Clostridium perfringens epsilon toxin induces permanent neuronal degeneration and behavioral changes

Clostridium perfringens epsilon toxin (ETX), the most potent toxin produced by this bacteria, plays a key role in the pathogenesis of enterotoxaemia in ruminants, causing brain edema and encephalomalacia. Studies of animals suffering from ETX intoxication describe severe neurological disorders that are thought to be the result of vasogenic brain edemas and indirect neuronal toxicity, killing oligodendrocytes but not astrocytes, microglia, or neurons in vitro. In this study, by means of intravenous and intracerebroventricular delivery of sub-lethal concentrations of ETX, the histological and ultrastructural changes of the brain were studied in rats and mice. Histological analysis showed degenerative changes in neurons from the cortex, hippocampus, striatum and hypothalamus. Ultrastructurally, necrotic neurons and apoptotic cells were observed in these same areas, among axons with accumulation of neurofilaments and demyelination as well as synaptic stripping. Lesions observed in the brain after sub-lethal exposure to ETX, result in permanent behavioral changes in animals surviving ETX exposure, as observed individually in several animals and assessed in the Inclined Plane Test and the Wire Hang Test. Pharmacological studies showed that dexamethasone and reserpine but not ketamine or riluzole were able to reduce the brain lesions and the lethality of ETX. Cytotoxicity was not observed upon neuronal primary cultures in vitro. Therefore, we hypothesize that ETX can affect the brain of animals independently of death, producing changes on neurons or glia as the result of complex interactions, independently of ETX-BBB interactions.Inst. de PatobiologíaFil: Morris, Winston Eduardo. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Patobiología; ArgentinaFil: Goldstein, Jorge. Universidad de Buenos Aires. Facultad de Medicina. Departamento de Fisiología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Redondo, Leandro Martí­n. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Patobiología; ArgentinaFil: Cangelosi, Adriana. Centro Nacional de Control de Calidad de Biológicos; ArgentinaFil: Geoghegan, Patricia. Centro Nacional de Control de Calidad de Biológicos; ArgentinaFil: Brocco, Marcela Adriana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico la Plata. Instituto de Investigaciones Biotecnológicas - Instituto Tecnológico Chascomús. Instituto de Investigaciones Biotecnológicas (sede Chascomús); ArgentinaFil: Loidl, Fabián C. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Biología Celular y Neurociencias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Fernandez Miyakawa, Mariano Enrique. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Patobiología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Hypothermic shock applied after perinatal asphyxia prevents retinal damage in rats

Perinatal asphyxia (PA) can cause retinopathy and different degrees of visual loss, including total blindness. In a rat model of PA, we have previously shown a protective effect of hypothermia on the retina when applied simultaneously with the hypoxic insult. In the present work, we evaluated the possible protective effect of hypothermia on the retina of PA rats when applied immediately after delivery. Four experimental groups were studied: Rats born naturally as controls (CTL), animals that were exposed to PA for 20 min at 37°C (PA), animals exposed to PA for 20 min at 15°C (HYP), and animals that were exposed to PA for 20 min at 37°C and, immediately after birth, kept for 15 min at 8°C (HYP-PA). To evaluate the integrity of the visual pathway, animals were subjected to electroretinography at 45 days of age. Molecular (real time PCR) and histological (immunohistochemistry, immunofluorescence, TUNEL assay) techniques were applied to the eyes of all experimental groups collected at 6, 12, 24, and 48 h, and 6 days after birth. PA resulted in a significant reduction in the amplitude of the a- and b-wave and oscillatory potentials (OP) of the electroretinogram. All animals treated with hypothermia had a significant correction of the a-wave and OP, but the b-wave was fully corrected in the HYP group but only partially in the HYP-PA group. The number of TUNEL-positive cells increased sharply in the ganglion cell layer of the PA animals and this increase was significantly prevented by both hypothermia treatments. Expression of the cold-shock proteins, cold-inducible RNA binding protein (CIRP) and RNA binding motif protein 3 (RBM3), was undetectable in retinas of the CTL and PA groups, but they were highly expressed in ganglion neurons and cells of the inner nuclear layer of the HYP and HYP-PA groups. In conclusion, our results suggest that a post-partum hypothermic shock could represent a useful and affordable method to prevent asphyxia-related vision disabling sequelae.Fil: Rey Funes, Manuel. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Biología Celular y Neurociencias; ArgentinaFil: Contartese, Daniela Soledad. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Biología Celular y Neurociencias; ArgentinaFil: Peláez, Rafael. Centro de Investigación Biomédica de La Rioja; EspañaFil: García Sanmartín, Josune. Centro de Investigación Biomédica de La Rioja; EspañaFil: Narro Íñiguez, Judit. Centro de Investigación Biomédica de La Rioja; EspañaFil: Soliño, Manuel. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Biología Celular y Neurociencias; ArgentinaFil: Fernández, Juan Carlos. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Biología Celular y Neurociencias; ArgentinaFil: Sarotto, Aníbal José. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Biología Celular y Neurociencias; ArgentinaFil: Ciranna, Nicolás S.. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Biología Celular y Neurociencias; ArgentinaFil: López Costa, Juan José. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Biología Celular y Neurociencias; ArgentinaFil: Dorfman, Verónica Berta. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Maimónides. Área de Investigaciones Biomédicas y Biotecnológicas. Centro de Estudios Biomédicos, Biotecnológicos, Ambientales y de Diagnóstico; ArgentinaFil: Larráyoz, Ignacio M.. Centro de Investigación Biomédica de La Rioja; EspañaFil: Loidl, C. Fabián. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Biología Celular y Neurociencias; ArgentinaFil: Martínez, Alfredo. Centro de Investigación Biomédica de La Rioja; Españ