title: Neonatal treatment with monosodium glutamate increases plasma corticosterone in the rat.
abstract: Monosodium glutamate (MSG) has been shown to alter several neuroendocrine functions in neonatally treated rats. To evaluate for possible alterations in the hypothalamic-pituitary-adrenal axis, we injected rats during the neonatal period with MSG or saline (controls). An increase in basal plasma corticosterone levels associated with a blunted circadian variation was observed. Ether exposure produced a significant elevation in plasma corticosterone concentration in both groups of animals. However, while the increase in controls was 181.3% for male and 193.9% for female rats, in the MSG-treated rats it was only 60.7 and 31.6%, respectively. The intraperitoneal administration of high dexamethasone doses blocked corticosterone secretion in both groups. However, whereas the lowest dose (0.10 microgram/kg) suppressed corticosterone secretion in control animals, it was ineffective in MSG-treated rats. The morphological study of adrenals revealed signs of a hyperfunctional state in MSG-treated rats. These data suggest that the central lesions produced by MSG treatment disrupt the regulation of the hypothalamic-pituitary-adrenal axis.
authors.affiliation: Department of Physiology, Escola Paulista de Medicina, São Paulo, Brazil.
authors.forename: M S
authors.initials: MS
authors.lastname: Dolnikoff
authors.forename: C E
authors.initials: CE
authors.lastname: Kater
authors.forename: M
authors.initials: M
authors.lastname: Egami
authors.forename: I S
authors.initials: IS
authors.lastname: de Andrade
authors.forename: M R
authors.initials: MR
authors.lastname: Marmo
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001835:Body Weight / Q000187:drug effects; D002940:Circadian Rhythm; D003345:Corticosterone / Q000097:blood*; D005260:Female; D005971:Glutamates / Q000494:pharmacology*; D007030:Hypothalamo-Hypophyseal System / Q000187:drug effects / Q000502:physiology; D008297:Male; D009929:Organ Size / Q000187:drug effects; D010913:Pituitary-Adrenal System / Q000187:drug effects / Q000502:physiology; D011247:Pregnancy; D051381:Rats; D011919:Rats, Inbred Strains; D012970:Sodium Glutamate / Q000494:pharmacology*
chemical_list: D005971:Glutamates; D012970:Sodium Glutamate; D003345:Corticosterone