Tubular aggregates in the skeletal muscle of the senescence-accelerated mouse; SAM

We investigated the skeletal muscles of nine strains of senescence accelera ted mouse (SAM), DDD, AKR/J, C57BL/6J, A/J and BALB/c mice. We found that m ale SAMP8, SAMP7, C57BL/6J, A/J acid BALB/c mice expressed tubular aggregat es (TAs) in their skeletal muscle. Among these strains, the SAMP8 strain, w hich exhibits a short life span and various age-associated neurodegenerativ e disorders plus mitochondrial dysfunction, showed TAs more markedly than t he others. Thus, we compared SAMP8 mice against SAMR1 mice, an accelerated senescence-resistant strain. Light- and electron micrographs showed that ma le SAMP8 mice exhibited an age-dependent aggravation of TA accumulation. Th ere were no significant differences in the serum lactate/pyruvate levels be tween the SAMP8 and SAMR1 mice. However, the serum creatine kinase (CK) lev els of the 3 and 6-month-old SAMP8 mice were higher than that of the corres ponding SAMR1 mice. Considering the serum CK levels and the mitochondrial d ysfunction of SAMP8 mice, we conclude that the TAs may be involved in the h omeostasis of energy metabolism that is not appropriately regulated in the SAMP8 mouse mitochondrion. (C) 2000 Elsevier Science Ireland Ltd. All right s reserved.