Short-term strength training and the expression of myostatin and IGF-I isoforms in rat muscle and tendon: differential effects of specific contraction types

2007 ◽  
Vol 102 (2) ◽  
pp. 573-581 ◽  
Author(s):  
K. M. Heinemeier ◽  
J. L. Olesen ◽  
P. Schjerling ◽  
F. Haddad ◽  
H. Langberg ◽  
...  
Keyword(s):  
Growth Factor ◽  
Medial Gastrocnemius ◽  
Mrna Levels ◽  
Eccentric Training ◽  
Sprague Dawley ◽  
Isometric Training ◽  
Specific Effects ◽  
Sprague Dawley Rats ◽  
Short Term Strength ◽  
Eccentric Actions

In skeletal muscle, an increased expression of insulin like growth factor-I isoforms IGF-IEa and mechano-growth factor (MGF) combined with downregulation of myostatin is thought to be essential for training-induced hypertrophy. However, the specific effects of different contraction types on regulation of these factors in muscle are still unclear, and in tendon the functions of myostatin, IGF-IEa, and MGF in relation to training are unknown. Female Sprague-Dawley rats were subjected to 4 days of concentric, eccentric, or isometric training ( n = 7–9 per group) of the medial gastrocnemius, by stimulation of the sciatic nerve during general anesthesia. mRNA levels for myostatin, IGF-IEa, and MGF in muscle and Achilles' tendon were measured by real-time RT-PCR. Muscle myostatin mRNA decreased in response to all types of training (2- to 8-fold) ( P < 0.05), but the effect of eccentric training was greater than concentric and isometric training ( P < 0.05). In tendon, myostatin mRNA was detected, but no changes were seen after exercise. IGF-IEa and MGF increased in muscle (up to 15-fold) and tendon (up to 4-fold) in response to training ( P < 0.01). In tendon no difference was seen between training types, but in muscle the effect of eccentric training was greater than concentric training for both IGF-IEa and MGF ( P < 0.05), and for IGF-IEa isometric training had greater effect than concentric ( P < 0.05). The results indicate a possible role for IGF-IEa and MGF in adaptation of tendon to training, and the combined changes in myostatin and IGF-IEa/MGF expression could explain the important effect of eccentric actions for muscle hypertrophy.

scholarly journals Differential Effects of Refeeding on Melanocortin-Responsive Neurons in the Hypothalamic Paraventricular Nucleus

Endocrinology ◽  
2008 ◽  
Vol 149 (9) ◽  
pp. 4329-4335 ◽  
Author(s):  
Edith Sánchez ◽  
Praful S. Singru ◽  
Runa Acharya ◽  
Monica Bodria ◽  
Csaba Fekete ◽  
...  
Keyword(s):  
Gene Expression ◽  
Paraventricular Nucleus ◽  
Hypothalamic Paraventricular Nucleus ◽  
Mrna Levels ◽  
Sprague Dawley ◽  
Early Action ◽  
Sprague Dawley Rats ◽  
Melanocortin Signaling ◽  
Agouti Related Protein ◽  
Serum Tsh

To explore the effect of refeeding on recovery of TRH gene expression in the hypothalamic paraventricular nucleus (PVN) and its correlation with the feeding-related neuropeptides in the arcuate nucleus (ARC), c-fos immunoreactivity (IR) in the PVN and ARC 2 h after refeeding and hypothalamic TRH, neuropeptide Y (NPY) and agouti-related protein (AGRP) mRNA levels 4, 12, and 24 h after refeeding were studied in Sprague-Dawley rats subjected to prolonged fasting. Despite rapid reactivation of proopiomelanocortin neurons by refeeding as demonstrated by c-fos IR in ARC α-MSH-IR neurons and ventral parvocellular subdivision PVN neurons, c-fos IR was present in only 9.7 ± 1.1% hypophysiotropic TRH neurons. Serum TSH levels remained suppressed 4 and 12 h after the start of refeeding, returning to fed levels after 24 h. Fasting reduced TRH mRNA compared with fed animals, and similar to TSH, remained suppressed at 4 and 12 h after refeeding, returning toward normal at 24 h. AGRP and NPY gene expression in the ARC were markedly elevated in fasting rats, AGRP mRNA returning to baseline levels 12 h after refeeding and NPY mRNA remaining persistently elevated even at 24 h. These data raise the possibility that refeeding-induced activation of melanocortin signaling exerts differential actions on its target neurons in the PVN, an early action directed at neurons that may be involved in satiety, and a later action on hypophysiotropic TRH neurons involved in energy expenditure, potentially mediated by sustained elevations in AGRP and NPY. This response may be an important homeostatic mechanism to allow replenishment of depleted energy stores associated with fasting.

scholarly journals Expression of nerve growth factor messenger RNA in pancreatic cancer tissues in Sprague Dawley rats

2005 ◽  
Vol 13 (18) ◽  
pp. 2227
Author(s):  
Zhu-Lin Yang ◽  
Xing-Hui Deng ◽  
Le-Ping Yang ◽  
Qing-Long Li ◽  
Wen-Tao Fan ◽  
...  
Keyword(s):  
Pancreatic Cancer ◽  
Nerve Growth Factor ◽  
Growth Factor ◽  
Messenger Rna ◽  
Sprague Dawley ◽  
Nerve Growth ◽  
Sprague Dawley Rats ◽  
Cancer Tissues

Epidermal growth factor accelerates renal tissue repair in a model of gentamicin nephrotoxicity in rats

1992 ◽  
Vol 263 (5) ◽  
pp. F806-F811 ◽  
Author(s):  
N. J. Morin ◽  
G. Laurent ◽  
D. Nonclercq ◽  
G. Toubeau ◽  
J. A. Heuson-Stiennon ◽  
...  
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Binding Sites ◽  
Renal Tissue ◽  
Sprague Dawley ◽  
Renal Tubular Cells ◽  
Sprague Dawley Rats ◽  
Epidermal Growth ◽  
Renal Tubular ◽  
Cessation Of Treatment

Epidermal growth factor (EGF) is a potent mitogen for renal tubular cells that possess specific high-affinity binding sites for this polypeptide. However, actual function of EGF within the kidney remains to be elucidated. We evaluated the effect of exogenous EGF administration on the rate of tubular regeneration in an experimental model of gentamicin (GT) nephrotoxicity. Female Sprague-Dawley rats were anesthetized, and a miniosmotic pump filled with mouse EGF or saline was implanted subcutaneously. Twenty-four hours later, GT (40 mg.kg-1 x 12 h-1 ip) was given for 4 and 8 days. Groups of treated animals and controls were killed either the day after cessation of treatment (days 5 and 9) or 4 and 8 days after the end of 8-day GT administration (days 12 and 16). Cortical GT levels of groups killed at days 5, 9, 12, and 16 were similar in animals infused with saline or EGF. Serum creatinine levels were significantly higher in GT-treated animals infused with EGF or saline and killed at days 9 and 12 compared with saline-treated animals infused with EGF or saline alone (P < 0.01). Blood urea nitrogen (BUN) also increased as a result of GT administration. However, in animals receiving GT and EGF and killed at day 16, mean BUN level was significantly lower (P < 0.01) compared with rats dosed with GT alone. In treated rats, the extent of tubular regeneration, evaluated by the rate of [3H]thymidine incorporation into renal cortical DNA or by the frequency of S-phase cells (histoautoradiography), was increased in a dose- and time-dependent fashion.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of TRH on thyrotroph function and number in rat pituitaries transplanted to renal capsule

1986 ◽  
Vol 251 (5) ◽  
pp. E563-E568
Author(s):  
S. Amr ◽  
S. S. Lippman ◽  
B. D. Weintraub
Keyword(s):  
Biologically Active ◽  
Constant Infusion ◽  
Control Group ◽  
Mrna Levels ◽  
Renal Capsule ◽  
Sprague Dawley ◽  
Subunit Mrna ◽  
Sprague Dawley Rats ◽  
Hypophysectomized Rats ◽  
Hypothalamic Influence

We investigated the function of thyrotrophs in rat pituitaries that were transplanted under the renal capsule of 3-wk-old male Sprague-Dawley rats, which were either intact or hypophysectomized. Groups of 12 animals were implanted with osmotic minipumps that delivered a constant infusion of either thyrotropin-releasing hormone (TRH; 1 mg X kg-1 X day-1) or normal saline for 1 wk. In hypophysectomized rats, TRH infusion led to the appearance of substantial amounts of biologically active serum TSH and prevented the hypothyroidism that occurred in the control group. However, TRH did not change the transplant contents of DNA, immunoactive TSH, and mRNA levels for TSH subunits. Comparison of sellar and renal pituitary tissues, obtained from intact rats after 1 wk of either saline or TRH infusion, showed that removal of the pituitary from hypothalamic influence resulted in a 90% depletion of the thyrotroph TSH content. TRH infusion depleted only 63% of the TSH content of sellar thyrotrophs. The mRNA levels for TSH beta-subunit were similar in sellar and transplanted pituitaries and did not significantly change after TRH infusion. When immunocytochemically stained using rat TSH antiserum, the thyrotrophs in pituitary transplants were morphologically and numerically indistinguishable from the thyrotrophs in sellar pituitaries, in the presence or absence of TRH. These data indicate that in transplanted pituitary, for up to 1 wk of a constant infusion, TRH does not significantly affect either the number of thyrotrophs or their ability to synthesize TSH subunit mRNA. However, it is required to maintain released TSH in circulation, since TSH levels were low in the absence of TRH.(ABSTRACT TRUNCATED AT 250 WORDS)

Dietary cholesterol stimulates CYP7A1 in rats because farnesoid X receptor is not activated

2004 ◽  
Vol 286 (5) ◽  
pp. G730-G735 ◽  
Author(s):  
Guorong Xu ◽  
Lu-xing Pan ◽  
Hai Li ◽  
Quan Shang ◽  
Akira Honda ◽  
...  
Keyword(s):  
Bile Acid ◽  
Target Genes ◽  
Dietary Cholesterol ◽  
Farnesoid X Receptor ◽  
Mrna Levels ◽  
Sprague Dawley ◽  
Bile Acid Pool ◽  
Acid Pool ◽  
Sprague Dawley Rats ◽  
Bile Acid Pool Size

Cholesterol feeding upregulates CYP7A1 in rats but downregulates CYP7A1 in rabbits. To clarify the mechanism responsible for the upregulation of CYP7A1 in cholesterol-fed rats, the effects of dietary cholesterol (Ch) and cholic acid (CA) on the activation of the nuclear receptors, liver X-receptor (LXR-α) and farsenoid X-receptor (FXR), which positively and negatively regulate CYP7A1, were investigated in rats. Studies were carried out in four groups ( n = 12/group) of male Sprague-Dawley rats fed regular chow (control), 2% Ch, 2% Ch + 1% CA, and 1% CA alone for 1 wk. Changes in mRNA expression of short heterodimer partner (SHP) and bile salt export pump (BSEP), target genes for FXR, were determined to indicate FXR activation, whereas the expression of ABCA1 and lipoprotein lipase (LPL), target genes for LXR-α, reflected activation. CYP7A1 mRNA and activity increased twofold and 70%, respectively, in rats fed Ch alone when the bile acid pool size was stable but decreased 43 and 49%, respectively, after CA was added to the Ch diet, which expanded the bile acid pool 3.4-fold. SHP and BSEP mRNA levels did not change after feeding Ch but increased 88 and 37% in rats fed Ch + CA. This indicated that FXR was activated by the expanded bile acid pool. When Ch or Ch + CA were fed, hepatic concentrations of oxysterols, ligands for LXR-α increased to activate LXR-α, as evidenced by increased mRNA levels of ABCA1 and LPL. Feeding CA alone enlarged the bile acid pool threefold and increased the expression of both SHP and BSEP. These results suggest that LXR-α was activated in rats fed both Ch or Ch + CA, whereas CYP7A1 mRNA and activity were induced only in Ch-fed rats where the bile acid pool was not enlarged such that FXR was not activated. In rats fed Ch + CA, the bile acid pool expanded, which activated FXR to offset the stimulatory effects of LXR-α on CYP7A1.

scholarly journals Intergenic bidirectional promoter and cooperative regulation of the IIx and IIb MHC genes in fast skeletal muscle

2008 ◽  
Vol 295 (1) ◽  
pp. R208-R218 ◽  
Author(s):  
Chiara Rinaldi ◽  
Fadia Haddad ◽  
Paul W. Bodell ◽  
Anqi X. Qin ◽  
Weihua Jiang ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Antisense Rna ◽  
Bidirectional Promoter ◽  
Regulatory Elements ◽  
Feedback Mechanism ◽  
Medial Gastrocnemius ◽  
Mrna Levels ◽  
Sprague Dawley ◽  
Dynamic Regulation ◽  
Mhc Genes

This study investigated the dynamic regulation of IIx-IIb MHC genes in the fast white medial gastrocnemius (WMG) muscle in response to intermittent resistance exercise training (RE), a model associated with a rapid shift from IIb to IIx expression ( 11 ). We investigated the effect of 4 days of RE on the transcriptional activity across the skeletal MHC gene locus in the WMG in female Sprague-Dawley rats. Our results show that RE resulted in significant shifts from IIb to IIx observed at both the pre-mRNA and mRNA levels. An antisense RNA (xII NAT) was detected in the intergenic (IG) region between IIx and IIb, extending across the entire IIx gene and into its promoter. The expression of the xII NAT was positively correlated with IIb pre-mRNA ( R = +0.8), and negatively correlated with IIx pre-mRNA ( R = −0.8). Transcription mapping of the IIx–IIb IG region revealed the generation of sense IIb and xII NATs from a single promoter region. This bidirectional promoter is highly conserved among species and contains several regulatory elements that may be implicated in its regulation. These results suggest that the IIx and the IIb genes are physically and functionally linked via the bidirectional promoter. In order for the IIx MHC gene to be regulated, a feedback mechanism from the IG xII NAT is needed. In conclusion, the IG bidirectional promoter generating antisense RNA appears to be essential for the coordinated regulation of the skeletal muscle MHC genes during dynamic phenotype shifts.

Weight reduction increases adipose but decreases cardiac LPL in reduced-obese Zucker rats

1991 ◽  
Vol 261 (2) ◽  
pp. E246-E251 ◽  
Author(s):  
D. H. Bessesen ◽  
A. D. Robertson ◽  
R. H. Eckel
Keyword(s):  
Adipose Tissue ◽  
Cardiac Muscle ◽  
Weight Reduction ◽  
Zucker Rats ◽  
Mrna Levels ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
Obese Rats ◽  
Obese Zucker Rats ◽  
Coordinate Changes

Lipoprotein lipase (LPL) activity and mRNA levels were measured in cardiac muscle and adipose tissue from lean, obese, and weight-stable reduced-obese Zucker rats, both fasted and 2 h after feeding. Fasting epididymal fat LPL activity was substantially higher in obese rats relative to lean rats [6.9 vs. 0.2 nmol free fatty acid (FFA).10(6) cells-1.min-1; P = 0.0001], and was higher still in reduced-obese rats (15.7 nmol FFA.10(6) cells-1.min-1; P = 0.002). Adipose tissue LPL increased with feeding in all three groups. In marked contrast, fasting cardiac muscle LPL was lower in obese rats relative to lean (28.8 vs. 38.5 nmol FFA.g-1.min-1; P = 0.0064) and was lower still in reduced-obese rats (14.5 nmol FFA.g-1.min-1; P = 0.0001). LPL mRNA levels increased in adipose tissue along with enzyme activity; however, the magnitude of the changes were relatively small, suggesting that the primary regulatory steps are posttranslational. Weight reduction studies were also carried out in Sprague-Dawley rats with similar results. These studies show that sustained weight reduction results in coordinate changes in tissue-specific LPL, favoring delivery of lipoprotein triglyceride fatty acids to adipose tissue relative to cardiac muscle and the restoration of energy stores.

Sign in / Sign up

Export Citation Format

Share Document