RESUMO
Polypyrrole (PPy) and polypyrrole/polyethylene glycol (PPy/PEG) implants synthesized by chemical, electro-chemical, and plasma polymerization methods were implanted into the injured spinal cord of rats to determine their effect on motor function recovery. Before implantation, the materials were characterized by infrared (IR) spectroscopy. An experimental model of traumatic spinal cord injury (TSCI) by complete transection at thoracic level 9, in rats was used. The polymer implants were inserted immediately after transection. Motor function recovery was evaluated once a week during 5 weeks using the Basso, Beattie and Bresnahan (BBB) motor scale. Histological evaluation was done at the end of the recovery evaluation period using hematoxylin/eosin stain. Results showed that animals implanted with polymers synthesized by plasma had a better integration into the nerve tissue, less inflammatory response and a better functional recovery than animals implanted with polymers synthesized by chemical or electrochemical methods.
En el presente trabajo se comparó el efecto de implantes poliméricos derivados del pirrol (polipirrol o PPy) y del copolímero polipirrol/polietilenglicol (PPy/PEG), obtenidos por diferentes métodos de síntesis: químico, electroquímico y polimerización por plasma con el propósito de determinar si el método de síntesis puede influir sobre el efecto que producen al ser implantados después de una lesión traumática de la médula espinal de ratas. Antes de realizar el implante, las características químicas y estructurales de los polímeros fueron analizadas por espectroscopia de infrarrojo (IR). Se utilizó un modelo experimental de lesión traumática de médula espinal (LTME) por sección completa en ratas. La LTME se realizó a nivel torácico 9 y el polímero fue implantado de inmediato en la zona de lesión. La recuperación de la función motora se evaluó mediante la escala Basso, Beattie y Bresnahan (BBB) una vez por semana durante 5 semanas. La evaluación histológica se realizó al término del seguimiento con la tinción de hematoxilina/eosina. Los resultados muestran que los animales implantados con polímeros sintetizados por plasma se integraron mejor al tejido nervioso, redujeron la respuesta inflamatoria y favorecieron una mayor recuperación funcional en comparación con los animales implantados con materiales sintetizados por métodos químicos o electroquímicos.
RESUMO
Polymers synthesized by plasma derived from pyrrole have been recently implanted in rats with spinal cord injuries (SCI) using a complete section model; the polymers contribute to the functional recovery after the injury. In this work, the SCI in rats was studied using noninvasive techniques such as magnetic resonance imaging (MRI). Also computerized axial tomography taken chronologically with and without polymeric implants. 3D reconstructions were used to follow the structural arrangement, the location of the implant and the formation of cysts. MRI shows a clear differentiation between white and gray matter, the implanted material and cysts due to secondary damage after the injury.
Polímeros sintetizados por plasma derivados del pirrol, han sido implantados en ratas con lesión de médula espinal (LME) usando un modelo de lesión por sección completa; los polímeros contribuyen a la recuperación funcional después de la lesión. En este trabajo, la LME se estudió usando técnicas no invasivas como imágenes por resonancia magnética (IRM) y tomografía axial computarizada tomada cronológicamente en sujetos con y sin implante polimérico. Se usaron reconstrucciones 3D para seguir el arreglo estructural, la localización del implante y la formación de quistes. Las IRM muestran una clara diferenciación entre materia gris, materia blanca, material implantado y quistes formados debido a los mecanismos de daño secundario después de la lesión.
RESUMO
STUDY DESIGN: This work is an experimental and prospective study in adult, female, Long-Evans rats. OBJECTIVES: The aim of this study was to probe the effect of metabolic inhibition after an acute traumatic spinal cord injury (TSCI) using a standardized contusion model (NYU impactor) to know whether the metabolic inhibition is a 'secondary mechanism of injury' or a mechanism of protection. SETTING: All experimental procedures were carried out in the Mexico City. METHODS: Animals were divided into five groups: one sham and four with TSCI, including no treatment, rotenone (inhibitor of mitochondrial complex I), sodium azide (inhibitor of mitochondrial complex IV) and pyrophosphate of thiamine or non-degradable cocarboxylase as a metabolic reactivator. RESULTS: After TSCI, the metabolic inhibition with sodium azide treatment diminished the lipid peroxidation process (malondialdehyde levels by spectrophotometric procedures) and the damage to the spinal cord tissue (morphometric analysis), and increased the activity of creatine kinase and lactate dehydrogenase enzymes (P<0.05) (measured by spectrophotometric procedures 24 h after TSCI as well as after the functional recovery of the hind limb (evaluated weekly for 2 months by the BBB (Basso, Beattie and Bresnahan) scale)) when compared with the TSCI group without treatment. CONCLUSION: The results show that the partial and transitory inhibition of the aerobic metabolism after an acute TSCI could be a self-protection mechanism instead of being a 'secondary mechanism of injury'.
Assuntos
Metabolismo Energético/efeitos dos fármacos , Fármacos Neuroprotetores/farmacologia , Traumatismos da Medula Espinal/tratamento farmacológico , Traumatismos da Medula Espinal/metabolismo , Medula Espinal/efeitos dos fármacos , Medula Espinal/metabolismo , Animais , Creatina Quinase/efeitos dos fármacos , Creatina Quinase/metabolismo , Modelos Animais de Doenças , Complexo de Proteínas da Cadeia de Transporte de Elétrons/efeitos dos fármacos , Complexo de Proteínas da Cadeia de Transporte de Elétrons/metabolismo , Metabolismo Energético/fisiologia , Inibidores Enzimáticos/farmacologia , Feminino , L-Lactato Desidrogenase/efeitos dos fármacos , L-Lactato Desidrogenase/metabolismo , Peroxidação de Lipídeos/efeitos dos fármacos , Peroxidação de Lipídeos/fisiologia , Masculino , Estresse Oxidativo/efeitos dos fármacos , Estresse Oxidativo/fisiologia , Estudos Prospectivos , Ratos , Ratos Long-Evans , Recuperação de Função Fisiológica/efeitos dos fármacos , Recuperação de Função Fisiológica/fisiologia , Rotenona/farmacologia , Azida Sódica/farmacologia , Medula Espinal/fisiopatologia , Traumatismos da Medula Espinal/fisiopatologia , Tiamina Pirofosfato/farmacologia , Resultado do Tratamento , Desacopladores/farmacologia , Complexo Vitamínico B/farmacologiaRESUMO
It has been described that febrile seizures during infancy increase risk of subsequent non-febrile seizures during the adulthood. However, latency period between febrile seizure and the onset of the first spontaneous seizure has not been evaluated. The present study was designed to investigate the susceptibility to subsequent seizures in immature rats that had experienced early-life hyperthermic seizures and before they achieved the adult age. The results were compared with those induced by hyperthermia alone. Pentylenetetrazol (PTZ) was applied 24h or 20 days after hyperthermic seizures or hyperthermia were induced in 10-day-old rats by a regulated stream of moderately heated air. One day after hyperthermic seizures or hyperthermia, animals demonstrated enhanced latency to the PTZ-induced myoclonic (88% and 53%, respectively), clonic (60% and 60%, respectively) and tonic seizures (233% and 659%, respectively). The incidence of myoclonic and clonic seizures was similar to that in control group (100%). However, hyperthermic seizures reduced (50%) the incidence of tonic seizures. Twenty days after hyperthermic seizures there was an augmented latency to tonic seizures (123%) and reduced incidence for all the PTZ-induced seizures (71% myoclonic; 71% clonic seizures; 57% tonic seizures) when compared with control group (100%). In contrast, hyperthermia enhanced only the latency to myoclonic (133%) and clonic seizures (659%). Our data indicate that hyperthermic seizures or hyperthermia induces a protective effect against PTZ-induced seizures during a latency period. A possible involvement of gamma-aminobutyric acid (GABA) system is discussed.
Assuntos
Febre/fisiopatologia , Convulsões/induzido quimicamente , Animais , Animais Recém-Nascidos , Convulsivantes/farmacologia , Modelos Animais de Doenças , Feminino , Masculino , Pentilenotetrazol/farmacologia , Gravidez , Ratos , Ratos Sprague-Dawley , Tempo de Reação/efeitos dos fármacos , Tempo de Reação/fisiologia , Convulsões/classificação , Fatores de TempoAssuntos
Colagenases/uso terapêutico , Transplante de Tecido Fetal , Sobrevivência de Enxerto , Hialuronoglucosaminidase/uso terapêutico , Traumatismos da Medula Espinal/cirurgia , Traumatismos da Medula Espinal/terapia , Medula Espinal/transplante , Animais , Adesão Celular , Cicatriz , Feminino , Inflamação , Laminectomia , Necrose , Ratos , Medula Espinal/patologia , Medula Espinal/fisiologia , Traumatismos da Medula Espinal/patologiaRESUMO
The pharmacokinetics of the immunosuppressive agent cyclosporin-A (CsA) were studied in rats submitted to spinal cord (SC) injury. A single CsA 10 mg/kg dose was given either intraperitoneally (i.p.) or orally to rats submitted to experimental SC injury at the T8 level. Twenty four hours after lesion (acute stage of SC injury) i.p. CsA bioavailability was increased, while t1/2 was prolonged. However, oral bioavailability was reduced. Seven weeks after lesion (chronic stage of SC injury) CsA bioavailability, by either route, was not significantly different from control values. Results indicate that parenteral CsA bioavailability is increased during the acute stage of SC lesion, probably due to an impaired elimination. Oral bioavailability, however, is decreased, since there is also an important reduction in gastrointestinal CsA absorption that overrides the effect of impaired elimination. Alterations in CsA pharmacokinetics appear to revert during the chronic stage of SC injury. Changes in CsA bioavailability, depending on the route of administration and on time, must be considered to design an adequate immunosuppressive treatment in SC injury.
Assuntos
Ciclosporina/farmacocinética , Imunossupressores/farmacocinética , Traumatismos da Medula Espinal/metabolismo , Administração Oral , Animais , Área Sob a Curva , Disponibilidade Biológica , Ciclosporina/sangue , Feminino , Meia-Vida , Imunossupressores/sangue , Injeções Intraperitoneais , Ratos , Traumatismos da Medula Espinal/sangueRESUMO
To evaluate the neuroprotective effect of transplants placed in the lesion zone after a complete spinal cord (SC) laceration, two independent series of experiments were carried out. In the first, allogeneic or xenogeneic fetal SC was transplanted into the gaps of the damaged lower thoracic SC of adult rats. In the transplanted rats the incidence of life-threatening complications was reduced, and the survival rate was increased compared with the control group (lesion, without implant). Histological examination showed less damage to the neighboring SC parenchyma in the transplanted rats. The measurement of this neuroprotective effect was made in a second series of experiments. Using the same model of SC injury, allogeneic fetal SC, autologous peripheral nerve and/or adipose tissue were implanted. Rats with implants of Gelfoam and damaged rats without implants were the controls. The implanted rats of all groups, including the Gelfoam group, showed a better survival rate than the nonimplanted rats. Significantly less damage to the neighboring SC parenchyma was measured in implanted rats with any of the live tissues tested compared with non-implanted rats, although no significant differences were observed between the Gelfoam group and the nonimplanted rats. Histological evidence of tissue implant survival was observed in all corresponding groups. It is concluded that the transplanted tissues tested here have a neuroprotective effect, possibly by acting as a buffer to neurotoxic substance(s) released by the stumps, and/or by exerting trophic effect(s) on the host.