We analyzed the cellular distribution of the pancreatic inflammatory protein lithostathine and its receptor EXTL3 in the brain of the lemurian primate Microcebus murinus which develops amyloid deposits along with aging. In adult animals (2-4.5 year-old), lithostathine and EXTL3 immunoreactivities were largely distributed in the whole brain, and more intensively in almost all cortical layers and hippocampal formation. Lithostathine was observed in the perikarya and neurites of cortical neurons but also in glial cells in the border of the ventricle and the corpus callosum.In healthy aged animals (8-13 year-old), highest densities of lithostathine containing cells were observed, mainly in occipital and parietal cortex. In aged animals with A deposits, the increase in lithostathine immunoreactivity was lower as compared with aged animals. Noteworthly, lithostathine-immunopositive cells did almost never colocalize with A plaques. In conclusion, lithostathine immunoreactivity in adult Microcebus murinus appeared ubiquitous and particularly in visual, sensorial and cognitive brain areas. Immunoreactivity increased with aging and appeared markedly affect in neuropathological conditions. Its possible neuroprotection or neurodegeneration role in Alzheimer pathology deserves therefore to be investigated.