Interaction of compensatory overload and hindlimb suspension on myosin isoform expression

1987 ◽  
Vol 62 (6) ◽  
pp. 2180-2186 ◽  
Author(s):  
R. W. Tsika ◽  
R. E. Herrick ◽  
K. M. Baldwin
Keyword(s):  
Specific Activity ◽  
Weight Bearing ◽  
Muscle Growth ◽  
The Other ◽  
Female Rats ◽  
Hindlimb Suspension ◽  
Simultaneous Exposure ◽  
Slow Myosin ◽  
Fast Myosin ◽  
Isoform Expression

The purpose of this study was to investigate the role of chronic weight-bearing activity as the primary inducer of compensatory muscle growth and changes in myosin isoform expression in rodent fast-twitch plantaris muscle. Thus, female rats were subjected to the independent and simultaneous exposure of functional overload (induced via synergist removal) and hindlimb unweighting (suspension) for 6 wk. Groups (n = 7/group) consisted of normal-control (NC); overload (OV); normal-suspension (N-SUS); and overload-suspension (OV-SUS). Body weight of both suspension groups was significantly less than both the NC and OV groups (P less than 0.001). Compared with the NC group, normalized plantaris weight (mg/g body wt) of both the OV and OV-SUS groups was greater, whereas that of the N-SUS was lower (P less than 0.001). However, normalized plantaris weight was greater in OV compared with OV-SUS by 35% (P less than 0.001). Myofibril protein content (mg/g) and Ca2+-regulated myofibril adenosinetriphosphatase (ATPase) specific activity were similar for all groups except that ATPase was lower in the OV group compared with the other groups (P less than 0.05). Native myosin isoform analysis revealed a significant increase in the expression of slow and intermediate myosin and the repression of fast myosin 1 (Fm1) in OV compared with NC. This shift in expression was not as pronounced in the OV-SUS group. Interestingly, only traces of slow myosin were observed in the N-SUS group compared with the other groups. These results suggest that weight bearing is an essential component of the overload model for inducing significant increases in both muscle mass and slow myosin isoform expression. Second, lack of weight bearing, while not markedly affecting fast myosins, appears to repress the expression of slow myosin.

Role of glucose transport in glycogen supercompensation in reweighted rat skeletal muscle

1996 ◽  
Vol 80 (5) ◽  
pp. 1540-1546 ◽  
Author(s):  
E. J. Henriksen ◽  
C. S. Stump ◽  
T. H. Trinh ◽  
S. D. Beaty
Keyword(s):  
Glucose Transport ◽  
Citrate Synthase ◽  
Specific Activity ◽  
Glycogen Synthase ◽  
Average Rate ◽  
Weight Bearing ◽  
Hindlimb Suspension ◽  
Transport Activity ◽  
Glut 4 ◽  
Insulin Dependent

Hindlimb weight bearing after a 3-day period of hindlimb suspension (reweighting) of juvenile rats results in a marked transient elevation in soleus glycogen concentration that cannot be explained on the basis of the activities of glycogen synthase and phosphorylase. We have hypothesized that enhanced glucose transport activity could underlie this response. We directly tested this hypothesis by assessing the response of insulin-dependent and insulin-independent glucose transport activity (in vitro 2-[1,2-3H]deoxy-D-glucose uptake) as well as glucose transporter (GLUT-4) protein levels during a 48-h reweighting period. After a net glycogen loss (from 29 +/- 2 to 16 +/- 1 nmol/mg muscle; P < 0.05) during the first 2 h of reweighting, glycogen accumulated at an average rate of 1.4 nmol.mg-1.h-1 up to 18 h, reaching an apex of 38 +/- 1 nmol/mg. During this same reweighting period, insulin-independent, but not insulin-dependent, glucose transport activity was significantly enhanced (P < 0.05 vs. weight-bearing control values) and was associated with an elevated level of GLUT-4 protein and the specific activity of total hexokinase. The specific activity of citrate synthase was also increased. By 24 h of reweighting, although insulin-independent glucose transport activity and GLUT-4 protein remained elevated, glycogen accumulation had ceased, likely due to enhanced phosphorylase activity at this time point. These results are consistent with the interpretation that the glycogen supercompensation seen during reweighting of the rat soleus may be regulated in part by an enhanced glucose flux arising from an increase in insulin-independent glucose transport activity and hexokinase activity.

beta-MHC transgene expression in suspended and mechanically overloaded/suspended soleus muscle of transgenic mice

1997 ◽  
Vol 272 (5) ◽  
pp. R1552-R1561 ◽  
Author(s):  
J. J. McCarthy ◽  
A. M. Fox ◽  
G. L. Tsika ◽  
L. Gao ◽  
R. W. Tsika
Keyword(s):  
Transgenic Mice ◽  
Soleus Muscle ◽  
Transgene Expression ◽  
Specific Activity ◽  
Fiber Type ◽  
Weight Bearing ◽  
Troponin C ◽  
Hindlimb Suspension ◽  
Regulatory Sequences ◽  
Type I

Non-weight-bearing (NWB) activity [space flight and hindlimb suspension (HS)] results in the loss of soleus muscle mass, a slow-to-fast fiber-type conversion, and decreased beta-myosin heavy chain (beta-MHC) protein and mRNA expression. To identify beta-MHC promoter sequences required for decreased beta-MHC expression in response to HS, we have modified an existing noninvasive hindlimb unweighting model to accommodate the use of (transgenic) mice. After 2 wk of HS, body and muscle (soleus > gastrocnemius > plantaris) weights were decreased as was the proportion of histochemically classified type I fibers in HS soleus muscle. Northern blot analysis revealed decreases in endogenous mRNA representing beta-MHC, slow myosin light chain 1 and 2, and cardiac/slow troponin C, whereas those representing skeletal troponin C, muscle creatine kinase, and glyceraldehyde-3-phosphate dehydrogenase increased. Protein extracts prepared from HS soleus (SS) muscle of mice harboring transgenes comprised of 5.6 or 0.6 kilobase of wild type (wt) mouse beta-MHC promoter (beta 5.6 wt, beta 0.6wt) and those carrying the simultaneous mutation (mut) of the MCAT, C-rich, and beta e3 subregions (beta 5.6mut3, beta 0.6mut3) revealed decreases in chloramphenicol acetyltransferase (CAT) specific activity relative to respective controls. Decreased CAT mRNA was observed for transgene beta 5.6mut3, line 85. Two weeks of the simultaneous imposition of mechanical overload (synergist ablation) and HS (MOV/HS) countermanded the loss in absolute and normalized SS weight but did not decrease beta 0.6wt transgene expression. These transgenic results demonstrate that regulatory sequences within a 600-base pair beta-MHC promoter are sufficient to direct decreased transcription of beta-MHC transgenes after 2 wk of HS.

scholarly journals Skeletal muscle fiber atrophy: altered thin filament density changes slow fiber force and shortening velocity

2005 ◽  
Vol 288 (2) ◽  
pp. C360-C365 ◽  
Author(s):  
D. A. Riley ◽  
J. L. W. Bain ◽  
J. G. Romatowski ◽  
R. H. Fitts
Keyword(s):  
Thin Filament ◽  
Weight Bearing ◽  
Hindlimb Suspension ◽  
Shortening Velocity ◽  
Cross Sectional ◽  
Thin Filaments ◽  
Specific Tension ◽  
Fast Myosin ◽  
Working Length ◽  
Filament Spacing

Single skinned fibers from soleus and adductor longus (AL) muscles of weight-bearing control rats and rats after 14-day hindlimb suspension unloading (HSU) were studied physiologically and ultrastructurally to investigate how slow fibers increase shortening velocity ( V0) without fast myosin. We hypothesized that unloading and shortening of soleus during HSU reduces densities of thin filaments, generating wider myofilament separations that increase V0 and decrease specific tension (kN/m2). During HSU, plantarflexion shortened soleus working length 23%. AL length was unchanged. Both muscles atrophied as shown by reductions in fiber cross-sectional area. For AL, the 60% atrophy accounted fully for the 58% decrease in absolute tension (mN). In the soleus, the 67% decline in absolute tension resulted from 58% atrophy plus a 17% reduction in specific tension. Soleus fibers exhibited a 25% reduction in thin filaments, whereas there was no change in AL thin filament density. Loss of thin filaments is consistent with reduced cross bridge formation, explaining the fall in specific tension. V0 increased 27% in soleus but was unchanged in AL. The V0 of control and HSU fibers was inversely correlated ( R = −0.83) with thin filament density and directly correlated ( R = 0.78) with thick-to-thin filament spacing distance in a nonlinear fashion. These data indicate that reduction in thin filament density contributes to an increased V0 in slow fibers. Osmotically compacting myofilaments with 5% dextran returned density, spacing, and specific tension and slowed V0 to near-control levels and provided evidence for myofilament spacing modulating tension and V0.

scholarly journals 6-Carboxymethyl genistein: a novel selective oestrogen receptor modulator (SERM) with unique, differential effects on the vasculature, bone and uterus

2002 ◽  
Vol 173 (3) ◽  
pp. 415-427 ◽  
Author(s):  
D Somjen ◽  
Y Amir-Zaltsman ◽  
B Gayer ◽  
T Kulik ◽  
E Knoll ◽  
...  
Keyword(s):  
Molecular Modelling ◽  
Oestrogen Receptor ◽  
Specific Activity ◽  
The Other ◽  
Female Rats ◽  
Rat Tissues ◽  
Receptor Modulator ◽  
Other Hand ◽  
Selective Oestrogen Receptor Modulator

The novel genistein (G) derivative, 6-carboxymethyl genistein (CG) was evaluated for its biological properties in comparison with G. Both compounds showed oestrogenic activity in vitro and in vivo. On the other hand G and CG differed in the following parameters: (i) only CG displayed mixed agonist-antagonist activity for oestrogen receptor (ER) alpha in transactivation assays and (ii) only CG was capable of attenuating oestrogen (E(2))-induced proliferation in vascular smooth muscle cells and of inhibiting oestrogen-induced creatine kinase (CK) specific activity in rat tissues. On the other hand only G enhanced the stimulatory effect on CK specific activity in the uterus. In comparison to the selective oestrogen receptor modulator (SERM) raloxifene (RAL), CG showed the same selectivity profile as RAL in blocking the CK response to E(2) in tissues derived from both immature and ovariectomized female rats. Molecular modelling of CG bound to the ligand binding domain (LBD) of ERbeta predicts that the 6-carboxymethyl group of CG almost fits the binding cavity. On the other hand, molecular modelling of CG bound to the LBD of ERalpha suggests that the carboxyl group of CG may perturb the end of Helix 11, eliciting a severe backbone change for Leu 525, and consequently induces a conformational change which could position Helix 12 in an antagonist conformation. This model supports the experimental findings that CG can act as a mixed agonist-antagonist when E(2) is bound to its receptors. Collectively, our findings suggest that CG can be considered a novel SERM with unique effects on the vasculature, bone and uterus.

Influence of weight bearing on the adaptations of rat plantaris to ablation of its synergists

1989 ◽  
Vol 67 (2) ◽  
pp. 636-642 ◽  
Author(s):  
R. N. Michel ◽  
A. E. Olha ◽  
P. F. Gardiner
Keyword(s):  
Weight Bearing ◽  
Female Rats ◽  
Hindlimb Suspension ◽  
Cross Sectional ◽  
Time To Peak ◽  
Fast Fiber ◽  
Expression Characteristic ◽  
St Number ◽  
Isometric Twitch ◽  
Whole Muscle

The present study was designed to determine the contribution of weight bearing to the adaptations of the plantaris (PL) to synergist removal. PL from female rats were exposed to 28 days of a simultaneous condition of synergist ablation and hindlimb suspension. At 28 days, contractile responses and morphological measures were obtained and compared with muscles that either had synergists intact or were weight bearing or a combination of both. Synergist ablation prolonged PL maximum isometric twitch tension (Pt), time to peak tension (12%), and one-half relaxation time (12%); increased Pt (26%), maximum isometric tetanic tension (Po, 44%), fatigue resistance (FI, 42%), and fast fiber cross-sectional area (FT CSA, 20%); and decreased Pt/Po (13%) over nonablation counterparts. Suspension decreased PL Pt (26%), Po (26%), rest length (16%), FT CSA (31%), and slow-twitch fiber (ST) number (24%) but increased FI (75%) over weight-bearing counterparts. PL from weight-bearing animals were heavier than from suspended animals, and the extent of this response was greatest after synergist removal. Whole muscle and ST CSA and ST area contribution were greater only in weight-bearing synergist ablation muscles. Daily weight bearing (4 h) in synergist ablation hindlimb suspension groups caused PL weights and ST expressions to be halfway between 24-h suspension and 24-h weight-bearing groups. Our results suggest that weight bearing is not essential to the induction of several adaptations associated with synergist ablation but is required to cause the large muscle mass and ST expression characteristic of this model.

Activity influences on soleus muscle myosin during rodent hindlimb suspension

1987 ◽  
Vol 63 (1) ◽  
pp. 138-144 ◽  
Author(s):  
D. B. Thomason ◽  
R. E. Herrick ◽  
K. M. Baldwin
Keyword(s):  
Normal Control ◽  
Soleus Muscle ◽  
Hindlimb Suspension ◽  
Muscle Weight ◽  
Slow Myosin ◽  
Hindlimb Unweighting ◽  
Ground Support ◽  
Fast Myosin ◽  
Cage Activity ◽  
Muscle Pair

This study examined the effect of stationary ground support (2 and 4 h/day) and uphill running (1.5 h/day, 20 m/min, 30% grade) activity patterns on soleus muscle atrophy and slow myosin loss during 4 wk of rodent hindlimb unweighting by tail suspension. We also examined the effect of uphill running during the last 4 wk of an 8-wk hindlimb unweighting program and during 4 wk of cage recovery after 4 wk of hindlimb unweighting. All forms of activity partially spared soleus muscle weight (mg), myofibril protein (mg/muscle pair and microgram/mg muscle), and relative and absolute slow myosin (SM) isoform content (% of total and mg/muscle pair, P less than 0.05). Relative to the normal control soleus muscle, the uphill running regimens resulted in 1) increased fast myosin isoform content and 2) diminished recovery of SM isoform content when coupled with cage activity recovery. Four weeks of cage recovery after 4 wk of hindlimb unweighting resulted in recovery of the relative SM isoform content to proportions exceeding normal control values, suggesting an apparent degradation of any normally existing fast myosin. These results indicate that, in the context of the hindlimb unweighting model, the mechanisms controlling the expression of soleus muscle SM and fast myosin genes can be affected differently by the diverse activities of stationary ground support, unrestricted cage activity, and programmed uphill running.

Hindlimb suspension suppresses muscle growth and satellite cell proliferation

1989 ◽  
Vol 67 (5) ◽  
pp. 1827-1834 ◽  
Author(s):  
K. C. Darr ◽  
E. Schultz
Keyword(s):  
Satellite Cell ◽  
Satellite Cells ◽  
Proliferative Activity ◽  
Weight Bearing ◽  
Muscle Growth ◽  
Experimental Period ◽  
Postnatal Growth ◽  
Longitudinal Growth ◽  
Hindlimb Suspension ◽  
Morphological Maturation

The effects of long-term hindlimb unweighting by tail suspension on postnatal growth of 20-day rat extensor digitorum longus (EDL) and soleus muscles were studied. Morphological assay indicated that radial growth of soleus myofibers was completely inhibited between 3 and 10 days of suspension and reduced thereafter, leading to a severe attenuation (-76% from control) over the total experimental period. Longitudinal growth rate, however, was accelerated 40% over weight-bearing controls. In addition, myofibers were arranged parallel to the long axis of the muscle, an orientation associated with chronologically younger muscles, suggesting morphological maturation of the soleus muscle had been delayed by suspension. In contrast, radial and longitudinal growth of EDL myofibers were minimally affected under similar conditions and remained within approximately 5% of control at all times. Suspension also influenced the normal changes that occur in satellite cell and myonuclear populations during postnatal growth. Both the number and proliferative activity of satellite cells were severely reduced in individual myofibers after only 3 days in both soleus and EDL muscles. The reduced number of satellite cells within 3 days of initiating hindlimb suspension appeared to be the result of their incorporation into myofibers while the long-lasting reduction appeared to be the added effects of decreased proliferative activity. In the soleus, this reduction in number and proliferation of satellite cells persisted throughout the experimental period and resulted in an overall 43% fewer myonuclei and 45% fewer satellite cells than control at 50 days of age. In contrast, both the total number and mitotic activity of satellite cells in the EDL rapidly returned to weight-bearing control levels by day 10 of suspension, resulting in no overall reduction in myonuclear accretion.

scholarly journals Baropodometric technology used to analyze types of weight-bearing during hemiparetic upright position

2012 ◽  
Vol 25 (3) ◽  
pp. 583-594 ◽  
Author(s):  
Lidiane Teles de Menezes ◽  
Paulo Henrique Ferreira de Araujo Barbosa ◽  
Abraão Souza Costa ◽  
Anderson Castro Mundim ◽  
Gabrielly Craveiro Ramos ◽  
...  
Keyword(s):  
Healthy Subjects ◽  
Center Of Pressure ◽  
Weight Bearing ◽  
Upright Position ◽  
The Other ◽  
Control Group ◽  
Gender And Age ◽  
Coordination System ◽  
Support Area ◽  
Arch Index

INTRODUCTION: Although baropodometric analysis has been published since the 1990s, only now it is found a considerable number of studies showing different uses in the rehabilitation. OBJECTIVE: To amplify the use of this technology, this research aimed to analyze baropodometric records during upright position of subjects with hemiparesis, describing a way to define weight-bearing profiles in this population. METHOD: 20 healthy subjects were matched by gender and age with 12 subjects with chronic spastic hemiparesis. This control group was formed to establish the limits of symmetry during weight-bearing distribution in the hemiparesis group. Next, hemiparesis group was submitted to procedures to measure baropodometric records used to provide variables related to the weight-bearing distribution, the arch index and the displacements in the center of pressure (CoP). Data were used to compare differences among kinds of weight-bearing distribution (symmetric, asymmetric toward non-paretic or paretic foot) and coordination system for CoP displacements. RESULTS: Hemiparesis group was compounded by eight symmetrics, eight asymmetrics toward non-paretic foot and four asymmetric toward paretic foot. Significant differences in the weight-bearing distributions between non-predominantly and predominantly used foot did not promote differences in the other baropodometric records (peak and mean of pressure, and support area). Mainly in the asymmetry toward non-paretic foot it was observed significant modifications of the baropodometric records. CONCLUSION: Baropodometric technology can be used to analyze weight-bearing distribution during upright position of subjects with hemiparesis, detecting different kinds of weight-bearing profiles useful to therapeutic programs and researches involving subjects with this disability.

Effects of the aqueous extract of Dicliptera verticillata on fertility and different stages of gestation in female rats

Zygote ◽  
2021 ◽  
pp. 1-7
Author(s):  
Stéphanie Ouabo Meguem ◽  
Landry Lienou Lienou ◽  
Marie Stéphanie Chekem Goka ◽  
Richard Simo Tagne ◽  
Didiane Mefokou Yemele ◽  
...  
Keyword(s):  
Medicinal Plant ◽  
Aqueous Extract ◽  
Implantation Rate ◽  
The Other ◽  
Female Rats ◽  
High Dose ◽  
Immature Female ◽  
Implantation Sites ◽  
Parameters Analysis ◽  
Hepatic Proteins

Summary Dicliptera verticillata is a medicinal plant traditionally used in western Cameroon to cure female infertility. This experiment was designed to assess the effects of the aqueous extract of Dicliptera verticillata (AEDv) on fertility and gestation in female rats. Oral increasing doses of AEDv were administered to immature female rats over 20 d. After this time, some animals were mated with fertile males and some fertility parameters were assayed; the other animals were euthanized for preliminary toxicity parameters analysis. The effects of AEDv on the different stages of gestation were assayed on selected animals previously controlled for estrous cycle regularity and mated. AEDv led to an increase in serum, uterine and ovarian proteins as well as in ovarian and uterine weights (P < 0.05) in immature female rats. Hepatic proteins significantly decreased (P < 0.01) in high dose-treated animals (50 and 100 mg/kg) compared with controls. The number of implantation sites and the fertility rate were significantly lower (P < 0.05), while the antifertility activity increased significantly (P < 0.05) in treated rats compared with controls. When administered from the 1st to the 5th day of pregnancy, AEDv led to a decrease of more than 60% in the implantation rate in high dose-treated rats (50, 100, and 400 mg/kg). From the 6th to the 9th day, the implantation, gestation rates and the number of fetuses decreased significantly in all treated groups. From the 11th to the 20th day, a 50% resorption and decrease in gestation rate were reported in 50 mg/kg dose-treated animals. AEDv possesses weak contraceptive and abortifacient effects during pregnancy.

scholarly journals Progesterone after Estradiol Modulates Shuttle-Cage Escape by Facilitating Volition

2015 ◽  
Vol 9s1 ◽  
pp. JEN.S32735
Author(s):  
Darryl J. Mayeaux ◽  
Sarah M. Tandle ◽  
Sean M. Cilano ◽  
Matthew J. Fitzharris
Keyword(s):  
Depressive Symptoms ◽  
Animal Models ◽  
Electric Shock ◽  
Ovarian Hormones ◽  
Learning Task ◽  
The Other ◽  
Female Rats ◽  
Animal Models Of Depression ◽  
Escape Learning

In animal models of depression, depression is defined as performance on a learning task. That task is typically escaping a mild electric shock in a shuttle cage by moving from one side of the cage to the other. Ovarian hormones influence learning in other kinds of tasks, and these hormones are associated with depressive symptoms in humans. The role of these hormones in shuttle-cage escape learning, however, is less clear. This study manipulated estradiol and progesterone in ovariectomized female rats to examine their performance in shuttle-cage escape learning without intentionally inducing a depressive-like state. Progesterone, not estradiol, within four hours of testing affected latencies to escape. The improvement produced by progesterone was in the decision to act, not in the speed of learning or speed of escaping. This parallels depression in humans in that depressed people are slower in volition, in their decisions to take action.

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