OBJECTIVE Dopamine receptors (DRs) are involved in the development and treatment of many neuropsychiatric disorders. Currently available dopaminergic drugs modulate both DRD2 and DRD3, leading to side effects and uncertainty as to the roles each DR subtype plays physiologically. Our lab employed high throughput screening paradigms to discover highly selective modulators for the DRD3. METHODS The NIH Molecular Libraries Program 400,000 + small molecule library was screened using the Discove RxPathHunter? β- arrestin assay for compounds that activate the DRD3 without effects on the DRD2. Confirmation and counter-screens assessed selectivity and mechanisms of action. We identified 62 potential agonists, and chose the most promising to perform a structure-activity relationship (SAR) study to increase potency while maintaining selectivity. The lead compound identified through this process, ML417, was also characterized using bioluminescence resonance energy transfer (BRET)-based β-arrestin recruitment and G-protein activation assays as well as p-ERK assays. Potential neuroprotective properties of this compound were assessed using a SHSY5Y neuronal cell model. RESULTS ML417 displays potent, DRD3-selective agonist activity in multiple functional assays. Binding and functional GPCR screens (>165 receptors) show ML417 has limited cross-reactivity with other GPCRs. ML417 also displays superior (compared to the reference compound pramipexole),dose-dependent protection against a decrease in neurite length induced by 10 μmol·L-1 of the neurotoxin, 6-hydroxydopamine, in the SHSY5Y cell model. CONCLUSION We have discovered and characterized ML417, a potent and highly selective DRD3 agonist. This compound will be useful as a research tool, and may prove useful as a therapeutic drug lead.

The German Registry of Adamantiades-Behcet's disease was founded in 1990 in Berlin and it provides current data on the epidemiology, the clinical manifestations and the course of the disease in Germany on a continuous basis. A total of 218 patients, including 89 German and 100 Turkish patients, had been reported to the German Registry until October 1997. One hundred and ninety-six patients fulfilled the criteria of the Behcet's disease classification tree. The prevalence of the disease evaluated in Berlin-West was 1.68/100,000 in 1989 and had risen to 2.26/100,000 by 1994. The median age of onset was 25 years (range 5 to 66 years; German-Turks, ns). Juvenile disease was recorded in 6.9% of patients. The complete clinical picture according to the criteria of the International Study Group of Behcet's Disease developed in 15.5 months. The interval between onset of the disease and diagnosis was 35 months, which was significantly longer than the duration of the development of the complete clinical picture (p < 0.0001). The disease was diagnosed later in German (48.5 months) than in Turkish patients (25.5 months, p = 0.003). While German patients presented an equal male-to-female ratio, a male predominance was shown in Turkish patients (M:F 2.1:1, p = 0.022). Familial occurrence was detected in 2.0% of German and 15.9% of Turkish patients (p = 0.013). The frequencies of major clinical manifestations were: oral ulcers 99%, skin lesions 76%, genital ulcers 75%, ocular manifestations 59%, arthritis 59%, and positive pathergy test 52%. Clinical differences between German and Turkish patients were only found in the frequency of ocular lesions (48% vs. 66%, p = 0.025). Oral ulcers were with 72% the most common onset symptom of the disease followed by erythema nodosum (9%), uveitis (7%), arthritis (7%), genital ulcers (3%), superficial thrombophlebitis (2%) and papules/sterile pustules (2%). Uveitis and erythema nodosum as onset symptoms shortened the median interval to diagnosis to 1.5 and 15 months, respectively, while arthritis delayed diagnosis (43.5 months; p = 0.029). A severe course developed in 25% of the patients; irreversible retinal vasculitis to blindness in 15%, sterile meningoencephalitis in 8%, severe arthritis in 5%, hemoptysis in 2%, lethal outcome in 2% and bowel perforation in 1%. The relative risk of HLA-B5 positive German natives developing the disease. HLA-B5 was confirmed as a marker of severe prognosis. Cardiolipin autoantibodies were associated with cutaneous vasculitis and superficial thrombophlebitis was correlated with systemic vessel involvement.
Adolescence ; Adult ; Aged ; Behcet's Syndrome/epidemiology* ; Behcet's Syndrome/complications ; Child ; Child, Preschool ; Europe/epidemiology ; Female ; Germany/epidemiology ; Human ; Male ; Middle Age ; Prognosis