Chronic physical stress changes gene expression of catecholamine biosynthetic enzymes in the adrenal medulla of adult rats

Abstract

In this study we examined how chronic forced running (CFR) affects the expression of catecholamine biosynthetic enzymes and cAMP response element-binding (CREB) in the adrenal medulla and the weight of adrenal glands of rats. Also, we examined how CFR and additional acute immobilization stress affect the expression of catecholamine biosynthetic enzymes in the adrenal medulla and the concentration of catecholamines and corticosterone (CORT) in the blood plasma. In this experiment we used as a model forced exercise in rats (treadmill running). We used the most advanced method for determining the level of gene expression, Real-time PCR with TaqMan probes, as well as Western blot analysis (ECL). We found that CFR decreases tyrosine hydroxylase (TH), and dopamine-β-hydroxylase (DBH) mRNA and protein levels in the adrenal medulla. The decreased TH and DBH mRNA levels coincide with the reduced expression of CREB in the adrenal medulla and with the reduced plasma CORT level. Additionally, CFR reduces the level of phenylethanolamine N-methyltransferase (PNMT) mRNA, but elevates its protein level in the adrenal medulla and increases the concentration of adrenaline (A) in the plasma. Reduced level of PNMT mRNA in the adrenal medulla coincides with reduced plasma CORT level. The additional acute immobilization stress increases gene expression of catecholamine biosynthetic enzymes in the adrenal medulla, as well as catecholamines and CORT levels in the plasma. The increased synthesis of PNMT enzyme in the adrenal medulla may result in an increased biosynthesis of A under chronic stress conditions. Additionally, increased level of catecholamines in the plasma after chronic physical stress is the allostatic load that may induce numerous diseases and pathological conditions

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

“…In this work, animals exposed to CSITR are already prepared to manage the new situation evoked by a novel stressor and the exaggerated response is not necessary. Our results, together with In our previous study we showed that long-term isolation had induced a reduction gene expression of catecholamine biosynthetic enzymes in the adrenal medulla (Gavrilović et al 2008). Also, in the present study we have found that the CSITR has induced a reduction of TH and DBH mRNAs and protein levels in the adrenal medulla.…”

“…Immobilization is frequently used as an additional acute stressor and considered as one of the most intensive stressors that significantly changes gene expression (Kvetnansky et al 2009). Our previous data showed that exposure of socially isolated rats to additional immobilization produced exaggerated responses in gene expression of catecholamine biosynthetic enzymes in the adrenal medulla (Gavrilović et al 2008). The response to novel additional acute immobilization stress might reveal the detailed mechanisms underlying the gene expression of catecholamine biosynthetic enzymes in the adrenal medulla in specific stress conditions.…”

“…Our earlier studies showed that long-term social isolation (12 weeks) of adult rat males produced a decreased gene expression of catecholamine biosynthetic enzymes in the adrenal medulla (Gavrilović et al 2008), and increased concentrations of catecholamines in the plasma (Gavrilović et al 2010). In this study we wanted to investigate whether treadmill exercise changed the activity of sympatho-adrenomedullary system of chronically psychosocially stressed rats.…”

Chronic Individual Housing-Induced Stress Decreased Expression of Catecholamine Biosynthetic Enzyme Genes and Proteins in Spleen of Adult Rats

“…Reverse transcription was performed employing Ready-To-Go You-Prime First-Strand Bead (Amersham Pharmacia Biotech, Uppsala, Sweden) and pd (N) 6 primer according to the manufacturer's protocol. Real-time RT-PCR assay was done exactly as previously described [21] . PCRs were performed in the ABI Prism 7,000 Sequence Detection System at 50 ° C for 2 min, 95 ° C for 10 min, followed by 40 cycles at 95 ° C for 15 s and 60 ° C for 1 min.…”

“…A reference, endogenous control, was included in each analysis to correct the differences in the interassay amplification efficiency and all transcripts were normalized to cyclophilin A (ID: Rn 00690933) expression. Western blot analysis was performed as previously described [21] . For measuring TH, DBH and PNMT protein levels, a monoclonal primary antibody against murine TH (monoclonal antibody against TH from mouse-mouse hybrid cells, clone 2/40/15, dilution 1: 5,000), anti-DBH (N-terminal) antibody, human (dilution 1: 1,000, Sigma) and polyclonal anti-PNMT primary antibody, and rabbit (dilution 1: 1,000, Protos Biotech Corp., New York, N.Y., USA), respectively, were used.…”