2007 — 2008 |
Loweth, Jessica Anne |
F31Activity Code Description: To provide predoctoral individuals with supervised research training in specified health and health-related areas leading toward the research degree (e.g., Ph.D.). |
Viral-Mediated Alterations in Camkii Alter Behavioral Responding to Amphetamine
[unreadable] DESCRIPTION (provided by applicant): Repeatedly exposing rats to drugs such as amphetamine (AMPH) can lead to enhanced locomotor responding, nucleus accumbens (NAcc) dopamine (DA) overflow and drug taking when rats are re-exposed to the drug weeks to months later. These phenomena, manifestations of sensitization, may play an important role in the transition from casual drug use to abuse. Unraveling the neuroadaptations that underlie the expression of sensitization-enhanced behavioral and neurochemical responding to the drug-- may help identify targets for therapeutic intervention. One of many proteins that play an important role in mediating signaling cascades underlying the expression of sensitization is calcium/calmodulin-dependent protein kinase II (CaMKII). While acute AMPH-induced locomotor responding and NAcc DA release are calcium-independent, sensitized locomotion and DA release are calcium and CaMKII-dependent. In addition, striatal slices from rats exposed to repeated, intermittent injections of AMPH show enhanced calmodulin levels and increased CaMKII activity compared to those obtained from saline-exposed controls. We hypothesize that using viral-mediated gene transfer to modify CaMKII levels in the NAcc will alter behavioral responding to AMPH. The experiments proposed in this grant application will test two main hypotheses. Hypothesis 1: Increasing levels of CaMKII in the NAcc will enhance locomotor responding to a low, threshold dose of AMPH and enhance self-administration of the drug, effects similar to those observed in rats exposed to a sensitizing drug regimen. Rats will be surgically implanted with bilateral guide cannulae and intravenous catheters. Microinjections of the viral vectors will then be made and locomotor and self- administration experiments will be conducted to determine how this manipulation alters sensitivity to AMPH. The efficacy of viral-mediated gene transfer will be determined using immunoblotting. Hypothesis 2: Increasing levels of an inactive mutant form of CaMKII in the NAcc of sensitized rats will diminish enhanced AMPH self-administration observed in these rats. Rats will be exposed to repeated, intermittent injections of AMPH followed by a withdrawal period, during which the animals will be surgically prepared. Following a period of drug self-administration, microinjections of the viral vectors will be made and the effect of this manipulation on drug self-administration subsequently assessed. Using an animal model of addiction is an effective way to study the transition form casual to compulsive drug use. This research will contribute to the ultimate goal of preventing drug addiction by investigating ways to prevent the enhanced drug taking observed in rats that have been previously exposed to AMPH. [unreadable] [unreadable] [unreadable]
|
1 |
2011 — 2013 |
Loweth, Jessica Anne |
F32Activity Code Description: To provide postdoctoral research training to individuals to broaden their scientific background and extend their potential for research in specified health-related areas. |
Cocaine-Induced Ampar Plasticity: Modulation by Metabotropic Glutamate Receptors? @ Rosalind Franklin Univ of Medicine &Sci
DESCRIPTION (provided by applicant): A major challenge for the clinical treatment of cocaine addiction is the propensity for abstinent users to relapse upon re-exposure to environmental cues previously associated with cocaine. This vulnerability to relapse may increase after the acute drug withdrawal stage. Similarly, cue-induced cocaine seeking in rats intensifies or "incubates" during the first months of withdrawal. This is mediated by an increase in GluA2-lacking, Ca2+ permeable (CP)-AMPARs in the nucleus accumbens (NAc). CP-AMPARs represent a very small percentage of the AMPARs in the NAc of drug-naive rats but accumulate in this region in association with the incubation of cue-induced seeking. These CP-AMPARs exhibit higher conductance than other AMPARs and are therefore likely to make NAc neurons more responsive to drug-related cues;in fact, blocking CP-AMPARs prevents the expression of incubated seeking. Thus, identifying the mechanism that leads to elevation of CP-AMPARs after cocaine withdrawal may help identify potential therapeutic targets for the treatment of cue-induced craving and relapse. In other brain regions, group I metabotropic glutamate receptor (mGluR) activation leads to the selective internalization of postsynaptic CP-AMPARs. While group I mGluRs do not seem to internalize AMPARs in the NAc, this has only been assessed in the NAc of drug-naive rodents, where CP-AMPAR levels are very low. Importantly, several studies report decreased group I mGluR levels in the NAc during withdrawal from repeated cocaine exposure. My central hypothesis is that group I mGluR activation selectively internalizes CP-AMPARs in the NAc and that CP-AMPARs accumulate during prolonged withdrawal from cocaine self- administration due to a decrease in group I mGluR levels in the NAc. I also hypothesize that group I mGluR activation in the NAc will prevent the expression of incubated cue-induced seeking by selectively internalizing CP-AMPARs in these cocaine-experienced rats. Aim 1 will use cultured NAc neurons, which express CP- AMPARs, to test the working hypothesis that group I mGluR activation leads to the selective internalization of CP-AMPARs. Immunocytochemical experiments will determine if surface expression of CP-AMPARs is altered by acute and long-term group I mGluR activation or inhibition. Aim 2 will test the working hypothesis that levels of group I mGluRs in the NAc decrease during prolonged withdrawal from extended access cocaine self- administration, and that pharmacological activation of NAc group I mGluRs in vivo reduces cue-induced cocaine seeking. Rats will self-administer cocaine or saline (controls) and biochemical studies will determine if group I mGluR surface, synaptic or extrasynaptic levels decrease in the NAc of "incubated" rats. Behavioral studies will determine if acute intra-NAc injection of a group I mGluR agonist reduces incubated cue-induced cocaine seeking and internalizes CP-AMPARs. While these studies are underway, I will participate in a Training Plan that employs coursework, individual mentoring, and collaborative interactions to develop the non- bench skills needed to reach my goal of becoming a principal investigator in an academic setting. PUBLIC HEALTH RELEVANCE: This proposal uses a rat model of addiction to study the cellular mechanisms that lead to intensification of cue- induced cocaine craving, a common trigger for relapse, after cocaine withdrawal. Our results may identify a molecular target (group I metabotropic glutamate receptors) for the development of medications to reduce cue- induced craving in abstinent cocaine addicts.
|
0.906 |
2014 — 2019 |
Loweth, Jessica Anne |
K99Activity Code Description: To support the initial phase of a Career/Research Transition award program that provides 1-2 years of mentored support for highly motivated, advanced postdoctoral research scientists. R00Activity Code Description: To support the second phase of a Career/Research Transition award program that provides 1 -3 years of independent research support (R00) contingent on securing an independent research position. Award recipients will be expected to compete successfully for independent R01 support from the NIH during the R00 research transition award period. |
Do Cocaine and Chronic Stress Converge in the Basolateral Amygdala? @ Rosalind Franklin Univ of Medicine & Sci
DESCRIPTION (provided by applicant): A major challenge for treating cocaine addiction is the propensity for abstinent users to relapse. Two important triggers for relapse are cues associated with prior drug use and stressful life events. During my postdoctoral training, I studied mechanisms in the nucleus accumbens (NAc) underlying the withdrawal-dependent intensification (incubation) of cue-induced cocaine craving. As a PI, I will incorporate the effect of chronic stress into my studies. To date, the majority of studies investigating stress-induced relapse vulnerability have examined the effects of acute stressors on the reinstatement of previously extinguished drug seeking behavior, a model which may not accurately depict the situation of addicts, who typically do not undergo extinction training and who may relapse after a long drug-free period. Thus, there is an urgent need for animal models that explore interactions between the effects of chronic stress and drug withdrawal on cue-induced cocaine craving. To address this need, I will study the effect of chronic stress during abstinence on relapse vulnerability using the 'incubation of cocaine craving' model mentioned above, in which cue-induced drug seeking in rats progressively intensifies during the first months of withdrawal from extended-access drug self-administration. By combining my long-standing interest in addiction with my emerging interest in the neurobiology of stress, I have developed a research program that will be independent of my Mentor's research and will allow me to pursue three long-term goals: developing animal models with better face validity for addiction, using in vivo models which preserve neuronal circuits and enable correlation of cellular and behavioral results, and ultimately contributing to development of pharmacotherapies to help recovering addicts maintain abstinence. This Research Plan, along with the Training Plan I have developed with my Mentor (Dr. Marina Wolf) and co- Mentors (Dr. J. Amiel Rosenkranz and Dr. Janice Urban), will enable me to achieve my career goal of becoming an independent researcher in an academic setting. My project draws on previous work from my co-Mentors on the basolateral amygdala (BLA), a critical region for behavioral responses to stress. Dr. Rosenkranz's lab has shown that chronic stress enhances excitatory drive in the BLA, while Dr. Urban's lab has found that repeated activation of NPY receptors in the BLA produces long-lasting stress resilience. Furthermore, recent work from the Dong lab (2013) has shown that glutamate projections from the BLA to the NAc are critical for the expression of incubated cue-induced cocaine seeking. Combining these lines of work, my central hypothesis is that cocaine withdrawal and chronic stress exposure produce a synergistic increase in BLA neuronal activity which facilitates incubation of craving, whereas treatments promoting stress resilience will prevent this facilitation by producing opposing neuroadaptations in the BLA. My preliminary data show that chronic food restriction stress during withdrawal does in fact accelerate the incubation of cocaine craving. In Aim 1 (K99), I will determine the persistence of this effect and whether it generalizes to repeated restraint stress, the form of stress used in many prior studies of the BLA. In Aim 2 (K99/R00), I will test my hypothesis that cocaine withdrawal and stress exert synergistic effects in the BLA by comparing intrinsic excitability, synaptic transmission, and morphological features of BLA neurons of rats that self-administer saline or cocaine and then either undergo repeated stress or control conditions during withdrawal. In Aim 3 (K99/R00), I will determine if NPY receptor activation in the BLA opposes the chronic stress-induced facilitation of incubation of cocaine seeking and employ biochemical methods to identify mechanisms in the BLA through which NPY signaling mediates these protective effects. During my prior training, I secured individual pre- and postdoctoral NRSA funding, published in high impact journals, and gained expertise in behavioral and biochemical approaches. However, to undertake my proposed experiments, I need training in electrophysiology and stress models, as well as more experience with non-bench skills required for independence. To accomplish these goals, I have put together an exceptional team of advisors. My Primary Mentor Dr. Wolf is an expert in cocaine-induced neuronal plasticity who will oversee my training. Dr. Rosenkranz (co-Mentor) uses electrophysiological approaches to study the effects of stress on affective behavior and physiology of the amygdala. He will train me to conduct in vivo intracellular recordings in BLA neurons and then assess their morphology. Dr. Urban (co-Mentor) is a neuroendocrinologist who studies adaptations in the amygdala contributing to stress resilience. She will provide training on models of stress resilience and NPY signaling. I will also be guided by a Research Committee composed of my Mentor, co-Mentors, and two other electrophysiologists at my University, Drs. Kuei-Yuan Tseng and Anthony West. All of these individuals have a strong history of collaborative interactions. Together, we have developed a Training Plan that utilizes regular individual meetings with Mentors, bi-annual meetings of the Research Committee, coursework (including seminars and journal clubs), and an institutional postdoctoral development program to develop the non-bench skills needed for my transition from a postdoctoral fellow to an independent investigator in an academic setting. This training plan is strengthened by an outstanding institutional environment offering excellent facilities and a concentration of addiction researchers in a collaborative and supportive setting.
|
0.948 |