RESUMO
OBJECTIVE: The objective was to establish a pattern of tumor growth of the C6 model of glioblastoma multiform in Wistar rats via magnetic resonance imaging (MRI) for the subsequent verification of tumor volume reduction due to magnetic hyperthermia therapy. METHODS: Young male Wistar rats weighing between 250 and 300 g were used for the C6 model. After the rats were anesthetized (55 mg/ kg ketamine and 11 mg/kg xylazine), C6 lineage tumorigenic cells suspended in culture medium (10(5) cells in 10 microl) were stereotaxically injected into the right frontal cortex (bregma coordinates: 2.0 mm anteroposterior, 3.0 mm laterolateral, and 2.5 mm depth) of the rats using a Hamilton syringe. For the control group, the rats were injected with culture medium without cells. MRI scans were performed at 14, 21, and 28 d after the injection using a 2.0 T MRI scanner (Bruker BioSpec, Germany). The animals were anesthetized with 55 mg/kg ketamine and 11 mg/kg xylazine before being examined. Coronal multilayers were acquired using a standard spin echo sequence with the following parameters: repetition/echo time = 4.000 ms/67.1 ms, field of view = 3.50, matrix = 192, slice thickness = 0.4 mm, and slice separation = 0 mm. RESULTS: The MRI analysis enabled a clear visualization of the tumor mass, and it was possible to establish the tumor volume parameters on the various days that were examined. The volume at 14 d after induction was 13.7 +/- 2.5 mm3. On days 21 and 28, the tumor volumes were 31.7 +/- 6.5 mm3 and 122.1 +/- 11.8 mm3, respectively. CONCLUSION: These results demonstrated that it is possible to evaluate the C6 model tumor volume in rats, which will allow for the future implementation and verification of magnetic hyperthermia therapy.
Assuntos
Neoplasias Encefálicas/terapia , Glioblastoma/terapia , Hipertermia Induzida/métodos , Magnetoterapia/métodos , Imageamento por Ressonância Magnética , Animais , Neoplasias Encefálicas/patologia , Linhagem Celular Tumoral/transplante , Lobo Frontal/patologia , Glioblastoma/patologia , Masculino , Ratos , Ratos Wistar , Carga TumoralRESUMO
The creatine (Cr) and phosphocreatine (PCr) system is essential for the buffering and transport of high-energy phosphates. Although achievements made over the last years have highlighted the important role of creatine in several neurological diseases, the adaptive processes elicited by this guanidino compound in hippocampus are poorly understood. In the present study, we showed that creatine (0.5-25mM) gradually increases the amplitude of first population spike (PS) and elicits secondary PS in stratum radiatum of the CA1 region, in hippocampal slices. Creatine also decreased the intensity of the stimulus to induce PS, when compared with hippocampal slices perfused with artificial cerebrospinal fluid (ACSF). The competitive NMDA receptor antagonist, 2-amino-5-phosphonopentanoic acid (AP5; 100microM) attenuated creatine-induced increase of amplitude of PS and appearance of secondary PS, providing pharmacological evidence of the involvement of NMDA receptors in the electrophysiological effects of creatine. Accordingly, creatine (0.01-1mM) increased [3H]MK-801 binding to hippocampal membranes by 55%, further indicating that this compound modulates NMDA receptor function. These results implicate the NMDA receptor in amplitude and population spike increase elicited by creatine in hippocampus. Furthermore, these data suggest that this guanidino compound may also play a putative role as a neuromodulator in the brain, and that at least some of its effects may be mediated by an increase in glutamatergic function.
Assuntos
Potenciais de Ação/efeitos dos fármacos , Creatina/farmacologia , Hipocampo/efeitos dos fármacos , Receptores de N-Metil-D-Aspartato/efeitos dos fármacos , Animais , Membrana Celular/efeitos dos fármacos , Maleato de Dizocilpina/farmacologia , Eletrofisiologia , Antagonistas de Aminoácidos Excitatórios/farmacologia , Espaço Extracelular/efeitos dos fármacos , Técnicas In Vitro , Masculino , Potenciais da Membrana/efeitos dos fármacos , Ratos , Ratos WistarRESUMO
Physical exercise and fitness programs in patients with epilepsy are still a matter of controversy. Effects of physical exercise in animals with epilepsy have been demonstrated. To further investigate the possible mechanisms by which physical activity interferes with epileptogenesis, the present work was aimed to study the effect of aerobic exercise on "in vitro" hippocampal electrophysiological parameters observed in rats submitted to the pilocarpine model of epilepsy. Electrophysiological changes were monitored by extracellular field potentials recorded from CA1 area. Control rats and rats with epilepsy were submitted to an aerobic exercise program. The number of population spikes (PS) and slope of field excitatory postsynaptic potentials (fEPSP) were analyzed. Trained rats with epilepsy exhibited a reduction in PS when compared with nontrained rats with epilepsy in different concentrations of extracellular potassium or bicuculline. Physical training also enhanced the late phase of LTP in rats with epilepsy. Our results indicate that physical training reduces CA1 hyperresponsiveness and can modify synaptic plasticity in rats submitted to the pilocarpine model of limbic epilepsy.