Michael R. Weed - US grants

The overall goals of the projects described here are to develop a rhesus monkey model for the cognitive effects of NeuroAIDS or MDMA-induces neurotoxicity. NueoAIDS is significant complication od Aids, affecting up to 30% symptomatic patients, while about 5-15% of those with AIDS develop frank dementia. The cognitive and psychomotor disturbances of NeuroAIDS greatly reduce the quality of life of affected individuals and their relations. "Ecstasy," or MDMA is an abused drug with demonstrated neurotoxic potential, but the behavioral effects MDMA-induced neurotoxicity remain to be shown. The behavioral battery developed by Dr. Gold is being used to study both of the topis in rhesus monkey models. The battery presently consists of six tasks which probe aspects of cognitive function mediated by different brain regions. A new task, visuo-spatial paired-associates learning task, will complement the regional sensitivity of the current tests by being sensitive to dysfunction in additional brain areas. The goals of task proposal are 1) to develop this human neuropsychological task for use in rhesus monkeys, 2) to develop additional testing measures for the battery to enhance its sensitivity without additional animal training, and 3) to use these enhancement to characterize cognitive of NeuroAIDS or MDMA-induced neurotoxicity.

[unreadable] DESCRIPTION (provided by applicant): As many as 40% of AIDS patients have been reported to suffer from alcoholism; however, little is known about the effect of alcohol abuse on AIDS. This proposal will develop a nonhuman primate (NHP) model of alcohol abuse and AIDS and will provide an important tool to help understand alcohol's effects on the progression of AIDS. The proposed research will develop a NHP model for the experimental analysis of both chronic, long-term alcohol consumption and HIV/AIDS. The model to be explored will combine current oral ethanol self-dosing techniques with a well-defined simian immunodeficiency virus (SIV)-macaque model of HIV/AIDS to investigate the viral, behavioral, and CNS consequences associated with chronic high-dose oral ethanol consumption, SIV viruses, and their combination. Automated oral self-dosing techniques will be employed to establish chronic high-dose oral ethanol consumption in macaques. Core body temperature and general activity, measures known to be sensitive to the effects of ethanol, will be continuously monitored by telemetry. Behavioral observations will monitor possible development of physical dependence and/or withdrawal. Assays of immune system function will be performed periodically throughout the experiment. Using these techniques, temperature, general activity, and behavioral observations and measures of immune system function will be recorded during baseline conditions, the development and maintenance of chronic ethanol ingestion, and during short-term abstinence. The effects of chronic high-dose oral ethanol consumption on the progression of SIV disease will be assessed by comparing all measures (body temperature, general activity, immune system function) in groups of ethanol-consuming and ethanol-free animals throughout SIV disease. Post mortem analysis will compare the severity of CNS pathology between ethanol-exposed and ethanol-naive animals. The proposed studies will provide important information on how ethanol consumption affects the course of SIV infection and the progression to AIDS. Furthermore, the proposed studies will investigate whether chronic alcohol consumption increases the CNS pathology produced by SlV infection. Once developed this model could be readily expanded to study alcohol's effects on a number of systems, including immune system function, cognitive and behavioral processes, and more detailed analysis of alcohol's effects on HIV/AIDS. By changing the availability of ethanol, the model could also investigate the effects of different patterns of alcohol exposure, including abstinence after chronic alcohol consumption and/or patterns of 'binge' drinking.

DESCRIPTION (provided by applicant): Approximately one third of new HIV infections occur as a consequence of drug abuse. Therefore, understanding the effects of drug abuse on AIDS remains an important goal CNS pathology in AIDS and many abused drugs, such as psychomotor stimulants, involve the neurotransmitter dopamine (DA). Predictibly, with DA insult there are also motor impairments in AIDS Because of the shared DA pathology, motor behaviors are likely to be doubly assaulted when AIDS and drug abuse are combined. The development of behavioral tests that are sensitive to CNS impairment is crucial to our understanding of the mechanisms behind the CNS pathology produced by AIDS. Demonstrating impairment earlier in the disease progression is necessary to identify which CNS changes are responsible for the CNS dysfunction associated with AIDS, and what mechanisms cause the dysfunction. Motor impairment has been shown to be a reliable marker for CNS impairment in AIDS, including impairment in cognitive function. This proposal will develop new procedures that will be incorporated into ongoing research on AIDS and abused drugs in macaques. A motor test that will simultaneously measure both behavioral and physiologic measures of fine motor control will be developed. This test, the "force and micro-tremor" test, will assess an animal's ability to regulate the amount of force with which it presses a rod Physiologic tremor will also be measured while the monkey presses the rod. Parameters of how much force should be required for each press, and how long the monkey should have to maintain the press will be investigated to determine the best method of measuring micro-tremor. The involvement of DA in the CNS pathology of both AIDS and many abused drugs makes understanding the effects of DA manipulations on this task important Increases and decreases in DA function will be assessed using pretreatments of cocaine and DAD 1 and D2 receptor antagonists, respectively. Once the parameters are established, the task will be trained in monkeys later infected with SIV, and the sensitivity of the task to SIV-induced motor impairment will be evaluated. The behavioral test developed in this proposal will be an important tool in our research on cognitive and motor consequences of AIDS and drug abuse, especially research on psychomotor stimulants and other drugs that have potential for damage to CNS dopaminergic systems.

[unreadable] DESCRIPTION (provided by applicant): Approximately 3-5% of children ages 3-17 in the U.S. are diagnosed with Attention Deficit / Hyperactivity Disorder (ADHD), and 4 million children are medicated chronically to treat ADHD. Methylphenidate (MPD) and amphetamine (Amph), control ADHD in the majority of those treated. However, there are concerns over long-lasting developmental changes in behavior, neurochemistry, growth rates and potential for substance abuse in children treated with MPD or Amph. The proposed research will test the hypothesis that chronic MPD or Amph results in long-term behavioral, physiologic and neurochemical alterations in preadolescent rhesus monkeys. Oral self-dosing techniques will provide non-stressful administration of MPD or Amph in doses within the therapeutic window for treatment of ADHD in children. Specific Aim 1 will determine if chronic MPD or Amph alters physiological development of preadolescent monkeys including circadian rhythms, body weights, food intake, and body growth rate. After 18 months of MPD or Amph administration, tests for behavioral sensitization to amphetamine will also be performed. Specific Aim 2 will test the hypothesis that chronic MPD or Amph alters the developing central nervous system including chronic activation of microglia and long-lasting alterations in dopaminergic function in preadolescent monkeys. Measures of dopaminergic function will include levels of dopamine transporters, dopamine D2 receptors and amphetamine-stimulated dopamine release. Specific Aim 3 will determine the effects of chronic MPD or Amph on development of executive function including inhibitory control and attentional set-shifting. Specific Aim 4 will test the hypothesis that monkeys previously exposed to MPD or Amph have a higher propensity to self-administer cocaine. The proposed studies provide a comprehensive interdisciplinary evaluation of the chronic effects of therapeutic doses of MPD and Amph in preadolescent nonhuman primates. These studies will advance understanding of the long-term neurochemical, behavioral and physiologic effects of chronic low-dose stimulant treatments and have direct translational application to the medication of children with ADHD. [unreadable] [unreadable]

[unreadable] DESCRIPTION (provided by applicant): Measures of pupillary and oculomotor function are exquisitely sensitive to modulation of the central nervous system (CNS) by drugs of abuse and CNS pathology in nonhuman primate (NHP) models of human diseases. However, techniques to study pupillary and oculomotor function in NHPs traditionally require invasive procedures including surgical implantation and/or restraint of the animals in specialized chairs. These techniques allow very powerful analyses of the visual system, but limit the number of researchers that can utilize eye-tracking in NHPs. This proposal will combine state-of-the-art, computerized video-based eye-tracking equipment with novel behavioral methods to develop a method for pupillometry and gaze-tracking in NHPs in their home cage. Specific Aim 1 is to develop a system that attaches to a nonhuman primate home cage and allows computer-based video recording of the nonhuman primate eye while the animal is awake and unrestrained. Measures to be recorded include estimates of pupil size and direction of the monkey's gaze. Specific Aim 2 is to develop a procedure for determination of pupillary light reflex. Determination of pupillary light reflex will be validated by measuring the effects of morphine in rhesus monkeys and baboons. Pupillometry will be measured in baboons to test the training methods and equipment in an additional nonhuman primate species. Specific Aim 3 is to develop a system to measure gaze direction while rhesus monkeys perform a visual smooth pursuit task. Sensitivity of the smooth pursuit task will be validated by testing the effects of diazepam on oculomotor performance of rhesus monkeys. Specific Aim 4 is to develop a test of recognition memory based on relative gaze times to two stimuli, the Visual Paired Comparisons test in rhesus monkeys. Administration of diazepam will test for the sensitivity of the paradigm to the amnesic effects of benzodiazepines. Measures of pupillary dilation will be included to address whether dilation due to cognitive load is evident in this paradigm. Home cage procedures will enable more researchers to eye-tracking techniques and reduce the technical difficulty of doing so. Home cage procedures will also reduce the stress to the NHP subjects inherent in restraint-based methods. The techniques presented here will be most attractive to non-traditional users of eye-based measures such as pharmacologists, neurotoxicologists and behavioral psychologists. [unreadable] [unreadable] [unreadable] [unreadable]

[unreadable] DESCRIPTION (provided by applicant): Cognitive impairment is a debilitating outcome of Alzheimer's Disease and Minor Cognitive Impairment. Cognitive impairment reduces quality of life and increases treatment costs. Relatively modest increases in cognitive function produce relatively large increases in quality of life and large decreases in cost of care. Palliative treatments enhancing cognitive function would benefit many patients until treatments for their underlying disorders are developed. One promising pharmacological target for such cognitive enhancers is the benzodiazepine (BZ) binding site on the gamma-aminobutyric acid (GABA) type A (GABAA) receptor- complex. Subtype-selective ligands have been developed for the GABAA-a5 BZ receptor (GABAAa5- BZr), which is predominately expressed in the hippocampus, a site important for memory function. Studies in rodent and nonhuman primate memory assays indicate that GABAAa5-BZr inverse agonists improve cognition with few adverse effects. In the proposed studies, 8 rhesus monkeys will be trained to perform tests from the CANTAB nonhuman primate neuropsychological testing battery. 4 monkeys will be also be trained on the delayed-match-to- sample test and implanted with radio-telemetry devices to measure cardiovascular and respiratory responses for dose-ranging studies. The dose-ranging cohort will determine active doses of the compounds in primates and also screen for compounds producing adverse effects prior to full cognitive testing in the CANTAB-trained monkeys. Novel compounds will be tested for toxicity in mice prior to testing in the dose- ranging or CANTAB-trained monkeys. The effects of GABAAa5-BZr ligands on cognitive function in macaques will be determined by pretreatments of GABAAa5-BZr agonists, antagonists and inverse agonists. These studies will test the hypothesis that activity at the GABAAa5-BZr can bi-directionally modulate cognition with agonists impairing cognitive performance and inverse agonists enhancing performance. The regional specificity of the CANTAB neuropsychological test battery will also allow for testing of the hypothesis that GABAAa5-BZr cognitive modulation will occur in tests mediated by temporal brain structures (i.e. the hippocampus) as opposed to tests mediated by frontal cortical structures. In addition, the ability of GABAAa5-BZr inverse agonists to reverse scopolamine-induced cognitive impairment will determine the potential effectiveness of these compounds as treatments for the cognitive impairment produced by Alzheimer's disease. Understanding the effects of GABAAa5-BZr ligands has important implications to the neuro- pharmacology, neuropsychology and neuroanatomy of cognition and will further development of a novel class of therapeutics for cognitive dysfunction in Alzheimer's disease and Minor Cognitive Impairment. [unreadable] [unreadable] [unreadable]

PROJECT SUMMARY Patients with Alzheimer?s disease (AD) suffer a progressive loss of memory and cognitive ability, and eventual loss of basic bodily functions and death. The incidence and toll of AD on the healthcare system continues to rise with significant societal impact. There are no treatments for AD to prevent its inexorable course, and the principal obstacle to developing new therapies for AD has been the inadequacy of available preclinical modeling, which almost exclusively involves rodents. Nonhuman primates (NHPs) share greater homology to humans than rodents in all respects, including genomics, physiology, cognitive processing, neuronal network complexity and dynamics of drug/target interactions. Given these translational advantages, the long-term goal of this project is to develop a new NHP model of AD that can be standardized and deployed in rigorous, reproducible studies to overcome critical current deficiencies in translating preclinical studies into novel clinical diagnostic strategies and therapies. The objective of this application is to expand and advance our Phase I work on a NHP model of AD in which intrathecal administration of amyloid ?-oligomers (A?Os) induces increased expression of phosphorylated tau in the medial temporal cortical memory circuit. This finding is consistent with our overall hypothesis that A?Os will trigger a cascade of accelerated pathology that mimics the changes occurring in the brains of AD patients. This hypothesis is based on a growing consensus in the AD research field that A?Os are the toxic species that provoke deposition of the characteristic tangles and plaques in the brain together with loss of neurons and synapses and associated cognitive decline. The hypothesis will be tested further in statistically meaningful designs by pursing three specific aims: 1) Determine the extent and persistence of induced cognitive deficits; 2) Confirm the predictive validity of the model using a pharmacological intervention, and 3) Assess the utility of EEG recordings from telemetry implants to track ongoing AD-like pathology. These studies will utilize in-life biomarkers (MRI-determined hippocampal volume, CSF analytes) together with post-mortem measurements (immunohistochemistry, biochemistry, electron microscopy) to establish the impact of A?Os administration in the brain of male and female St. Kitts green monkeys, a species that has been well characterized for its propensity to develop naturally occurring features of AD pathology. The approach is innovative because it represents a substantial shift from current AD research paradigms and tests a novel theoretical concept. The research is significant because it is expected to 1) overcome critical deficiencies in current animal AD models by validating an accelerated, inducible NHP model of sporadic AD in both males and females, 2) permit effective translation of basic discoveries into novel clinical diagnostic strategies and therapies, and 3) help understand possible sex differences in disease susceptibility and progression. Success with this program would provide a valuable resource to research groups in need of a relevant, reliable model of AD for basic research, and diagnostic and therapeutic development.