Serum carnosinase activities in central nervous system disorders.

Serum carnosinase activity was assayed in five groups of patients with neurological disorders. Enzyme activities in patients with idiopathic epilepsy (mean +/- S.E.M., 148 +/- 11 nmol/ml per min) and motor neurone disease (155 +/- 15 nmol/ml per min) were similar to the control group (161 +/- 7 nmol/ml per min). Reduced serum carnosinase activity was observed in patients with Parkinson's disease (109 +/- 11 nmol/ml per min, P < 0.005), multiple sclerosis (82.5 +/- 10.0 nmol/ml per min, P < 0.005) and patients following a cerebrovascular accident (74.6 +/- 5.4 nmol/ml per min, P < 0.001) compared with the control group. Carnosinase activity, 5-10% of that found in serum, was detected in CSF samples. The cause of reduced serum carnosinase activities in central nervous system disorders is unclear, although anoxic damage to carnosinase-producing cells or disruption of the blood-brain barrier may be responsible.