EFFECT OF L-GLUTAMATE ON CHOLINERGIC NEUROTRANSMISSION IN VARIOUS BRAIN-REGIONS AND DURING THE DEVELOPMENT OF RATS, WHEN ADMINISTERED PERINATALLY

Glutamate, as a monosodium salt (MSG) has neurotoxic effects on some b rain regions when systemically given to young rats. Few studies have b een conducted to establish the mechanisms involved in studying neuroto xicity resulting in neuronal death by glutamate (Glu) and its effects as related to different brain neuropathologies under bz-vivo condition s and where the cholinergic system shows vul nerability. Thus, this pa per aims to evaluate the binding kinetics of quinuclyidyl benzylate (Q NB) to muscarinic receptors for acetylcholine and the activity of chol ine acetyltransferase (CAT) in rats treated with MSG (4 mg/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 per inatal treatment with MSG significantly decreases the CAT activity and increases the afinity of [H-3]-QNB and the number of receptors of the brain cortex during the ages studied. The striatum showed increased C AT 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 modifie d the CAT activity but had no effect on the [H-3]-QNB binding kinetics in any of the regions studied. The results show that MSG alters choli nergic neurotransmission in the central nervous system (CNS) and induc es the development of compensating events suggesting an involvement in neuronal plasticity during the development of rat CNS. (C) 1997 Elsev ier Science Ltd.