Monosodium glutamate affects the temporal characteristics of biochemical variables in Wistar rats.

Monosodium glutamate (MSG) was administrated chronically for 60 days to Wistar rats and 24 h rhythms of glucose, cholesterol, total protein and alkaline phosphatase were studied. MSG treatment was found to cause acrophase delays in the glucose and alkaline phosphatase rhythms and advances in acrophases of cholesterol and total protein levels. Amplitude and mesor values of these rhythms were found to be altered during MSG treatment. Glutamate levels in the brain were found to be significantly increased, which could alter these biochemical rhythms by modulating the transmission in retinohypothalamic tract and in the hypothalamic nuclei, probably including suprachiasmatic nuclei.