Recombinant human α2-adrenoceptor subtypes: comparison of [3H]rauwolscine, [3H]atipamezole and [3H]RX821002 as radioligands

AbstractKinetic, saturation and competition binding assays were employed to optimize and validate radioligand binding methods for characterization of recombinant human α2-adrenoceptor subtypes and for screening of new subtype-selective ligands. Stable transfected lines of Shionogi 115 mouse mammary tumour cells (5115) and three structurally different antagonist radioligands, [3H]rauwolscine, [3H]atipamezole and [3H]RX821002, were used. Specificity of α2-adrenergic binding was defined with 100 μM (−)-adrenaline. Steady-state was reached with all three radioligands within 15–30 min at 25°C, and the binding was rapidly reversible. The receptor affinities (α2-C10) were highest in glycylglycine, almost equally high in K+-phosphate, and lowest in Tris buffer for all three [3H]-ligands. This was mainly caused by different association rates. [3H]RX821002 was bound with high affinity and similar kinetic properties to all three αa2adrenoceptor subtypes in K+-phosphate buffer, and had the highest proportion of specific binding (96–98%). [3H]RX821002 and K+-phosphate buffer were subsequently used in competition assays. The rank order of affinity of compounds selective for α2-adrenoceptor subtypes was α2-C1O > α2-C4 > α2-C2 for oxymetazoline, α2-C4 > α2-C2 > α2-C10 for prazosin and α2-C2 > α2-C4 > α2-C10 for chlorpromazine. The drug affinities (Ki values) determined in this system were in close agreement with earlier results with [3H]rauwolscine in Tris buffer (r = 0.94). Agonist competition for [3H]RX821002 binding was biphasic in K+-phosphate buffer supplemented with 10 MM MgCl2, indicating functional coupling of receptors to G-proteins. Accordingly high-affinity binding of the agonists (−)-noradrenaline and UK14,304 was eliminated by 10 μM Gpp(NH)p in the assays. Our results confirm that [3H]RX821002 is a suitable radioligand for the characterization of all three human α2-adrenoceptor subtypes and for the determination of the subtype-selectivity of new α2-adrenoceptor agonists and antagonists

Proclamation from Kettering Mayor to Horn

A proclamation given in honor of Charles Horn by the mayor of Kettering, Ohio. The proclamation was issued in response to Horn chaperoning of a large group of Girl Scouts on a bicycling trip alone.https://corescholar.libraries.wright.edu/special_ms629_papers/1001/thumbnail.jp

A PET-CT study on neuroinflammation in Huntington’s disease patients participating in a randomized trial with laquinimod

Microglia activation, an indicator of central nervous system inflammation, is believed to contribute to the pathology of Huntington's disease. Laquinimod is capable of regulating microglia. By targeting the translocator protein, 11C-PBR28 PET-CT imaging can be used to assess the state of regional gliosis in vivo and explore the effects of laquinimod treatment. This study relates to the LEGATO-HD, multi-centre, double-blinded, Phase 2 clinical trial with laquinimod (US National Registration: NCT02215616). Fifteen patients of the UK LEGATO-HD cohort (mean age: 45.2 ± 7.4 years; disease duration: 5.6 ± 3.0 years) were treated with laquinimod (0.5 mg, N = 4; 1.0 mg, N = 6) or placebo (N = 5) daily. All participants had one 11C-PBR28 PET-CT and one brain MRI scan before laquinimod (or placebo) and at the end of treatment (12 months apart). PET imaging data were quantified to produce 11C-PBR28 distribution volume ratios. These ratios were calculated for the caudate and putamen using the reference Logan plot with the corpus callosum as the reference region. Partial volume effect corrections (Müller-Gartner algorithm) were applied. Differences were sought in Unified Huntington's Disease Rating Scale scores and regional distribution volume ratios between baseline and follow-up and between the two treatment groups (laquinimod versus placebo). No significant change in 11C-PBR28 distribution volume ratios was found post treatment in the caudate and putamen for both those treated with laquinimod (N = 10) and those treated with placebo (N = 5). Over time, the patients treated with laquinimod did not show a significant clinical improvement. Data from the 11C-PBR28 PET-CT study indicate that laquinimod may not have affected regional translocator protein expression and clinical performance over the studied period

Prolactin releasing peptide has high affinity and efficacy at neuropeptide FF2 receptors.

ABSTRACT Neuropeptide FF (NPFF) and prolactin-releasing peptide (PrRP) are two members of the RFamide peptide family. In this study we investigated whether these RFamide peptides, which have common structural features in their C-terminal RFamide motif and share several physiologically important functions, could exert their effects through the same set of receptors. The affinity and functional activity of several related RFamide peptides were determined at the human neuropeptide FF receptor subtype 2 (hNPFF2) and the human prolactin-releasing peptide (hPrRP) receptors. The full-length human prolactin releasing peptide 31 (hPrRP31) had significantly higher efficacy compared with NPFF and its stable analog, (1DMe)Y8Fa, at the hNPFF2 receptor. In contrast, NPFF and (1DMe)Y8Fa were not efficacious at the hPrRP receptor. Our study indicated a generally relatively low level of discrimination for RFamide peptides at the NPFF receptor, whereas the hPrRP receptor clearly preferred PrRP or very closely related peptides. The seemingly promiscuous binding of the RFamide peptides to the NPFF receptor was further confirmed by receptor autoradiography. PrRP may thus signal through the NPFF receptors in vivo

152 Development of Deutetrabenazine as a Potential New Non-Antipsychotic Treatment for Tourette Syndrome in Children and Adolescents

Tourette syndrome (TS) is a neurodevelopmental disorder characterized by the hyperkinetic movements of motor and phonic tics manifested in young age. Currently approved treatments in the United States are antipsychotics: haloperidol, pimozide, and aripiprazole, which are associated with serious side effects, including tardive dyskinesia (TD). Deutetrabenazine, a vesicular monoamine transporter type 2 (VMAT2) inhibitor, was approved in 2017 by the US FDA for the treatment of chorea associated with Huntington's disease and TD. Three ongoing studies (Alternatives for Reducing Tics in TS [ARTISTS]) are evaluating the efficacy, safety, and tolerability of deutetrabenazine in reducing tics in TS in children and adolescents (age 6-16 years). ARTISTS 1, a phase 2/3, response-driven, dose-titration, placebo-controlled study, randomizes patients (N=116) 1:1 to deutetrabenazine or placebo for 12 weeks. ARTISTS 2, a phase 3, fixed-dose study, randomizes patients (N=150) 1:1:1 to deutetrabenazine high or low dose, or placebo for 8 weeks. The primary efficacy outcome in these pivotal studies is change from baseline to end of treatment in the Total Tic Score (TTS) of the Yale Global Tic Severity Scale (YGTSS). Additional efficacy endpoints and safety/tolerability are also evaluated. ARTISTS is a 56-week, open-label, single-arm, long-term safety/tolerability study in patients who have successfully completed either ARTISTS 1 or ARTISTS 2. Not available yet. TS can have potentially long-term life impact, and there remains unmet medical need for effective and well-tolerated treatments. Three ARTISTS studies will evaluate the efficacy, safety, and tolerability of deutetrabenazine in patients with tics in TS. The studies are sponsored by Teva Pharmaceuticals and operationalized by Teva's development partner, Nuvelution TS Pharma INC