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Background and Objective: Parkinson disease (PD) is the second most common neurologic disorder that results following degeneration of dopaminergic neurons in the pars compacta of substintia nigra (SNc). The 1-methyl-1,2,3,6-tetrahydropiridine (MPTP) is a chemical neurotoxin that widely used in animal models of PD. This study was carried out to evaluate the numerical density of dark neurons (DNs) in the SNc in mice subjected to intraperitoneal and intranasal injection of different doses of MPTP. Methods: In this experimental study, 90 male adult BALB/c mice were randomly allocated into four experimental groups including: group 1 (MPTP was injected via i.p. at the dose of 20mg/kg per 2 hours for 4 times), group 2 (MPTP was injected via i.p. at the dose of 30mg/kg for 5 consecutive days), group 3 (MPTP was injected via i.n. at a single dose of 1mg/kg), group 4 (MPTP was injected via i.n. at a single dose of 1mg/kg), four sham and one normal groups. 20 days after the final injection, the animal's brain were removed and stained by toluidine blue. Numerical density of DNs was counted. Results: Intranasal injection of MPTP significantly increased density of dark neurons in the pars compacta of substintia nigra in compare to intraperitoneally injection of MPTP (P<0.05). Conclusion: Intranasal injection of MPTP is more effective manner to induce degeneration of neurons in substintia nigra in animal model of Parkinson's disease.

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Background and Objective: Parkinson's disease is a neurological disorder caused by the loss of dopaminergic neurons in pars compacta of substantial nigra. The most important symptoms of this disease include slow motion, lack of movement, tremor and imbalance. This study was done to determine the effect of probiotic Lactobacillus paracasei on motor disorders caused by injection of 6-hydroxy dopamine in Parkinson's model in male rats.
Methods: In this experimental study, 48 male rats were randomly allocated into six groups. To create an animal model of Parkinson's disease, a black body component in male rats was injected 6-hydroxy dopamine (6-OHDA) (0.5 mg/kg) unilaterally by stereotaxic apparatus. After 3 weeks of recovery, to evaluation of degradation rate, animals were received apomorphine, intraperitoneally. In the first experiment, rats were randomly divided into Sham and Parkinson's (injured) groups, the Sham group were received only water and food, and the injured group received 6-hydroxy-dopamine. In the second experiment, male rats were divided into 4 groups of 8 rats, each of the 4 groups was injected 6-hydroxy-dopamine and 21 days later, they were tested for assay of apomorphine. The results were recorded, then for 28 days, the first group was taken as control. The second group of saline, the third group of milk, the fourth group of milk and probiotic were gavaged. At the end of day 28, once again, each group was subjected to rotation of apomorphine test and the rotations were recorded.
Results: The behavioral analysis of saline, milk, milk plus probiotics were indicated that the group receiving probiotic Lactobacillus paracasei plus milk was significantly less apomorphine rotation test than the saline group (P<0.05).
Conclusion: It seems that probiotic Lactobacillus paracasei can reduces Parkinson’s disease symptoms.