Marvin R. Diaz, Ph.D - US grants

[unreadable] DESCRIPTION (provided by applicant): Alcoholism is a devastating disease that affects people world-wide, and better treatments for alcoholism are needed. Alcoholism is co-morbid with anxiety disorders, in that people with anxiety disorders are at a high risk of becoming alcoholics. Similarly, alcoholics often develop anxiety disorders during periods of abstinence and withdrawal (WD), therefore increasing the relapse rate. Interestingly, the amygdala, the brain region responsible for initiating and processing anxiety-like behaviors, has been shown to be affected by alcohol. Alcohol and WD increase activity levels in specific nuclei of the amygdala, particularly that of the basolateral amygdala (BLA) - the primary input of the anxiety circuit. Moreover, alterations in neurotransmitter function have also been found in the BLA in response to alcohol and moreso during alcohol WD. Specifically, the GABAergic system, which acts to control over-excitability of the the BLA, may play an important role in the development of WD-induced anxiety. In the BLA, the GABAergic system is comprised of multiple GABAergic inhibitory interneuron populations. Together they regulate the output from the BLA [unreadable] based on the specific input into the BLA. The two better characterized populations are the cortically [unreadable] controlled feedforward-inhibitory interneurons located in the external capsule (paracapular intercalated cell masses - pICM) and the local feedback-inhibitory interneurons. The relative activity level of these two populations has been shown to differentially affect BLA function depending on the dopaminergic (DAergic) innervation from the ventral tegmental area. Specifically, anxiety-like behaviors can be altered by changing GABAergic function through manipulations of specific DA receptors in the BLA. pICM interneuron activity can be suppressed by DA D1 and D3 (recent finding from our lab) receptor activation, while local interneuron activity can be faciliated by DA D1 receptor activation. Interestingly, alcohol and stress increase DA release in the amygdala, and possibly alter the balance between pICM and local interneuron activity. Therefore, using an ethanol inhalation protocol, a well established animal model of alcoholism, we first propose to characterize the pICM and local GABAergic input as they change during chronic intermittent ethanol (CIE) and WD in order to understand how the whole system functions. Secondly, we will characterize how the modulation of pICM and local interneurons by DA is altered during CIE and WD. Understanding the processes involved in the development of alcohol withdrawal-induced anxiety will allow for better treatments for alcoholism and other drugs of abuse. Better treatments will help to decrease the risk of relapse. [unreadable] [unreadable] [unreadable] [unreadable]

Ethanol use is a common occurrence worldwide, and the onset of ethanol exposure is a major contributing factor to ethanol abuse. Adolescence is a developmental period when ethanol use is typically initiated, making it a highly vulnerable time to predispose future abuse and alterations in neurobehavioral function. Moreover, adolescents consume more ethanol per drinking session than adults, perhaps due to the greater sensitivity to the anxiolytic properties of ethanol during this highly stressful and anxiety-provoking developmental stage. However, the neurobiological mechanisms of acute ethanol in adolescents are poorly understood. The opioid system is a major target of ethanol and kappa opioid receptors (KORs), particularly, have been shown to play a major role in the neurophysiological effects of ethanol in the reward and anxiety circuits. The basolateral amygdala (BLA), a key structure of the reward and anxiety circuits, is involved in ethanol-seeking behaviors. Specifically, alterations in GABA transmission within the BLA are associated with the anxiolytic properties of ethanol and ethanol-seeking. Importantly, KOR activation modulates BLA excitability and anxiety-like behaviors in an age-dependent manner, suggesting that KORs may significantly contribute to the increased sensitivity to the anxiolytic properties of ethanol in adolescents, which may drive increased ethanol consumption in adolescence. Thus, the overarching goal of this proposal is to test the interactions between BLA KORs and ethanol consumption in adolescents. Importantly, preliminary findings indicate that a KOR agonist potentiates GABAergic transmission within the BLA of adolescents, but not adults, and this effect is similar to that of acute ethanol. This suggests that ethanol may hijack the KOR system, thereby resulting in anxiolysis, which helps promote ethanol consumption in adolescents. Two Specific Aims will (1) determine the functional interactions between BLA KOR activation and acute ethanol in vitro and (2) examine the interaction of BLA KORs and acute ethanol on anxiety-like behavior and ethanol consumption. These innovative studies will test novel and unique hypotheses surrounding the developmental differences of ethanol and describe neural mechanisms specific to adolescent ethanol exposure.

Abstract The incidence of alcohol drinking and alcohol abuse during pregnancy is strikingly high which can lead to a spectrum of deficits in offspring termed Fetal Alcohol Spectrum Disorders. One of the most common consequences of prenatal alcohol exposure (PAE) is the emergence of anxiety disorders in adolescence, which are surprisingly observed following exposure to moderate levels of ethanol ? a common pattern of alcohol consumption in pregnancy. Despite these compelling epidemiological data, the neurobiological mechanisms underlying moderate PAE-induced anxiety are not well understood. Synaptic activity and plasticity within the basolateral amygdala (BLA) is driven, in part, through inputs from the medial prefrontal cortex (mPFC), and are associated with regulation and expression of anxiety-like behaviors. Additionally, BLA synaptic activity and plasticity is modulated by the dynorphin/kappa opioid receptor (DYN/KOR) system that is also associated with alterations in anxiety-like behaviors. Although studies have shown that PAE can alter mPFC function, increase BLA plasticity, and reduce amygdala KOR levels (an effect opposite of what is seen following exposure to ethanol in adulthood), whether moderate PAE at levels more likely seen in pregnant women affects these targets and the interaction(s) between these alterations during the highly vulnerable developmental period of adolescence are unknown. We have recently characterized a model of moderate PAE using a single exposure to vaporized ethanol on gestational day (G) 12, a developmental epoch during which the amygdala begins to appear, that produces increased social anxiety-like behaviors in adolescent offspring. Based on this, we hypothesize that moderate G12 PAE increases anxiety-like behavior in adolescence through enhanced mPFC?BLA synaptic plasticity and reduced DYN/KOR function. To test our hypothesis, Aim 1 will examine the impact of moderate G12 PAE on alterations in mPFC?BLA synaptic plasticity using in vitro optogenetic and electrophysiological tools. Aim 2 will test the effect of moderate G12 PAE on KOR modulation of mPFC?BLA synaptic plasticity using a combination of molecular, electrophysiological and in vivo optogenetics coupled with behavioral pharmacology. These innovative studies will test novel and unique hypotheses surrounding the long-term effects of moderate PAE and describe neural mechanisms specific to deficits in anxiety-like behaviors.

Abstract Alcohol drinking and alcohol abuse during pregnancy is surprisingly high which can lead to a spectrum of deficits in offspring termed Fetal Alcohol Spectrum Disorders. One of the most common consequences of prenatal alcohol exposure (PAE) is the emergence of anxiety disorders that are apparent in childhood and persist through adulthood. Coincident and highly associated with anxiety is the prevalence of alcohol abuse in individuals with PAE. Importantly, these observations are evident even following exposure to moderate levels of ethanol ? a common pattern of alcohol consumption in pregnancy. Despite compelling epidemiological data, the neurobiological mechanisms underlying moderate PAE-induced anxiety are not well understood. The actions of corticotropin-releasing factor (CRF) through its cognate receptor, CRF1R, are involved in alcohol exposure-induced anxiety and alcohol preference in adult males, and their expression is altered by PAE in anxiety-related brain structures. However, the developmental time-course of CRF1R function and how its function is altered by PAE across ontogeny is unknown. We have recently characterized a model of moderate PAE using a single exposure to vaporized ethanol on gestational day (G) 12, a developmental epoch during which the amygdala begins to appear, that produces increased anxiety-like behaviors in adolescent male offspring and affects emotional processing in adult males, with no apparent effects in females. Based on this, we hypothesize that G12 PAE reduces CRF1R function through ontogeny, which contributes to the biphasic anxiety phenotype and results in alterations in acute alcohol and CRF1R interactions. To test our hypothesis, Aim 1 will determine the developmental time-course of CRF1R function within the central amygdala and its relation to anxiety-like behaviors. Aim 2 will examine the impact of moderate G12 PAE on alterations to CRF1R function within the central amygdala across development and into adulthood, as it contributes to PAE-induced alterations in anxiety-like behavior. Finally, Aim 3 will test the effect of moderate G12 PAE on acute ethanol- CRF1R interactions within the central amygdala and how CRF1R contribute to ethanol intake across ontogeny. These innovative studies will test novel and unique hypotheses surrounding the long-term effects of moderate PAE and describe neural mechanisms specific to deficits in anxiety-like behaviors and its association with elevated ethanol intake in an age- and sex-specific manner.