Possible defect in cholinergic neurons of muscular dystrophic mice

Abstract

The cholinoacetyltransferase activity (CAT) in diaphragm of mice of Bar Harbor strain (129 ReJ dγ/dγ) with muscular dystrophy was significantly lower than that of phenotypically normal litter mates (129 ReJ dγ/+). CAT, tyrosine hydroxylase (TH), dopamine-β-hydroxylase (DβH) activities were found identical in adrenal gland and brain homogenates of normal and dystrophic mice. Subacute injections of atropine (72 µmol/kg i. p., twice daily for 3 days) failed to increase the activity of adrenal CAT in dystrophic mice but increased this enzyme activity in adrenals of normal litter mates. The concentration in brain of dopamine, norepinephrine, serotonin, acetylcholine (ACh), -aminobutyric acid (GABA) and some of their precursors were measured. Only the concentration of ACh was significantly lower in the brain of muscular dystrophic mice. The rate of accumulation of brain ACh concentration after the injection of oxotremorine (5μmol/kg i. p.) is slower in muscular dystrophic animals than in normal litter mates. Furthermore, the turnover rate of ACh in total brain was slower in muscular dystrophic mice than in phenotypically normal litter mates. The turnover rate of brain dopamine and norepinephrine in these 2 groups of animals was similar.