Effect of a 14-day hindlimb suspension on β-adrenoreceptors in rats

Bouzeghrane, Fatiha; Somody, Laurence; Gallo-Bona, Noëlle; Gauquelin‐Koch, Guillemette; Gharib, Claude; S, Fagette

doi:10.1016/s0742-8413(99)00015-8

Cited by 3 publications

(2 citation statements)

References 23 publications

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“…Indeed, besides the metabolic effects induced on muscle, immobilization affects also the metabolism of extra-muscular districts. Among these changes, it is noteworthy to mention the onset of an insulin-resistance syndrome (20), the increase of norepinephrine turnover in the brain (21), and the reduction of sympathetic nervous system activity (22).…”

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confidence: 99%

Enhanced expression of hepatic lipogenic enzymes in an animal model of sedentariness

Vecchini

Ceccarelli

Orvietani

et al. 2003

Journal of Lipid Research

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The hindlimb-suspended rat was used as animal model to investigate the effects induced by immobilization of the skeletal muscle in the expression of the genes encoding hepatic lipogenic enzymes. Following a 14-day period of immobilization, rats were injected intraperitoneally with radioactive acetate, and the labeling of hepatic lipids and cholesterol was evaluated 15 min after the isotope injection. The incorporation of labeled acetate in lipids and cholesterol was almost three times higher in the liver of immobilized rats than in control animals as a consequence of the enhanced transcription of the genes encoding acetyl-CoA synthase, acetyl-CoA carboxylase, fatty acid synthase, and 3-hydroxy-3-methylglutaryl-CoA reductase. The high expression of the key enzymes for fatty acid and cholesterol synthesis induced by immobilization was not paralleled by an increase of the hepatic sterol-regulatory element binding protein (SREBP)-1 and SREBP-2 mRNA content. However, the expression of the mature form of SREBP-1 and SREBP-2 was higher in the nuclear fraction of immobilized rat liver than in controls due to a significant increase of the cleavage of the native proteins. Immobilization also affected the expression of proteins involved in lipid degradation. In fact, the hepatic content of peroxisome proliferator-activated receptor-␣ (PPAR ␣ ) mRNA and of PPAR ␣ target genes encoding carnitine palmitoyl transferase-1 and acyl-CoA oxidase were significantly increased upon immobilization. -Vecchini, A., V. Ceccarelli, P. Orvietani, P. Caligiana, F. Susta, L. Binaglia, G. Nocentini, C. Riccardi, and P. Di Nardo.

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confidence: 99%

Enhanced expression of hepatic lipogenic enzymes in an animal model of sedentariness

Vecchini

Ceccarelli

Orvietani

et al. 2003

Journal of Lipid Research

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“…It might be explained by a combination of two observations: ®rstly, that secretion of catecholamines from the adrenal medulla was increased after sympathectomy (Kolibal-Pegher et al 1994); secondly, that the biochemical properties of cardiac b-adrenoceptors were unchanged after suspension (Bouzeghrane et al 1999). …”

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confidence: 99%

Effect of tail suspension on haemodynamics in intact and sympathectomized rats

Tarasova

Figourina²,

Зотов

et al. 2001

European Journal of Applied Physiology

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The effect of a 2-week tail suspension on mean arterial pressure (MAP) and pulse interval (PI) was studied in conscious chronically instrumented intact and sympathectomized rats. Sympathectomy was induced by 6-hydroxydopamine (100 mg x kg(-1), i.v.), injected 1 day before, and on days 5 and 10 of suspension. During suspension the intact rats had the same levels of MAP and PI as the intact controls. After release from suspension their MAP did not change: PI decreased (by 9%), but only for 1 h. Sympathectomy augmented the haemodynamic changes after release from suspension: tachycardia (10%) and hypotension (19%) were observed during the entire recording period (2 h). Therefore, in rats, post-suspension hypotension becomes apparent only after elimination of sympathetic influences. In spite of unaltered systemic parameters, intact post-suspension rats showed diminished responses to intravenous administration of tyramine (100 microg x kg(-1)) and phenylephrine (1-2 microg x kg(-1)). In addition, they showed augmented haemodynamic changes associated with natural behaviour. The increase of MAP and the decrease of PI on transition from rest to movement were more pronounced in the intact post-suspension rats than in the control rats (MAP 8.3% vs 4.5%, PI 15% vs 9%). In control rats the spectrum power density of low-frequency (0.0195-0.25 Hz) MAP fluctuations depended only weakly on behavioural activity, whereas in post-suspension intact rats it was profoundly augmented during movements (by 170%). Since the rapid adjustment of haemodynamics to behavioural activity is controlled by the sympathetic nervous system, the unbalanced condition of the cardiovascular system after suspension may reflect an altered sympathetic nerve control of the circulation.

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Blood pressure and mesenteric resistance arterial function after spaceflight

Hatton

Chapman

et al. 2002

Journal of Applied Physiology

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Ground studies indicate that spaceflight may diminish vascular contraction. To examine that possibility, vascular function was measured in spontaneously hypertensive rats immediately after an 18-day shuttle flight. Isolated mesenteric resistance arterial responses to cumulative additions of norepinephrine, acetylcholine, and sodium nitroprusside were measured using wire myography within 17 h of landing. After flight, maximal contraction to norepinephrine was attenuated (P < 0.001) as was relaxation to acetylcholine (P < 0.001) and sodium nitroprusside (P < 0.05). At high concentrations, acetylcholine caused vascular contraction in vessels from flight animals but not in vessels from vivarium control animals (P < 0.05). The results are consistent with data from ground studies and indicate that spaceflight causes both endothelial-dependent and endothelial-independent alterations in vascular function. The resulting decrement in vascular function may contribute to orthostatic intolerance after spaceflight.

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Effect of a 14-day hindlimb suspension on β-adrenoreceptors in rats

Cited by 3 publications

References 23 publications

Enhanced expression of hepatic lipogenic enzymes in an animal model of sedentariness

Enhanced expression of hepatic lipogenic enzymes in an animal model of sedentariness

Effect of tail suspension on haemodynamics in intact and sympathectomized rats

Blood pressure and mesenteric resistance arterial function after spaceflight

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