Rabbit Muscle Research Articles

Structural and Spectroscopic Characterization of Supported Sarcoplasmic Reticulum Membranes on Solid Substrates.

Sarcoplasmic reticulum (SR) membranes from rabbit muscle were deposited on silicon substrates and characterized by the combination of spectral ellipsometry (SE), high energy specular X-ray reflectivity (XRR), specular neutron reflectivity (NR), and attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. Following the optimization of the preparative conditions by SE, the detailed structures in the direction perpendicular to the membrane were probed by XRR. ATR-FTIR data showed strong signals from amide I and amide II bands of the native SR membranes containing a large amount of Ca2+-ATPase, which could not be achieved by the reconstitution in artificial lipid membranes. The treatment with protease led to a significant decrease in the amide peaks, and the XRR data confirmed the modulation of the membrane structures. The obtained data show the potential of the in situ combination of reflectivity and vibrational spectroscopy of native supported membranes in order to unravel both structure and dynamics of complex biological membranes.

Development of Ocular Muscle Stimulation Systems and Optimization of Electrical Stimulus Parameters for Paralytic Strabismus Treatment.

Paralysis of the extraocular muscles can lead to complications such as strabismus, diplopia, and loss of stereopsis. Current surgical treatments aim to mitigate these issues by resecting the paralyzed muscle or transposing the other recti muscles to the paralyzed muscle, but they do not fully improve the patient's quality of life. Electrical stimulation shows promise, while requiring further in vivo experiments and research on various stimulation parameters. In this study, we conducted experiments on rabbits to stimulate the superior rectus (SR) muscles using different parameters and stimulation waveforms. To provide various types of electrical stimulation, we developed the ocular muscle stimulation systems capable of both current controlled stimulation (CCS) and high-frequency stimulation (HFS), along with the chip that enables energy-efficient and safe switched-capacitor stimulation (SCS). We also developed electrodes for easy implantation and employed safe and efficient stimulation methods including CCS, SCS, and HFS. The in vivo animal experiments on normal and paralyzed SR muscles of rabbits showed that eyeball abduction angles were proportional to the current and pulse width of the stimulation. With the decaying exponential stimuli of the SCS system, eyeball abductions were 2.58× and 5.65× larger for normal and paralyzed muscles, respectively, compared to the rectangular stimulus of CCS. HFS achieved 0.92× and 0.26× abduction for normal and paralyzed muscles, respectively, with half energy compared to CCS. In addition, the continuous changes in eyeball abduction angle in response to varying stimulation intensity over time were observed.

Changes in rabbit meat texture and calpain system genes expression following dietary supplementation with algae or vegetable oils

Abstract Meat texture is one of the most important parameters of meat quality and it could be improved by lipid sourced from vegetable oils. This study was undertaken to analyze the changes in meat texture, and in the mRNA expression of calpains (CAPN1 and CAPN3) and calpastatin 2 (CAST2) following diet supplemented with 1% algae (A), 3% sunflower (OS) oil, or 3% soybean oil (SO), using Blanc de Termonde rabbits at different age (12 and 18 weeks). Animals in the control group (C) received feed without additives. Animals were randomly sorted (40 rabbits/each group, balanced for sex). The General Linear Model (GLM) procedure was used to analyze the data and the Tukey–Kramer test was used for multiple comparisons. Our results indicate that the texture of rabbit meat depends on the age and algae, sunflower, and soybean oil supplementation, and diet-age interaction. The influence of the diet on CAPN1, CAPN3, and CAST2 expression depends on the rabbit age. In 12-week-old animals, meat shear force was greater following algae and soybean oil supplementation. Moreover, soybean oil decreased CAPN1, CAPN3, and CAST2, and algae supplement decreased CAST2 genes expression in rabbit muscle. In 18-week-old rabbits, supplementation with sunflower or soybean oil improved meat hardness, chewiness, and shear force. Additionally, sunflower oil increased CAPN1 and decreased CAST2 gene expression in the muscle tissue, providing new information about the molecular mechanism of meat texture in rabbits.

Integrated analysis of intestinal microbial community and muscle transcriptome profile in rabbits

Intestinal microbial community plays an important part in maintaining health and skeletal muscle development in livestock. This study is the first of its kind in the world. In order to better understand the relationship between gut microbiota and gene expression in skeletal muscle of rabbits, caecum contents and longissimus dorsi tissues of rabbits at 0 d (S1), 35 d (S2) and 70d (S3) were collected and subjected for 16S rRNA sequencing and transcriptome sequencing. Our results showed that, among three groups of rabbits, Firmicutes and Bacteroidetes were the dominant phyla at the phylum level, while Akmansia, Bacteroides and Ruminobacter were the dominant genera at the genus level, and the relative abundance of Akmansia and Bacteroides increased firstly and then decreased from 0 d to 70 d. By analyzing the transcriptome sequencing data, we identified 2866, 2446 and 4541 differentially expressed genes (DEGs) in S1 vs S2, S2 vs S3 and S1 vs S3 groups, respectively. Finally, we performed correlation analysis between gut microbiota and the expression levels of muscle development-related genes of rabbits at 0 d and 70 d. Compared with 0 day old rabbits, in 70 day old rabbits Acinetobacter and Cronbacter with decreased abundance, and Ruminococcaceae_UCG-014 and Ruminococcus_1 with increase abundance is beneficial to caecum health in rabbits. These results will lay a foundation for further re-searches about the relationship between caecum microflora and muscle development in rabbits.

Physicochemical and Spectroscopic Characterization of Glycogen and Glycogen Phosphorylase b Complexes

Glycogen is a natural polysaccharide used as an energy storage macromolecule. The role of glycogen metabolism in type 2 diabetes mellitus has been under investigation for several years, along with its implication in cancer and cardiovascular and neurodegenerative diseases. Previous studies using pig liver glycogen with rabbit muscle glycogen phosphorylase (RMGPb), which catalyzes the first step of glycogen degradation to glucose-1-phosphate, showed that the surface of an average glycogen molecule is covered by a total of 20 RMGPb dimeric molecules. In this work, we selected oyster glycogen (Glyc) to investigate its interaction with RMGPb by employing biophysical techniques. Dynamic, static, and electrophoretic light scattering were used to investigate the solution behaviors and structures of both the Glyc molecule itself and the formed complexes between Glyc and GPb at different mixing ratios. It was established that the interaction between oyster Glyc and RMGPb is similar to that previously reported for pig liver glycogen. Moreover, the structure of the complexed GPb was monitored by fluorescence and FTIR spectroscopy.

Effects of supplementing pistachio skins in the diet on growth performance and the fatty acid profile of Biceps femoris and Longissimus dorsi muscles in rabbits

Effects of supplementing pistachio skins in the diet on growth performance and the fatty acid profile of Biceps femoris and Longissimus dorsi muscles in rabbits

Synthesis of Chiral Acyclic Pyrimidine Nucleoside Analogues from DHAP-Dependent Aldolases.

Dihydroxyacetone phosphate (DHAP)-dependent aldolases catalyze the aldol addition of DHAP to a variety of aldehydes and generate compounds with two stereocenters. This reaction is useful to synthesize chiral acyclic nucleosides, which constitute a well-known class of antiviral drugs currently used. In such compounds, the chirality of the aliphatic chain, which mimics the open pentose residue, is crucial for activity. In this work, three DHAP-dependent aldolases: fructose-1,6-biphosphate aldolase from rabbit muscle, rhanmulose-1-phosphate aldolase from Thermotoga maritima, and fuculose-1-phosphate aldolase from Escherichia coli, were used as biocatalysts. Aldehyde derivatives of thymine and cytosine were used as acceptor substrates, generating new acyclic nucleoside analogues containing two new stereocenters with conversion yields between 70% and 90%. Moreover, structural analyses by molecular docking were carried out to gain insights into the diasteromeric excess observed.

Rabbit muscle pyruvate kinase activators: Synthesis, molecular docking and theoretical studies of N-substituted sulfonamide derivatives

Pyruvate kinase (PK) activators have potential therapeutic applications in diseases such as sickle cell anemia. In this study, N-Substituted sulfonamide derivatives of 1,4-dihydropyridines were synthesized and evaluated as PK activators in vitro and using molecular docking studies. The compounds were synthesized by reacting dicarbonyl compounds with ammonium acetate, 5-nitrobenzaldehyde, and alumina sulfuric acid (ASA), followed by reduction and sulfonylation. The structures of the compounds were analyzed using spectroscopic techniques. DFT calculations provided insights into the electronic properties. Molecular docking of the compounds into the active site of PK showed favorable binding interactions. ADME evaluation indicated suitable solubility, BBB permeation, and lack of CYP450 inhibition. Overall, this study demonstrates the potential of new hybrid 1,4-dihydropyridine substituted sulfonamides as PK activators for further development. According to AC50 values, the compound (DTSF7, 0.97μM) is about 100-fold higher affective than the clinically used sulfonamide compound (AC50 = 90μM) for PK.

Elements in Serum, Muscle, Liver, and Kidney of Rabbits Fed Macroalgae-Supplemented Diets.

The addition of marine macroalgae to animal feed has garnered interest due to the demonstrated benefits of gut health in many livestock species. Most macroalgae have a higher mineral content than terrestrial vegetables, making them an attractive, sustainable source of minerals. However, some macroalgae contain elevated concentrations of iodine and arsenic, which may be transferred to the meat of livestock fed with macroalgae. This study evaluated the mineral profile of rabbit serum, muscle, liver, and kidney of rabbits fed diets supplemented with different marine macroalgae, with the goal of improving post-weaning gut health and reducing reliance on antibiotics. We found increased deposition of iodine in muscle, liver, and kidney due to macroalgae supplementation, which is particularly promising for regions with low iodine endemicity. Higher, though relatively low arsenic concentrations, compared to those in other animal meats and food sources, were also detected in the muscle, liver, and kidney of macroalgae-fed rabbits. The absence of apparent interactions with other micronutrients, particularly selenium, suggests that the inclusion of macroalgae in rabbit diets will not affect the overall mineral content. Enhanced bioavailability of elements such as phosphorus and iron may provide additional benefits, potentially reducing the need for mineral supplementation.

Concentration of selected biogenic and risk elements in liver, kidneys and muscle of domestic rabbit and wild brown hare

In the present study the concentration of selected elements in tissues of domestic rabbits and of wild brown-hares (kidneys, liver, and muscle – m. quadriceps femoris) in Slovakian habitats were determined. After mineralization the elements examined were detected using flame atomic absorption spectrophotometry/graphite furnace atomic absorption spectrophotometry. For rabbits, Fe in the liver was correlated with essential (Mn, Cu) (R 2 = 0.94, p < 0.05; R 2 = 0.96, p < 0.05 respectively) or toxic (Pb) elements (R 2 = −0.93, p < 0.05). For hares, significant correlations were found between Cd and Cu or between Cd and Mn in the kidneys (R 2 = −0.96, p < 0.05; R 2 = 0.92, p < 0.05 respectively), which is the target organ for Cd. Higher concentrations of the elements were found in hare tissue, and this may be linked to pollution of their wild habitats. The xenobiotic elements as well as the essential elements were accumulated in the kidneys of the hares than rabbits. For liver, differences were less pronounced and significance was only for Fe and Cu. Muscle of hares was more contaminated than of rabbits for both biogenic and toxic elements. These results show that detectable concentrations of inorganic elements. These levels may be linked to contamination of the natural habitats of wild biota due to industry, traffic, agriculture, and urban sprawl.

Microbiological and Physicochemical Changes in Rabbit Meat During Ambient Storage

This study aimed to evaluate the changes in rabbit meat during storage at ambient temperature (30 ± 1ºC) for nine hours. The study focused on two rabbit muscle parts: the hind leg and the saddle, investigated in terms of microbiological parameters such as aerobic plate count (APC) and total coliform count (TCC); and physicochemical parameters such as pH, color, total myoglobin concentration, and lipid oxidation. Data obtained were subjected to statistical analysis at a 5% significance level (p &lt; 0.05). Results revealed that the pH of both portions of rabbit muscle decreases over time during storage. This decrease is attributed to the growth of acid-producing microorganisms, which ultimately leads to spoilage in rabbit meat. On the contrary, color values (L*, a*, and b*) showed an increasing trend in both muscle portions, indicating a discoloration of rabbit meat during storage. Both lipid oxidation and total myoglobin content of rabbit meat did not change significantly during storage, but lipid oxidation varied between muscle parts. Based on the microbiological analysis of rabbit meat, both aerobic plate count (APC) and total coliform count (TCC) increased significantly during storage in both muscle portions. Results of the study suggest that freshly slaughtered rabbit meat must remain at ambient storage for the shortest time, as this storage condition will cause spoilage of meat, making it unfit for human consumption.

Acupotomy ameliorates knee osteoarthritis-related collagen deposition and fibrosis in rabbit skeletal muscle through the TGF-β/Smad pathway

ObjectiveTo investigate the effects of acupotomy on skeletal muscle fibrosis and collagen deposition in a rabbit knee osteoarthritis (KOA) model. MethodsRabbits (n = 18) were randomly divided into control, KOA, and KOA + acupotomy (Apo) groups (n = 6). The rabbits in the KOA and Apo groups were modeled using the modified Videman's method for 6 weeks. After modeling, the Apo group was subjected to acupotomy once a week for 3 weeks on the vastus medialis, vastus lateralis, rectus femoris, biceps femoris, and anserine bursa tendons around the knee. The behavior of all animals was recorded, rectus femoris tissue was obtained, and histomorphological changes were observed using Masson staining and transmission electron microscopy. The expression of transforming growth factor-β1 (TGF-β1), Smad 3, Smad 7, fibrillar collagen types I (Col-I) and III (Col-III) was detected using Western blot and real-time polymerase chain reaction (RT-PCR). ResultsHistological analysis revealed that acupotomy improved the microstructure and reduced the collagen volume fraction of rectus femoris, compared with the KOA group (P = .034). Acupotomy inhibited abnormal collagen deposition by modulating the expression of fibrosis-related proteins and mRNA, thus preventing skeletal muscle fibrosis. Western blot and RT-PCR analysis revealed that in the Apo group, Col-I, and Col-III protein levels were significantly lower than those in the KOA group (both P < .01), same as Col-I and Col-III mRNA levels (P = .0031; P = .0046). Compared with the KOA group, the protein levels of TGF-β1 and Smad 3 were significantly reduced (both P < .01), as were the mRNA levels of TGF-β1 and Smad 3 (P = .0007; P = .0011). Conversely, the levels of protein and mRNA of Smad 7 were significantly higher than that in the KOA group (P < .01; P = .0271). ConclusionAcupotomy could alleviate skeletal muscle fibrosis and delay KOA progress by inhibiting collagen deposition through the TGF-β/Smad pathway in the skeletal muscle of KOA rabbits.

Synthesis, In Silico and Kinetics Evaluation of N-(β-d-glucopyranosyl)-2-arylimidazole-4(5)-carboxamides and N-(β-d-glucopyranosyl)-4(5)-arylimidazole-2-carboxamides as Glycogen Phosphorylase Inhibitors.

Recently studied N-(β-d-glucopyranosyl)-3-aryl-1,2,4-triazole-5-carboxamides have proven to be low micromolar inhibitors of glycogen phosphorylase (GP), a validated target for the treatment of type 2 diabetes mellitus. Since in other settings, the bioisosteric replacement of the 1,2,4-triazole moiety with imidazole resulted in significantly more efficient GP inhibitors, in silico calculations using Glide molecular docking along with unbound state DFT calculations were performed on N-(β-d-glucopyranosyl)-arylimidazole-carboxamides, revealing their potential for strong GP inhibition. The syntheses of the target compounds involved the formation of an amide bond between per-O-acetylated β-d-glucopyranosylamine and the corresponding arylimidazole-carboxylic acids. Kinetics experiments on rabbit muscle GPb revealed low micromolar inhibitors, with the best inhibition constants (Kis) of ~3-4 µM obtained for 1- and 2-naphthyl-substituted N-(β-d-glucopyranosyl)-imidazolecarboxamides, 2b-c. The predicted protein-ligand interactions responsible for the observed potencies are discussed and will facilitate the structure-based design of other inhibitors targeting this important therapeutic target. Meanwhile, the importance of the careful consideration of ligand tautomeric states in binding calculations is highlighted, with the usefulness of DFT calculations in this regard proposed.

Shift from Pro- to Anti-Inflammatory Phase in Pelvic Floor Muscles at Postpartum Matches Histological Signs of Regeneration in Multiparous Rabbits.

Background and Objectives: Pelvic floor muscles (PFM) play a core role in defecation and micturition. Weakening of PFM underlies urogynecological disorders such as pelvic organ prolapse and stress urinary incontinence. Vaginal delivery damages PFM. Muscle trauma implies an inflammatory response mediated by myeloid cells, essential for subsequent recovery. Molecular signaling characterizing the pro-inflammatory phase shifts M1 macrophages to M2 macrophages, which modulate muscle repair. The present study aimed to evaluate histological characteristics and the presence of M1 and M2 macrophages in bulbospongiosus (Bsm) and pubococcygeus muscles (Pcm). Materials and Methods: Muscles from young nulliparous (N) and multiparous rabbits on postpartum days three (M3) and twenty (M20) were excised and histologically processed to measure the myofiber cross-sectional area (CSA) and count the centralized myonuclei in hematoxylin-eosinstained sections. Using immunohistochemistry, M1 and M2 macrophages were estimated in muscle sections. Kruskal-Wallis or one-way ANOVA testing, followed by post hoc tests, were conducted to identify significant differences (p < 0.05). Results: The myofiber CSA of both the Bsm and Pcm of the M3 group were more extensive than those of the N and M20 groups. Centralized myonuclei estimated in sections from both muscles of M20 rabbits were higher than those of N rabbits. Such histological outcomes matched significant increases in HLA-DR immunostaining in M3 rabbits with the CD206 immunostaining in muscle sections from M20 rabbits. Conclusions: A shift from the pro- to anti-inflammatory phase in the bulbospongiosus and pubococcygeus muscles of multiparous rabbits matches with centralized myonuclei, suggesting the ongoing regeneration of muscles.

Novel tetrazole and 1,3,4-oxadiazole derivatives synthesis, molecular docking, ADME, potential activator for rabbit muscle pyruvate kinase

Novel tetrazole and 1,3,4-oxadiazole derivatives synthesis, molecular docking, ADME, potential activator for rabbit muscle pyruvate kinase

Structural variations of pectinate muscles across sheep and rabbit atria.

The right and left atria play important roles in overall cardiac performance, both at rest and during exercise. Atrial dysfunction due to congenital or acquired heart diseases can result in significant disability or death. The prevalence of such conditions has been rising due to the increasing age of the population as well as the progressively larger number of patients with Grown-up congenital heart disease (GUCH). Left and right atria were collected from rabbits and juvenile sheep, and pattern recognition and image analysis were used to illustrate the microstructure and orientation of the pectinate muscles. The aim of this study is to observe the differences in the structure of the pectinate muscles in both rabbits and sheep. Through image analysis and pattern recognition, we were able to identify the orientation of the patterns that can help produce off-the-shelf patches that are capable of mimicking and/or reproducing most of the functions of normal atrial tissue. The microstructure of the pectinate muscles is unique and provides remarkable functionality to the atria.

Intersubunit communication in glycogen phosphorylase influences substrate recognition at the catalytic sites

Glycogen phosphorylase (GP) is biologically active as a dimer of identical subunits, each activated by phosphorylation of the serine-14 residue. GP exists in three interconvertible forms, namely GPa (di-phosphorylated form), GPab (mono-phosphorylated form), and GPb (non-phosphorylated form); however, information on GPab remains scarce. Given the prevailing view that the two GP subunits collaboratively determine their catalytic characteristics, it is essential to conduct GPab characterization to gain a comprehensive understanding of glycogenolysis regulation. Thus, in the present study, we prepared rabbit muscle GPab from GPb, using phosphorylase kinase as the catalyst, and identified it using a nonradioactive phosphate-affinity gel electrophoresis method. Compared with the half-half GPa/GPb mixture, the as-prepared GPab showed a unique AMP-binding affinity. To further investigate the intersubunit communication in GP, its catalytic site was probed using pyridylaminated-maltohexaose (a maltooligosaccharide-based substrate comprising the essential dextrin structure for GP; abbreviated as PA-0) and a series of specifically modified PA-0 derivatives (substrate analogs lacking part of the essential dextrin structure). By comparing the initial reaction rates toward the PA-0 derivative (Vderivative) and PA-0 (VPA-0), we demonstrated that the Vderivative/VPA-0 ratio for GPab was significantly different from that for the half-half GPa/GPb mixture. This result indicates that the interaction between the two GP subunits significantly influences substrate recognition at the catalytic sites, thereby providing GPab its unique substrate recognition profile.

Development of Mass Spectrometry Imaging on skeletal muscle to characterize the local pro-inflammatory and pro-resolution lipid responses in a vaccination context

Vaccine reactogenicity is well documented at the clinical level but the mechanism involved at the local or systemic level are still poorly understood. Muscular tissue where most vaccines are administered is the first place of interaction between the vaccine formulation and the host's immune cells. So far, this site of vaccine administration is not well documented from a mechanistic standpoint. The study of early molecular events at the injection site is crucial to understand the local response to vaccines. In this paper, we report a standardized workflow, from the injection of vaccine formulations in rabbit muscle, to the analysis by desorption electrospray ionization and histology staining to understand the role of lipids involved in the inflammation and its resolution on striated muscular tissue. The analysis of lipid mediators was optimized at the site of needle insertion to allow the spatial comparison of cellular infiltrates at the injection site. We showed that lipids were distributed across the spatial tissue morphology in a time-dependent manner. The MS imaging applied to vaccinology could pave the way to a better understanding of vaccine reactogenicity and mechanism of action.

Isolated Cardiac Ryanodine Receptor Function Varies Between Mammals.

Concerted robust opening of cardiac ryanodine receptors' (RyR2) Ca2+ release 1oplasmic reticulum (SR) is fundamental for normal systolic cardiac function. During diastole, infrequent spontaneous RyR2 openings mediate the SR Ca2+ leak that normally constrains SR Ca2+ load. Abnormal large diastolic RyR2-mediated Ca2+ leak events can cause delayed after depolarizations (DADs) and arrhythmias. The RyR2-associated mechanisms underlying these processes are being extensively studied at multiple levels utilizing various model animals. Since there are well-described species-specific differences in cardiac intracellular Ca2+ handing in situ, we tested whether or not single RyR2 function in vitro retains this species specificity. We isolated RyR2-rich heavy SR microsomes from mouse, rat, rabbit, and human ventricular muscle and quantified RyR2 function using identical solutions and methods. The single RyR2 cytosolic Ca2+ sensitivity was similar across these species. However, there were significant species differences in single RyR2 mean open times in both systole and diastole-like solutions. In diastole-like solutions, single rat/mouse RyR2 open probability and frequency of long openings (> 6ms) were similar, but these values were significantly greater than those of either single rabbit or human RyR2s. We propose these in vitro single RyR2 functional differences across species stem from the species-specific RyR2 regulatory environment present in the source tissue. Our results show the single rabbit RyR2 functional attributes, particularly in diastole-like conditions, replicate those of single human RyR2 best among the species tested.

Evaluation of acoustic-thermal simulations of invivo magnetic resonance guided focused ultrasound ablative therapy.

To evaluate numerical simulations of focused ultrasound (FUS) with a rabbit model, comparing simulated heating characteristics with magnetic resonance temperature imaging (MRTI) data collected during invivo treatment. A rabbit model was treated with FUS sonications in the biceps femoris with 3D MRTI collected. Acoustic and thermal properties of the rabbit muscle were determined experimentally. Numerical models of the rabbits were created, and tissue-type-specific properties were assigned. FUS simulations were performed using both the hybrid angular spectrum (HAS) method and k-Wave. Simulated power deposition patterns were converted to temperature maps using a Pennes' bioheat equation-based thermal solver. Agreement of pressure between the simulation techniques and temperature between the simulation and experimental heating was evaluated. Contributions of scattering and absorption attenuation were considered. Simulated peak pressures derived using the HAS method exceeded the simulated peak pressures from k-Wave by 1.6 ± 2.7%. The location and FWHM of the peak pressure calculated from HAS and k-Wave showed good agreement. When muscle acoustic absorption value in the simulations was adjusted to approximately 54% of the measured attenuation, the average root-mean-squared error between simulated and experimental spatial-average temperature profiles was 0.046 ± 0.019 °C/W. Mean distance between simulated and experimental COTMs was 3.25 ± 1.37 mm. Transverse FWHMs of simulated sonications were smaller than in invivo sonications. Longitudinal FWHMs were similar. Presented results demonstrate agreement between HAS and k-Wave simulations and that FUS simulations can accurately predict focal position and heating for invivo applications in soft tissue.