Biomedical subjects

Anselmo Sigari Moriscot

Publications and source records attributed to Anselmo Sigari Moriscot.

6 recordsLinked to original sources

PubMed2007

Short bouts of stretching increase myo-D, myostatin and atrogin-1 in rat soleus muscle.

Stretching is widely used in rehabilitation and sports activities to improve joint range-of-motion and flexibility in humans, but the effect of stretching on the gene expression of skeletal muscle is poorly understood. We evaluated the effect of short bouts of passive stretching of rat soleus muscle on myo-D, myostatin, and atrogin-1 gene expressions. Six groups of animals were submitted to a single session of stretching (10 stretches of 1 minute with 30 seconds of rest between them, performed manually) and were evaluated immediately (I), and 8, 24, 48, 72, and 168 hours after the session. To evaluate the effect of repetitive sessions of stretching on the soleus muscle over 1 week, three groups of animals received a single session per day of stretching and the muscle was evaluated immediately after 2, 3, and 7 sessions. The mRNA levels of myo-D, myostatin, and atrogin-1 were determined by real-time polymerase chain reaction. A single session of stretching increased the mRNA levels of myo-D (after 24 h), myostatin (I, and 168 h later), and atrogin-1 (after 48 h). Repeated daily session of stretching over 1 week increased myostatin (after 7 sessions) and atrogin-1 expression (after 2, 3, and 7 sessions). Thus, short bouts of passive stretching are able to increase the gene expression of factors associated with muscle growth (myo-D), negative regulation of muscle mass (myostatin), and atrophy (atrogin-1), indicating muscle remodeling through different pathways.

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PubMed2006

Prolonged dark adaptation changes connexin expression in the mouse retina.

In the retina, ambient light levels influence the cell coupling provided by gap junction (GJ) channels, to compensate the visual function for various lighting conditions. However, the effects of ambient light levels on expression of connexins (Cx), the proteins that form the GJ channels, are poorly understood. In the present study, we first determined whether gene expression of specific Cx (Cx26, Cx31.1, Cx36, Cx37, Cx40, Cx43, Cx45, Cx50, and Cx57) was affected by prolonged dark adaptation. Cx mRNA relative levels were determined in mouse retinas dark adapted for 3 hr, 1 day, and 7 days by using quantitative real-time PCR. Transcript levels of some Cx were repressed after 3 hr (Cx57), 1 day (Cx45), or 7 days (Cx36 and Cx43) of dark adaptation; others were increased after 1 day (Cx50) or 7 days (Cx31.1 and Cx37); and two of them (Cx26 and Cx40) were not significantly altered. The second aim was to determine whether prolonged dark adaptation affects protein expression of two important Cx in retina: neuronal Cx36 and glial Cx43. We were able to demonstrate that important changes in protein distribution and expression also took place in retina during long-term dark adaptation. Given their localization, the specific alterations in Cx expression may reflect their distinct response to ambient light levels.

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PubMed2006

mTOR pathway inhibition attenuates skeletal muscle growth induced by stretching.

The present study has aimed to verify the influence of calcineurin and mTOR pathways in skeletal muscle longitudinal growth induced by stretching. Male Wistar rats were treated with cyclosporin-A or rapamycin for 10 days. To promote muscle stretching, casts were positioned so as completely to dorsiflex the plantar-flexor muscles at the ankle in one hind limb during the last 4 days of treatment with either cyclosporin-A or rapamycin. Thereafter, we determined soleus length, weight, protein content, and phenotype. In addition, NFATc1, Raptor, S6K1, 4E-BP1, iNOS, and nNOS gene expression in the soleus were determined by real-time polymerase chain reaction. Soleus length, weight, and protein content were significantly reduced by rapamycin treatment in animals submitted to stretching (P<0.05). In contrast, cyclosporin-A treatment did not alter these parameters. In all cyclosporin-A treated groups, there was a significant reduction in NFATc1 expression (P<0.001). Similarly, a significant reduction was noted in Raptor (P<0.001) and S6K1 (P<0.01) expression in all rapamycin-treated groups. No alteration was observed in 4E-BP1 gene expression among rapamycin-treated groups. Stretching increased gene expression of both NOS isoforms in skeletal muscle. Rapamycin treatment did not interfere with NOS gene expression (P<0.05). Cyclosporin-A treatment did not impair muscle growth induced by stretching but instead caused a marked slow-to-fast fiber shift in the soleus; this was attenuated by stretching. The data presented herein indicate that mTOR pathway is involved in skeletal muscle longitudinal growth.

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PubMed2006

Expression of connexins 36, 43, and 45 during postnatal development of the mouse retina.

Gap junction channels formed by connexins (Cx) may play essential roles in some processes that occur during retinal development, such as apoptosis and calcium wave spread. The present study was undertaken to determine the distribution pattern of Cx36, Cx43, and Cx45 by immunofluorescence, as well as their gene expression levels by quantitative PCR during postnatal development of the mouse retina. Our results showed an increased expression of neuronal Cx36 from P1 until P10, when this Cx reached adult levels, and it was mainly distributed in the outer and inner plexiform layers. In turn, Cx43 was almost absent in retinal progenitor cells at P1, it became more prominent in glial cell processes about P10, and did not change until adulthood. Double-labeling studies in situ and in vitro with antivimentin, a Müller cell marker, confirmed that Cx43 was expressed by these cells. In addition, quantitative PCR showed that Cx43 and vimentin shared very similar temporal expression patterns. Finally, in contrast to Cx36 and Cx43, Cx45 mRNA was strongly down-regulated during development. In early postnatal days, Cx45 was seen ubiquitously distributed throughout the retina in cells undergoing proliferation and differentiation, as well in differentiated neurons. In adult retina, this protein had a more restricted distribution both in neurons and glial cells, as confirmed in situ and in vitro. In conclusion, we observed a distinct temporal expression pattern for Cx36, Cx43, and Cx45, which is probably related to particular roles in retinal function and maintenance of homeostasis during development of the mouse retina.

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PubMed2005

Protecting RNA in fixed tissue: an alternative method for LCM users.

RNA degradation is a major drawback in most common fixation protocols in techniques that require both RNA integrity and preserved morphology, such as laser capture microdissection (LCM) followed by RT-PCR. Moreover, RNA isolation kits especially developed for LCM samples are very expensive. Our aim was to determine an easy protocol that ideally must provide an acceptable morphology, allow proper laser capture of selected cells and improve RNA yield and quality. In this study, retinas were dissected, briefly incubated in a RNA preservative and fixed in 2% paraformaldehyde before being cut on a cryostat. LCM was carried out in retinal sections for immediate RNA isolation, by using TRIzol common protocol with minor modifications. Real-time PCR was performed next in order to compare availability of RNA from samples submitted to different protocols. The use of the RNA preservative followed by a fast fixation did not jeopardize tissue morphology, allowing microdissection of selected cells, combined to minor modifications in usual RNA isolation procedures, significantly improved RNA yield and quality. Furthermore, only LCM samples submitted to our protocol provided amplifiable mRNA, as determined by real-time PCR. Taken together, the combination of the described procedures resulted in a reliable alternative for LCM users.

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PubMed2003

Temporal and topographic ultrastructural alterations of rat heart myofibrils caused by thyroid hormone.

In order to further our understanding regarding the temporal and topographic ultrastructural aspects of the myocardium under thyrotoxicosis, thyroxine (T4; 25 and 100 microg/100 g bw) was administered to young rats 24 hours after birth until 15 days. The animals were then sacrificed, the hearts excised and weighed, and the ventricle tissue samples were then processed for confocal and transmission electron microscopy. At 48/72 hours and 1 week after initiation of T4 treatment with 100 microg/100 g bw, numerous lamellar bodies (probably formed by phospholipids) progressively accumulated in the heart. These bodies were observed in the cytosol, inside mitochondria and in the extracellular matrix. At 2 weeks of T4 treatment with 100 microg/100 g bw, lamellar bodies were virtually absent. Changes in cell shape, disorganization of intercellular junctions, and substantial myofibrillar disarray were observed in many cardiomyocytes. A gradient of myofibrillar disarray, which increased in abundance and intensity from the endocardium to the epicardium, was also observed. Immunocytochemical staining for desmin showed that the arrangement of this protein was disorganized in many cells of T4-treated rats as compared with normal ones, confirming ultrastructural data. The predominant appearance of myofibrillar disarray, associated with disorganization of cytoskeletal proteins in the deep myocardium, may be due to higher mechanical wall stress and consequent higher metabolic demand. Alternatively, differential sensitivity of cardiomyocytes to thyroid hormone in different areas is also a possibility.

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