Effect of L-glutamate on cholinergic neurotransmission in various brain regions and during the development of rats, when administered perinatally

Abstract

Glutamate, as a monosodium salt (MSG) has neurotoxic effects on some brain regions when systemically given to young rats. Few studies have been conducted to establish the mechanisms involved in studying neurotoxicity resulting in neuronal death by glutamate (Glu) and its effects as related to different brain neuropathologies under in-vivo conditions and where the cholinergic system shows vulnerability. Thus, this paper aims to evaluate the binding kinetics of quinuclynidyl benzylate (QNB) to muscarinic receptors for acetylcholine and the activity of choline acetyltransferase (CAT) in rats treated with MSG (4mg/g on days 1, 3, 5, and 7 after birth) during the rat development stages (days 14, 21, 30 and 60) in different brain regions. The results show that perinatal treatment with MSG significantly decreases the CAT activity and increases the afinity of [ 3H]-QNB and the number of receptors of the brain cortex during the ages studied. The striatum showed increased CAT activity and B MAX on days 30 and 60 after birth. Affinity and the number of receptors increased in the hippocampus only between days 21 through 60 after birth. NaCl given at MSG equimolar doses only modified the CAT activity but had no effect on the [ 3H]-QNB binding kinetics in any of the regions studied. The results show that MSG alters cholinergic neurotransmission in the central nervous system (CNS) and induces the development of compensating events suggesting an involvement in neuronal plasticity during the development of rat CNS.