Accumulation of Serum Amyloid A fibrils in mouse brain following chronic Systemic Amyloidosis

Abstract

Prolonged injection of casein results in Systemic amyloidosis in mice with impaired hepatic functions due to excessive serum amyloid A (SAA) fibril deposition in liver, spleen and kidney. In the present work, we have shown that Systemic amyloidosis results in accumulation of SAA fibrils in the brain. We have carried out radiolabeling studies to source the SAA fibrils and serum amyloid P component (SAP) that are present in the brain of the affected mice. Results of these experiments suggest that the systemic amyloidosis results in selective crossing of SAA and SAP proteins through blood brain barrier (BBB). Injection of 125 I SAA and 125 I SAP to casein treated mice resulted in the accumulation of these proteins in the liver to the maximum extent and to about 20% (compared to liver) localization in the brain. The Congo red stained polarizing microscopic pictures of the cerebral cortex have shown the presence of amyloid fibrils in the brain of the mice with systemic amyloidosis. Immunohistochemical studies also indicate that the abundance of SAA and SAP in the mice brain following chronic systemic amyloidosis condition. The present study provides a basis for investigation on the effect of systemic amyloidosis to the brain in chronic inflammation of mouse.