Rabbit Muscle Research Articles

The Characterization and Differential Analysis of m6A Methylation in Hycole Rabbit Muscle and Adipose Tissue and Prediction of Regulatory Mechanism about Intramuscular Fat.

N6-methyladenosine (m6A) widely participates in various life processes of animals, including disease, memory, growth and development, etc. However, there is no report on m6A regulating intramuscular fat deposition in rabbits. In this study, m6A modification of Hycole rabbit muscle and adipose tissues were detected by MeRIP-Seq. In this case, 3 methylases and 12 genes modified by m6A were found to be significantly different between muscle and adipose tissues. At the same time, we found 3 methylases can regulate the expression of 12 genes in different ways and the function of 12 genes is related to fat deposition base on existing studies. 12 genes were modified by m6A methylase in rabbit muscle and adipose tissues. These results suggest that 3 methylases may regulate the expression of 12 genes through different pathways. In addition, the analysis of results showed that 6 of the 12 genes regulated eight signaling pathways, which regulated intramuscular fat deposition. RT-qPCR was used to validate the sequencing results and found the expression results of RT-qPCR and sequencing results are consistent. In summary, METTL4, ZC3H13 and IGF2BP2 regulated intramuscular fat by m6A modified gene/signaling pathways. Our work provided a new molecular basis and a new way to produce rabbit meat with good taste.

Histological, immunohistochemical and ultrastructural features of polyglucosan bodies in uterine smooth muscle of pet rabbits (Oryctolaguscuniculus)

We document the frequency and morphological and immunohistochemical features of inclusion bodies in uterine smooth muscle cells in 56 (76%) of 74 investigated pet rabbits (Oryctolagus cuniculus). Inclusion bodies began to appear at the age of 2 years and their frequency increased with age (P = 0.047, r = 0.33). They ranged from 5 to 20 μm in diameter, were slightly basophilic to amphophilic with well-delimited oval bodies in haematoxylin and eosin-stained tissue sections and formed in the cytoplasm of the uterine smooth muscle cells with displacement of the cell nuclei. The inclusion bodies were positive with periodic acid–Schiff, Best's carmine, Lugol's iodine and Grocott's methenamine silver methods. They were immunoreactive to a monoclonal antibody raised against human polyglucosan and negative with monoclonal antibodies for several intermediate filament proteins. Electron microscopy revealed that they were non-membranous structures composed of electron-dense amorphous material. The morphological, histochemical, immunohistochemical and ultrastructural features of the inclusion bodies in the rabbi uteri were similar to those of human polyglucosan bodies (PGBs). PGBs appear to occur at a high frequency in the uterus of rabbits, which are known to be susceptible to uterine diseases.

Use of Moringa oleifera leaves (sole or combined with concentrate) in rabbit feeding: Effects on performance, carcass characteristics and meat quality attributes

Sixty Chinchilla rabbits (28 days old) were divided into three equal groups (n = 20). Rabbits in MOL0 (control) were fed pellets containing 700 g cowpea hay/kg pellet as forage source, whereas rabbits in MOL700 and MOL950 were fed pellets containing 700 and 950 g moringa leaves/kg feed pellets, respectively. Average daily gain and feed conversion ratio was comparable in MOL700 and MOL0, however, it was higher in MOL950. Among the carcass traits, dressing percent was higher while, chilling loss was lower in MOL700 treatment. The Longissimus thoracis muscle of rabbits fed moringa leaves containing pellets (MOL700 and MOL950) had lower saturated fatty acid content, higher C18:3n-3 and total n-3 fatty acids along with lower thrombogenic index value. Hence, incorporating moringa leaves at 70% level is beneficial in terms of improved growth performance and functional attributes of meat than diet- containing sole moringa leaves.

Морфологические особенности хвостобедренной мышцы у представителей зайцеобразных

The article presents the results of research, a comprehensive methodological approach, including anatomical macro- and micropreparation, macromorphometry, biomechanical modelling, light microscopy of histological sections stained with hematoxylin and eosin, Mallory with subsequent micromorphometry. The digital material was subjected to statistical processing. The studies were carried out at the Department of Anatomy and Histology of Animals named after Professor A. F. Klimov of the K.I. Skryabin Moscow State Automobile Academy of Veterinary Medicine and Biology. Pelvic limbs of the rabbit of the Soviet chinchilla breed (n=20) and pelvic limbs of the Rusak hare (n=12), without signs of pathology, with body weight from 4 to 7 kg served as the material for the study. During comparative analysis, macro- and micromorphological features of the caudalfemoral muscles, influencing the character of the statolocomotor act in the studied animals, were established. The mechanical advantage of the caudofemoral muscle in rabbit compared to hare was established, which is confirmed by the features of its micromorphological picture: in rabbit, thickening of muscle bundles and fibres in the bundle is accompanied by a decrease in their number, while in hare, a decrease in the thickness of bundles and fibres - by an increase in their quantitative representation in the bundle. The obtained results are normative in the issues of experimental modelling of pathologies of musculoskeletal organs.

Postmortem Distribution and Postmortem Redistribution of Carbofuran-7-Phenyl Glucuronic Acid in Rabbits.

To establish a carbofuran intragastric administration death model in rabbits, and to observe the postmortem distribution and postmortem redistribution of carbofuran-7-phenyl glucuronic acid (Glu-7PH) in rabbits. The postmortem distribution: Rabbits were given an administration of 1/2LD50, LD50, 2LD50 carbofuran. Dead rabbits were dissected immediately. Rabbits that had remained alive 2 hours were sacrificed by carbon dioxide (CO2) inhalation and dissected immediately. The myocardium, cardiac blood, liver, spleen, lung, kidney, brain and right hindlimb muscle were collected. The postmortem redistribution: After giving an administration of 4LD50 carbofuran, the myocardium, cardiac blood, liver, spleen, lung, kidney, brain, and right hindlimb muscle were collected at 0, 12, 24, 48, and 72 h postmortem in supine position at 15 ℃ room temperature. The quantity of Glu-7PH was determined by LC-MS/MS. The postmortem distribution: Among the three dose groups, there were significant differences in the quantities of Glu-7PH in different tissues. The postmortem redistribution: There was no significant difference in the Glu-7PH quantities in cardiac blood, mycardium, spleen, kidney, brain and right hindlimb muscle, but there was a significant difference in the Glu-7PH quantities in the liver and lung. The mycardium, cardiac blood, liver, lung, kidney, brain and hindlimb muscle of rabbits can be used as appropriate samples for Glu-7PH detection. However, it should be noted that Glu-7PH was redistributed postmortem in rabbit liver and lung.

Antioxidants status and physiological responses to early and late heat stress in two rabbit breeds.

Early life heat stress negatively affects rabbit production and well-being. However, the physiological response to acute heat stress in later life is not clearly defined. The present study aims to investigate the effects of early and late heat stress at 36°C on some blood constituents, antioxidant enzymes activity in the blood, and muscle in New Zealand white and Baladi Black rabbits. A total of sixty post-weaning rabbits of each breed were randomly divided into two groups; control groups (NZWC and BBC) and early heat-stressed groups for six hours at 36 ± 1°C and 62% relative humidity (RH) (NZWT and BBT groups). After heat stress, six rabbits from each group were slaughtered for blood and muscle tissue collection. The surviving rabbits were kept at 28 ± 1°C and 40% RH till 13 weeks of age. At the end of 13 weeks, all rabbits were exposed to late heat stress as precious described to perform four groups: single late stressed groups; NZWC2, BBC2, and double stressed groups; NZWT2 and BBT2. After late heat stress, six rabbits from each group were slaughtered for blood and muscle tissue collection. The early and late heat stress caused a significant reduction in the blood creatine kinase, lactate dehydrogenase, and high-density lipoprotein and antioxidant enzymes' activity in blood and muscle of both NZW and BB rabbits compared with the control groups. While, the blood total cholesterol, triglycerides, total lipids levels, and lipid peroxidation activity in blood and muscle were significantly increased due to the early and late heat-stressed both breeds compared with the control groups. It could be concluded that the early heat stress at 36°C has negative effects on several physiological indicators and antioxidant activities in the blood and muscle of NZW and BB rabbits.

Analysis of lncRNA in the skeletal muscle of rabbits at different developmental stages.

It is universally acknowledged that lncRNA plays an important role in the regulation of animal skeletal muscle development regulation. However, there is a lack of relevant research on lncRNA in rabbit skeletal muscle development. Thus, we explored the expression profiles of lncRNA in rabbits at three growth stages (2-week-old fetus, 6-week-old post-weaning, and 6-month-old adult) using RNA-seq. A total of 554 differentially expressed lncRNAs (235 up- and 319 down-regulated) were found between the post-weaning and fetus groups and 19 (7 up- and 12 down-regulated) between the post-weaning and adult groups and 429 (115 up- and 314 down-regulated) between the fetus and adult. The enrichment pathways in the post-weaning and fetus groups were mainly concentrated at AMPK and PI3K-Akt signaling pathways, and the co-expression results revealed that LINC-2903, LINC-2374, LINC-8591 plays a role in early maintenance of skeletal muscle development. The enriched pathways in the fetus and adult groups were mainly involved in PI3K-Akt signaling pathways with a strong association found in mTOR signaling pathways. Analysis of the co-expression results suggests that LINC-5617 may be involved in the proliferation of embryonic skeletal muscle cells, and that LINC-8613 and LINC-8705 may provide energy for postnatal skeletal muscle development. The specific roles of different lncRNAs in different developmental stages of New Zealand White rabbits obtained. This will contribute to the subsequent study on the regulatory mechanism of muscle development in New Zealand White rabbits.

The effects of treatment using polydeoxyribonucleotide through extracorporeal shock wave therapy: synergic regeneration effects on atrophied calf muscles in immobilized rabbits.

BackgroundThis study aimed to examine the synergic effects of polydeoxyribonucleotide (PDRN) through extracorporeal shock wave therapy (ESWT) on atrophied calf muscles in cast-immobilized rabbit models.MethodsTwenty male New Zealand rabbits (aged 12 weeks) were allocated into four groups. Four types of procedures [0.7 mL normal saline to Group 1 (G1-NS); 0.7 mL PDRN to Group 2 (G2-PDRN); ESWT to Group 3 (G3-ESWT); and 0.7 mL PDRN with ESWT to Group 4 (G4-PDRN + ESWT)] were injected to the atrophied calf muscles of the rabbits after two weeks of cast immobilization. Radial ESWT (0.1 mJ/mm2, 3 Hz, 1,500 shocks) was performed twice weekly. The circumference of the calves, compound muscle action potential (CMAP) of the tibial nerves, and thickness of the gastrocnemius (GCM) muscle were evaluated after two weeks of treatment. Type I and II GCM muscle fibers were immunohistochemically stained using monoclonal anti-myosin, anti-VEGF (vascular endothelial growth factor), and anti-PECAM-1 (platelet endothelial cell adhesion molecule-1) antibodies, and the cross-sectional area (CSA), VEGF ratio, and PECAM ratio were measured after 2 weeks of treatment. Statistical differences among the four groups were determined using analysis of variance (ANOVA).ResultsThe G4-PDRN + ESWT group had a significantly greater circumference of calf muscles, thickness of the GCM muscle, CMAP of the tibial nerve, and CSA of the GCM muscle fibers (type I, II, and total) (hereinafter termed “the four categories”) than those in the remaining three groups (P<0.05). Rabbits in the G3-ESWT group had significantly higher results in the four categories than in G1-NS and G2-PDRN groups (P<0.05). G2-PDRN rabbits had significantly higher results in the four categories than those in G1-NS (P<0.05). The VEGF and PECAM-1 ratio of the medial GCM muscle fibers in G4-PDRN + ESWT were significantly higher than those in the remaining three groups (P<0.05).ConclusionsESWT combined with PDRN injection was more effective in muscle regeneration than ESWT, PDRN injection alone, or normal saline injection on atrophied calf muscles in rabbit models.

Comparisons of Phosphofructokinases-1 from Rabbit, Chicken, and Fish

Background: Previous studies suggested that glycogen storage was facilitated by ascorbate inhibition of phosphofructokinase-1 (PFK-1) in resting mammalian muscle; these studies showed that purified PFK-1 from fish or chicken muscle has properties similar to PFK-1 from mammalian muscles. Materials and Methods: The enzymes utilized in the assay systems came from Sigma-Aldrich Co. Rabbit (Oryctolagus cuniculus) muscle G-actin (A 2522) was free of aldolase, LDH (EC 1.1.1.28) or AK (EC 2.7.4.3) activity and rabbit muscle aldolase (EC 4.1.2.13) was free of AK (EC 2.7.4.3) and LDH activity. Rabbit muscle PFK-1 (RPFK-1), chicken (Gallus gallus) muscle PFK- 1 (CPFK-1) and Pacific red snapper (Lutjanus peru) muscle PFK-1 (FPFK-1) used in these tests were prepared from frozen tissues with modifications of a method. AK, LDH, and aldolase activity were absent in purified FPFK- 1 and CPFK-1 preparations. Results: It can be shown that the following enzymes associated with glycolysis are not inhibited by 0.1 M ascorbate under our conditions: rabbit muscle aldolase (EC 4.1.2.13); rabbit muscle glyceraldehyde 3-phosphate dehydrogenase (EC 1.2.1.12); rabbit muscle phosphoglucose isomerase (EC 5.3.1.9); rabbit muscle pyruvate kinase (EC 2.7.1.40); yeast hexokinase (EC 2,7.1.1); and yeast 3-phosphoglyceric phosphokinase (EC 2.7.2.3). Rabbit muscle enolase (EC4.2.1.11) is inhibited under our conditions. Conclusion: In summary, FPFK-1 and CPFK-1, possess characteristics and behaviors similar to RPFK-1, e.g., losses of activities due to dilutions and protections of some of these activity losses by rabbit muscle aldolase. These interactions of a mammalian aldolase with fish and a bird PFK-1’s suggests a conservative evolutionary relationship among aldolases and PFK-1’s.

Inhibition by Ascorbate among Phosphofructokinase-1, Aldolase, Enolase, and Lactate Dehydrogenase in Rabbit Muscle

Background: These studies examined mutual protective relationships among rabbit muscle aldolase, enolase, phosphofructokinase-1 (PFK-1) and LDH from inhibitions by ascorbate (AA). It was proposed earlier that specific inhibitions of PFK-1 and LDH by AA faciltated glycogen storage in resting muscle by inhibiting glycolysis. Materials and Methods: The L-ascorbate (AA), L-ascorbyl dibutyrate (AADB), L-ascorbyl dipalmitate (AADP), L-ascorbyl palmitate (AAP), and L- ascorbyl stearate (AS) are shown in Figure 1 and were obtained from TCI and Alfa Aesar. Unless otherwise stated, all enzymes come from rabbit and all experimental temperatures were 25°C, pH 8.0. Results: Rabbit muscle enolase was examined for its protective effect on other rabbit muscle glycolytic enzymes against inhibitions by ascorbate (AA) and some AA-faty acid derivatives. The IC50 values of enolase by ascorbate (AA) and IC50 values of AA-fatty acid derivatives were compared to estimate inhibition potency. For example, ascorbyl dipalmitate (AADP) was 156 times more inhibitory to enolase than AA. It was previously shown that rabbit muscle aldolase prevented LDH activity loses due to AA inhibition and prevented PFK-1 activity losses due both to dilution and AA inhibition; enolase was found to have the same effects as aldolase. Additionally, PFK-1 prevented enolase and LDH inhibitions by AA. LDH did not prevent enolase or PFK-1 from inhibition by AA. LDH did stimulate enolase activity but not PFK-1 activity. Conclusion: The results suggest that interactions among glycolytic enzyme serve to mutually protect one another from activity losses. The inhibition properties of the AA-fatty acid derivatives are discussed in relation to their possible roles in cancer and diabetes.

Quantitative assessment of changes in skeletal muscle injury by computer-aided analysis based ontwo-dimensional ultrasonography combined with contrast-enhanced ultrasonography and estimated by a modified semi-quantitative scoring system: Anexperimental study in a contusion model.

The aim of this study was to investigate the potential application of computer-aided analysis in the quantitative assessment of changes in skeletal muscle injury in the rabbit contusion model. Forty healthy rabbits were randomly divided into control (n=5) and contusion (n=35) groups. Rabbits in the contusion group were used to construct a muscle contusion model induced by a hammer hitting the right gastrocnemius, while the muscles of rabbits in the control group were non-injured. Two-dimensional ultrasound (2D US) and contrast-enhanced ultrasonography (CEUS) were performed on the rabbits that had received skeletal muscle contusion injury at 1h, and 1, 3, 7, 14, 21 and 28 days after injury. Afterwards, a multiscale blob feature (MBF) method was used to extract the textural features from the 2D US, and the muscle injuries were quantitatively evaluated. The eight textural parameters of skeletal muscle analysed by MBF at 1h, and 1, 3 and 7 days post-injury were found to be significantly higher in the contusion group than in the control group (p &lt; .05). On Day 14, the textural parameters (e.g., greyscale mean [Mean], greyscale standard deviation [SDev], number of blobs, average size of blobs, homogeneity of distribution, periodicity of distribution [POD] and irregularity) were also evidently higher in the contusion group than in the control group (p &lt; .05). On Day 28, Mean, SDev and POD in the contusion group were markedly higher (p &lt; .05). After that, the microcirculation in the injured areas increased from Day 7 to Day 21 after injury, but decreased on Day 28 after injury. Thus the quantitative assessment of changes in skeletal muscle injury (SMI) using computer-aided analysis allowed us to describe the geometric features of injured muscle fibres and the microperfusion changes estimated by the modified semi-quantitative scoring system. This provides a scientific basis for the development of a novel approach for the evaluation of SMI and rehabilitation process.

N6-Methyladenosine Methylome Profiling of Muscle and Adipose Tissues Reveals Methylase-mRNA Metabolic Regulatory Networks in Fat Deposition of Rex Rabbits.

Simple SummaryN6-methyladenosine is the most prevalent internal form of modification found in recent years and plays an important role in gene regulation, which can regulate many physiological processes, such as fat deposition, immunity, and reproduction. The intramuscular fat content is an important problem to be solved in the development of animal husbandry. In order to find a way to increase the intramuscular fat content of Rex rabbit muscles, we explored the methylation modification genes related to fat deposition in Rex rabbit muscle and adipose tissue. We found 5 differential methylases and 12 key genes for methylation modification related to fat deposition between muscle and adipose tissues samples. In addition, five differential methylases were found to regulate adipogenesis by affecting the expression of screened genes in different ways. These findings provided a theoretical basis for our future research on the function of methylation modification during the growth of fat deposits and provided a new way to increase intramuscular fat in Rex rabbits.N6-methyladenosine (m6A) is the most prevalent internal form of modification in messenger RNA in higher eukaryotes and plays an important role in cancer, immunity, reproduction, development, and fat deposition. Intramuscular fat is the main factor used to measure the meat quality of an animal. The deposition of intramuscular fat and perirenal fat increases with age. However, there is no data on m6A modification of Rex rabbits and its potential biological roles in adipose deposition and muscle growth. Here, we performed two high-throughput sequencing methods, m6A-modified RNA immunoprecipitation sequence (MeRIP-seq) and RNA sequence (RNA-seq), to identify key genes with m6A modification on fat deposition in the muscle and adipose tissues of Rex rabbits. Then, qRT-PCR was used to identify the differently methylated genes related to fat deposition. Our findings showed that there were 12,876 and 10,973 m6A peaks in the rabbit muscle and adipose tissue transcriptomes, respectively. Stop codons, 3′-untranslated regions, and coding regions were found to be mainly enriched for m6A peaks. In addition, we found 5 differential methylases and 12 key genes of methylation modification related to fat deposition between muscle and adipose tissues samples. The expression levels of six random key genes were significantly higher in the fat than that in the muscle of Rex rabbits at different stages (p < 0.01). Finally, five differential methylases were found to regulate adipogenesis by affecting the expression of screened genes in different ways. These findings provided a theoretical basis for our future research on the function of m6A modification during the growth of fat deposits.

Growth Performance, Carcass Traits, Muscle Fatty Acids, Intramuscular Fat, Cholesterol, and Antioxidant Status in Rabbits Supplemented with Kigelia pinnata Leaf Meal

AbstractThe effects of dietary Kigelia pinnata leaf (KPL) on growth, carcass, muscle fatty acids, antioxidant status, cholesterol, physicochemical properties, and sensory profile of Longissimus thoracis et lumburum (LTL) muscle in rabbits are investigated. Seventy‐two, 32 d old male New Zealand rabbits (684 ± 18 g) are randomly assigned to diets containing either no KPL (KPL‐0), 5% KPL (KPL‐5) or 10% KPL (KPL‐10) for eight weeks, and euthanized, and the LTL is refrigerated for 6 days. Dietary KPL does not influence growth performance and carcass cuts in rabbits. Abdominal fat is lower in KPL‐ rabbits than in the KPL‐0 rabbits. Supplemented LTL has lower intramuscular fat and cholesterol, and higher crude protein, polyphenol content, glutathione reductase, and catalase compared with the control LTL. Concentration of C18:3n‐3, C22:6n‐3, and C20:5n‐3 is higher in supplemented LTL than the control LTL. Supplemented meat has lower cook loss than the KPL‐0 meat at 24 h postmortem. The KPL‐10 meat has higher redness and lower malondialdehyde content than other meats on d 6 postmortem. Juiciness and overall acceptance of the supplemented meat are higher than that of the KPL‐0 meat. Supplementation with KPL‐10 enhances muscle n‐3 fatty acids, sensorial quality, and oxidative stability of rabbit meat.Practical Applications: Practical applications: Rabbit meat is replete in n‐6 polyunsaturated fatty acid (PUFA) but low in n‐3 PUFA, which heightens its n‐6/n‐3 ratio. Higher n‐6/n‐3 PUFA intake can pose serious health risks to consumers. This suggests a need to ameliorate the n‐3 PUFA of rabbit meat. Dietary KPL causes ≈147–184% increase in n‐3 PUFA and a 66–77% decrease in n‐6/n‐3 ratio in rabbit meat. Moreover, KPL improves sensorial quality and oxidative stability and lowers intramuscular fat and cholesterol content of rabbit meat. These results support the delivery of a healthier rabbit meat that responds to consumer demands. This study explicates the potential of KPL in ameliorating the nutritional value and sensory quality of rabbit meat.

Reprint of: The Content of Troponin, Tropomyosin, Actin, and Myosin in Rabbit Skeletal Muscle Myofibrils

A stacking sodium dodecyl sulfate polyacrylamide gel electrophoresis system has been used to resolve and quantify all the major myofibrillar protein components (actin, myosin, tropomyosin, and troponin C, T, and I). Quantification was achieved by densitometry of the fast green-stained gels calibrated with the use of purified proteins. The approximate molar ratios of these proteins in rabbit muscle are: actin : myosin: tropomyosin: troponin T: troponin I: troponin C = 7:1:1:1:1:1. On the basis of these results and available structural information one obtains an estimate of 254 myosin molecules per thick filament.

Histopathological changes in extraocular muscles of rabbits following injection of Bupivacaine 5mg/ml versus 7.5mg/ml.

: Purpose To compare the histopathological effects of injecting 2 concentrations of Bupivacaine (5mg/ml and 7.5mg/ml) in the superior rectus muscle of rabbits, and to compare these to conventional extraocular muscle surgery in previous studies. Methods Eighteen albino rabbits’ eyes were used. The superior rectus muscles were injected with Bupivacaine 5mg/ml (Group B5, 10 eyes) or 7.5mg/ml (Group B7, 8 eyes). The rabbits were sacrificed and eyes enucleated 6 weeks later for histopathological evaluation. Results were compared to the average of those obtained, by 3 previous studies, after conventional superior rectus resection in rabbits. Results Foreign body reaction was absent in all specimens. Conjunctival and scleral inflammation, perimuscular adhesions, intramuscular fibrosis, conjunctival and scleral oedema and muscle atrophy were higher in group B7, while conjunctival hyperaemia and muscle hypertrophy were higher in group B5 (p > .05). On comparison to conventional surgery, conjunctival inflammation and hyperaemia, foreign body reaction, and adhesions were less after bupivacaine injection (p >.05 for all except for intensity of conjunctival inflammation in B5 versus conventional surgery). Scleral inflammation was more frequent after bupivacaine injection (p <.05). Muscle fibrosis was more frequent in group B7 and conventional surgery than in group B5 (p >.05). Conclusions Both Bupivacaine concentrations effectively produced the desired muscle hypertrophy and fibrosis, so the lower concentration may be used for muscle strengthening to correct strabismus. Bupivacaine injection, although produced no foreign body reaction, did not significantly lower the development of undesired postoperative adhesions and caused more scleral inflammation.

Low-frequency electrical stimulation alleviates immobilization-evoked disuse muscle atrophy by repressing autophagy in skeletal muscle of rabbits

BackgroundThe study aimed to investigate the effect of low-frequency electrical stimulation (LFES) on disuse muscle atrophy and its mechanism in a rabbit model of knee extension contracture.MethodsThis study involved two experiments. In the time-point experiment, 24 rabbits were randomly divided into 4 groups: Control 1 (Ctrl1 group), immobilization for 2 weeks (I-2 group), immobilization for 4 weeks (I-4 group), and immobilization for 6 weeks (I-6 group). In the intervention experiment, 24 rabbits were randomly divided into 4 groups: Control 2 (Ctrl2 group), electrical stimulation (ESG group), natural recovery (NRG group), and electrical stimulation treatment (ESTG group). All intervention effects were assessed by evaluating the knee joint range of motion (ROM), cross-sectional area (CSA) of the rectus femoris muscle, and expression of autophagy-related proteins.ResultsThe time-point experiment showed that immobilization reduced the knee ROM, reduced the rectus femoris muscle CSA, and activated autophagy in skeletal muscle. The levels of five autophagy-related proteins [mammalian target of rapamycin (mTOR), phosphorylated mTOR (p-mTOR), autophagy-related protein 7 (Atg7), p62, and microtubule-associated protein light chain 3B-II (LC3B-II)] were significantly elevated in the skeletal muscle of the I-4 group. The intervention experiment further showed that LFES significantly improved the immobilization-induced reductions in ROM and CSA. Additionally, LFES resulted in a significant decrease in the protein expression of mTOR, p-mTOR, Atg7, p62, and LC3B-II in the rectus femoris muscle.ConclusionsLFES alleviates immobilization-evoked disuse muscle atrophy possibly by inhibiting autophagy in the skeletal muscle of rabbits.

The Antispasmodic Effect of Warionia saharae Essential Oil in Experimental Models and its Mechanism of Action.

With several medicinal and aromatic species, the Asteraceae family is one of the largest angiosperm families. The genus Warionia is represented in this family by only one species, Warionia saharae. In Moroccan traditional medicine, this species is widely used to treat gastrointestinal problems. Essential oil of this plant (EoWs) was studied for possible myorelaxant and antispasmodic activities to rationalize some of the traditional uses. In this investigation, hydrodistillation was used to obtain the essential oil from the aerial part of the dry plant extract (EoWs), which was then analyzed using gas chromatography coupled to mass spectrometry (GC/MS). The major compounds identified in the EoWs are nerolidyl acetate (21.44%), β-Eudesmol (19.47%), linalool (16.48%), 1-terpinene-4-ol (10.93%), and cineole (5.34%). EoWs is relatively safe in the case of acute intake up to 2 g/kg body weight of albino mice. The effect of EoWs on intestinal relaxation was investigated using rabbit and rat jejunal smooth muscle. We have noticed that EoWs produce a myorelaxation on basal rabbit jejunum's contractions in a concentration-dependent manner with a maximal effect at 30 μg/mL. This myorelaxation was not dependent on adrenergic receptors. When the rat jejunums were pre-contracted with 25 mM KCl or 10 μM Carbachol (CCh), EoWs had an antispasmodic action with an IC50 values of 15.76 ± 0.37 and 12.04 ± 0.30 μg/mL, respectively. Preliminary results showed that it is probable that our plant might act directly through the NO and guanylate cyclase signaling pathway and on muscarinic but not nicotinic receptors. The results reveal that the Essential oil of W. saharae appears to have an impact on intestinal relaxation in vitro conditions. This finding lends credence to the traditional usage of this plant to treat intestinal disorders.

Increased angiogenic factors in the aqueous and vitreous humors after disinsertion of extraocular muscle and the effects of triamcinolone acetate injection

The four extraocular rectus muscles in the rabbits were disinserted for induction of anterior segment ischemia (ASI) and the changes in the concentrations of prostaglandin E2 (PGE2), hypoxia-inducible factor-1 (HIF-1α), and vascular endothelial growth factor (VEGF) in the aqueous and vitreous humor were evaluated. Disinsertion of four rectus muscles in rabbits was performed in the right eyes of rabbits (ASI group). The concentrations of PGE2, HIF-1α, and VEGF in the aqueous and vitreous humor were measured at 1, 3, 6, 12, and 24 h by ELISA. The concentrations were compared with those of the fellow eyes (contralateral group) and normal healthy eyes (control group). Subconjunctival injection of triamcinolone acetonide (TA) was administered and three cytokine concentrations in the aqueous humor and vitreous humor were measured at 12 h after TA injection. A total of 48 eyes from 28 rabbits were included. The concentrations of PGE2, HIF-1α, and VEGF in the aqueous humor in the ASI and contralateral groups were significantly higher than those in the control group (p < 0.05, all). The aqueous and vitreous humor concentrations of VEGF in eyes with simultaneous TA injection were significantly lower than were those in the ASI group (p = 0.02, all). The concentration of PGE2, HIF-1α, and VEGF in the aqueous humor was increased after induction of ASI and TA injection seems to be effective in inhibiting VEGF elevation in ASI.

Effect of acupotomy intervention on the morphology and ultrastructure of rectus femoris muscle in rabbits with knee osteoarthritis

To observe the effect of acupotomy on the morphology and ultrastructure of rectus femoris muscle in rabbits with knee osteoarthritis and to reveal the possible therapeutic mechanism involved in the effect of acupotomology on the treatment of knee osteoarthritis(KOA). Twenty-four male New Zealand rabbits aged 6 months and weighed (2.0±0.5) kg were randomly divided into blank group, model group and acupotomy group, 8 rabbits in each group. KOA model was established by modified Videman method with left hind limb extended plaster immobility for 6 weeks. In acupotomy group, the transfascial focal points of quadriceps femoris muscle were released by acupotomy under the guidance of Jingjin theory for 4 times and once a week, and the treatment points include Hedingci, Binwaixia, Binneixia. Blank group and model group were fed normally without intervention. One week after the end of the intervention, the pennation angle(PA), muscle thickness(MT), cross-sectional area(CSA) and strain ratio(SR) of rectus femoris were measured by ultrasound. HE staining was used to observe the changes of the tissue morphology, the number of muscle fibers and the average area of muscle fibers. The myofibril of rectus femoris, sarcomere and myofilament were observed by transmission electron microscope. The PA of rectus femoris muscle in the blank group was (9.05±0.21)°. The MT was(1.09±0.09) cm and the CSA was(1.30±0.01) cm2. The PA of rectus femoris muscle in the model group was (3.06±0.15)°. The MT was (0.71±0.02) cm and the CSA was(0.77±0.02) cm2. The PA of rectus femoris muscle in the acupotomy group was (6.94±0.28)°. The MT was (0.80±0.05) cm and the CSA was(0.94±0.03) cm2. The muscle PA, MT and CSA of rectus femoris in the model group were significantly smaller than those in the blank group (P<0.05). Those in acupotomy group were significantly increased compared with those in model group (P<0.05). The SR of rectus femoris muscle was 1.19±0.02 in the blank group, 3.50±0.05 in the model group and 1.99±0.07 in the acupotomy group. The elastic SR of the model group was significantly higher than that of the blank group (P<0.05). These in acupotomy group was significantly lower than that in model group(P<0.05). The results of HE staining showed:in blank group, the fascicles of rectus femoris were arranged neatly, the number of beam of muscle fibers within the fixed visual field was 94.38±3.50 and the average CSA was(0.75±0.22) mm2. In model group, the fascicles of rectus femoris with different sizes were disorganized with a small amount of inflammatory cell infiltration, the number of beam of muscle fibers within the fixed visual field was 196.63±2.62 and the average CSA was(0.26±0.03) mm2. Compared to the blank group, a significant increase in the number of muscle fibers in the fixed field in the model group (P<0.05) and the average CSA decreased significantly(P<0.05). In acupotomy group, the rectus femoris fascicles in the acupotomy group tended to be arranged in a more orderly manner, with the inflammatory cells decreased, the number of beam of muscle fibers within the fixed visual field was 132.88±4.61 and the average CSA was(0.70±0.07) mm2. Compared to the model group, a significant decrease in the number of muscle fibers in the fixed field in the model group(P<0.05) and the average CSA increased significantly(P<0.05). The results of transmission electron microscope showed:compared with the blank group, the overall arrangement of the myofibrils of the rectus femoris in the model group was less structured. There was fracture between the muscle fibers and the sarcomere, the myofilaments were disordered, and the fracture of the Z line was discontinuous. Compared with the model group, the myofibrillar texture of rectus femoris in acupotomy group was clearer, and the Z line was more continuous. Based on the jingjin theory, the release of quadriceps femoris by acupotomy can effectively improve the morphology and structure of rectus femoris, and promote the repair and reconstruction of chronic skeletal muscle injury in rabbits with KOA, which may be one of the mechanisms of acupotomy in the treatment of KOA.

Dietary Plukenetia conophora seed alters muscle cholesterol, antioxidant enzymes, and fatty acids in growing rabbits

The influence of dietary inclusion of Plukenetia conophora seed (PCS) on growth, carcass, muscle antioxidant enzymes, fatty acids, meat quality, and sensory attributes of Longissimus thoracis et lumburum muscle in rabbits was examined. Seventy-two, 28 d old male New Zealand rabbits (750 ± 20 g) were randomly allotted to diets containing either no PCS (PCS-0), 2.5% PCS (PCS-2.5) or 5% PCS (PCS-5) for eight weeks, and euthanized. PCS-5 rabbits had higher (P < 0.05) body and carcass weights than the PCS-0 rabbits. Dietary PCS improved feed efficiency in rabbits. Muscle antioxidant enzymes activities and total phenols were higher while muscle cholesterol was lower (P < 0.05) in supplemented meat than the PCS-0 meat. The concentration of C22:6n-3, C20:5n-3 and C18:3n-3 was higher (P < 0.05) in the supplemented meat than the PCS-0 meat. Sensory attributes, carbonyl, and TBARS values and physicochemical properties of meat did not differ among diets. Supplementation of PCS-5 enhances muscle n-3 fatty acids without impairing the sensory properties, and oxidative stability of rabbit meat.