Psychobiotics improve propionic acid-induced neuroinflammation in juvenile rats, rodent model of autism

Abstract

This study aimed to evaluate the protective and therapeutic potency of bee pollen and probiotic mixture on brain intoxication caused by propionic acid (PPA) in juvenile rats. Five groups of six animals each, were used: the control group only receiving phosphate-buffered saline; the bee pollen and probiotic-treated group receiving a combination of an equal quantity of bee pollen and probiotic (0.2 kg/kg body weight); the PPA group being treated for 3 days with an oral neurotoxic dose of PPA (0.25 kg/kg body weight); the protective and therapeutic groups receiving bee pollen and probiotic mixture treatment right before and after the neurotoxic dose of PPA, respectively. The levels of interleukin (IL)-1ß, IL-6, IL-8, IL-10, IL-12, tumor necrosis factor α, and interferon γ (IFN-γ) were investigated to evaluate the neuroinflammatory responses in brain tissues from different animal groups. The much higher IL-1β, IL-8, and IFN-γ, as pro-inflammatory cytokines (P < 0.001), together with much lower IL-10, as anti-inflammatory cytokine (P < 0.001) compared to controls clearly demonstrated the neurotoxic effects of PPA. Interestingly, the mixture of bee pollen and probiotics was effective in alleviating PPA neurotoxic effects in both therapeutic and protective groups demonstrating highly significant changes in IL-1β, IL-8, IL-10, and IFN-γ levels together with non-significant reduction in IL-6 levels compared to PPA-treated rats. Overall, our findings demonstrated a new approach to the beneficial use of psychobiotics presenting as bee pollen and probiotic combination in neuroinflammation through cytokine changes as a possible role of glial cells in gut-brain axis.

Keywords: autism; bee pollen; cytokines; neurotoxic; probiotic; psychobiotics.

Figure 1

Diagrammatic scheme of the animal experiments. PPA was a product of Sigma-Aldrich (USA). Bee pollen (NZ Bee Pollen Granules) and probiotics (PROTEXIN^®) were products of Happy Valley (New Zealand) and Probiotics International Limited (UK), respectively.

Figure 2

Mean value ± S.D. of all the measured parameters in brain homogenate of treated rats’ pups compared to control group. Only P values ≤0.05 were considered significant. ^a is the comparison between control vs PPA-treated groups; ^b is the comparison between PPA-treated group vs therapeutic and protective groups; ^c is the comparison between therapeutic vs protective groups.