Alterations in Insulin and Glucagon Secretion by Monosodium Glutamate Lesions of the Hypothalamic Arcuate Nucleus

This study was performed to determine the effects of monosodium glutamate (MSG) induced lesions of the hypothalamic arcuate nucleus (ARC) on glucose tolerance and insulin and glucagon secretion in male golden hamsters. Eight day old hamsters were given a single s.c. injection of 5.8 mg/g BW MSG or hypertonic saline (controls). Studies were initiated when the hamsters were 3 months of age. At this age there were no body weight differences. Glucose (180 mg/100 g BW) was administered via stomach tube to 18 control and 18 MSGtreated hamsters. Animals were anesthetized with ether and a single blood sample from the portal vein was taken either before or at 30 or 60 min after glucose administration (n = 6/group). Glucose concentrations were similar in both groups at all time periods. Insulin concentrations in the MSG group were significantly (P < 0.05) elevated in MSG-treated hamsters compared to controls at the 60 min time point. Glucose suppressed glucagon (P < 0.05) in control but not in MSGtreated hamsters. ...