INDUCTION OF METALLOTHIONEIN IN ASTROCYTES AND MICROGLIA IN THE SPINAL-CORD FROM THE MYELIN-DEFICIENT JIMPY MOUSE

Jimpy is a shortened life span murine mutant whose genetic disorder re sults in severe pathological alterations in the CNS, including hypomye lination, oligodendrocyte death and strong astroglial and microglial r eaction. The knowledge of metallothionein (MT) regulation in the CNS a nd especially of MT presence in specific glial cell types under pathol ogical conditions is scarce. In the present study, immunocytochemical detection of MT-I + II has been performed in spinal cord sections from 10-12- and 20-22-day-old jimpy and normal animals. The identification of MT-positive glial cells was achieved through double labeling combi ning MT immunocytochemistry and selective markers for oligodendrocytes , astrocytes and microglia. MT was found in glial cells and was presen t in the spinal cord of jimpy and normal mice at both ages, but there were remarkable differences in MT expression and in the nature of MT-p ositive glial cells depending on the type of mouse. The number of MT-p ositive cells was higher in jimpy than in normal spinal cords, This wa s apparent in all spinal cord areas, although it was more pronounced i n white than in the gray matter and at 20-22 days than at 10-12 days. The mean number of MT-positive glia in the jimpy white matter was 1.9- fold (10-12 days) and 2.4-fold (20-22 days) higher than in the normal one. Astrocytes were the only parenchymal glial cells that were positi vely identified as MT-producing cells in normal animals, Interestingly , MT in the jimpy spinal cord was localized not only in astrocytes but also in microglial cells, The occurrence of MT induction in relation to reactive astrocytes and microglia, and its role in neuropathologica l conditions is discussed. (C) 1997 Elsevier Science B.V.