et al, 1990).…”