Research Note: Muscle hypertrophy is associated with reversed sexual dimorphism in body size of quail.

Sexual dimorphism is phenotypic differences between males and females in the same species. In general, males in most animals are larger than females at the same age, however, in quail, females have a larger body size with greater muscle mass than males. To understand what characteristics in muscle growth play roles in reversed sexual dimorphism in quail, the weights and the characteristics of the pectoralis major and gastrocnemius muscles (PM and GM, respectively) of male and female quail were compared in the current study. The data showed that 15-wk-old female quail have significantly heavier bodies, and PM and GM weights compared to male quail (1.27-folds, 1.29-folds, and 1.16-folds, respectively). To compare muscle characteristics such as hypertrophy (increased size) and hyperplasia (increased cell number), the PM and GM were stained using hematoxylin and eosin, and then histological characteristics such as total cross-sectional area (CSA), number and size of myofibers, and muscle bundle of the muscles were measured and analyzed. In both PM and GM, there were no differences in total numbers of myofibers and muscle bundles as well as the average numbers of myofibers per bundle between sexes. However, the sizes of myofiber and the bundle were significantly increased in female compared to male (1.33-folds and 1.28-folds in PM, and both 1.23-folds in GM, respectively). The findings of the current study suggest that muscle hypertrophy in female quail, not hyperplasia, can be attributed to the sexual dimorphism in quail size.

Clinical findings using echocardiography and plasma cardiac troponin I and pathological findings in dogs with hypertrophic cardiomyopathy: A retrospective study.

Background: Hypertrophic cardiomyopathy (HCM) is considered rare in dogs, and there is a lack of clinical data. Cardiac troponin I (cTnI) is a biomarker of cardiomyocyte damage and necrosis and can be used to diagnose cat and human HCM. Aim: We investigated whether the presence of cTnI in clinical data can be used in conjunction with echocardiography to diagnose canine HCM. Methods: This study comprised client-owned dogs with clinical evidence of concentric hypertrophy on echocardiographic images, serum total thyroxine levels of ≤5 µg/dl, systolic blood pressure of ≤180 mmHg, and absence of aortic stenosis. All cases were necropsied. Results: Cardiomyocyte hypertrophy (mean diameter, 18.3 ± 1.8 µm), myocardial fiber disarray (70%), interstitial fibrosis (80%), and small vessel disease (100%) were assessed. In dogs with HCM, the left ventricles were concentric, almost symmetrical, and hypertrophied above the aortic diameter. The end-diastolic interventricular septum normalized to body weight [intraventricular septal thickness in diastole (IVSDN)] was 0.788 [interquartile range (IQR), 0.7-0.92], which exceeded the normal range (5%-95%, IQR: 0.33-0.52). In total, 70% of the dogs with HCM had syncope and dyspnea, and all dogs had high cTnI levels (median, 3.94 ng/ml), exceeding the upper limit of normal (0.11 ng/ml) and indicating cardiomyocyte damage. IVSDN and serum cTnI levels were correlated (ρ = 0.839, p = 0.01). Conclusion: Ventricular wall thickening and high serum cTnI levels can provide a presumptive diagnosis of HCM and prompt the initiation of treatment or additional diagnostic investigations.

Melatonin supplementation promotes muscle fiber hypertrophy and regulates lipid metabolism of skeletal muscle in weaned piglets.

Melatonin has been reported to play crucial roles in regulating meat quality, improving reproductive properties, and maintaining intestinal health in animal production, but whether it regulates skeletal muscle development in weaned piglet is rarely studied. This study was conducted to investigate the effects of melatonin on growth performance, skeletal muscle development, and lipid metabolism in animals by intragastric administration of melatonin solution. Twelve 28-d-old DLY (Duroc × Landrace × Yorkshire) weaned piglets with similar body weight were randomly divided into two groups: control group and melatonin group. The results showed that melatonin supplementation for 23 d had no effect on growth performance, but significantly reduced serum glucose content (P < 0.05). Remarkably, melatonin increased longissimus dorsi muscle (LDM) weight, eye muscle area and decreased the liver weight in weaned piglets (P < 0.05). In addition, the cross-sectional area of muscle fibers was increased (P < 0.05), while triglyceride levels were decreased in LDM and psoas major muscle by melatonin treatment (P < 0.05). Transcriptome sequencing showed melatonin induced the expression of genes related to skeletal muscle hypertrophy and fatty acid oxidation. Enrichment analysis indicated that melatonin regulated cholesterol metabolism, protein digestion and absorption, and mitophagy signaling pathways in muscle. Gene set enrichment analysis also confirmed the effects of melatonin on skeletal muscle development and mitochondrial structure and function. Moreover, quantitative real-time polymerase chain reaction analysis revealed that melatonin supplementation elevated the gene expression of cell differentiation and muscle fiber development, including paired box 7 (PAX7), myogenin (MYOG), myosin heavy chain (MYHC) IIA and MYHC IIB (P < 0.05), which was accompanied by increased insulin-like growth factor 1 (IGF-1) and insulin-like growth factor binding protein 5 (IGFBP5) expression in LDM (P < 0.05). Additionally, melatonin regulated lipid metabolism and activated mitochondrial function in muscle by increasing the mRNA abundance of cytochrome c oxidase subunit 6A (COX6A), COX5B, and carnitine palmitoyltransferase 2 (CPT2) and decreasing the mRNA expression of peroxisome proliferator-activated receptor gamma (PPARG), acetyl-CoA carboxylase (ACC) and fatty acid-binding protein 4 (FABP4) (P < 0.05). Together, our results suggest that melatonin could promote skeletal muscle growth and muscle fiber hypertrophy, improve mitochondrial function and decrease fat deposition in muscle.

Due to its extensive biological functions, melatonin has been widely used in animal production in recent years. The purpose of this study was to investigate the effects of melatonin on growth performance, muscle development, and lipid metabolism of weaned piglets. Twelve 28-d-old DLY (Duroc × Landrace × Yorkshire) weaned piglets were randomly divided into two groups: control group and melatonin group. The results showed that melatonin supplementation daily had no effect on growth performance, but increased muscle weight, eye muscle area, and decreased the liver weight in weaned piglets. Consistently, the cross-sectional area of myofiber increased, while triglyceride levels decreased in muscle. Melatonin induced the expression of genes related to skeletal muscle hypertrophy and fatty acid oxidation in muscle through transcriptome sequencing. Additionally, melatonin regulated cholesterol metabolism, protein digestion and absorption, and mitophagy signaling pathways in muscle. Gene set enrichment analysis also confirmed the effects of melatonin on skeletal muscle development and mitochondrial function. Moreover, melatonin supplementation elevated the gene expression of cell differentiation and muscle fiber development. Additionally, melatonin inhibited the mRNA expression related to fat synthesis while improved mitochondrial function in muscle. Together, our results suggest melatonin could promote skeletal muscle growth and muscle fiber hypertrophy, enhance mitochondrial function and decrease fat deposition in muscle.

In ovo probiotic supplementation promotes muscle growth and development in broiler embryos.

In chickens, muscle development during embryonic growth is predominantly by myofiber hyperplasia. Following hatch, muscle growth primarily occurs via hypertrophy of the existing myofibers. Since myofiber number is set at hatch, production of more muscle fibers during embryonic growth would provide a greater myofiber number at hatch and potential for posthatch muscle growth by hypertrophy. Therefore, to improve performance in broilers, this study investigated the effect of in ovo spray application of probiotics on overall morphometry and muscle development in broiler embryos. For the study, fertile Ross 308 eggs were sprayed with different probiotics; Lactobacillus paracasei DUP 13076 (LP) and L. rhamnosus NRRL B 442 (LR) prior to and during incubation. The embryos were sacrificed on d 7, 10, 14, and 18 for embryo morphometry and pectoralis major muscle (PMM) sampling. Muscle sections were stained and imaged to quantify muscle fiber density (MFD), myofiber cross-sectional area (CSA), and nuclei density. Additionally, gene expression assays were performed to elucidate the effect of probiotics on myogenic genes. In ovo probiotic supplementation was found to significantly improve embryo weight, breast weight, and leg weight (P < 0.05). Further, histological analysis of PMM revealed a significant increase in MFD and nuclei number in the probiotic-treated embryos when compared to the control (P < 0.05). In 18-day-old broiler embryos, myofibers in the treatment group had a significantly smaller CSA (LP: 95.27 ± 3.28 µm2, LR: 178.84 ± 15.1 µm2) when compared to the control (211.41 ± 15.67 µm2). This decrease in CSA was found to be associated with a concomitant increase in MFD (fibers/mm2) in the LP (13,647 ± 482.15) and LR (13,957 ± 463.13) group when compared to the control (7,680 ± 406.78). Additionally, this increase in myofibrillar hyperplasia in the treatment groups was associated with upregulation in the expression of key genes regulating muscle growth including MYF5, MYOD, MYOG, and IGF-1. In summary, in ovo spray application of probiotics promoted overall embryo growth and muscle development in broilers.

Aorto-septal angle, isolated basal septal hypertrophy, and systolic murmur in 122 cats.

INTRODUCTION/OBJECTIVES: Systolic murmurs in the absence of cardiac structural abnormalities are common in cats. Narrow aorto-septal angle (AoSA) and septal remodeling can be a cause of a systolic murmur in elderly human beings. The aim of this study was to measure the AoSA in cats and to investigate the association between the AoSA and the presence of a murmur and isolated basal septal hypertrophy (IBSH). ANIMALS: The study population comprised 122 cats. MATERIALS AND METHODS: A physical exam, blood pressure measurement, chest radiographs, and echocardiography were performed. RESULTS: A systolic murmur was audible in 39/122 cats. A difference between cats with and without a murmur was found for age (P=0.0001), interventricular basal septal thickness (BIVSd) (P=0.004), AoSA (P=0.003), aortic (P<0.0001), and pulmonic (P=0.021) flow velocity, the presence of IBSH (P<0.0001), and systolic anterior motion of the mitral valve (P=0.0002). More than 50% of cats with a murmur had an AoSA ≤122°. Less than 25% of the cats with an AoSA ≥137° had a murmur. The AoSA narrowed 0.55°/year of age (P<0.001), whereas the BIVSd increased 0.11 mm/year of age (P<0.0001); the BIVSd increased as the AoSA narrowed. In all cats with AoSA < 120°, IBSH was present. CONCLUSIONS: This study demonstrates that the probability of having a systolic murmur in cats is increased by the presence of a narrow AoSA. Aging was associated with a narrower AoSA and a thicker basal septum; these findings might represent an age-related heart remodeling.

Short communication: In ovo injection of all-trans retinoic acid causes adipocyte hypertrophy in embryos but lost its effect in posthatch chickens.

The regulation of adipose deposition in broiler chickens is an important factor for production efficiency to poultry producers and health concerns to customers. Although vitamin A and its metabolite [all-trans retinoic acid (atRA)] have been used for studies on adipogenesis in mammals and avian, effects of embryonic atRA on adipose development in embryonic (E) and posthatch (D) ages in broiler chickens have not been studied yet. Different concentrations of atRA (0 M-2 µM) were injected in broiler eggs at E10, and adipose tissues were sampled at E16. Percentages of adipose tissues in chicken embryos were significantly increased in the group injected with 500 nM of atRA compared to the 0 M group (P < 0.05). In addition, the adipocyte cross-sectional area (CSA) was significantly greater by in ovo injection of 500 nM atRA compared to the injection of 0 M (P < 0.01). Moreover, in ovo atRA-injected embryos were hatched and BWs were measured at D0, D7, and D14. BWs were not different from those of the 0 M group. Percentages of adipose tissues and CSA of the in ovo atRA-injected group (500 nM) were not different from those of the 0 M group at D14. Taken together, the current study clearly showed that in ovo injection of atRA promoted adipose deposition with hypertrophy during embryonic development, but its effects were not maintained in early posthatch age in broiler chickens, implying that embryonic atRA has an important role in the regulation of adipose development in chicken embryos.

Two branchial pathological conditions, nuclear hypertrophy and abnormal epithelial proliferation, in Mya arenaria from northwest Russian coasts.

Histopathological analysis of soft-shell clams Mya arenaria collected from 2 northwest Russian locations disclosed high prevalence of 2 pathological gill conditions. One involved the occurrence of more or less extended gill areas in which the branchial filaments showed hyperchromatic (basophilic) epithelium with some hypertrophied nuclei, which were considered presumptive signs of viral infection. Another pathological condition involved abnormal proliferation of the branchial epithelium, which lost the main differential features of the normal branchial epithelium (ciliated and simple cell layer structure), becoming non-ciliated, pseudostratified or stratified hyperchromatic epithelium with abundant mitotic figures and frequent apoptotic cells. The most complex cases involved loss of the normal branchial filament architecture, which was replaced with tumour-like growths consisting of branching, convoluted epithelial projections with a connective stroma. Images suggesting migration (invasion) of cells from the abnormally proliferating epithelium to the subjacent connective tissue, which would involve malignancy, were observed in one individual. The occurrence of both pathological conditions in clams from both locations and their co-occurrence in one clam suggest the possibility of a common, possibly viral, aetiology. Furthermore, the high prevalence of the abnormal proliferative disorder in non-polluted areas suggests an infectious aetiology. Additional studies are needed to assess a viral aetiology for the nuclear hypertrophy and/or the abnormal epithelial proliferation as well as the malignancy of the latter condition.

Vascular, cardiac, and renal lesions attributed to primary systemic hypertension in western pygmy marmosets (Cebuella pygmaea).

In a retrospective study of a western pygmy marmoset (Cebuella pygmaea) colony, postmortem examination of 1/8 juvenile and 29/47 adult animals identified vascular, cardiac, and renal lesions consistent with systemic hypertension. This included frequent renal arteriolar hypertrophy, hyaline and proliferative arteriolosclerosis, fibrinoid necrosis of arterioles, glomerulosclerosis, and nephrosclerosis. Affected animals ranged from 0.6 to 12 years of age (mean 6 years) and had an observed male predominance. Genealogical relatedness was evident in several breeding pairs and spanned multiple generations. Concurrent cardiac and renal disease was commonly identified, although frequently subclinical, and both were important causes of morbidity and mortality in affected animals. Cardiomegaly and hypertrophy were typical features and were accompanied by left atrial thrombosis in 10 animals. Signs of heart failure included chronic pulmonary edema in 20 cases and body cavity effusions in 17. In the kidneys, 19 cases had glomerular disease and hypertensive vasculopathy, and 26 cases had nephrosclerosis or glomerulosclerosis. Common extrarenal secondary causes of hypertension were excluded by necropsy examination. The pathogenesis is suggested to involve primary hypertension leading to renal and cardiac disease. Elevated sympathetic activity might be an underlying factor in the frequent development of primary systemic hypertension in the pygmy marmoset, as for the owl monkey.

Neural Hypertrophy and Hyperplasia in a Case of Chronic Ovine Pancreatitis.

Nerves can be severely reshaped in human pancreatic diseases such as chronic pancreatitis (CP) and pancreatic cancer, in which pancreatic nerves can undergo hypertrophy or hyperplasia. This neural plasticity is associated with neuropathic pain. Although there are several animal models of CP, pancreatic neuropathy is not well-characterized. Thus, the translational value of these in-vivo models cannot be entirely ascertained for the study of neural plasticity. We now describe spontaneous alterations characteristic of pancreatic neural plasticity in a lamb. Microscopic lesions of chronic sclerosing pancreatitis were associated with neuronal hypertrophy and hyperplasia. Although CP and pancreatic tumours are common in many animal species, to the authors' knowledge, spontaneous occurrence of associated pancreatic neural plasticity has not been reported in any non-human species. Sheep might be a suitable animal model for the study of this condition.

CT findings in a dog with subacute myopathy and later fibrotic contracture of the infraspinatus muscle.

A 5-year-old Norwegian elkhound was referred due to an acute onset of lameness and persistent shoulder pain over a period of 3 weeks. Computed tomography demonstrated an enlarged, hypoattenuating right infraspinatus muscle with peripheral contrast enhancement and a nonenhancing center, without concurrent lesions in superficial structures or bones. The right infraspinatus muscle showed progressive atrophy on consecutive CT studies. The dog developed clinical symptoms compatible with fibrotic infraspinatus contracture 2 months after the initial presentation, and was treated with infraspinatus tenotomy. Histopathological diagnoses based on intraoperative biopsy samples were fibrotic muscle atrophy and muscle hypertrophy with regeneration.

Dorsal Atlantoaxial Ligament Hypertrophy as a Cause for Clinical Signs in Dogs with Dens Abnormalities.

The objective of this study is to suggest clinical and subclinical atlantoaxial (AA) instability as a cause for dorsal AA ligament hypertrophy responsible for clinical signs in dogs with dens abnormalities. Clinical information from five dogs with malformed dens and dorsal spinal cord compression at the AA junction was collected. All dogs had neck pain, associated with tetraparesis in three cases. Radiological examination revealed hypoplastic dens in two dogs and a defect in its ossification in the other three. Stress views were able to demonstrate obvious AA instability only in two cases, but it was suspected in the other owing to response to surgical fixation of the joint and the presence of a dorsal compressive band, which was considered an enlarged dorsal AA ligament. Surgical and histopathological examination of compressive tissue confirmed hypertrophy of the ligament. Long-term prognosis in the four operated cases, either by dorsal decompression and ventral fixation or by ventral fixation alone, was excellent. A malformed dens can cause subclinical instability, unnoted in dynamic studies. As instability may lead to hypertrophy of joint ligaments, soft tissue changes (specifically dorsal AA ligament hypertrophy) points out this instability and the need for joint fixation if surgical management is required.

Myocardial Changes in Diabetic and Nondiabetic Nonhuman Primates.

Diabetic human patients have increased risk of heart failure compared to healthy subjects. The underlying mechanisms for this are not fully understood, and to help develop improved treatment strategies, well-characterized animal models are essential. To investigate cardiac dysfunction in diabetes, this study evaluated myocardial changes in 10 aging rhesus monkeys with and without diabetes. Based on evaluation of plasma glycosylated hemoglobin and glucose, 7 of 10 rhesus macaques had diabetes for a minimum of 11 months, while 3 of 10 were categorized as nondiabetic. A detailed histological examination of formalin-fixed left ventricular myocardial samples was followed by a semiquantitative evaluation of myocardial fibrosis and fat infiltration; digital quantifications of myocardial collagen, lipofuscin, and nuclear area fractions; and measurements of cardiomyocyte diameter. Histological myocardial evaluation revealed the presence of lipofuscin; large nuclei; interstitial, replacement, and vascular fibrosis; adipocyte infiltration; and vacuolar degeneration with atrophy of cardiomyocytes and fibrosis. However, there were no differences between groups for semiquantitative fat infiltration, fibrosis, cardiomyocyte size, collagen, or nuclear and lipofuscin area fraction. Lipofuscin area fraction correlated with plasma insulin, triglyceride, total cholesterol, and high-density lipoprotein cholesterol concentrations. In conclusion, myocardial pathological changes were found in left ventricular myocardium in aged rhesus macaques, independent of the stage of diabetes. The duration of diabetes might have been too short to cause differences between groups.

Hypertrophic muscle growth and metabolic efficiency were impaired by chronic heat stress, improved by zilpaterol supplementation, and not affected by ractopamine supplementation in feedlot lambs1.

Feedlot performance is reduced by heat stress and improved by ß adrenergic agonists (ßAA). However, the physiological mechanisms underlying these outcomes are not well characterized, and anecdotal reports suggest that ßAA may confound the effects of heat stress on wellbeing. Thus, we sought to determine how heat stress and ßAA affect growth, metabolic efficiency, and health indicators in lambs on a feedlot diet. Wethers (38.6 ± 1.9 kg) were housed under thermoneutral (controls; n = 25) or heat stress (n = 24) conditions for 21 d. In a 2 × 3 factorial, their diets contained no supplement (unsupplemented), ractopamine (ß1AA), or zilpaterol (ß2AA). Blood was collected on days -3, 3, 9, and 21. On day 22, lambs were harvested and ex vivo skeletal muscle glucose oxidation was determined to gauge metabolic efficiency. Feet and organ tissue damage was assessed by veterinary pathologists. Heat stress reduced (P < 0.05) feed intake by 21%, final bodyweight (BW) by 2.6 kg, and flexor digitorum superficialis (FDS) muscle mass by 5%. ß2AA increased (P < 0.05) FDS mass/BW by 9% and average muscle fiber area by 13% compared with unsupplemented lambs. Blood lymphocytes and monocytes were greater (P < 0.05) in heat-stressed lambs, consistent with systemic inflammation. Plasma insulin was 22% greater (P < 0.05) and glucose/insulin was 16% less (P < 0.05) in heat-stressed lambs than controls. Blood plasma urea nitrogen was increased (P < 0.05) by heat stress on day 3 but reduced (P < 0.05) on days 9 and 21. Plasma lipase and lactate dehydrogenase were reduced (P < 0.05) by heat stress. Glucose oxidation was 17% less (P < 0.05) in muscle from heat-stressed lambs compared with controls and 15% greater (P < 0.05) for ß2AA-supplemented compared with unsupplemented lambs. Environment and supplement interacted (P < 0.05) for rectal temperature, which was increased (P < 0.05) by heat stress on all days but more so (P < 0.05) in ß2AA-supplemented lambs on days 4, 9, and 16. Heat stress increased (P < 0.05) the frequency of hoof wall overgrowth, but ßAA did not produce any pathologies. We conclude that reduced performance in heat-stressed lambs was mediated by reduced feed intake, muscle growth, and metabolic efficiency. ß2AA increased muscle growth and improved metabolic efficiency by increasing muscle glucose oxidation, but no such effects were observed with ractopamine. Finally, ßAA supplementation was not detrimental to health indicators in this study, nor did it worsen the effects of heat stress.

Pseudodiverticula of the Small Intestine Associated With Idiopathic Smooth Muscle Hypertrophy in Domestic Rabbits ( Oryctolagus cuniculus).

Acquired outpouches of the intestinal tract are referred to as pseudodiverticula or false pulsion diverticula. In contrast to true diverticula, in which the wall contains all layers of the intestinal tract, the wall of pseudodiverticula lacks the tunica muscularis. Smooth muscle hypertrophy of the small intestine is commonly considered a cause of pseudodiverticulosis in animals due to increased intraluminal pressure. This study reports pseudodiverticula associated with idiopathic smooth muscle hypertrophy of the small intestine in lagomorphs. Four domestic rabbits had single or multiple (up to 200) pseudodiverticula of various size in the small intestine. In all cases the tunica muscularis was diffusely thickened, significantly exceeding reference thickness of 14 rabbits (mean, 112.3 µm; range, 26.3-389.0 µm). Clinical signs were considered to be caused by severe necrosis and inflammation of the wall of large pseudodiverticula, leading to perforation with subsequent peritonitis and mesenteric and omental abscess formation in 2 cases.

Myocardial hypertrophy associated with long-term phenylpropanolamine use in a dog.

CASE DESCRIPTION A 9-year-old spayed female Dalmatian was examined because of progressive pelvic limb paraparesis. CLINICAL FINDINGS The dog had a history of chronic urinary incontinence and had been treated with phenylpropanolamine (PPA) for almost 8.5 years. Intervertebral disk disease at T12-13 was diagnosed, and a hemilaminectomy was performed. Three days after surgery, the dog developed a ventricular tachyarrhythmia. Severe left and mild right ventricular hypertrophy were detected by echocardiography. TREATMENT AND OUTCOME The arrhythmia was controlled with sotalol. Phenylpropanolamine administration was discontinued immediately before surgery and was not resumed. Heart rate and rhythm and blood pressure were within reference limits, and the ventricular hypertrophy had almost completely resolved 5 months later. Sotalol administration was discontinued. Shortly after the 5-month recheck evaluation, PPA administration was resumed, albeit at a lower dosage than that before surgery, for control of urinary incontinence. At the 10-month recheck evaluation, the dog was hypertensive and ventricular hypertrophy had recurred. Discontinuation of PPA administration was recommended but not heeded. The dog developed marked azotemia 1.5 years after surgery, which was managed by the referring veterinarian, and was subsequently lost to follow-up. CLINICAL RELEVANCE The fact that the ventricular hypertrophy almost completely resolved when PPA administration was discontinued and then recurred after it was resumed strongly suggested the drug was an important contributing factor to the cardiac disease of this patient. Patients receiving PPA on a long-term basis should be frequently monitored for cardiac disease, and use of other adrenergic receptor agonists should be avoided in such patients.

Chronic heat stress affects muscle hypertrophy, muscle protein synthesis and uptake of amino acid in broilers via insulin like growth factor-mammalian target of rapamycin signal pathway.

Heat stress markedly impairs the growth performance of broilers, such as the reduction of breast muscle mass and yield. The aim of this study was to examine the molecular mechanism of depressed muscle mass and yield caused by heat stress. A total of 144 (28-day-old) male broilers were allocated randomly into 3 treatment groups: (1) the normal control group (environment temperature was 22°C), (2) the heat stress group (environment temperature was 32°C), (3) the pair-fed group (environment temperature was 22°C and pair-fed to heat stress group). The experiment lasted for 14 d (from the age of 28 to 42 d). After 14 d of heat exposure, heat stress decreased (P < 0.05) broiler average daily gain, breast muscle mass, and muscle yield, and increased (P < 0.05) feed to gain ratio. After 14 d of heat exposure, heat stress increased (P < 0.05) the activities of aspartate aminotransferase and the concentrations of uric acid and most amino acids in serum, and reduced (P < 0.05) the concentration of insulin like growth factor 1 (IGF-1) in serum. Additionally, heat stress decreased (P < 0.05) the mRNA expressions of IGF-1, IGF-1 receptor, insulin receptor substrate 1, mammalian target of rapamycin (mTOR), the 70 kD ribosomal protein S6 kinase, myogenic differentiation, myogenin, solute carrier family 38 member 2, solute carrier family 7 member 5, and solute carrier family 3 member 2 of the breast muscle. In conclusion, chronic heat stress resulted in lower breast muscle mass and yield, and decreased muscle protein synthesis and amino acid transportation by downregulating IGFs-mTOR signal pathway. These findings have important practical significance in discovering effective means to alleviate muscle loss caused by chronic heat stress.

γ-Secretase Inhibition Induces Muscle Hypertrophy in a Notch-Independent Mechanism.

A wide variety of cellular processes and signaling events are regulated by the proteolytic enzyme γ-secretase. Notch-1 is one of the substrates of γ-secretase and its role in the regulation of muscle differentiation has been well described. Importantly, besides Notch-1, a number of proteins have been identified to undergo proteolysis by γ-secretase. To date, the specific role of γ-secretase during embryonic skeletal muscle differentiation has not been studied. Therefore, we address this question through the analysis of in vitro grown chick myogenic cells during the formation of multinucleated myotubes. The γ-secretase inhibitor DAPT (N-N[-(3,5-Difluorophenacetyl-l-alanyl)]-S-328 phenylglycine-t-butyl-ester) induces muscle hypertrophy. Knockdown of Notch-1 using siRNA specific to chick shows no significant effect in myotube size, suggesting that γ-secretase-dependent effects on muscle hypertrophy in chick myogenic cells are Notch-1-independent. We also investigate the effects of γ-secretase inhibition in the whole proteomic profile of chick myogenic cells. We identified 276 differentially expressed proteins from Label-free proteomic approach. Data overview of interaction network obtained from STRING show that after γ-secretase inhibition cells exhibited imbalance in protein metabolism, cytoskeleton/adhesion, and Sonic Hedgehog signaling. The collection of these results provides new insights into the role of γ-secretase in skeletal muscle hypertrophy.

Esophageal smooth muscle hypertrophy causing regurgitation in a rabbit.

A five-year-old rabbit was evaluated for a 7 to 8 month history of regurgitation, weight loss, and hyporexia. Previously performed whole body radiographs, plasma biochemistry results and complete blood count revealed had no significant abnormalities. A computed tomography (CT) scan revealed a circumferential caudal esophageal thickening. The animal received supportive care until euthanasia was performed 6 weeks later. Caudal esophageal smooth muscle hypertrophy was diagnosed on necropsy. This case indicates that regurgitation can occur in rabbits and advanced imaging can investigate the underlying cause.

Sensibilidade e especificidade do exame eletrocardiográfico na detecção de sobrecargas atriais e/ou ventriculares em gatos da raça Persa com cardiomiopatia hipertrófica / Sensitivity and specificity of electrocardiographic examination in detecting ventricular or atrial overloads in Persian cats with hypertrophic cardiomyopathy

A cardiomiopatia hipertrófica (CMH) é a principal cardiopatia dos felinos e é caracterizada por hipertrofia miocárdica concêntrica, sem dilatação ventricular. O ecocardiograma é o melhor meio diagnóstico não invasivo para a diferenciação das cardiomiopatias e é considerado padrão ouro para a detecção de hipertrofia ventricular presente na CMH. Alterações eletrocardiográficas também são comuns em animais com CMH e o eletrocardiograma (ECG) é um teste de triagem para detecção de hipertrofia ventricular em humanos, sendo um exame rápido e facilmente disponível. Em gatos, poucos estudos foram realizados quanto à sensibilidade e especificidade do ECG na detecção de hipertrofia ventricular. Com a intenção de avaliar o uso do ECG como ferramenta de triagem para diagnóstico de CMH em felinos, gatos da raça Persa (n=82) foram avaliados por meio de exames ecocardiográfico e eletrocardiográfico. Animais com bloqueios e/ou distúrbios de condução foram excluídos da análise estatística (n=22). Posteriormente, os animais incluídos foram classificados em: normais (n=38), suspeitos (n=6) e acometidos pela CMH (n=16)...

Hypertrophic cardiomyopathy (HCM) is the most common feline heart disease and is characterized by increased cardiac mass with a hypertrophied and not dilated left ventricle. The echocardiography is the best noninvasive diagnostic tool for the differentiation of cardiomyopathies and is considered the gold standard for detection of ventricular hypertrophy present in HCM. Electrocardiographic changes are also common in animals with HCM and the electrocardiogram (ECG) is quick, easy and highly available screening test for the detection of ventricular hypertrophy in humans. In cats, few studies have been conducted regarding the sensitivity and specificity of ECG in detecting ventricular hypertrophy. With the intention of evaluating the use of ECG as a screening tool for diagnosis of HCM in cats, Persian cats (n=82) were evaluated by echocardiographic and electrocardiographic examinations. Animals with blocks and/or conduction disturbances were excluded from statistical analysis (n=22). Subsequently the animals included were classified as normal (n=38), suspicious (n=6) and affected by HCM (n=16)...

Morphological and morphometric analysis of skeletal muscle between male and female young adult Colossoma macropomum (Characiformes: Serrasalmidae)

This study aimed to evaluate muscle organization in tambaqui in order to describe the muscle growth process. We analyzed the morphometric pattern of fibers from white muscle of young-adults (300 days) by smaller diameter. The organization of white muscle exhibited a typical morphological pattern found in other fish species. Heavier animals showed higher frequency of larger diameter fibers (>50 m ) and smaller animals had higher frequency of smaller diameter fibers ( 20 m ) (P =0.005). However, both animals showed the same frequency of intermediate diameter fibers (20-50 m ). Body weight showed a positive correlation with muscle diameter fiber (r=0.45), being 20-50 m the diameters that contributed the most to animal weight (P 0.0001). A weak correlation between fiber diameter and animal sex was observed (r=0.2). Females showed higher frequency of large fiber diameters (>50 m ) than males. However, there was no difference between body weight and sex (P =0.8). Our results suggest that muscle growth is by hypertrophy and hyperplasia due to a mosaic appearance from different diameters fibers, which is characteristic of large size fish species.

O objetivo deste trabalho foi avaliar a organização muscular em tambaqui, a fim de descrever o processo de crescimento muscular. Foi analisado o padrão morfométrico das fibras do músculo branco de animais com 300 dias de idade usando o método de diâmetro menor. O músculo branco apresentou uma organização morfológica padrão encontrado em peixes. Animais de maior peso apresentaram maior frequência de fibras de maior diâmetro (> 50 m ) e os animais de menor peso apresentaram maior frequência de fibras de menor diâmetro ( 20 m ) (P = 0,005). Entretanto, ambos os animais, com maior e menor peso, apresentaram frequências semelhantes de fibras de diâmetro intermediário (20-50 m ). O parâmetro peso corporal mostrou correlação positiva com o diâmetro da fibra muscular (r = 0,45), sendo as fibras de diâmetro intermediários (20-50 m ) que mais contribuíram para o peso do animal (P 0,0001). Fêmeas apresentaram maior frequência de fibras de maior diâmetro (>50 m ) que machos. Observou-se uma fraca correlação entre o diâmetro da fibra e o sexo dos animais (r = 0,2). Apesar de fraca, a correlação estimada é corroborada pela fibras de grandes diâmetros (> 50 m ) serem mais frequente nas fêmeas que nos machos. No entanto, não houve diferença entre o peso corporal dos animais aos 300 dias de idade e sexo (P = 0,8). Os resultados encontrados sugerem que o crescimento muscular ocorre por hipertrofia e hiperplasia, caracterizado pela aparência em mosaico de fibras de diferentes diâmetros, característico de peixes de grande tamanho.