Jim C. Gourdon

The highly selective 5-HT 2A antagonist EMD-281,014 reduces dyskinesia and psychosis in the l -DOPA-treated parkinsonian marmoset

ABSTRACT Blockade of serotonin 2A (5‐HT2A) receptors is regarded as an anti‐dyskinetic and anti‐psychotic strategy in Parkinsons disease (PD). However, the 5‐HT2A antagonists tested so far exhibited affinity for other receptors, which might have played a role in their action. EMD‐281,014 is the most selective 5‐HT2A antagonist available, with approximately 2,000‐fold selectivity over serotonin 2C (5‐HT2C) receptors. EMD‐281,014 was previously tested in the clinic and has high translational potential. In the present study, we assessed the effect of EMD‐281,014 on dyskinesia and psychosis in the 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP)‐lesioned common marmoset. We first determined the pharmacokinetic profile of EMD‐281,014 in the marmoset, after which doses leading to clinically‐relevant plasma levels (0.01, 0.03 and 0.1mg/kg) or vehicle were administered to MPTP‐lesioned marmosets, in combination with L‐3,4‐dihydroxyphenylalanine (l‐DOPA). The effects of EMD‐281,014 on dyskinesia, psychosis‐like behaviours (PLBs) and parkinsonism were then evaluated. When added to l‐DOPA, EMD‐281,014 (0.03 and 0.1mg/kg) reduced peak dose dyskinesia, by 41.8% and 54.5% (P<0.05 and P<0.001), when compared to l‐DOPA/vehicle. EMD‐281,014 (0.03 and 0.1mg/kg) also significantly reduced the severity of peak dose PLBs, by 42.5% and 45.9% (P<0.05 and P<0.001), when compared to vehicle. The anti‐dyskinetic and anti‐psychotic effects of EMD‐281,014 were achieved without interfering with l‐DOPA anti‐parkinsonian action. Our results suggest that highly‐selective 5‐HT2A receptor blockade with EMD‐281,014 is an effective way to alleviate both dyskinesia and psychosis in PD, without adversely affecting parkinsonian disability. HIGHLIGHTSEMD‐281,014 is a potent and highly selective 5‐HT2A antagonist.We have determined the pharmacokinetic profile of EMD‐281,014 in the marmoset.EMD‐281,014 reduces l‐DOPA‐induced dyskinesia in the MPTP‐lesioned marmoset.EMD‐281,014 reduces dopaminergic psychosis in the MPTP‐lesioned marmoset.EMD‐281,014 does not hinder the anti‐parkinsonian effect of l‐DOPA.

Development of a selective and sensitive high-performance liquid chromatography-tandem mass spectrometry assay to support pharmacokinetic studies of LY-487,379 in rat and marmoset

Drugs modulating the metabotropic glutamate type 2 receptor (mGluR2) activity may have therapeutic benefits in treating a large spectrum of neuro-psychiatric disorders, from schizophrenia to Parkinsons disease, both as a symptomatic therapy and potential disease-modifying paradigm. LY-487,379 is a highly selective mGluR2 positive allosteric modulator that is widely used to study mGluR2 function using experimental animal models. The common marmoset is a small primate that has long been used in neuroscience. However, given its small size and small circulating blood volume, conducting studies to determine the PK profile of LY-487,379 is challenging. We developed and validated a sensitive and selective analytical method that enables quantification of LY-487,379 using a limited volume of plasma (10 μL). The analytical method consists of protein precipitation followed by high-performance liquid chromatography with heat assisted electrospray ionization mass spectrometry (HPLC-HESI-MS/MS). The chromatographic separation was achieved using gradient elution with a mobile phase consisting of acetonitrile and 0.01% formic acid in water on a Thermo Scientific Aquasil C18 analytical column (100 × 2.1 mm I.D., 5 μm) operating at 40 °C and at a flow rate of 300 μL/min. The method displays a linear relationship ranging from 0.2 to 100 ng/mL. Intra- and inter-day relative standard deviations are <1.4% and 7.9%, respectively and the relative error ranged from -6.9 to 9.7%. The method was used to quantify LY-487,379 in both rat and marmoset plasma, and PK parameters were determined after a single subcutaneous dose of 1.0 mg kg-1 in both species and significant differences in Cmax, AUC and T1/2 were observed.

Physiological and pharmacokinetic effects of multilevel caging on Sprague Dawley rats under ketamine-xylazine anesthesia

While the cage refinement is a necessary step towards improving the welfare of research rats, increasing the complexity and surface area of the living space of an animal may have physiological impacts that need to be taken into consideration. In this study, ketamine (80 mg/kg) and xylazine (10 mg/kg) caused a short duration anesthesia that was significantly decreased in Sprague-Dawley rats housed in multilevel cages (MLC), compared to rats housed in standard cages (SDC). The withdrawal reflex, the palpebral reflexes and the time-to-sternal all occurred earlier in MLC housed rats, suggesting an effect of housing on the physiology of the rats. In addition, during anesthesia, cardiac frequencies were increased in animals housed in the smaller SDC. Respiratory frequencies, the blood oxygen saturation and rectal temperatures during anesthesia did not vary between conditions during the anesthesia. While xylazine pharmacokinetics were unchanged with caging conditions, the clearance and half-lives of ketamine and its metabolite, norketamine, were altered in the rats housed in MLC. Finally, while no difference was ultimately seen in rat body weights, isolated liver and adrenal gland weights were significantly lighter in rats housed in the MLC. Increasing cage sizes, while having a positive impact on wellbeing in rats, can alter anesthetic drug metabolism and thus modify anesthesia parameters and associated physiological processes.

Granulosa cells of prepubertal cattle respond to gonadotropin signaling and upregulate genes that promote follicular growth and prevent cell apoptosis: MICHALOVIC et al.

Oocytes collected from prepubertal animals are known to be less developmentally competent than those from adult animals. There is evidence suggesting that acquisition of developmental competence in bovine oocytes may be linked to the expression profile of genes in the granulosa cells (GCs). Cumulus–oocyte complexes (COC) and GCs were collected from 12 Holstein heifers between 2 and 6 months of age (nine follicle‐stimulating hormone [FSH] treated and three untreated) and eight FSH‐treated cows. The COCs from prepubertal animals were matured, fertilized, and cultured in vitro to assess development to the blastocyst stage. The relative messenger RNA (mRNA) abundance of FSHR, StAR, CYP19A1, HSD3B1, CX43, FOXO1, and XIAP in GCs were quantified by real‐time quantitative polymerase chain reaction. Results from this study revealed that GCs of prepubertal animals respond to FSH treatment by increasing mRNA levels of genes promoting estradiol synthesis and follicular growth ( FSHR and CYP19A1), and preventing cell apoptosis ( XIAP), and by decreasing mRNA levels of genes promoting progesterone production ( StAR and HSD3B1). This study also revealed that the relative mRNA abundance of FOXO1 in GCs is associated with oocyte competence to support embryo development to the blastocyst stage in prepubertal Holstein heifers.