Reactive astrocytes express PARP in the central nervous system of SOD(G93A) transgenic mice

In the present study, we used the transgenic mice expressing a human Cu/Zn SOD mutation (SOD1(G93A)) as an in vivo model of amyotrophic lateral sclerosis (ALS) and performed immunohistochemical studies to investigate the changes of poly(ADP-ribose) polymerase (PARP) in the central nervous system. In the spinal cord of symptomatic transgenic mice, immunohistochemistry showed intensely stained PARP-immunoreactive glial cells with the appearance of astrocytes, which were confirmed as astrocytes by double-immunofluorescences. In the brainstem and cerebellum, PARP-immunoreactive astrocytes were observed in the medullary and pontine reticular formation, hypoglossal nucleus, vestibular nucleus, cochlear nucleus and cerebellar nuclei. On the contrary, no PARP-immunoreactive glial cells were observed in control mice although PARP-immunoreactive motor neurons were found. In presymptomatic transgenic mice, a few moderately stained neurons were observed, whereas PARP-immunoreactive astrocytes were not detected. The present study provides the first evidence that PARP-immunoreactive astrocytes were found in the central nervous system of symptomatic SOD1(G93A) transgenic mice, suggesting that reactive astrocytes may play an important role in the pathogenesis and progress of ALS.