A pharmacological analysis of food intake regulation in rats treated neonatally with monosodium L-glutamate (MSG).
Studies were conducted to examine deficits in food intake regulation in MSG-treated rats that result from known or suspected damage to neurotransmitter systems involved in feeding. Male rats were injected with either MSG (4 mg/g) or sodium chloride on postnatal days 2 and 4 (MSG-Lo) or postnatal days 2, 4, 6 and 8 (MSG-Hi). As adults, MSG-treated and control rats (n = 12/group) were examined for deficits in pharmacologically elicited feeding and other measures of food intake regulation. A second group of MSG-treated (n = 9/group) and control rats (n = 12) were used to measure basal blood pressure and nociceptive reactivity in adulthood. Organ weights, body weight and neuropeptide Y (NPY) content in brain regions were determined at the end of the study. MSG-Hi rats consumed significantly less food than controls during the dark part of the light cycle. Both MSG-Hi and MSG-Lo groups ate significantly less food than controls after a 48-hour fast. MSG-Hi and MSG-Lo rats consumed significantly less food than controls in response to 1.0 mg/kg morphine. MSG-Hi rats consumed significantly less food than controls during the dark phase and significantly more food than controls during the light phase in response to naloxone (1.0 mg/kg). MSG-Lo ate significantly more than controls in response to 0.1 mg/kg guanfacine. MSG-Hi and MSG-Lo showed a significant attenuation in diazepam-stimulated feeding when compared to controls. Blood pressure was significantly lower in both MSG-Hi and MSG-Lo rats compared to controls. Tail flick latencies were not altered by MSG-treatment.(ABSTRACT TRUNCATED AT 250 WORDS)
Dawson
R
R
Department of Pharmacodynamics, College of Pharmacy University of Florida, Gainesville 32610.
Wallace
D R
DR
Gabriel
S M
SM
D000818:Animals; D000831:Animals, Newborn / Q000502:physiology*; D001794:Blood Pressure / Q000187:drug effects; D001835:Body Weight / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004435:Eating / Q000187:drug effects*; D005260:Female; D005971:Glutamates / Q000633:toxicity*; D008297:Male; D009479:Neuropeptides / Q000494:pharmacology; D009929:Organ Size / Q000187:drug effects; D011247:Pregnancy; D051381:Rats; D011919:Rats, Inbred Strains; D011930:Reaction Time / Q000187:drug effects; D012970:Sodium Glutamate / Q000633:toxicity*; D015016:Yohimbine / Q000494:pharmacology
D005971:Glutamates; D009479:Neuropeptides; D015016:Yohimbine; D012970:Sodium Glutamate