Changes in neurotransmitter parameters in the brain induced by L-cysteine injections in the young rat.

A single subcutaneous injection of L-cysteine (1.2 mg/g body wt.) to 4-day-old rats leads to atrophy of the brains examined 27-31 days later. The brains could be separated into two groups (type 1 and 2) on account of the degree of atrophy. Type-1 lesion, with a brain weight reduction of 20%, was dominated by a severe reduction in high-affinity uptake of L-glutamate in CNS regions receiving corticofugal fibers such as thalamus and striatum. Glutamate decarboxylase was only reduced in cortical structures. In type-2 lesion, with a severe brain atrophy of about 50%, high-affinity glutamate uptake was further reduced and there was a more pronounced reduction in glutamate decarboxylase activity in several brain regions. Cholinergic neurons were less affected by the lesion and the levels of choline acetyltransferase showed a relative increase in brain regions which partly compensated for their reduction in size.