Chronic Treatment with the Probiotics Lacticaseibacillus rhamnosus GG and Bifidobacterium lactis BB12 Attenuates Motor Impairment, Striatal Microglial Activation, and Dopaminergic Loss in Rats with 6-Hydroxydopamine-induced Hemiparkinsonism.

Gut dysbiosis is considered a risk factor for Parkinson's disease (PD), and chronic treatment with probiotics could prevent it. Here we report the assessment of a probiotic mixture [Lacticaseibacillus rhamnosus GG (LGG), and Bifidobacterium animalis lactis BB-12 (BB-12)] administered to male rats 2 weeks before and 3 weeks after injecting 6-hydroxydopamine (6-OHDA) into the right striatum, a model that mimics the early stages of PD. Before and after lesion, animals were subjected to behavioral tests: narrow beam, cylinder test, and apomorphine (APO)-induced rotations. Dopaminergic (DA) denervation and microglia recruitment were assessed with tyrosine hydroxylase (TH+) and ionized calcium-binding protein-1 adapter (Iba1+) immunostaining, respectively. Post 6-OHDA injury, rats treated with sunflower oil (probiotics vehicle) developed significant decrease in crossing speed and increases in contralateral paw slips (narrow beam), forepaw use asymmetry (cylinder), and APO-induced rotations. In striatum, 6-OHDA eliminated ≈2/3 of TH+ area and caused significant increase of Iba1+ microglia population. Retrograde axonal degeneration suppressed ≈2/5 of TH+ neurons in the substantia nigra pars compacta (SNpc). In hemiparkinsonian rats, probiotics treatment significantly improved the crossing speed, and also reduced paw slips (postlesion days 14 and 21), the loss of TH+ neurons in SNpc, and the loss of TH+ area and of Iba1+ microglia count in striatum, without affecting the proportion of microglia morphological phenotypes. Probiotics treatment did not attenuate forepaw use asymmetry nor APO-induced rotations. These results indicate that the mixture of probiotics LGG and BB-12 protects nigrostriatal DA neurons against 6-OHDA-induced damage, supporting their potential as preventive treatment of PD.

Chronic feeding with 3% dried raw blueberries (V. corymbosum) reduces apomorphine-induced rotations and striatal dopaminergic loss in hemiparkinsonian rats.

Blueberries (BB) are rich in antioxidant polyphenols, and their intake could prevent Parkinson's disease (PD). Here we assessed whether rats chronically fed dried raw BB develop resistance to dopaminergic denervation and motor disorders caused by unilateral intrastriatal injection of 6-hydroxydopamine (6-OHDA), a dopaminergic neurotoxin acting mainly by inducing oxidative stress. Male rats were fed either with LabDiet® alone or supplemented with 3% lyophilized raw BB for 2 weeks before and 3 weeks after injecting 6-OHDA (day 0) or vehicle (mock lesion) into the right striatum. The cylinder test was performed on days -14, -7, -1, +7, +14, and +21; the percentage of ipsilateral forepaw (IF) use asymmetry was determined by counting the wall contacts made with either forepaw or with both. Apomorphine (0.25 mg/kg, s.c.)-induced rotation was performed on days -1, +7, +14, and +21. Full contralateral rotations were counted in 3-min periods, every 15 min, up to 90 min. Striatal slices were immunostained for tyrosine hydroxylase (TH) and the ionized calcium-binding protein-1 adapter (Iba1) [immunoreactive area or microglia count in right striatum expressed as % of the left striatum]. Antioxidants in BB methanolic extracts neutralized the free radical 2,2-diphenyl-1-picrylhydrazyl in a concentration-dependent manner. Anthocyanins have been reported as the most abundant polyphenols in BB. Using the pH differential method, the total anthocyanin content (malvidin-3-glucoside equivalents) in raw BB averaged 21.04 mg/g dry weight. The range of anthocyanin intake by rats throughout the study varied from 37.7 to 72.2 mg/kg body weight. The time and food type factors, as well as their interaction were significant according to two-way RM-ANOVA in both the apomorphine-induced rotations and the cylinder test. Compared with LabDiet® alone, chronic supplementation with 3% dried raw BB decreased apomorphine-induced rotations on days +14 and +21 (p < 0.001) and produced a 46% reduction in total rotations post-surgery (p < 0.05), but only caused a partial, non-significant, decrease of IF asymmetry. BB supplementation reduced TH loss in the striatum (p < 0.05) but did not attenuate the increase of Iba1+ microglia. The consumption of 3% dried raw blueberries attenuates dopaminergic denervation and partially reverses motor disorders in the 6-OHDA-induced PD model in rats. The phytochemicals of raw blueberries that contribute to the observed neuroprotective effect are yet to be identified.