Quantification of psychosine in the serum of twitcher mouse by LC-ESI-tandem-MS analysis

Globoid cell leukodystrophy or Krabbe disease is an inherited autosomal recessive disorder caused by mutations in the galactosylceramidase (GALC) gene. Deficiency of GALC results in the accumulation of a highly cytotoxic metabolite galactosylsphingosine (psychosine). In the present study, we describe the development and validation of a sensitive and specific LC-ESI-tandem-MS method for the determination of psychosine in the serum of twitcher mice, the naturally occurring animal model of this disease. The method was validated in terms of accuracy, precision, specificity, linearity and sensitivity. Calibration plots were linear over the concentration range of 2.5-50ng/mL. Recovery of psychosine from serum was in the range 94.20-98.02%. The results of this study show that in the affected mice the concentration of psychosine (ranging from 2.53 to 33.27ng/mL) increased significantly with the progression of the disease. The maximum level (33.27ng/mL) was detected in the serum of one of the twitcher mice sacrificed at 40PND. Psychosine was not detected at significant levels in wild type mice. These results clearly demonstrate that this noninvasive, rapid, and highly sensitive LC-ESI-tandem-MS method is a very useful approach for the detection of psychosine in serum.