Expression of presenilin 1 mRNA in rat peripheral organs and brain.

At least 50 different mutations in the presenilin 1 gene have been shown to cause early onset familial Alzheimer's disease. Although presenilin 1 has an obvious role in the pathogenesis of Alzheimer's disease, its function is still unknown. In the present study, the occurrence and distribution of presenilin 1 mRNA was examined in rat peripheral organs as well as in the brain by in situ hybridization histochemistry, using a radiolabelled oligonucleotide probe. In comparison to the brain, a high presenilin 1 mRNA expression was found in the testis, kidney, spleen, adrenal gland and thymus. It was also observed in skeletal muscle, liver, small intestine and lung, whereas no presenilin 1 could be detected in the heart, spinal cord and pancreas. Since presenilin 1 mRNA was found to be abundant in peripheral tissues which apparently are not affected in Alzheimer's disease, additional functions of presenilin 1 are suggested, unrelated to its role in the pathological processes of the disease.