Monosodium glutamate, a food additive, induces depressive-like and anxiogenic-like behaviors in young Rats

• Published in: Life sciences (1973) 2014-06, Vol.107 (1-2), p.27-31
• Main Authors: Quines, Caroline B., Rosa, Suzan G., Da Rocha, Juliana T., Gai, Bibiana M., Bortolatto, Cristiani F., Duarte, Marta Maria M.F., Nogueira, Cristina W.
• Format: Article
• Language: English
• Subjects: Adrenocorticotropic Hormone - metabolism; Animals; Animals, Newborn; Anxiety Disorders - chemically induced; Anxiety Disorders - metabolism; Anxiogenic-like behavior; Behavior, Animal - drug effects; Cerebral Cortex - drug effects; Corticosterone - metabolism; Depressive Disorder - chemically induced; Depressive Disorder - metabolism; Depressive-like behavior; Fear - drug effects; Female; Flavoring Agents - toxicity; HPA axis; Hypothalamo-Hypophyseal System - drug effects; Hypothalamo-Hypophyseal System - metabolism; Injections, Subcutaneous; Locomotion - drug effects; Male; Monosodium glutamate; Pituitary-Adrenal System - drug effects; Pituitary-Adrenal System - metabolism; Radioimmunoassay; Rats; Rats, Wistar; Serotonin; Serotonin - metabolism; Sodium Glutamate - toxicity; Swimming - physiology
• ISSN: 0024-3205; 1879-0631
• DOI: 10.1016/j.lfs.2014.04.032

Monosodium glutamate (MSG) has been the target of research due to its toxicological effects. We investigated the depressive- and anxiogenic-like behaviors in rats exposed to neonatal subcutaneous injection of MSG. The involvement of the serotonergic system, by measuring [3H] serotonin (5-HT) uptake in cerebral cortices, and the hypothalamic pituitary adrenal (HPA) axis, by determining serum adrenocorticotropic hormone (ACTH) and corticosterone levels, was also examined. Male and female newborn Wistar rats were divided into control and MSG groups, which received, respectively, a daily subcutaneous injection of saline (0.9%) or MSG (4g/kg/day) from the 1st to 5th postnatal day. The behavioral tests [spontaneous locomotor activity, contextual fear conditioning, and forced swimming test (FST)] were performed from the 60th to 64th postnatal day. MSG-treated animals showed alteration in the spontaneous locomotor activity, an increase in the number of fecal pellets and the number of animal's vocalizations and urine occurrence, and a decrease in the grooming time. The MSG exposure increased the immobility time in the FST and the freezing reaction in the contextual fear conditioning. Additionally, MSG treatment increased the [3H]5-HT uptake in the cerebral cortices of rats and induced a deregulation of HPA axis function (by increasing serum ACTH and corticosterone levels). In conclusion MSG-treated rats are more susceptible to develop anxiogenic- and depressive-like behaviors, which could be related to a dysfunction in the serotonergic system.