Effect of wheat and Bengalgram diets on brain glutamate metabolism in postweanling rats

Six groups of five female rats each aged 6 weeks at start were fed different diets for a period of 15 days. The protein sources of diets used were: a) 10% casein: b) wheat: c) Bengalgram: d) wheat + lysine: and e) Bengalgram + methionine + cystine + tryptophan, all containing 1.6 g nitrogen/100 g, and f) 20% casein (3.2 g nitrogen/100 g diet). The group of five rats fed a 10% casein diet served as control. It was observed that total brain RNA, protein and free alpha amino nitrogen content and protein/DNA ratio were significantly decreased on wheat and Bengalgram diets as compared to the control. The specific activities of glutamine synthetase, glutaminase I, glutaminase II and glutamate decarboxylase and concentrations of aspartic acid, glutamic acid, glutamine and gamma-aminobutyric acid (GABA) in the brain were also decreased on wheat and Bengalgram diets. The fortification of wheat with lysine and of Bengalgram with methionine, cystine and tryptophan did not alter brain weight and DNA content. While brain RNA, protein free alpha amino nitrogen (F alpha AN) and activities of enzymes of glutamic acid metabolism and related amino acid levels were restored, the activity of enzyme glutamine transferase and alanine concentration remained unaltered on various diets fed. The observations on 20% casein diet showed that levels were similar to those observed on 10% casein diet.