Reprint of “Effects of amphetamine, diazepam and caffeine on polysomnography (EEG, EMG, EOG)-derived variables measured using telemetry in Cynomolgus monkeys”

The Spontaneous Incidence of Neurological Clinical Signs in Preclinical Species Using Cage-side Observations or High-definition Video Monitoring: A Retrospective Analysis

When conducting toxicology studies, the interpretation of drug-related neurological clinical signs such as convulsions, myoclonus/myoclonic jerks, tremors, ataxia, and salivation requires an understanding of the spontaneous incidence of those observations in commonly used laboratory animal species. The spontaneous incidence of central nervous system clinical signs in control animals from a single facility using cage-side observations or high definition video monitoring was retrospectively analyzed. Spontaneous convulsions were observed at low incidence in Beagle dogs and Sprague-Dawley rats but were not identified in cynomolgus monkeys and Göttingen minipigs. Spontaneous myoclonic jerks and muscle twitches were observed at low incidence in Beagle dogs, cynomolgus monkeys, and Sprague-Dawley rats but were not seen in Göttingen minipigs. Spontaneous ataxia/incoordination was identified in all species and generally with a higher incidence when using video monitoring. Salivation and tremors were the two most frequent spontaneous clinical signs and both were observed in all species. Data from the current study unveil potential limitations when using control data obtained from a single study for toxicology interpretation related to low incidence neurological clinical signs while providing historical control data from Beagle dogs, cynomolgus monkeys, Sprague-Dawley rats, and Göttingen minipigs.

Emerging Electroencephalographic Biomarkers to Improve Preclinical to Clinical Translation in Alzheimer's Disease

Continually emerging data indicate that sub-clinical, non-convulsive epileptiform activity is not only prevalent in Alzheimer's disease (AD) but is detectable early in the course of the disease and predicts cognitive decline in both humans and animal models. Epileptiform activity and other electroencephalographic (EEG) measures may hold powerful, untapped potential to improve the translational validity of AD-related biomarkers in model animals ranging from mice, to rats, and non-human primates. In this review, we will focus on studies of epileptiform activity, EEG slowing, and theta-gamma coupling in preclinical models, with particular focus on its role in cognitive decline and relevance to AD. Here, each biomarker is described in the context of the contemporary literature and recent findings in AD relevant animal models are discussed.

Involvement of endocannabinoid system, inflammation and apoptosis in diabetes induced liver injury: Role of 5-HT3 receptor antagonist

Confident relationships between diabetes andliver damagehave previously been established. This study was designed to evaluate hepaticinflammation, apoptosis, and endocannabinoid system alterations in diabetes with or withouttropisetrontreatment. Rats were assigned to five equal groups: control, tropisetron, diabetes, tropisetron+diabetes, and glibenclamide+diabetes (n = 7 in each group). Rats were treated with tropisetron (3 mg/kg) and glibenclamide (1 mg/kg) as a positive control for two weeks after type 1 diabetes induction.Inflammatory cytokines tumor necrosis factor-alpha and interleukin 6 (TNF-α and IL-6) levels, apoptotic cells, and fatty acid amide hydrolase (FAAH) enzyme, at both transcriptional and protein levels increased, while the gene expression of cannabinoid receptor 1 (CB1) and its protein level decreased in the diabetic liver compared to the control. Treatment with tropisetron reversed TNF-α, apoptotic index, and endocannabinoid system components. These effects were equipotent with glibenclamide, indicating that tropisetroncan protect liver tissue against diabetic disturbances. These findings strongly support the idea that diabetes-induced liver abnormality is mediated by inflammatory reactions, apoptosis, and endocannabinoid system, and that these effects can be alleviated by using tropisetron as an antioxidant and anti-inflammatory agent.

Seizure liability assessments using the hippocampal tissue slice: Comparison of non-clinical species

INTRODUCTION

Traditionally, rat hippocampal tissue slice models are used as an in vitro electrophysiology assay to assess seizurogenic potential in early drug development despite non-clinical species-specific differences noted during in vivo seizure studies.

METHODS

Hippocampal tissue slices were acutely isolated from rats, minipigs, dogs and nonhuman primates (NHP). Population spikes (PS) were evoked through stimulation of the CA3 Schaffer collateral pathway and recorded using in vitro electrophysiological techniques via an extracellular electrode placed within the CA1 stratum pyramidale cell body layer.

RESULTS

Hippocampal slices, across all species, displayed a concentration-dependent increase in PS area and number with the pro-convulsant pentylenetetrazol (PTZ; 0.1-10mM). Beagle dogs exhibited higher sensitivities to PTZ-induced changes in PS area and number compared to both rats and NHPs which presented nuanced differences in their responsiveness to PTZ modulation. Minipigs were comparatively resistant to PTZ-induced changes in both PS area and number. Rat and NHP hippocampal tissues were further characterized with the pro-convulsant agents 4-aminopyradine (4-AP; 1-100μM) and cefazolin (0.001-10mM). Rats possessed higher sensitivities to 4-AP- and cefazolin-induced changes to both PS area and number whereas NHP displayed greater modulation in PS duration. The anti-convulsant agents, diazepam (10-500μM) and lidocaine (1-500μM), were also tested on either rat and/or NHP tissue with both drugs repressing PS activation at high concentrations.

DISCUSSION

Hippocampal tissue slices, across all species, possessed distinct sensitivities to pro- and anti-convulsant agents which may benefit the design of non-clinical seizure liability studies and their associated data interpretation.