• Molecules and Cells
• /
• v.20 no.2
• /
• pp.263-270
• /
• 2005

Transactivation of EGF-receptor (EGFR) by G-protein coupled receptors (GPCRs) is emerging as an important pathway in cell proliferation, which plays a crucial role in the development of atherosclerotic lesion. Angiotensin II (Ang II) has been identified to have a major role in the formation of atherosclerotic lesions, although the underlying mechanisms remain largely unclear. We hypothesize that Ang II promotes the proliferation and migration of smooth muscle cells through the release of heparin-binding epidermal growth factor like growth factor (HB-EGF), transactivation of EGFR and activation of Akt and Erk 1/2, with matrix metalloproteases (MMPs) playing a dispensable role. Primary rat aortic smooth muscle cells were used in this study. Smooth muscle cells rendered quiescent by serum deprivation for 12 h were treated with Ang II (100 nM) in the presence of either GM6001 ($20{\mu}M$), a specific inhibitor of MMPs or AG1478 ($10{\mu}M$), an inhibitor of EGFR. The levels of phosphorylation of EGFR, Akt and Erk 1/2 were assessed in the cell lysates. Inhibition of MMPs by GM6001 significantly attenuated Ang II-stimulated phosphorylation of EGFR, suggesting that MMPs may be involved in the transactivation of EGFR by Ang II receptor. Furthermore Ang II-stimulated proliferation and migration of smooth muscle cells were significantly blunted by inhibiting MMPs and EGFR and applying HB-EGF neutralization antibody, indicating that MMPs, HB-EGF and EGFR activation is necessary for Ang-II stimulated migration and proliferation of smooth muscle cells. Our results suggest that inhibition of MMPs may represent one of the strategies to counter the mitogenic and motogenic effects of Ang II on smooth muscle cells and thereby prevent the formation and development of atherosclerotic lesions.

• Journal of Oral Medicine and Pain
• /
• v.42 no.4
• /
• pp.109-115
• /
• 2017

Purpose: This study analyzed the effects of digastric muscle injury on mandibular growth in young rats. Methods: Fourteen 4-week-old Wistar rats were divided into 3 groups; experimental group A (n=6) with unilateral (right) shortening of the posterior digastric muscle, experimental group B (n=6) with bilateral shortening of the posterior digastric muscles, and control group C (n=2) who underwent a sham operation. Eight weeks after the operation all animals were sacrificed and the outcomes were compared using body weight evaluation, mensurations on lateral radiograph of hemimandibles and histological evaluation. Results: There was no significant difference between groups A and B in body weight gain. Comparison of the mean values of hemimandible distance on radiograph was performed. The difference in group mean value of mandible-related distances was analyzed using the Wilcoxon test (rank sum test) and a comparison of the homonymous distances of group A and B was performed using the Mann-Whitney test. There were differences between sides in mandibular length in group B and mandibular ramus height and transverse width of the condyle in group A (all, p<0.05). There were differences in condylar height and mandibular length on the left side between groups A and B (p<0.05). Histologic examination of temporomandibular joint showed similar findings in all specimens. Conclusions: Injury of the posterior belly of the digastric muscle during the rat growth period induced shortening of mandibular ramus height and transverse width of the condyle. It can be inferred that trauma to the posterior belly of the digastric muscle affects horizontal and vertical growth of the mandible.

• Preventive Nutrition and Food Science
• /
• v.21 no.3
• /
• pp.281-288
• /
• 2016

This study was designed to investigate the effects of dietary astaxanthin levels on growth performance, feed utilization, muscle pigmentation, and antioxidant capacity in juvenile rainbow trout. Four experimental diets were formulated to contain 0, 50, 75, and 100 mg/kg astaxanthin (designed as AX0, AX50, AX75, and AX100). Each diet was fed to triplicate groups of fish (18.5 g/fish) for 10 weeks. Growth performance and muscle composition of fish were not affected by dietary astaxanthin levels. Total carotenoid concentration in the muscle of fish fed the AX50 diet was higher than that of fish fed the AX0 diet, but no significant differences were observed between these fish and those fed the AX75 and AX100 diets. Muscle astaxanthin content increased with increased astaxanthin in the diet. Deposition of astaxanthin in the flesh resulted in a decrease in lightness and an increase in redness and yellowness. The fillets from trout fed the AX75 diet had significantly lower lightness than trout fed the AX50 and AX100 diets. Fish fed the AX50 and AX75 diets showed significantly lower catalase activity than those fed the control diet. Total antioxidant status increased significantly in all astaxanthin supplemented groups when compared to the control group. Superoxide dismutase activity was significantly decreased in fish fed the AX50 diet compared to fish fed the AX0 diet. These findings suggest that while fillet pigmentation increased with increasing dietary astaxanthin concentration, indices of fish antioxidant capacity may not be affected in a dose dependent manner.

• Asian-Australasian Journal of Animal Sciences
• /
• v.20 no.4
• /
• pp.501-510
• /
• 2007

The present study was conducted to establish primary bovine muscle satellite cell (MSC) culture conditions and to investigate the effects of various steroid hormones on transcription of the genes involved in muscle cell proliferation and differentiation. Of three different types of proteases (type II collagenase, pronase and trypsin-EDTA) used to hydrolyze the myogenic satellite cells from muscle tissues, trypsin-EDTA treatment yielded the highest number of cells. The cells separated by hydrolysis with type II collagenase and incubated on gelatin-coated plates showed an enhanced cell attachment onto the culture plate and cell proliferation at an initial stage of cell growth. In this study, the bovine MSCs were maintained in vitro up to passage 16 without revealing any significant morphological change, and even to when the cells died at passage 21 with decreased or almost no cell growth or deformities. When the cells were incubated in a steroid-depleted environment (DMEM(-)/10% CDFBS (charcoal-dextran stripped FBS)), they grew slowly initially, and were widened and deformed. In addition, when the cells were transferred to an incubation medium containing steroid (DMEM(+)/10% FBS), the deformed cells resumed their growth and returned to a normal morphology, suggesting that steroid hormones are crucial in maintaining normal MSC morphology and growth. The results demonstrated that treatments with 19-nortestosterone and testosterone significantly increased AR gene expression (p<0.05), implying that both testosterone and 19-nortestosterone bind with AR and that the hormone bound-AR complex up-regulates the genes of its own receptor (AR) plus other genes involved in satellite cell growth and differentiation in bovine muscle.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.40
• /
• pp.5.1-5.8
• /
• 2018

Background: The objective of this study was to evaluate the influence of masticatory muscle injection of botulinum toxin type A (BTX-A) on the growth of the mandibular bone in vivo. Methods: Eleven Sprague-Dawley rats were used, and BTX-A (n = 6) or saline (n = 5) was injected at 13 days of age. All injections were given to the right masseter muscle, and the BTX-A dose was 0.5 units. All of the rats were euthanized at 60 days of age. The skulls of the rats were separated and fixed with 10% formalin for micro-computed tomography (micro-CT) analysis. Results: The anthropometric analysis found that the ramus heights and bigonial widths of the BTX-A-injected group were significantly smaller than those of the saline-injected group (P < 0.05), and the mandibular plane angle of the BTX-A-injected group was significantly greater than in the saline-injected group (P < 0.001). In the BTX-A-injected group, the ramus heights II and III and the mandibular plane angles I and II showed significant differences between the injected and non-injected sides (P < 0.05). The BTX-A-injected side of the mandible in the masseter group showed significantly lower mandibular bone growth compared with the non-injected side. Conclusion: BTX-A injection into the masseter muscle influences mandibular bone growth.

• Journal of Korean Academy of Nursing
• /
• v.22 no.3
• /
• pp.325-336
• /
• 1992

The purpose of this study was to determine the effect of exercise training on the length and circumference of atrophied muscles to see whether improvement in restoring the atrophied muscle mass, of either length or circumference growth could be induced through exercise training. Adult female Wistar rats were maintained for 14 days with hindlimb suspension. Rats were then assigned randomly to a sedentary group or training group. The length and circumference of both atrophied soleus and plantaris muscle for the training and sedentary groups following hindlimb suspension were compared with those of a control group. Length and circumference of both atrophied soleus and plantaris muscle in trained group was compared with those in the sedentary group. The results can be summarized as follows ; 1) Atrophy of soleus and plantaris muscle was induced with hindlimb suspension. 2) The circumference of both the soleus and plantaris muscle following hindlimb suspension was reduced to 51. 72%, 66.67% respectively compared to the control group. The length of both the soleus and plantaris muscle following hindlimb suspension did not show any difference compared to the control group. 3) There was no difference in length for either the atrophied soleus or plantaris muscle between the trained and the sedentary group during recovery from hindlimb suspension. 4) The circumference of both the atrophied soleus and plantaris muscle did not return to normal in the sedentary group, however, the circumference of both the atrophied soleus and plantaris muscle were significantly greater than of the control in the trained group, 14.22% and 9.38% respectively. 5) The circumference of both the atrophied soleus and plantaris muscle in the trained group was significantly larger than that of both muscles in the sedentary group at day 28 of recovery. From these results, it can be suggested that improvement in restoring the atrophied muscle mass through exercise training might be induced by growth of the muscle circumference.

• Animal Bioscience
• /
• v.36 no.2_spc
• /
• pp.374-384
• /
• 2023

Skeletal muscle metabolism regulates homeostatic balance in animals. The metabolic impact persists even after farm animal skeletal muscle is converted to edible meat through postmortem rigor mortis and aging. Muscle metabolites resulting from animal growth and postmortem storage have a significant impact on meat quality, including flavor and color. Metabolomics studies of postmortem muscle aging have identified metabolisms that contain signatures inherent to muscle properties and the altered metabolites by physiological adaptation, with glycolysis as the pivotal metabolism in postmortem aging. Metabolomics has also played a role in mining relevant postmortem metabolisms and pathways, such as the citrate cycle and mitochondrial metabolism. This leads to a deeper understanding of the mechanisms underlying the generation of key compounds that are associated with meat quality. Genetic background, feeding strategy, and muscle type primarily determine skeletal muscle properties in live animals and affect post-mortem muscle metabolism. With comprehensive metabolite detection, metabolomics is also beneficial for exploring biomarker candidates that could be useful to monitor meat production and predict the quality traits. The present review focuses on advances in farm animal muscle metabolomics, especially postmortem muscle metabolism associated with genetic factors and muscle type.

• Asian-Australasian Journal of Animal Sciences
• /
• v.18 no.5
• /
• pp.716-722
• /
• 2005

Carcass weight and backfat thickness are primary yield grading factors. Insulin-like growth factor (IGF)-I/-II, transforming growth factor $\beta$1 (TGF-$\beta$1), and epidermal growth factor (EGF) regulate the proliferation and differentiation of cells including adipocytes. Also, interleukin (IL)-2/-6, cortisol, and dehydroepiandrosterone-sulfate (DHEA-S) are known to be related to muscle growth and fat depth. However, the relationships between endocrine factors and carcass grade have not been studied. Therefore, this study aimed to measure the concentrations of endocrine factors in serum and muscle, and to investigate the relationship of endocrine factors with carcass grade. A total of 60 crossbred gilts (Duroc${\times}$Yorkshire${\times}$Landrace) were used. Blood from the jugular vein was collected at antemortem (7 days before slaughter) and postmortem periods, and M. Longissimus was collected at 45 min and 24 h after slaughter. The concentrations of IGF-I/-II, EGF, TGF-$\beta$1, IL-2/-6, cortisol and DHEA-S were analyzed by radioimmunoassay (RIA) or enzyme-linked immunosorbent assay (ELISA). In general, IGF and EGF concentrations in serum and muscle of grade A carcasses were found to be higher than those of grade C carcasses at antemortem and postmortem periods, whereas the pattern of TGF-$\beta$1 concentration was reversed. In particular, the concentrations of muscle IGF-I (24 h postmortem) and serum TGF-$\beta$1 (antemortem) were significantly different between grades A and C (p<0.05). The present results indicate that serum and muscle growth factors affect carcass weight and backfat thickness, and indirectly suggest the possibility that carcass grade could be predicted by expression of serum and/or muscle growth factors.

• Asian-Australasian Journal of Animal Sciences
• /
• v.14 no.5
• /
• pp.720-732
• /
• 2001

Skeletal muscle is of major economic importance since it is finally converted to meat for consumers. The increase in meat production with low costs of production may be achieved by optimizing muscle growth, whereas a high meat quality requires, among other factors, the optimization of intramuscular glycogen and fat stores. Thus, research in energy metabolism aims at controling muscle metabolism, but also liver and adipose tissue metabolism in order to optimize energy partitioning in favour of muscles. Liver is characterized by high anabolic and catabolic rates. Metabolic enzymes are regulated by nutrients through short-term regulation of their activities and long-term regulation of expression of their genes. Consequences of liver metabolic regulation on energy supply to muscles may affect protein deposition (and hence growth) as well as intramuscular energy stores. Adipose tissues are important body reserves of triglycerides, which result from the balance between lipogenesis and lipolysis. Both processes depend on the feeding level and on the nature of nutrients, which indirectly affect energy delivery to muscles. In muscles, the regulation of rate-limiting nutrient transporters, of metabolic enzyme activities and of ATP production, as well as the interactions between nutrients affect free energy availability for muscle growth and modify muscle metabolic characteristics which determine meat quality. The growth of tissues and organs, the number and the characteristics of muscle fibers depend, for a great part, on early events during the fetal life. They include variations in quantitative and qualitative nutrient supply to the fetus, and hence in maternal nutrition. During the postnatal life, muscle growth and characteristics are affected by the age and the genetic type of the animals, the feeding level and the diet composition. The latter determines the nature of available nutrients and the rate of nutrient delivery to tissues, thereby regulating metabolism. Physical activity at pasture also favours the orientation of muscle metabolism, towards the oxidative type. Consequently, breeding systems may be of a great importance during the postnatal life. Research is now directed towards the determination of individual tissue and organ energy requirements, a better knowledge of nutrient partitioning between and within organs and tissues. The discovery of new molecules (e. g. leptin), of new molecular mechanisms and of more powerful techniques (DNA chips) will help to achieve these objectives. The integration of the different levels of knowledge will finally allow scientists to formulate new types of diets adapted to sustain a production of high quality meat with lower costs of production.

• Animal Bioscience
• /
• v.35 no.4
• /
• pp.577-586
• /
• 2022

Objective: The objective of this study was to evaluate the effects of supplementing quercetin extracted from Sophora japonica flower (QS) to the diet of broiler chicks on their growth performance, apparent nutrient digestibility, cecal microbiota, serum lipid profiles, relative organ weight, and breast muscle quality. Methods: A total of 1,088 1-day-old broiler chicks (mixed sex) were randomly assigned to four groups based on the initial body weight (43.00±0.29 g). The experimental period was 35 days (starter, days 0 to 7; grower, days 7 to 21; finisher, days 21 to 35). There were 17 replicate cages per treatment and 16 birds per cage. Dietary treatments consisted of birds receiving basal diet without quercetin as the control group and treatment groups consisted of birds fed basal diet supplemented with 0.2, 0.4, or 0.6 g/kg QS. Results: With the increase of the QS dosage, body weight gain during days 0 to 7 (p = 0.021), 7 to 21 (p = 0.010), and 1 to 35 (p = 0.045), feed intake during days 0 to 7 (p = 0.037) and 1 to 35 (p = 0.025), apparent dry matter digestibility (p = 0.008), apparent energy retention (p = 0.004), cecal lactic acid bacteria counts (p = 0.023), the relative weight of breast muscle (p = 0.014), pH value from breast muscle (p<0.001), and the water holding capacity of breast muscle (p = 0.012) increased linearly, whereas the drip loss from breast muscle (p = 0.001) decreased linearly. Conclusion: The addition of QS in the diet of broiler chicks had positive effects on the breast muscle yield and breast muscle quality, and improved the dry matter digestibility and energy retention by increasing cecal beneficial bacteria counts, thus improving growth performance.