Strain-specific sensitivity to MPTP of C57BL/6 and BALB/c mice is age dependent

Administration of MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) to adult (2-month to 4-month-old) male C57BL/6 mice (MPTP-sensitive) is a valuable Parkinson's disease model. At comparable age, other strains, such as BALB/c, are minimally affected by MPTP (MPTP-resistant). However, the maintenance of resistance to MPTP throughout aging in MPTP-resistant strains has not been studied. Here, we show that, as previously reported, 1-month and 18-month-old C57BL/6 mice are least and most sensitive to MPTP, respectively. MPTP, as expected, did not affect the younger (1-month and 3-month-old) BALB/c mice, but it markedly decreased striatal dopamine in the older (10-month and 18-month-old) BALB/c mice. These data suggest that the sensitivity to MPTP is age dependent and that mice from an MPTP-resistant strain lose their resistance as they age.