title: The probiotic Bifidobacteria infantis: An assessment of potential antidepressant properties in the rat.
abstract: It is becoming increasingly apparent that probiotics are important to the health of the host. The absence of probiotic bacteria in the gut can have adverse effects not only locally in the gut, but has also been shown to affect central HPA and monoaminergic activity, features that have been implicated in the aetiology of depression. To evaluate the potential antidepressant properties of probiotics, we tested rats chronically treated with Bifidobacteria infantis in the forced swim test, and also assessed the effects on immune, neuroendocrine and central monoaminergic activity. Sprague-Dawley rats were treated for 14 days with B. infantis. Probiotic administration in naive rats had no effect on swim behaviours on day 3 or day 14 following the commencement of treatment. However, there was a significant attenuation of IFN-gamma, TNF-alpha and IL-6 cytokines following mitogen stimulation (p<0.05) in probiotic-treated rats relative to controls. Furthermore, there was a marked increase in plasma concentrations of tryptophan (p<0.005) and kynurenic acid (p<0.05) in the bifidobacteria-treated rats when compared to controls. Bifidobacteria treatment also resulted in a reduced 5-HIAA concentration in the frontal cortex and a decrease in DOPAC in the amygdaloid cortex. The attenuation of pro-inflammatory immune responses, and the elevation of the serotonergic precursor, tryptophan by bifidobacteria treatment, provides encouraging evidence in support of the proposition that this probiotic may possess antidepressant properties. However, these findings are preliminary and further investigation into the precise mechanisms involved, is warranted.
authors.affiliation: Department of Psychiatry and Alimentary Pharmacobiotic Centre, Biosciences Institute, University College Cork, Cork, Ireland. lieve.desbonnet@gmail.com
authors.forename: Lieve
authors.initials: L
authors.lastname: Desbonnet
authors.forename: Lillian
authors.initials: L
authors.lastname: Garrett
authors.forename: Gerard
authors.initials: G
authors.lastname: Clarke
authors.forename: John
authors.initials: J
authors.lastname: Bienenstock
authors.forename: Timothy G
authors.initials: TG
authors.lastname: Dinan
mesh_terms: D000818:Animals; D000928:Antidepressive Agents / Q000097:blood / Q000378:metabolism / Q000494:pharmacology*; D001522:Behavior, Animal / Q000187:drug effects; D001644:Bifidobacterium; D015306:Biogenic Monoamines / Q000378:metabolism; D001921:Brain / Q000187:drug effects / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D003345:Corticosterone / Q000097:blood; D003346:Corticotropin-Releasing Hormone / Q000187:drug effects / Q000378:metabolism; D016207:Cytokines / Q000097:blood / Q000187:drug effects; D003863:Depression / Q000097:blood / Q000378:metabolism / Q000517:prevention & control*; D004195:Disease Models, Animal; D005434:Flow Cytometry; D007031:Hypothalamus / Q000187:drug effects / Q000378:metabolism; D007124:Immunoenzyme Techniques; D007422:Intestines / Q000382:microbiology; D007736:Kynurenic Acid / Q000378:metabolism; D008297:Male; D016133:Polymerase Chain Reaction; D019936:Probiotics / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013315:Stress, Psychological / Q000097:blood / Q000378:metabolism*; D014364:Tryptophan / Q000187:drug effects / Q000378:metabolism; D014667:Vasopressins / Q000187:drug effects / Q000378:metabolism
chemical_list: D000928:Antidepressive Agents; D015306:Biogenic Monoamines; D016207:Cytokines; D014667:Vasopressins; D014364:Tryptophan; D003346:Corticotropin-Releasing Hormone; D007736:Kynurenic Acid; D003345:Corticosterone