Billy R. Martin - US grants

A major aim of this application is to identify causes of the toxic effects that appear immediately or at prolonged periods of time after phencyclidine (PCP) use. There has been considerable speculation that mobilization of PCP from storage sites may play a role in delayed toxicity. We plan to continue our studies of tissue sequestration of PCP and, more importantly, PCP metabolites in acutely and chronically-treated animals. Due to the fact that PCP is most commonly abused by smoking, emphasis will be placed upon identification of PCP pyrolysis products and quantitation of their delivery in smoke. Cigarettes containing PCP radiolabeled in the phenyl and piperidine moieties will be 'smoked' so that the pyrolysis products can be isolated. Following identification of all major pyrolysis products, mice will be exposed to smoke from these cigarettes in order to study the long-term biodisposition of PCP, its pyrolysis products and their metabolites. We will also examine the possibility that some of the adverse effects of PCP arise from smoking piperidinocyclohexanecarbonitrile (PCC), a frequent contaminant of PCP. Pyrolysis studies will allow us to estimate the quantity of PCC and cyanide that smokers are being exposed to. Emergency treatment of PCP abusers is usually carried out to reverse CNS effects ranging from extremely bizarre behavior to coma. Although treatments frequently includes urine acidification, there is no direct evidence that this procedure significantly alters brain levels of PCP. We propose to evaluate the effectiveness of urine acidification for altering the biodisposition of PCP in rats with particular emphasis on brain levels. The effectiveness of charcoal and cholestyramine to retard absorption of PCP from the gastrointestinal tract will also be evaluated. A combination of treatments may prove to be more efficacious than a single treatment. The last objective is to identify areas of the rat brain upon which PCP produces its behavioral effects. We plan to correlate the behavioral effects (drug discrimination) to the biodisposition of PCP in both tolerant and nontolerant rats as well as after administration of PCP intraventricularly and into specific brain sites. The research proposed in this application will enable us to better understand the toxic manifestations of PCP abuse and will provide assistance in developing a rational treatment for these clinical problems.

Despite the fact that marihuana is one of the major drugs of abuse, relatively little is known regarding the mechanism by which its principal psychoactive constituent, delta 9- tetrahydrocannabinol (THC), produces its subjective effects. It is hypothesized that the behavioral effects of delta 9-THC represent a composite of effects that arise from the actions of cannabinoids produce these behavioral effects. The emphasis will be directed toward determining whether behavioral effects of delta 9-THC are mediated either through a specific cannabinoid receptor or through membrane perturbation. Therefore, a major objective will be to determine whether the pharmacological profile of cannabinoids can be separated into individual behavioral components by evaluating synthetic analogs for their ability to produce motor hypoactivity, hypothermia, catalepsy and antinociception in mice, stimulus generalization to delta 9-THC in delta 9-THC trained rats and monkeys and behavioral effects (static ataxia) in dogs. Partition coefficients of the analogs will be determined as well as the degree to which the analogs cause membrane perturbation. A correlation between the pharmacological profile of the analogs and their actions on these biochemical systems should provide insight into their mechanism of action. In addition, efforts will be made to determine whether or not specific cannabinoid receptor exists. Attempts will be made to establish an in vitro binding assay by synthesizing radiolabeled ligands that regain behavioral activity but are less lipophilic than delta 9-THC. These radiolabeled ligands will include potential photoaffinity labels (azido compounds) as well as nitrogen mustards. Efforts will also be made to isolate specific binding sites by affinity chromatography. In addition, attempts will be made to develop a specific cannabinoid antagonist. The analogs that exhibit little or no agonistic activity will be evaluated in the above mentioned behavioral tests as potential antagonists of delta 9-THC. The results of these experiments will provide important insights into the mechanism by which cannabinoids produce their central effects. Identification of the neurochemical processes involved in the subjective effects of cannabinoids will lead to a better understanding of the etiology of recreational use of marihuana and may lead to the development of an effective deterrent. In addition, identification of the biochemical events associated with cannabinoid behavioral effects may provide insights into the processes involved in mental abberations.

As a result of frequent abuse of drugs by smoking or inhalation, a major of goal of this proposal is to study the pharmacological and toxicological effects of drugs of abuse by the inhalation route. A common practice for PCP abuse is smoking PCP-laced cigarettes. It is well-documented that PCP is readily degraded (about 50%) during the smoking process to several products. A specific aim of this grant is to examine PCP analogs that are abused to determine whether they are degraded to a similar extent and whether potentially dangerous pyrolytic products are formed. Cocaine is another drug that is abused primarily by the inhalation route. Although cocaine is smoked occasionally, it has become increasingly popular to "free base" cocaine, the process of inhaling the volatilized free based. Two particularly alarming aspects of "free basing" is that it increases both the addictive potential and the toxicity of cocaine. A goal of this research is to elucidate the mechanisms that are responsible for the changes in the pharmacological properties of cocaine following inhalation. A specific aim of this proposal is to quantitate cocaine and its pyrolysis products that are delivered in the vapor during a typical "free basing" session. Additionally, rats will be exposed to cocaine vapor so that the concentrations of cocaine and its pyrolysis products can be determined in plasma, brain, heart and lung. The time course of cocaine and pyrolysis products is these tissues can then be correlated with the effects of "free basing" on heart rate and blood pressure. There are also indications that PCP and cocaine have been co-abused. Upon completion of the cocaine inhalation studies, the consequences of co-administration of PCP and cocaine by inhalation can be assessed in terms of enhanced cardiovascular toxicity. If co-administration results in unexpected pharmacological effects, then biodisposition of PCP and cocaine will be studied following inhalation of the drug combination. The last objective is to continue our investigation of PCP site of action in the brain. While several different approaches are currently being employed to identify sites and mechanism(s) of PCP action in the central nervous system, our observation that PCP is relatively inactive following intraventricular (i.v.t.) administration in rats provides an exciting lead that warrants further investigation. Autoradiographic studies will be carried out to determine whether differences in the localization of PCP after i.v.t. and i.p. administration can explained the differences in potency by these two routes. The research proposed in this application will enables us to better understand the toxic manifestations of drugs or drug combinations when they are abused either by smoking or inhalation. An explanation for the toxicity of drugs of abuse by different routes of administration will enable rational therapies for medical emergencies to be developed as well as serving to educate the public of the dangers of drug abuse.

drug abuse;

biomedical equipment purchase;

A large number of investigators at Virginia Commonwealth University (VCU) have made significant contributions to our knowledge of drugs of abuse and related phenomena during the past two decades. The interests of these researchers encompass behavioral, pharmacokinetic, neurochemical, and pharmacological characterization of all classes of abused drugs. While there have always been active collaborations among these investigators, the drug abuse research effort at VCU has been enhanced by the creation of the NIDA Center on Drug Abuse Research. The primary objective of the Center is to foster interdisciplinary research on drug abuse at VCU. The Center will continue to provide a mechanism for bringing together scientists from many different disciplines (pharmacology, toxicology, physiology, histology, biostatistics, neurology, medicinal chemistry, microbiology, pediatrics, substance abuse medicine, etc.) who have had the opportunity to share information and ideas regarding abused drugs. Another major contribution has been to facilitate the training and development of young scientists in drug abuse research. Our success in stimulating collaborative research as well as in recruiting young investigators into drug abuse research is reflected in the growth of the Center which is composed of a core and eight research projects. The role of the Core is to provide program management and facilitate interaction and cooperation among the participants through its administrative, drug synthesis, instrumentation and statistical components. The objective of Project 1 is to test the dopamine hypothesis of the mechanism of action of cocaine through structure-activity relationship studies in rats. Project 2 is designed to verify that there is an increased incidence of apnea in infants exposed in utero to drugs of abuse and to devise effective treatment strategies. The objective of Project 3 is to understand in a comprehensive manner how cocaine affects the cerebral circulation and microvascular function. The evaluation of the functional role of central nicotine receptors will be carried out in Project 4. The hypothesis to be tested is that nicotine agonists and antagonists act through two distinct receptor systems which have not yet been fully characterized. Studies will be conducted in both normal and brain-injured adults as well as in neonatal animals. The impact of opioid exposure on the fetus during pregnancy has not been fully explored. Therefore, the effects of in utero methadone exposure on brain neurochemistry will continue to be evaluated in Project 5. The growing concern as to when and how pain in newborns should be treated forms the basis of Project 6. The emphasis will be placed upon the assessment of the development of opioid tolerance and dependence in neonatal rats. Project 7 will be devoted to the cloning of cannabinoid receptors and subsequent pharmacological characterization in order to establish the functional role of these receptor in the central nervous system. Finally, the objective of Project 8 will be the elucidation of the antinociceptive mechanism(s) of cannabinoids with particular emphasis on second messenger systems.

Despite the fact that marijuana is one of the major drugs of abuse, it has been only recently that major advances have been made in understanding the actions of the cannabinoids on the central nervous system. The development of potent cannabinoid agonists led to the discovery of cannabinoid receptors in brain. However, the precise role of these receptors in brain remains to be fully established. It is our hypothesis that the behavioral effects of delta9-THC does not arise from its actions on a single biochemical system but rather represent the actions of cannabinoids on several biochemical systems. the goal of the proposed research is to identify additional receptors and/or mechanisms through which cannabinoids produce their behavioral effects and determine their exact role in the brain. The emphasis will be directed toward characterizing the pharmacological profile of newly synthesized cannabinoids in order to determine whether there is a common pharmacophore for all cannabinoid behavioral effects. Synthetic analogs will be evaluated for their ability to produce motor hypoactivity, hypothermia, catalepsy and antinociception in mice, and stimulus generalization to delta9-THC in delta9-THC-trained rats and monkeys. In addition, attempts will be made to develop specific cannabinoid antagonists by evaluating analogs that exhibit little or no agonistic activity in the above mentioned behavioral tests as potential antagonists of delta9-THC. Potential irreversible antagonists include nitrogen mustard, isothiocynate, and photoaffinity label analogs. In order to ascertain that novel analogs which have been used to label the cannabinoid receptor share all of the properties of delta9-THC, cross tolerance studies will be conducted to determine whether delta9-THC- tolerant mice are completely tolerant to all of the effects of the novel analogs CP 55,950 and WIN 55,212. Delta9-THC and related analogs will also be evaluated in rats trained to discriminate CP 55,940 from vehicle to determine whether there is complete generalization. An additional strategy will be to identify the central sites which are responsible for specific actions of the cannabinoids. Potent cannabinoid agonists and putative antagonists will be administered via indwelling cannula into rat brain regions. Identification of specific brain sites will allow us to conduct subsequent studies to determine whether the effects associated with this region are mediated through the adenylate cyclase system. In addition to evaluating receptor affinity of new analogs in the 3H-CP 55,940 receptor assay, studies will be conducted to determine whether alterations in cannabinoid receptor density and KD account for development of tolerance. Autoradiography will be used to determine whether the nitrogen mustards eliminate cannabinoid receptor binding uniformly throughout the brain. Finally, characterization of cannabinoid action on adenylate cyclase will include evaluation of novel agonists and antagonists in brain membranes and in primary cell culture. These in vitro studies will be complemented with in vivo studies which will be carried out to determine whether tolerance results in alterations in adenylate cyclase activity.

Despite the fact that marijuana is one of the major drugs of abuse, it has been only recently that major advances have been made in understanding the actions of the cannabinoids on the central nervous system. The development of potent cannabinoid agonists led to the discovery of cannabinoid receptors in brain. However, the precise role of these receptors in brain remains to be fully established. It is our hypothesis that the behavioral effects of delta9-THC does not arise from its actions on a single biochemical system but rather represent the actions of cannabinoids on several biochemical systems. the goal of the proposed research is to identify additional receptors and/or mechanisms through which cannabinoids produce their behavioral effects and determine their exact role in the brain. The emphasis will be directed toward characterizing the pharmacological profile of newly synthesized cannabinoids in order to determine whether there is a common pharmacophore for all cannabinoid behavioral effects. Synthetic analogs will be evaluated for their ability to produce motor hypoactivity, hypothermia, catalepsy and antinociception in mice, and stimulus generalization to delta9-THC in delta9-THC-trained rats and monkeys. In addition, attempts will be made to develop specific cannabinoid antagonists by evaluating analogs that exhibit little or no agonistic activity in the above mentioned behavioral tests as potential antagonists of delta9-THC. Potential irreversible antagonists include nitrogen mustard, isothiocynate, and photoaffinity label analogs. In order to ascertain that novel analogs which have been used to label the cannabinoid receptor share all of the properties of delta9-THC, cross tolerance studies will be conducted to determine whether delta9-THC- tolerant mice are completely tolerant to all of the effects of the novel analogs CP 55,950 and WIN 55,212. Delta9-THC and related analogs will also be evaluated in rats trained to discriminate CP 55,940 from vehicle to determine whether there is complete generalization. An additional strategy will be to identify the central sites which are responsible for specific actions of the cannabinoids. Potent cannabinoid agonists and putative antagonists will be administered via indwelling cannula into rat brain regions. Identification of specific brain sites will allow us to conduct subsequent studies to determine whether the effects associated with this region are mediated through the adenylate cyclase system. In addition to evaluating receptor affinity of new analogs in the 3H-CP 55,940 receptor assay, studies will be conducted to determine whether alterations in cannabinoid receptor density and KD account for development of tolerance. Autoradiography will be used to determine whether the nitrogen mustards eliminate cannabinoid receptor binding uniformly throughout the brain. Finally, characterization of cannabinoid action on adenylate cyclase will include evaluation of novel agonists and antagonists in brain membranes and in primary cell culture. These in vitro studies will be complemented with in vivo studies which will be carried out to determine whether tolerance results in alterations in adenylate cyclase activity.

There is convincing evidence that endogenous cannabinoids exist in both the brain and the immune system. Two G-protein coupled cannabinoid receptors have been cloned. One is found throughout the brain in high concentrations, as well as in several peripheral tissues, whereas the other is localized exclusively in the periphery. The isolation and identification of endogenous cannabinoids, such as anandamide, led to intensified efforts to understand the functional significance of endogenous cannabinoids. Manipulation of these endogenous ligands should reveal their functional role, especially as mediated through cannabinoid receptors, and lead to a better understanding of the etiology of cannabis abuse, identification of therapeutic uses of cannabinoids, and establishment of either deleterious or protective effects on the immune system. Studies on the immune system are important since they may allow for articulation of a mechanism by which endogenous cannabinoids modulate immune function. Such modulation may be of consequence among immune compromised individuals, especially AIDS patients. The recent development of SR141716A, a potent cannabinoid antagonist, serves as an exciting new probe for fulfilling these objectives. The purpose of this proposal is to establish a multidisciplinary program, consisting of six research projects and an administrative core, to define the functional role of endogenous cannabinoids. Each P.I. is an experienced researcher who will make a unique contribution. Professor Mechoulam proposes to isolate and identify other endogenous cannabinoids from tissue fractions which exhibit cannabinoid activity. Dr. Razdan will carry out a synthetic program in which he will provide novel and innovative probes to the other members of the research team. His objectives include preparation of stable and highly potent analogs of the endogenous substances and analogs of SR141716A. Dr. Martin's research group will conduct pharmacological evaluation of endogenous ligands and analogs of endogenous agonists and of the antagonist. This group also will use both tolerance development and the antagonist to explore the plasticity of the receptor and gene expression. Dr. Aceto will determine the pharmacological consequences of chronic exposure of delta9-THC and anandamide to rats and assess their dependence liability. Drs. Cabral and Kaminski propose to establish the effects of endogenous ligands on the immune system and to elucidate a natural role of cannabinoids in immune function. Dr. Kaminski has evidence that two endogenous ligands exert different effects on immune cells. Dr. Cabral hypothesizes that endogenous ligands attenuate macrophage function which could provide neuroprotection in the brain of AIDS patients. The coordination of this highly successful research team through a program project mechanism should be highly productive and fruitful.

The major endeavor of this project is to characterize the pharmacological actions of the endogenous cannabinoids and identify commonalities and differences between delta/9-THC and the endogenous cannabinoids. We propose to continue the structure-activity relationship studies that have thus far resulted in potent and stable anandamide analogs. We intend to expand these SAR studies to gain a better understanding of how anandamide interacts with cannabinoid receptors. Analogs that are tetrahydrocannabinol/anandamide hybrids will provide a better understanding of structural features that are common for both of them. We also plan to prepare stable and potent analogs of 2-arachidonyl-glycerol which will greatly enhance our ability to fully characterize its pharmacological properties. These analogs will be evaluated for CB1 and CB2 receptor affinity, activation of 35/S-GTPgammaS binding, potency in the mouse tetrad assay, and mouse and rat drug discrimination. We will also pursue new leads in making derivatives of the CB1 selective antagonist SR141716A. While there is no question that anandamide interacts with the cannabinoid receptor and produces pharmacological effects similar to those of delta/9-THC, there are several differences in their pharmacological profile. We will undertake studies to determine whether these differences between anandamide and delta9-THC are due to pharmacokinetic or pharmacodynamics factors. Studies will be carried out to more clearly define the relationship between brain levels of anandamide and pharmacological effects it produces and to determine whether manipulation of its pharmacological effects with metabolic inhibitors is associated with concomitant changes in potency. Presently, it does not appear that annandamide is capable of producing either tolerance or dependence to the same extent as delta/9-THC. Several different strategies will be employed to determine whether anandamide can produce robust tolerance. The conditions under which tolerance develops to anandamide will be used to assess the dependence liability of anandamide. Development of dependence by anandamide would suggest a role for the endogenous system in addictive disorders, whereas failure of anandamide to produce dependence would provide further evidence that the actions of THC and anandamide are not identical. The development of stable and potent analogs of 2-arachidonyl-glycerol will allow us to evaluate the tolerance and dependence liability of this endogenous ligand as well. One additional means of assessing the THC-like properties of anandamide is the use of drug discrimination in mice and rats. Attempts will be made to train animals to higher and lower doses of THC which will increase the likelihood of uncovering THC-like responding by anandamide.

DESCRIPTION (provided by applicant): Marijuana has been the most prevalent illicit drug of abuse for many years; yet, major questions remain regarding the health consequences of long-term use. The pharmacological and toxicological properties of smoked marijuana have not been thoroughly investigated because of the challenges posed by inhalation studies, particularly with a smoked plant material. Instead, the research emphasis has been on the major psychoactive constituent in marijuana, delta-9-tetrahydrocannabinol (THC). The gap in our knowledge has led to speculation that constituents other than THC contribute to marijuana's effects. Equally important is the question of what adverse effects result from long-term use of marijuana for either recreational or medicinal purposes. Our first goal is to determine whether the effects of marijuana are due solely to THC. We will expose mice acutely to marijuana smoke as well as THC vapor to determine whether the effects on motor activity, pain sensitivity, body temperature, and memory are identical. We will examine marijuana samples with different quantities of cannabinoids, as well as spike them with known cannabinoids. Blood and brain levels of THC will be determined by mass spectrometry to establish dosimetry and pharmacokinetic factors. The second goal will be to determine whether chronic exposure of marijuana smoke and THC inhalation in mice produces similar degrees of drug dependence, cognitive impairment, immunosuppression in lung, and tumor proliferation. Mice will be exposed repetitively to marijuana smoke or THC inhalation for either one week, two weeks, and three months. At the end of each exposure period, they will be challenged with the CB1 receptor antagonist SR 141716A to assess the degree of dependence. The Morris water maze will be used to assess alterations in reference and working memory. Finally, immune function and tumor proliferation, as well as the histopathology, will be evaluated in the lungs of animals exposed for varying periods of time. The discovery of the central and peripheral endocannabinoid systems consisting of CB1 and CB2 cannabinoid receptors, signal transduction pathways, endocannabinoids [i.e., anandamide (AEA) and 2-arachidonyl glycerol (2-Ara-GI)], putative AEA membrane transporter (AMT) and AEA's metabolic enzyme fatty acid amidohydrolase (FAAH), provides an opportunity to determine which effects of marijuana smoke are mediated through this system

The Mass Spectrometry Center at Virginia Commonwealth University currently consists of a Hewlett Packard 5988A quadrapole Mass Spectrometer (MS) that has been supported by the NIDA Center on Drug Abuse Research for the past eight years. We are requesting funds for the purchase of a MicroMass Quattro II MS in order to replace this instrument. The need for this replacement is two-fold: the Hewlett Packard 5988A has become outdated and it has limited capabilities. This proposal requests a multi-user instrument that will meet a wide range of MS needs within the university. Neuroscientists represent a major user group who are concentrating on drug abuse research. The primary thrust of their research has been the identification and quantitation of drugs in biological fluids where sensitivity is a major concern. Conversely, we have other researchers who are interested in the structural elucidation of carbohydrates, peptides and proteins where the availability of the state-of-the-art soft ionization capabilities is crucial. We have a third group of investigators who use direct probe for the structural verification of newly synthesized compounds. In order to accommodate the research needs of this wide range of scientists, we have chosen a Micromass Quattro II Triple Stage Quadropole Mass Spectrometer and the MassLynx-NT Mass Spectrometer Workstation. The Quattro II fulfills our needs because it has a multiple inlet adapter that accommodates direct probe, gas chromatography (GC) and liquid chromatography (LC) in contrast to almost to most instruments on the market that allow for either GC or LC, but not both. The Atmospheric Pressure Ionization LC-MS interface accommodates electrospray, nanospray, and atmospheric pressure chemical ionization that are particularly important for the structural elucidation of large molecules. Electron Ionization (EI) and Chemical Ionization (CI) capabilities are essential for full range of analyses by GC. The Direct Insertion Probe eliminates the need for development of either GC or LC methods for structural analysis of pure volatile samples. The HP 6890 GC will allow us to use many of the standard methods that have already been developed for quantitation of drugs biological fluids. The NIST library, BioLynx software, and the MaxEnt will provide us with reference spectra and allow us to sequence and determine molecular weights of proteins. We believe this requested instrumentation will allow these highly productive researchers to enhance their existing research programs as well as accommodate their needs for several years in the future.

The College on Problems of Drug Dependence (CPDD) will hold its 61st Annual Scientific Meeting at the Acapulco Princess Hotel in Acapulco, Mexico, from June 12 through June 17, 1999. There will be 5 days of scientific sessions which will be made up of volunteer oral presentations, poster sessions, and 12 or 13 timely symposia. Special attention is given to the needs of young scientists, trainees, students, and underrepresented populations in the field. Such attention is needed to insure a continued cadre of scientists for the field of drug abuse. One emphasis of the meeting will be on drug abuse problems in Mexico and how they relate to problems in the United States. There will be a good balance of all fields and topics representing the drug abuse research community. Although final symposia choices will not be made by the Program Committee of CPDD until the fall of 1998, among the list of symposia and chairs that have already been submitted and are under consideration by the Program Committee are the following: Novel Substances Related to the Opioid System: An Update on the Orphanins and the Endomorphins, Chair: Huda Akil; The Epidemiology of Drug Use and Consequences, Chair: Clyde McCoy; Genes Induced by Psychostimulant Drugs, Chairs: Michael Kuhar and Scott Mackler; Drug Use and Addiction as an Emerging Disease, Chairs: Henry Francis and Phillip Peterson; Contigency Management for Real-life Drug Abuse Treatment, Chairs: Leslie Amass and Martin Iguchi; Abuse Liability of New Treatments for Heroin Addiction, Chair: Sandy Comer; Effects of Drugs of Abuse on Chemokines, Cytokines, and Infection, Chairs: Toby Eisenstein and Barbara Bayer; Treatment Process Studies: Findings on Patient Motivation, Engagement, Retention, and Outcomes, Chair: Dwayne Simpson. Plenary and award lectures as well as several satellite meetings and speciality workshops will complete the program. The Proceedings will be published as an archival NIDA monograph and will be mailed to all meeting registrants and to all NIDA grantees.

Nicotine's high addiction liability is well recognized, as is the fact that smoking cessation strategies, including behavioral modification and pharmacotherapies, have low success rates. Understanding the biological basis of nicotine dependence is essential if we are to develop new treatment strategies. Tremendous progress has been made in the past decade regarding the actions of nicotine at ion-gated cholinergic receptors (nA ChR). Of the large number of possible nAChR subtypes, o402 and

The Core provides the mechanism for integrating and coordinating the interdisciplinary approaches to drug abuse research at Virginia Commonwealth University (VCU). It provides shared resources and serves to Facilitate communication among all investigators in the Center. Moreover, the Core is available to all drug abuse researchers at VCU. It serves as a mechanism for fostering interactions among the participants in the Center and those who are supported by other NIDA grants. The Core consists of four components. The Administrative Component is responsible for scheduling drug abuse seminars, attending to travel for invited speakers, organizing regular meetings for participating faculty, coordinating scientific exchange, distribution of drugs to collaborators, and fostering training. The Mass Spectrometry Component provides qualitative and quantitative sample analysis that is essential for many of the drug abuse research projects at the University. The Small Grants Program will support two VCU faculty members yearly. The goals are to fund promising young investigators who demonstrate potential for independent research, to attract senior scientists from other fields into drug abuse research, and to foster new collaborations. Past awardees have subsequently been very successful in obtaining their own individual funding as a result of the Small Grants Program. The Mouse 'Knock-out Facility'provides genetically modified mice to investigators working in cannabinoid, opioid, and nicotine areas. The facility will allow sufficient breeding so that adequate numbers of animals will be available. A major advantage of a Center Core is that it provides shared resources that are more economical and that are sometimes not available unless they are funded by this type mechanism. Of course, the Core also affords the opportunity for researchers from many different disciplines to become familiar with areas of research that will complement their own endeavors. It is also through the Core that we are able to be a national resource.