Neonatal monosodium glutamate treatment alters rat intestinal muscle reactivity to some agonists

The following study is an investigation of the changes in the contractile r eactivity of visceral muscles in response to agonists and alterations in me tabolic parameters after neonatal rat treatment with monosodium-L-glutamate . This treatment markedly sensitizes ileum and colon preparations to adenos ine-5'-triphosphate (ATP) stimulation and also increases the colon activity to acetylcholine (p < 0.05). Response to bradykinin remained unchanged, wh ile ileum activity to angiotensin II was characterized by a reduction in th e maximal tension (E-max) and an increase in the EC50 (p < 0.05) value. The responses of nonintestinal muscle preparations from monosodium-glutamate-t reated rats to both ATP and bradykinin did not show a significant differenc e when compared to the controls. This treatment diminished food intake, fec es excretion and increased plasma insulin, nonesterified fatty acids and tr iglyceride concentrations(p < 0.001). These results suggest that the change s in intestinal muscle activity, in response to agonists, can be due to met abolic alterations as well as the monosodium glutamate action on enteric ne urons and/or smooth muscle receptors. (C) 1999 Elsevier Science B.V. All ri ghts reserved.