Reactive Gliosis after brain ischemia is reduced in animals previously exposed to intermittent hypoxia.

AVILÉS-REYES RX, ANGELO MF, VILLARREAL A, RAMOS AJ.

Cordoba, Argentina

Congreso; I Reunión Conjunta de Neurociencias; 2009

SAN-Taller de Neurociencias

Cerebral ischemia has a major impact on public health. Sleep apnea syndrome (SA) is also a serious public health problem in adult population. A common complication of SA is brain ischemia; however SA patients usually succeed in the post-stroke recovery. In an attempt to understand the clinical observations, we exposed adult male Wistar rats (230-250g) to an experimental model of sleep apnea by intermittent hypoxia (IH) by cycling oxygen level every 6 min from 21% to 10%O2 for 5 days, 8 h/day, during the sleep phase. Another set of animals were exposed to the same chambers but in normoxic conditions (Nx). On the sixth day both groups were subjected to brain ischemia induced by cortical desvascularization (CD). Animals were sacrificed at 3 and 7 days post lesion (dpl), and brains were processed for immunocytochemistry and image analysis. Glial Fibrillary Acidic Protein (GFAP) and Vimentin immunostaining showed that reactive gliosis was restricted to the ischemic hemisphere, being maximal in the penumbra area that surrounds the ischemic core. To analyze the intensity of reactive gliosis, morphometric parameters of penumbra astrocytes were studied in IH and Nx animals located at differents distances from the ischemic core. Our results showed that reactive gliosis normally induced by brain ischemia was significantly diminished in animals previously exposed to IH compared with Nx animals. These preliminary results raise the hypothesis that probably IH exposed brain develop a degree of adaptation or tolerance to a subsequent ischemic injury, thus supporting clinical observations from SA patients. Supported by CONICET PIP6063, PIP1728, PICT jovenes 33735, IBRO RHF     Cerebral ischemia has a major impact on public health. Sleep apnea syndrome (SA) is also a serious public health problem in adult population. A common complication of SA is brain ischemia; however SA patients usually succeed in the post-stroke recovery. In an attempt to understand the clinical observations, we exposed adult male Wistar rats (230-250g) to an experimental model of sleep apnea by intermittent hypoxia (IH) by cycling oxygen level every 6 min from 21% to 10%O2 for 5 days, 8 h/day, during the sleep phase. Another set of animals were exposed to the same chambers but in normoxic conditions (Nx). On the sixth day both groups were subjected to brain ischemia induced by cortical desvascularization (CD). Animals were sacrificed at 3 and 7 days post lesion (dpl), and brains were processed for immunocytochemistry and image analysis. Glial Fibrillary Acidic Protein (GFAP) and Vimentin immunostaining showed that reactive gliosis was restricted to the ischemic hemisphere, being maximal in the penumbra area that surrounds the ischemic core. To analyze the intensity of reactive gliosis, morphometric parameters of penumbra astrocytes were studied in IH and Nx animals located at differents distances from the ischemic core. Our results showed that reactive gliosis normally induced by brain ischemia was significantly diminished in animals previously exposed to IH compared with Nx animals. These preliminary results raise the hypothesis that probably IH exposed brain develop a degree of adaptation or tolerance to a subsequent ischemic injury, thus supporting clinical observations from SA patients. Supported by CONICET PIP6063, PIP1728, PICT jovenes 33735, IBRO RHF     Cerebral ischemia has a major impact on public health. Sleep apnea syndrome (SA) is also a serious public health problem in adult population. A common complication of SA is brain ischemia; however SA patients usually succeed in the post-stroke recovery. In an attempt to understand the clinical observations, we exposed adult male Wistar rats (230-250g) to an experimental model of sleep apnea by intermittent hypoxia (IH) by cycling oxygen level every 6 min from 21% to 10%O2 for 5 days, 8 h/day, during the sleep phase. Another set of animals were exposed to the same chambers but in normoxic conditions (Nx). On the sixth day both groups were subjected to brain ischemia induced by cortical desvascularization (CD). Animals were sacrificed at 3 and 7 days post lesion (dpl), and brains were processed for immunocytochemistry and image analysis. Glial Fibrillary Acidic Protein (GFAP) and Vimentin immunostaining showed that reactive gliosis was restricted to the ischemic hemisphere, being maximal in the penumbra area that surrounds the ischemic core. To analyze the intensity of reactive gliosis, morphometric parameters of penumbra astrocytes were studied in IH and Nx animals located at differents distances from the ischemic core. Our results showed that reactive gliosis normally induced by brain ischemia was significantly diminished in animals previously exposed to IH compared with Nx animals. These preliminary results raise the hypothesis that probably IH exposed brain develop a degree of adaptation or tolerance to a subsequent ischemic injury, thus supporting clinical observations from SA patients. Supported by CONICET PIP6063, PIP1728, PICT jovenes 33735, IBRO RHF     Cerebral ischemia has a major impact on public health. Sleep apnea syndrome (SA) is also a serious public health problem in adult population. A common complication of SA is brain ischemia; however SA patients usually succeed in the post-stroke recovery. In an attempt to understand the clinical observations, we exposed adult male Wistar rats (230-250g) to an experimental model of sleep apnea by intermittent hypoxia (IH) by cycling oxygen level every 6 min from 21% to 10%O2 for 5 days, 8 h/day, during the sleep phase. Another set of animals were exposed to the same chambers but in normoxic conditions (Nx). On the sixth day both groups were subjected to brain ischemia induced by cortical desvascularization (CD). Animals were sacrificed at 3 and 7 days post lesion (dpl), and brains were processed for immunocytochemistry and image analysis. Glial Fibrillary Acidic Protein (GFAP) and Vimentin immunostaining showed that reactive gliosis was restricted to the ischemic hemisphere, being maximal in the penumbra area that surrounds the ischemic core. To analyze the intensity of reactive gliosis, morphometric parameters of penumbra astrocytes were studied in IH and Nx animals located at differents distances from the ischemic core. Our results showed that reactive gliosis normally induced by brain ischemia was significantly diminished in animals previously exposed to IH compared with Nx animals. These preliminary results raise the hypothesis that probably IH exposed brain develop a degree of adaptation or tolerance to a subsequent ischemic injury, thus supporting clinical observations from SA patients. Supported by CONICET PIP6063, PIP1728, PICT jovenes 33735, IBRO RHF