RESUMEN

The combustion of fossil fuels contributes to air pollution (AP), which was linked to about 8.79 million global deaths in 2018, mainly due to respiratory and cardiovascular-related effects. Among these, particulate air pollution (PM2.5) stands out as a major risk factor for heart health, especially during vulnerable phases. Our prior study showed that premature exposure to 1,2-naphthoquinone (1,2-NQ), a chemical found in diesel exhaust particles (DEP), exacerbated asthma in adulthood. Moreover, increased concentration of 1,2-NQ contributed to airway inflammation triggered by PM2.5, employing neurogenic pathways related to the up-regulation of transient receptor potential vanilloid 1 (TRPV1). However, the potential impact of early-life exposure to 1,2-naphthoquinone (1,2-NQ) on atrial fibrillation (AF) has not yet been investigated. This study aims to investigate how inhaling 1,2-NQ in early life affects the autonomic adrenergic system and the role played by TRPV1 in these heart disturbances. C57Bl/6 neonate male mice were exposed to 1,2-NQ (100 nM) or its vehicle at 6, 8, and 10 days of life. Early exposure to 1,2-NQ impairs adrenergic responses in the right atria without markedly affecting cholinergic responses. ECG analysis revealed altered rhythmicity in young mice, suggesting increased sympathetic nervous system activity. Furthermore, 1,2-NQ affected ß1-adrenergic receptor agonist-mediated positive chronotropism, which was prevented by metoprolol, a ß1 receptor blocker. Capsazepine, a TRPV1 blocker but not a TRPC5 blocker, reversed 1,2-NQ-induced cardiac changes. In conclusion, neonate mice exposure to AP 1,2-NQ results in an elevated risk of developing cardiac adrenergic dysfunction, potentially leading to atrial arrhythmia at a young age.

Asunto(s)

Contaminantes Atmosféricos , Naftoquinonas , Masculino , Animales , Ratones , Contaminantes Atmosféricos/toxicidad , Adrenérgicos , Células Receptoras Sensoriales , Atrios Cardíacos , Polvo

RESUMEN

The aim of this study was to determine whether increases in post-exercise endocrine response to low-load resistance exercise with blood flow restriction and high-load resistance exercise would have association with increases in muscle size and strength after an 8-week training period. Twenty-nine untrained men were randomly allocated into three groups: low-load resistance exercise with (LL-BFR) or without blood flow restriction (LL), and high-load resistance exercise (HL). Participants from LL-BFR and LL groups performed leg extension exercise at 20% of one repetition maximum (1RM), four sets of 15 repetitions and the HL group performed four sets of eight repetitions at 80% 1RM. Before the first training session, growth hormone (GH), insulin-like growth factor 1 (IGF-1), testosterone, cortisol, and lactate concentration were measured at rest and 15 min after the exercise. Quadriceps CSA and 1RM knee extension were assessed at baseline and after an 8-week training period. GH increased 15 min after exercise in the LL-BFR (p = 0.032) and HL (p < 0.001) groups, with GH concentration in the HL group being higher than in the LL group (p = 0.010). There was a time effect for a decrease in testosterone (p = 0.042) and an increase in cortisol (p = 0.005), while IGF-1 remained unchanged (p = 0.346). Both muscle size and strength were increased after training in LL-BFR and HL groups, however, these changes were not associated with the acute post-exercise hormone levels (p > 0.05). Our data suggest that other mechanisms than the acute post-exercise increase in systemic hormones induced by LL-BFR and HL produce changes in muscle size and strength.

RESUMEN

Citrus fruit peel comprises a pleasant mix of volatile compounds together with fibers, nutrients, and bioactive compounds. Therefore, it has great potential for use as a food ingredient. Studies evaluating the volatile composition of citrus peel flours are limited for most citruses. The goal of this study was to characterize, by HS-SPME/GC-MS, the volatile profile of citrus peel flours made from fruits commonly grown in Brazil. Two composite samples of ten types of citrus peel flours from consecutive harvests were evaluated. 69 volatile compounds were assigned, 49 in Tahiti acid lime, 49 in Sicilian lemon, 37 in Persian lime, 34 in Italian tangerine and oval kumquat, 33 in Valencia orange, 32 in Baia orange and round kumquat, 28 in Blood-of-Mombuca orange and 26 in Lima orange. 26 major compounds represented 93-99% of the total chromatogram peak area. Terpenic compounds were predominant in all samples, especially monoterpenes (about 48-97% of the total chromatogram peak area), while lower proportions of aldehydes (0.2-16.1%), monoterpene alcohols (0.4-11.8%) and esters (0.0-7.7%) were observed. Even though a few compounds like limonene, ß-myrcene, linalool, α-pinene and valencene were detected in all citrus, volatile compounds followed specific patterns in the different citruses, with a clear distinction among them, especially between lemon flours and the remaining flours. The variety of volatile profiles and singular specific volatolomic signatures in citrus peels can be explored for different applications related to food flavoring and preservation, and promotion of good health. These aspects should be thoroughly investigated in future studies.

Asunto(s)

Citrus , Harina , Brasil

RESUMEN

Lipopolysaccharide (LPS) is a component of gram-negative bacteria wall that elicits inflammatory response in the host through the toll-like receptor 4 (TLR4) activation. In the lower urinary tract (LUT), bacteria-derived LPS has been associated with lower urinary tract symptoms (LUTS); however, little is known about the effects of LPS in the urethral smooth muscle (USM). In the present study, we evaluated the functional and molecular effects of LPS in mouse USM in vitro, focusing on the LPS-induced TLR4-signaling pathway. Male C57BL6/JUnib and TLR4 knockout mice (TLR4 KO) were used. The USM contraction was performed in the presence of LPS (62.5-500 µg/mL), indomethacin (10 µM), L-NAME (100 µM), and TAK 242 (1 µM). The RT-PCR assay for the IL-1ß, NF-kB, and COX-2 genes was also evaluated in the presence of LPS (125 µg/mL) and caspase 1 inhibitor (20 µM). Our results showed that LPS reduces mouse USM contraction elicited by phenylephrine and vasopressin. This LPS-induced urethral inhibitory effect was not reversed by the TLR4 inhibition or its absence in the TLR4 KO mice. Conversely, indomethacin (but not L-NAME) reversed the LPS-induced USM hypocontractility. Molecular protocols indicated upregulation of IL-1ß, NF-kß, and COX-2 mRNA upon LPS incubation, which were blunted by caspase 1 inhibition. Our data showed that LPS reduced mouse USM contraction independently of TLR4 activation, involving caspase 1 and IL1ß, NF-kB, and COX-2 gene overexpression. Therefore, this alternative pathway might be a valuable target to reduce the LPS-induced urethral dysfunction under infection and inflammatory conditions.

Asunto(s)

Lipopolisacáridos , FN-kappa B , Animales , Ciclooxigenasa 2/genética , Ciclooxigenasa 2/metabolismo , Lipopolisacáridos/toxicidad , Masculino , Ratones , Músculo Liso/metabolismo , FN-kappa B/genética , FN-kappa B/metabolismo , Transducción de Señal

RESUMEN

Diosmin is a flavone glycoside clinically used as the main component of Daflon for the treatment of venous diseases. Several studies demonstrated that this natural compound can induce apoptosis in different tumors. However, isolated diosmin has not been studied regarding its effects on glioblastoma so far. Since glioblastoma is a highly lethal and fast-growing brain tumor, new therapeutic strategies are urgently needed. Herein, we evaluated the role of this flavonoid against glioblastoma cells using in vitro assays. Diosmin significantly reduced the viability of GBM95, GBM02, and U87MG glioblastoma cells, but not of healthy human astrocytes, as verified by MTT assay. Vimentin immunostaining showed that diosmin induced morphological changes in GBM95 and GBM02 cells, making them smaller and more polygonal. Diosmin did not inhibit GBM95 and GBM02 cell proliferation, but it caused DNA fragmentation, as verified by the TUNEL assay, and increased cleaved caspase-3 expression in these cells. In summary, diosmin is able to induce caspase-dependent apoptosis specifically in tumor cells and, therefore, could be considered a promising therapeutic compound against glioblastoma.

Asunto(s)

Apoptosis/efectos de los fármacos , Diosmina/farmacología , Neoplasias Encefálicas/patología , Línea Celular Tumoral , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Glioblastoma/patología , Humanos , Transducción de Señal/efectos de los fármacos

RESUMEN

Interstitial Cystitis/Bladder Pain Syndrome (IC/BPS) is a chronic inflammatory disease without consistently effective treatment. We investigate the role of toll-like receptor 4 (TLR4) on voiding dysfunction and inflammation in the cyclophosphamide (CYP)-induced mouse cystitis. Male C57BL/6 [wild-type, (WT)] and/or TLR4 knockout (TLR4-/-) mice were treated with an injection of CYP (300 mg/kg, 24 h) or saline (10 ml/kg). The pharmacological blockade of the TLR4 by resatorvid (10 mg/kg) was also performed 1 h prior CYP-injection in WT mice. Urodynamic profiles were assessed by voiding stain on filter paper and filling cystometry. Contractile responses to carbachol were measured in isolated bladders. In CYP-exposed WT mice, mRNA for TLR4, myeloid differentiation primary response 88, and TIR-domain-containing adapter-inducing interferon-ß increased by 45%, 72%, and 38%, respectively ( P < 0.05). In free-moving mice, CYP-exposed mice exhibited a higher number of urinary spots and smaller urinary volumes. Increases of micturition frequency and nonvoiding contractions, concomitant with decreases of intercontraction intervals and capacity, were observed in the filling cystometry of WT mice ( P < 0.05). Carbachol-induced bladder contractions were significantly reduced in the CYP group, which was paralleled by reduced mRNA for M2 and M3 muscarinic receptors. These functional and molecular alterations induced by CYP were prevented in TLR4-/- and resatorvid-treated mice. Additionally, the increased levels of inflammatory markers induced by CYP exposure, myeloperoxidase activity, interleukin-6, and tumor necrosis factor-alpha were significantly reduced by resatorvid treatment. Our findings reveal a central role for the TLR4 signaling pathway in initiating CYP-induced bladder dysfunction and inflammation and thus emphasize that TLR4 receptor blockade may have clinical value for IC/BPS treatment.

Asunto(s)

Antiinflamatorios/farmacología , Ciclofosfamida , Cistitis Intersticial/prevención & control , Sulfonamidas/farmacología , Receptor Toll-Like 4/antagonistas & inhibidores , Receptor Toll-Like 4/deficiencia , Vejiga Urinaria/efectos de los fármacos , Proteínas Adaptadoras del Transporte Vesicular/genética , Proteínas Adaptadoras del Transporte Vesicular/metabolismo , Animales , Cistitis Intersticial/inducido químicamente , Cistitis Intersticial/genética , Cistitis Intersticial/metabolismo , Modelos Animales de Enfermedad , Mediadores de Inflamación/metabolismo , Interleucina-6/metabolismo , Masculino , Ratones Endogámicos C57BL , Ratones Noqueados , Factor 88 de Diferenciación Mieloide/genética , Factor 88 de Diferenciación Mieloide/metabolismo , Peroxidasa/metabolismo , Receptor Muscarínico M2/genética , Receptor Muscarínico M2/metabolismo , Receptor Muscarínico M3/genética , Receptor Muscarínico M3/metabolismo , Transducción de Señal/efectos de los fármacos , Receptor Toll-Like 4/genética , Factor de Necrosis Tumoral alfa/metabolismo , Vejiga Urinaria/metabolismo , Vejiga Urinaria/fisiopatología , Micción/efectos de los fármacos , Urodinámica/efectos de los fármacos

RESUMEN

OBJECTIVE: intra-articular co-injection of kaolin with carrageenan (CGN) in rodents is widely used as an experimental model of arthritis. However, the ability of kaolin to cause arthritis and related immune responses when administered alone is unclear. We evaluated the contribution of prostanoids and sensory C-fibres (and their neuropeptide substance P) to kaolin-induced inflammation in the rat knee. METHODS: Wistar rats, 8-10 weeks old, received an intra-articular injection of kaolin (1-10 µg/joint) or saline into the knee joint. Knee inflammation, proinflammatory cytokines, pain behaviour and secondary tactile allodynia were assessed over 5 h, when synovial leukocyte counts, histopathological changes and proinflammatory cytokine levels were evaluated. RESULTS: The intra-articular injection of kaolin caused a dose- and time-dependent knee swelling and impairment of motion that were associated with secondary tactile allodynia, elevated concentrations of IL-1ß, IL-6 and TNFα, leukocyte infiltration, and histopathological changes in the ipsilateral hindpaw. The neurokinin-1 (NK1) receptor antagonist SR140333 or neonatal treatment with capsaicin markedly reduced the inflammatory parameters, cytokines and allodynia but failed to significantly inhibit the impaired motion. The cyclo-oxygenase inhibitor indomethacin partially inhibited knee oedema and allodynia but did not affect the leukocyte influx, myeloperoxidase activity or impaired motion in the kaolin-injected rat. CONCLUSIONS: We show the first evidence that intra-articular injection of kaolin without CGN produced severe acute monoarthritis. This was highly dependent on substance P (released from C-fibres) and NK1 receptor activation, which stimulated local production of proinflammatory cytokines. This model may be of critical importance for mechanistic studies and screening new anti-inflammatory/analgesic drugs.

Asunto(s)

Antidiarreicos/toxicidad , Artritis/inducido químicamente , Caolín/toxicidad , Receptores de Neuroquinina-1/metabolismo , Animales , Animales Recién Nacidos , Artritis/complicaciones , Artritis/tratamiento farmacológico , Capsaicina/toxicidad , Citocinas/metabolismo , Modelos Animales de Enfermedad , Edema/etiología , Inhibidores Enzimáticos/uso terapéutico , Hiperalgesia/etiología , Indometacina/uso terapéutico , Articulación de la Rodilla/patología , Masculino , Dimensión del Dolor , Peroxidasa/metabolismo , Piperidinas/uso terapéutico , Quinuclidinas/uso terapéutico , Ratas , Ratas Wistar , Líquido Sinovial/metabolismo

RESUMEN

Although it is well known that the thyroid hormone (T3) is an important positive regulator of cardiac function over a short term and that it also promotes deleterious effects over a long term, the molecular mechanisms for such effects are not yet well understood. Because most alterations in cardiac function are associated with changes in sarcomeric machinery, the present work was undertaken to find novel sarcomeric hot spots driven by T3 in the heart. A microarray analysis indicated that the M-band is a major hot spot, and the structural sarcomeric gene coding for the M-protein is severely down-regulated by T3. Real-time quantitative PCR-based measurements confirmed that T3 (1, 5, 50, and 100 physiological doses for 2 days) sharply decreased the M-protein gene and protein expression in vivo in a dose-dependent manner. Furthermore, the M-protein gene expression was elevated 3.4-fold in hypothyroid rats. Accordingly, T3 was able to rapidly and strongly reduce the M-protein gene expression in neonatal cardiomyocytes. Deletions at the M-protein promoter and bioinformatics approach suggested an area responsive to T3, which was confirmed by chromatin immunoprecipitation assay. Functional assays in cultured neonatal cardiomyocytes revealed that depletion of M-protein (by small interfering RNA) drives a severe decrease in speed of contraction. Interestingly, mRNA and protein levels of other M-band components, myomesin and embryonic-heart myomesin, were not altered by T3. We concluded that the M-protein expression is strongly and rapidly repressed by T3 in cardiomyocytes, which represents an important aspect for the basis of T3-dependent sarcomeric deleterious effects in the heart.

Asunto(s)

Cardiomegalia/genética , Conectina/genética , Regulación hacia Abajo/genética , Hormonas Tiroideas/farmacología , Animales , Animales Recién Nacidos , Secuencia de Bases , Cardiomegalia/etiología , Cardiomegalia/fisiopatología , Línea Celular , Células Cultivadas , Conectina/metabolismo , Regulación hacia Abajo/efectos de los fármacos , Hipotiroidismo/genética , Masculino , Ratones , Datos de Secuencia Molecular , Contracción Miocárdica/efectos de los fármacos , Contracción Miocárdica/genética , Miocitos Cardíacos/efectos de los fármacos , Miocitos Cardíacos/metabolismo , Análisis de Secuencia por Matrices de Oligonucleótidos , Regiones Promotoras Genéticas/genética , Unión Proteica/efectos de los fármacos , Unión Proteica/genética , ARN Mensajero/genética , ARN Mensajero/metabolismo , Ratas , Ratas Wistar , Receptores de Hormona Tiroidea/metabolismo , Sarcómeros/metabolismo , Tirotoxicosis/complicaciones , Triyodotironina/farmacología , Regulación hacia Arriba/efectos de los fármacos , Regulación hacia Arriba/genética

RESUMEN

The Rio Grande do Sul state, in Southern Brazil, is one of the foci of human cystic echinococcosis (CE). The sheep strain (G1) of Echinococcus granulosus and Echinococcus ortleppi (also known as cattle strain G5) have been reported before to infect livestock. However, up to the present, no molecular data are available on isolates of the E. granulosus complex from humans and dogs. The present study analyzed hydatid cysts from 6 CE patients and adult worms from 12 dogs. Sequencing of the mitochondrial cox1 and 12S rRNA genes detected the E. granulosus G1 genotype from four human cases, the G3 genotype (or buffalo strain) from one human case and E. ortleppi from another human case, respectively. Ten of the twelve dogs were found infected with the G1 genotype, and one dog each harbored worms of the G3 genotype and E. ortleppi. Obvious morphological differences were recognized between the G1 and E. ortleppi adult worms from dogs in this region. The buffalo strain (G3) is for the first time reported from South America.

Asunto(s)

Equinococosis/parasitología , Echinococcus/clasificación , Animales , Secuencia de Bases , Brasil/epidemiología , ADN Mitocondrial/genética , Equinococosis/epidemiología , Echinococcus/genética , Genotipo , Humanos , Datos de Secuencia Molecular , Especificidad de la Especie

RESUMEN

In this study we investigated the gene expression of proteins related to myostatin (MSTN) signaling during skeletal muscle longitudinal growth. To promote muscle growth, Wistar male rats were submitted to a stretching protocol for different durations (12, 24, 48, and 96 hours). Following this protocol, soleus weight and length and sarcomere number were determined. In addition, expression levels of the genes that encode MSTN, follistatin isoforms 288 and 315 (FLST288 and FLST315), follistatin-like 3 protein (FLST-L3), growth and differentiation factor-associated protein-1 (GASP-1), activin IIB receptor (ActIIB), and SMAD-7 were determined by real-time polymerase chain reaction. Prolonged stretching increased soleus weight, length, and sarcomere number. In addition, MSTN gene expression was increased at 12-24 hours, followed by a decrease at 96 hours when compared with baseline values. FLST isoforms, FLST-L3, and GASP-1 mRNA levels increased significantly over all time-points. ActIIB gene expression decreased quickly at 12-24 hours. SMAD-7 mRNA levels showed a late increase at 48 hours, which peaked at 96 hours. The gene expression pattern of inhibitory proteins related to MSTN signaling suggests a strong downregulation of this pathway in response to prolonged stretching.

Asunto(s)

Regulación de la Expresión Génica , Ejercicios de Estiramiento Muscular , Músculo Esquelético/crecimiento & desarrollo , Miostatina/antagonistas & inhibidores , Animales , Regulación hacia Abajo , Masculino , Músculo Esquelético/metabolismo , Miostatina/metabolismo , Ratas , Ratas Wistar , Sarcómeros/metabolismo , Transducción de Señal

RESUMEN

In addition to reducing blood pressure, hydralazine can reduce the production of inflammatory cytokines and reduce the expression of leukocyte adhesion molecules. Differences in leukocyte behavior and leukocyte adhesion molecule expression in spontaneously hypertensive rats (SHR) compared to normotensive rats have been reported. However, whether hydralazine can reduce leukocyte migration in vivo in hypertension and in normotension remains unknown. To address this question, male SHR and Wistar rats were treated for 15 days with hydralazine at a dose of ~3.5 mg/kg or ~14 mg/kg in their drinking water. The numbers of rollers and adherent and migrated cells were determined by direct vital microscopy, and blood pressure was assessed by tail plethysmography. In addition, following treatment with the higher dose, immunohistochemistry was used to measure the expression of intercellular adhesion molecule-1 (ICAM-1), P-selectin, and platelet-endothelial cell adhesion molecule-1 (PECAM-1) in endothelial cells, while flow cytometry was used to evaluate the expression of leukocyte CD18 and L-selectin. Hydralazine reduced leukocyte adherence and migration in SHR either at the higher, that reduced blood pressure levels, or lower dose, which did not reduce it. Reduced ICAM-1 expression might be involved in the reduced migration observed in SHR. In Wistar rats, only at the higher dose hydralazine reduced blood pressure levels and leukocyte migration. Reduced P-selectin expression might be involved. We therefore conclude that hydralazine reduces leukocyte migration by different mechanisms in SHR and Wistar rats, specifically by reducing ICAM-1 expression in the former and P-selectin expression in the latter.

Asunto(s)

Antiinflamatorios/farmacología , Antihipertensivos/farmacología , Moléculas de Adhesión Celular/metabolismo , Quimiotaxis de Leucocito/efectos de los fármacos , Hidralazina/farmacología , Hipertensión/tratamiento farmacológico , Leucocitos/efectos de los fármacos , Animales , Velocidad del Flujo Sanguíneo/efectos de los fármacos , Presión Sanguínea/efectos de los fármacos , Peso Corporal/efectos de los fármacos , Antígenos CD18/metabolismo , Adhesión Celular/efectos de los fármacos , Moléculas de Adhesión Celular/genética , Modelos Animales de Enfermedad , Endotelio Vascular/efectos de los fármacos , Endotelio Vascular/inmunología , Citometría de Flujo , Hipertensión/inmunología , Hipertensión/fisiopatología , Inmunohistoquímica , Molécula 1 de Adhesión Intercelular/metabolismo , Selectina L/metabolismo , Recuento de Leucocitos , Rodamiento de Leucocito/efectos de los fármacos , Leucocitos/inmunología , Masculino , Microscopía por Video , Selectina-P/metabolismo , Molécula-1 de Adhesión Celular Endotelial de Plaqueta/metabolismo , Pletismografía , ARN Mensajero/metabolismo , Ratas , Ratas Endogámicas SHR , Ratas Wistar , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa

RESUMEN

UNLABELLED: The effect of 30 minutes of passive stretch of the rat soleus muscle on the myogenic differentiation, myostatin, and atrogin-1 gene expressions. OBJECTIVE: To evaluate the effect of passive stretch, applied for 30 minutes to the rat soleus muscle, on the myogenic differentiation (myoD), myostatin, and atrogin-1 gene expressions. DESIGN: Case-controlled study. SETTING: University laboratory. ANIMALS: Fifty 12-week-old male Wistar rats. INTERVENTIONS: Six groups of animals were given a single stretch bout and were evaluated immediately and 8, 24, 48, 72, and 168 hours later. Another 3 groups were evaluated immediately after 2, 3, and 7 stretches. An intact control group was also analyzed. MAIN OUTCOME MEASURES: The messenger ribonucleic acid (mRNA) levels of myoD, myostatin, and atrogin-1 were assessed by real-time polymerase chain reaction. RESULTS: Twenty-four hours after a single session of stretch only, the myoD mRNA levels had increased compared with the control group, whereas an increase in the atrogin-1 expression was observed after 2, 3, and 7 stretches. CONCLUSIONS: A single session of passive stretch increased the myoD gene expression, a factor related to muscle growth. Interestingly, daily stretches increased the atrogin-1 gene expression, a gene primarily associated with muscle atrophy. The results indicated that gene expression was responsive to the number of stretch sessions.

Asunto(s)

Proteínas Musculares/biosíntesis , Músculo Esquelético/metabolismo , Proteína MioD/biosíntesis , Proteínas Ligasas SKP Cullina F-box/biosíntesis , Estrés Mecánico , Factor de Crecimiento Transformador beta/biosíntesis , Animales , Diferenciación Celular , Expresión Génica , Masculino , Proteínas Musculares/genética , Proteína MioD/genética , Miostatina , Reacción en Cadena de la Polimerasa , ARN Mensajero/biosíntesis , Ratas , Ratas Wistar , Proteínas Ligasas SKP Cullina F-box/genética , Factor de Crecimiento Transformador beta/genética

RESUMEN

Triiodothyronine (T3) is known to play a key role in the function of several tissues/organs via the thyroid hormone receptor isoforms alpha (TRalpha) and beta (TRbeta). We have investigated the effects of GC-24, a novel synthetic TRbeta-selective compound, on skeletal muscle fiber-type determination, cross-sectional area, and gene expression in rat skeletal muscles. For fiber typing, cross sections of soleus and extensor digitorum longus (EDL) muscles were stained for myosin ATPase activity at various pHs. Serum T3, T4, and cholesterol levels were also determined. Analysis of highly T3-responsive genes, viz., myosin heavy chain IIa (MHCIIa) and sarcoendoplasmic reticulum adenosine triphosphatase (SERCA1), was performed by quantitative real-time polymerase chain reaction. Equimolar doses of T3 and GC-24 had a similar cholesterol-lowering effect. T3, but not GC-24, decreased fiber type I and increased fiber type II abundance in soleus and EDL muscles. Conversely, in EDL, both T3 and GC-24 decreased the mean cross-sectional area of type I fibers. MHCIIa gene expression was reduced (approximately 50%) by T3 and unchanged by GC-24. SERCA1 gene expression was strongly induced by T3 (approximately 20-fold) and mildly induced by GC-24 (approximately two-fold). These results show that GC-24 does not significantly alter the composition of skeletal muscle fiber type and further strengthens the putative use of GC compounds as therapeutic agents.

Asunto(s)

Acetatos/farmacología , Compuestos de Bencidrilo/farmacología , Fibras Musculares de Contracción Rápida/efectos de los fármacos , Fibras Musculares de Contracción Lenta/efectos de los fármacos , Músculo Esquelético/efectos de los fármacos , Receptores beta de Hormona Tiroidea/agonistas , Acetatos/uso terapéutico , Animales , Compuestos de Bencidrilo/uso terapéutico , ATPasas Transportadoras de Calcio/genética , Diferenciación Celular/efectos de los fármacos , Diferenciación Celular/fisiología , Tamaño de la Célula/efectos de los fármacos , Colesterol/metabolismo , Expresión Génica/efectos de los fármacos , Expresión Génica/fisiología , Fibras Musculares de Contracción Rápida/metabolismo , Fibras Musculares de Contracción Lenta/metabolismo , Músculo Esquelético/citología , Músculo Esquelético/metabolismo , Cadenas Pesadas de Miosina/genética , Fenotipo , ARN Mensajero/efectos de los fármacos , ARN Mensajero/metabolismo , Ratas , Ratas Wistar , ATPasas Transportadoras de Calcio del Retículo Sarcoplásmico , Receptores beta de Hormona Tiroidea/metabolismo , Triyodotironina/efectos adversos

RESUMEN

This work was undertaken to provide further insights into the expression of tropism-related genes in regenerating skeletal muscle of adult rats treated with cyclosporin-A (CsA), a calcineurin inhibitor. Rats were treated with CsA for 5 days and, on the 6th day, were submitted to cryolesion of the soleus muscles. CsA treatment continued for 1, 10, and 21 days after cryolesion. Muscles were removed, frozen, and stored in liquid nitrogen. Body and muscle weights, histological sections stained with toluidine blue, and gene expression of the regeneration molecular markers, viz., desmin and neonatal myosin heavy chain, were assessed to confirm that cryolesion and CsA treatment were effective during the allowed regeneration time. Quantitative reverse transcription/polymerase chain reaction demonstrated that myostatin gene expression was not altered by either cryolesion or CsA treatment combined with cryolesion. Calpain-3 gene expression decreased at 1 day after cryolesion and also following CsA treatment combined with cryolesion. However, calpain-3 gene expression was strongly up-regulated (approximately five-fold) 10 days after cryolesion and returned to control levels at day 21. CsA treatment blocked calpain-3 gene expression rise induced by 10 days of cryolesion. Atrogin-1 gene expression was decreased at 1 day after cryolesion and following cryolesion combined with CsA treatment, returning to control levels at day 10. These results suggest that (1) calpain-3 has a differential role in the early and late stages of regeneration in a calcineurin-dependent manner, and (2) atrogin-1 is involved in the early stages of regeneration independently of calcineurin.

Asunto(s)

Calpaína/genética , Ciclosporina/farmacología , Inhibidores Enzimáticos/farmacología , Expresión Génica/efectos de los fármacos , Isoenzimas/genética , Proteínas Musculares/genética , Músculo Esquelético/efectos de los fármacos , Proteínas Ligasas SKP Cullina F-box/genética , Factor de Crecimiento Transformador beta/genética , Animales , Peso Corporal/efectos de los fármacos , Calpaína/metabolismo , Frío/efectos adversos , Criocirugía , Cartilla de ADN/química , Modelos Animales de Enfermedad , Inyecciones Intraperitoneales , Isoenzimas/metabolismo , Masculino , Proteínas Musculares/metabolismo , Músculo Esquelético/lesiones , Músculo Esquelético/metabolismo , Miostatina , ARN Mensajero/metabolismo , Ratas , Ratas Wistar , Regeneración/fisiología , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Proteínas Ligasas SKP Cullina F-box/metabolismo , Factor de Crecimiento Transformador beta/metabolismo

RESUMEN

Thyrotoxicosis is frequently associated with increased bone turnover and decreased bone mass. To investigate the role of thyroid hormone receptor-beta (TR beta) in mediating the osteopenic effects of triiodothyronine (T3), female adult rats were treated daily (64 days) with GC-1 (1.5 microg/100 g body wt), a TR beta-selective thyromimetic compound. Bone mass was studied by dual-energy X-ray absorptiometry of several skeletal sites and histomorphometry of distal femur, and the results were compared with T3-treated (3 microg/100 g body wt) or control animals. As expected, treatment with T3 significantly reduced bone mineral density (BMD) in the lumbar vertebrae (L2-L5), femur, and tibia by 10-15%. In contrast, GC-1 treatment did not affect the BMD in any of the skeletal sites studied. The efficacy of GC-1 treatment was verified by a reduction in serum TSH (-52% vs. control, P < 0.05) and cholesterol (-21% vs. control, P < 0.05). The histomorphometric analysis of the distal femur indicated that T3 but not GC-1 treatment reduced the trabecular volume, thickness, and number. We conclude that chronic, selective activation of the TR beta isoform does not result in bone loss typical of T3-induced thyrotoxicosis, suggesting that the TR beta isoform is not critical in this process. In addition, our findings suggest that the development of TR-selective T3 analogs that spare bone mass represents a significant improvement toward long-term TSH-suppressive therapy.

Asunto(s)

Enfermedades Óseas Metabólicas/prevención & control , Receptores de Hormona Tiroidea/agonistas , Triyodotironina/análogos & derivados , Triyodotironina/efectos adversos , Animales , Peso Corporal/efectos de los fármacos , Densidad Ósea/efectos de los fármacos , Enfermedades Óseas Metabólicas/inducido químicamente , Colesterol/sangre , Femenino , Fémur , Ratas , Ratas Wistar , Receptores de Hormona Tiroidea/efectos de los fármacos , Receptores de Hormona Tiroidea/metabolismo , Receptores beta de Hormona Tiroidea , Tirotoxicosis/inducido químicamente , Tirotoxicosis/complicaciones , Tirotropina/sangre , Tiroxina/sangre , Triyodotironina/administración & dosificación