Nitric oxide synthase expression in naturally infected sheep brain with Listeria monocytogenes and relationship with cell death

Karayiğit, Mehmet Önder

Nitric oxide synthase expression in naturally infected sheep brain with Listeria monocytogenes and relationship with cell death

Karayiğit, Mehmet Önder

Background: Nitric oxide is synthesized from L-arginine and catalyzed by a family of NOS. There are three different NOS isoforms: neuronal (nNOS), inducible (iNOS) and endothelial (eNOS). Nitric oxide is an important apoptosis regulator in mammalian system that can induce and prevent apoptosis depending on levels of NO production and environmental conditions of the cell. NOS expression and its relationship with apoptosis has not been well elucidated in listerial meningoencephalitis in sheep. The aim of this study was to investigate eNOS and iNOS expressions in the brain of sheep with natural listeriosis and to compare them with apoptosis which is shaped in the region.Materials, Methods & Results: In the study, formalin fixed and paraffin embedded brainstem tissue from 25 sheep naturally infected with LM were used from archives. Five μm-thick section was taken from each block. Histopathologically, sections were stained with H&E. Five normal sheep brain tissues were used as control. At the end of the study, Histopathologically in brainstem tissue infected with LM, multifocal microabscesses in different sizes mixed with neutrophils and macrophages were detected and perivascular mononuclear cell infiltration and meningitis characterized by mononuclear cell infiltration were found. All sections were also immunohistochemically stained with LM, eNOS and iNOS antibodies. In addition, TUNEL method was used to determine apoptosis in brain tissues. As a result of immunostaining, listeria immunoreactivity was observed in microabscesses. The Listeria antigens were detected mainly in the cytoplasm of the neutrophils and macrophages and located extracellulary in microabscesses. Both eNOS and iNOS immunoreactivity were observed in very few neurons and glial cells in normal control sheep. Neurons and glial cells in brain tissues of infected animals stained with eNOS and iNOS.[...][(AU)