Idiopathic Parkinson’s disease (PD) is a neurodegenerative disorder of mature and older individuals. Since all aged individuals do not develop PD, predisposing conditions may exist that pair with the stress placed on the basal ganglia during aging to produce the symptoms of PD. In this project we used 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) to test the hypothesis that a sensitization stage and a precipitating stage underlie idiopathic PD. To induce the sensitization stage, pregnant C57BL/6J mice were treated with MPTP (10mg/kg/dy) during gestation days 8–12 to target the emerging fetal nigrostriatal dopamine neurons. For the precipitating stage, the 3-months old offspring were administered MPTP for 7 days, to simulate the changes that occur during aging. The weights and motor activity of the offspring, HPLC striatal dopamine and its metabolites and Western blot for tyrosine hydroxylase (TH) were determined. Offspring exposed to prenatal MPTP showed lower birth weights that eventually recovered. Prenatal MPTP also reduced motor activity by 10–30%, striatal TH by 38%, dopamine by 14%, homovanillic acid by 16.5% and 3-methoxytyramine by 66%. The postnatal MPTP was more potent in the prenatal MPTP-exposed offspring. MPTP at 10, 20 and 30mg/kg, dose-relatedly, reduced striatal TH by 9.4%, 48.6% and 82.4% in the prenatal-PBS mice and by 48%, 78.7% and 92.7% in the prenatal-MPTP groups. More importantly, postnatal MPTP at 10mg/kg that showed slight effects on DA, DOPAC, HVA and 3-MT in the prenatal-PBS offspring, showed 69.9%, 80.0%, 48.4% and 65.4% reductions in the prenatal-MPTP mice. The study may identify a new model for PD, and the outcome suggests that some cases of idiopathic PD may have a fetal basis in which early subtle nigrostriatal impairments occurred and PD symptoms are precipitated later by deteriorating changes in the nigrostriatum, that would not caused symptoms in individuals with normal nigrostriatal system.

Aims L-3,4-Dihydroxyphenylalanine (L-DOPA) is the most effective symptomatic treatment for Parkinson’s disease (PD), but PD patients usually experience a successful response to L-DOPA therapy followed by a progressive loss of response. L-DOPA efficacy relies on its decarboxylation by aromatic L-amino acid decarboxylase (AAAD) to form dopamine (DA). So exogenous L-DOPA drives the reaction and AAAD becomes the rate limiting enzyme in the supply of DA. In turn, exogenous L-DOPA regulates the expression and activity of AAAD as well as the synthesis of DA and its metabolites, changes that may be linked to the efficacy and side-effects of L-DOPA. Main Methods One-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse PD model was utilized to study the effects of L-DOPA on the steady-state level and activity of AAAD, tyrosine hydroxylase (TH), DA and the metabolites of DA. The MPTP and control mice were treated twice daily with PBS or with 100 mg/kg of L-DOPA for 14 days and the expression and activity of AAAD, the expression of TH and the levels of DA and its metabolites were determined 24 hrs after L-DOPA or PBS treatment, when exogenous L-DOPA is eliminated. Key Findings In the MPTP model, L-DOPA reduced the steady-state expression and the activity of striatal AAAD by 52% and 50%, respectively, DA and metabolites were also significantly decreased. Significance The outcome shows that while L-DOPA replenishes striatal DA it also down-regulates AAAD and the steady-state synthesis and metabolic capability of the dopaminergic system. These findings are important in the precipitation of L-DOPA induced side effects and the management of L-DOPA therapy.

Background: Degeneration of nigrostriatal (NS) dopamine (DA) neurons is the major neuropathological marker of Parkinson's disease (PD). The cause for the disorder is unknown, but a prenatal sensitization stage and a postnatal precipitating stage may be involved. The sensitization stage is based on studies showing that prenatal exposure to low doses of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) during the birth of substantia nigra (SN) DA neurons reduced DA, its metabolites, tyrosine hydroxylase (TH), the number of NS neurons as well as locomotor activities of the offspring. The observation that motor activities of the toxin-exposed animals deteriorated during aging, produced the condition equated to the precipitating stage. Other studies suggest that curcumin may offer protection. Purpose: For this project, we studied the protection offered by curcumin and an antioxidant formulation from MPTP-induced toxicity. Methods: Four groups of adult mice were pretreated, every other day for 27 days, with curcumin, 25 μg or 50 μg per mice of 25 g average body weight (equated to 1 mg/kg or 2 mg/kg) or with 25 mg/kg or 50 mg/kg of the antioxidant formulation. A control group received saline. MPTP was administer at the 20th day of pretreatment and all treatments continued for 7 days, then the animals were studied for changes in motor activities, striatal DA and DA metabolites as well as striatal and midbrain TH. The changes are indicative of PD-like NS damage. Results: The data showed that MPTP markedly reduced movements, as well as DA, its metabolites and TH. Curcumin and the antioxidant formulation blocked and ameliorated the toxic effects of MPTP. MPTP reduced DA to 49.1%. Curcumin restored DA to 87.3% and 84.8%, and the antioxidants restored and elevated DA to 132.1% and 121.2%. MPTP reduced striatal TH to 45.1%. The doses of curcumin restored TH to 60.9% and 75.1% and the antioxidants restored TH to 90.7% and 94.7%. Curcumin and the antioxidants reduced MPTP-induced death. Conclusion: The results demonstrated that curcumin and the antioxidants blocked the PD-like toxic effects of MPTP, indicative of the potentials as preventative measure for PD.

Loss of function KCNK3 mutation is one of the gene variants driving hereditary pulmonary arterial hypertension (PAH). KCNK3 is expressed in several cell and tissue types on both membrane and endoplasmic reticulum and potentially plays a role in multiple pathological process associated with PAH. However, the role of various stressors driving the susceptibility of KCNK3 mutation to PAH is unknown. Hence, we exposed kcnk3fl/fl animals to hypoxia, metabolic diet and low dose lipopolysaccharide (LPS) and performed molecular characterization of their tissue. We also used tissue samples from KCNK3 patients (skin fibroblast derived inducible pluripotent stem cells, blood, lungs, peripheral blood mononuclear cells) and performed microarray, immunohistochemistry (IHC) and mass cytometry time of flight (CyTOF) experiments. Although a hypoxic insult did not alter vascular tone in kcnk3fl/fl mice, RNASeq study of these lungs implied that inflammatory and metabolic factors were altered, and the follow-up diet study demonstrated a dysregulation of bone marrow cells in kcnk3fl/fl mice. Finally, a low dose LPS study clearly showed that inflammation could be a possible second hit driving PAH in kcnk3fl/fl mice. Multiplex, IHC and CyTOF immunophenotyping studies on human samples confirmed the mouse data and strongly indicated that cell mediated, and innate immune responses may drive PAH susceptibility in these patients. In conclusion, loss of function KCNK3 mutation alters various physiological processes from vascular tone to metabolic diet through inflammation. Our data suggests that altered circulating immune cells may drive PAH susceptibility in patients with KCNK3 mutation.

Membrane-bound BAFF (mBAFF) was labeled with a rat Buffy-2 Ab to BAFF (Alexis Biochemicals) and a PEconjugated anti-rat Ab (BD PharMingen). In Results, the "CD77 sorting" label in Figure 1A is incorrect. The correct label is "CD38 sorting," as detailed in the legend and in the first paragraph of Materials and Methods.