IU Indianapolis ScholarWorks :: Browsing by Subject "Amygdala"

Browsing by Subject "Amygdala"

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Abnormal Amygdala Functional Connectivity Associated With Emotional Lability in Children With Attention-Deficit/Hyperactivity Disorder
(Elsevier, 2014-03) Hulvershorn, Leslie A.; Mennes, Maarten; Castellanos, F. Xavier; Di Martino, Adriana; Milham, Michael P.; Hummer, Tom A.; Roy, Amy Krain; Department of Psychiatry, IU School of Medicine
Objective A substantial proportion of children with attention-deficit/hyperactivity disorder (ADHD) also display emotion regulation deficits manifesting as chronic irritability, severe temper outbursts, and aggression. The amygdala is implicated in emotion regulation, but its connectivity and relation to emotion regulation in ADHD has yet to be explored. The purpose of this study was to examine the relationship between intrinsic functional connectivity (iFC) of amygdala circuits and emotion regulation deficits in youth with ADHD. Method Bilateral amygdala iFC was examined using functional magnetic resonance imaging in 63 children with ADHD, aged 6 to 13 years. First, we examined the relationship between amygdala IFC and parent ratings of emotional lability (EL) in children with ADHD. Second, we compared amygdala iFC across subgroups of children with ADHD and high EL (n = 18), ADHD and low EL (n = 20), and typically developing children (TDC), all with low EL (n = 19). Results Higher EL ratings were associated with greater positive iFC between the amygdala and rostral anterior cingulate cortex in youth with ADHD. EL scores were also negatively associated with iFC between bilateral amygdala and posterior insula/superior temporal gyrus. Patterns of amygdala-cortical iFC in ADHD participants with low EL were not different from the comparison group, and the effect sizes for these comparisons were smaller than those for the trend-level differences observed between the high-EL and TDC groups. Conclusions In children with ADHD and a range of EL, deficits in emotion regulation were associated with altered amygdala–cortical iFC. When comparing groups that differed on ADHD status but not EL, differences in amygdala iFC were small and nonsignificant, highlighting the specificity of this finding to emotional deficits, independent of other ADHD symptoms.
Angiotensin II's role in sodium lactate-induced panic-like responses in rats with repeated urocortin 1 injections into the basolateral amygdala: amygdalar angiotensin receptors and panic
(Elsevier, 2013) Johnson, Philip L.; Sajdyk, Tammy J.; Fitz, Stephanie D.; Hale, Mathew W.; Lowry, Christopher A.; Hay-Schmidt, Anders; Shekhar, Anantha; Anatomy, Cell Biology and Physiology, School of Medicine
Rats treated with three daily urocortin 1 (UCN) injections into the basolateral amygdala (BLA; i.e., UCN/BLA-primed rats) develop prolonged anxiety-associated behavior and vulnerability to panic-like physiological responses (i.e., tachycardia, hypertension and tachypnea) following intravenous infusions of 0.5 M sodium lactate (NaLac, an ordinarily mild interoceptive stressor). In these UCN-primed rats, the osmosensitive subfornical organ (SFO) may be a potential site that detects increases in plasma NaLac and mobilizes panic pathways since inhibiting the SFO blocks panic following NaLac in this model. Furthermore, since SFO neurons synthesize angiotensin II (A-II), we hypothesized that the SFO projects to the BLA and releases A-II to mobilizing panic responses in UCN/BLA-primed rats following NaLac infusions. To test this hypothesis, rats received daily bilateral injections of UCN or vehicle into the BLA daily for 3 days. Five to seven days following the intra-BLA injections, we microinjected either the nonspecific A-II type 1 (AT1r) and 2 (AT2r) receptor antagonist saralasin, or the AT2r-selective antagonist PD123319 into the BLA prior to the NaLac challenge. The UCN/BLA-primed rats pre-injected with saralasin, but not PD123319 or vehicle, had reduced NaLac-induced anxiety-associated behavior and panic-associated tachycardia and tachypnea responses. We then confirmed the presence of AT1rs in the BLA using immunohistochemistry which, combined with the previous data, suggest that A-II's panicogenic effects in the BLA is AT1r dependent. Surprisingly, the SFO had almost no neurons that directly innervate the BLA, which suggests an indirect pathway for relaying the NaLac signal. Overall these results are the first to implicate A-II and AT1rs as putative neurotransmitter-receptors in NaLac induced panic-like responses in UCN/BLA-primed rats.
Assessment of fear and anxiety associated behaviors, physiology and neural circuits in rats with reduced serotonin transporter (SERT) levels
(Springer Nature, 2019-01-22) Johnson, Philip L.; Molosh, Andrei I.; Federici, Lauren M.; Bernabe, Cristian; Haggerty, David; Fitz, Stephanie D.; Nalivaiko, Eugene; Truitt, William; Shekhar, Anantha; Anatomy and Cell Biology, IU School of Medicine
Genetic variation in serotonin transporter (SERT) that reduces transcriptional efficiency is associated with higher anxiety and fear traits and a greater incidence of post traumatic stress disorder (PTSD). Although previous studies have shown that rats with no expression of SERT (SERT-/-) have increased baseline anxiety behaviors, SERT+/- rats with low SERT expression (and more relevant to the clinical condition with low SERT expression) do not. Yet, no systematic studies of fear acquisition/extinction or their underlying neural mechanisms have been conducted in this preclinical genetic SERT+/- model. Here we sought to determine if SERT+/- or SERT-/-, compared to wildtype, rats would show exacerbated panic responses and/or persistent conditioned fear responses that may be associated with PTSD or phobia vulnerability. Results: Only SERT-/- rats showed increased baseline anxiety-like behaviors with heightened panic respiratory responses. However SERT+/- (also SERT-/-) rats showed enhanced acquisition of fear and delayed extinction of fear that was associated with changes in serotonergic-related genes (e.g., reduced 5-HT1A receptor) and disrupted inhibition within the basolateral amygdala (BLA). Furthermore, the disrupted fear responses in SERT+/- rats were normalized with 5HT1A antagonist infusions into the BLA. Enhanced acquisition and failure to extinguish fear memories displayed by both SERT-/- and SERT+/- rats are cardinal symptoms of disabling anxiety disorders such as phobias and PTSD. The data here support the hypothesis that reduced SERT function is a genetic risk that disrupts select gene expression and network properties in the amygdala that could result in vulnerability to these syndromes.
Association between poor tolerability of antidepressant treatment and brain functional activation in youth at risk for bipolar disorder
(Brazilian Psychiatric Association, 2021-02-01) Nery, Fabiano G.; Masifi, Sheela L.; Strawn, Jeffrey R.; Duran, Luis R.; Weber, Wade A.; Welge, Jeffrey A.; Adler, Caleb M.; Strakowski, Stephen M.; DelBello, Melissa P.; Psychiatry, School of Medicine
Objective: To investigate whether poor antidepressant tolerability is associated with functional brain changes in children and adolescents of parents with bipolar I disorder (at-risk youth). Methods: Seventy-three at-risk youth (ages 9-20 years old) who participated in a prospective study and had an available baseline functional magnetic resonance imaging (fMRI) scan were included. Research records were reviewed for the incidence of adverse reactions related to antidepressant exposure during follow-up. The sample was divided among at-risk youth without antidepressant exposure (n=21), at-risk youth with antidepressant exposure and no adverse reaction (n=12), at-risk youth with antidepressant-related adverse reaction (n=21), and healthy controls (n=20). The fMRI task was a continuous performance test with emotional distracters. Region-of-interest mean activation in brain areas of the fronto-limbic emotional circuit was compared among groups. Results: Right amygdala activation in response to emotional distracters significantly differed among groups (F3,66 = 3.1, p = 0.03). At-risk youth with an antidepressant-related adverse reaction had the lowest amygdala activation, while at-risk youth without antidepressant exposure had the highest activation (p = 0.004). Conclusions: Decreased right amygdala activation in response to emotional distracters is associated with experiencing an antidepressant-related adverse reaction in at-risk youth. Further studies to determine whether amygdala activation is a useful biomarker for antidepressant-related adverse events are needed.
Changes in Gene Expression within the Extended Amygdala following Binge-Like Alcohol Drinking by Adolescent Alcohol-Preferring (P) Rats
(Elsevier, 2014-02) McBride, William J.; Kimpel, Mark W.; McClintick, Jeanette N.; Ding, Zheng-Ming; Edenberg, Howard J.; Liang, Tiebing; Rodd, Zachary A.; Bell, Richard L.; Department of Psychiatry, IU School of Medicine
The objective of this study was to determine changes in gene expression within the extended amygdala following binge-like alcohol drinking by male adolescent alcohol-preferring (P) rats. Starting at 28 days of age, P rats were given concurrent access to 15 and 30 % ethanol for 3 one-h sessions/day for 5 consecutive days/week for 3 weeks. Rats were killed by decapitation 3 h after the first ethanol access session on the 15th day of drinking. RNA was prepared from micropunch samples of the nucleus accumbens shell (Acb-sh) and central nucleus of the amygdala (CeA). Ethanol intakes were 2.5 – 3.0 g/kg/session. There were 154 and 182 unique named genes that significantly differed (FDR = 0.2) between the water and ethanol group in the Acb-sh and CeA, respectively. Gene Ontology (GO) analyses indicated that adolescent binge drinking produced changes in biological processes involved with cell proliferation and regulation of cellular structure in the Acb-sh, and in neuron projection and positive regulation of cellular organization in the CeA. Ingenuity Pathway Analysis indicated that, in the Acb-sh, there were several major intracellular signaling pathways (e.g., cAMP-mediated and protein kinase A signaling pathways) altered by adolescent drinking, with 3-fold more genes up-regulated than down-regulated in the alcohol group. The cAMP-mediated signaling system was also up-regulated in the CeA of the alcohol group. Weighted gene co-expression network analysis indicated significant G-protein coupled receptor signaling and transmembrane receptor protein kinase signaling categories in the Acb-sh and CeA, respectively. Overall, the results of this study indicated that binge-like alcohol drinking by adolescent P rats is differentially altering the expression of genes in the Acb-sh and CeA, some of which are involved in intracellular signaling pathways and may produce changes in neuronal function.
Chronic Stress and Sex as Mediators of the Basolateral-Centromedial Amygdala Circuit and its Response to Acute Ethanol
(2020-05) Gainey, Sean; Logrip, Marian L.; Lapish, Christopher C.; Baucum II, Anthony J.
Anxiety disorders are the most common class of mental disorders in the United States, and they both promote and exacerbate disorders of substance abuse. Mounting evidence of sex differences in the relationship between anxiety disorders and alcoholism supports the potential existence of an anxiety-dependent vulnerability to alcohol abuse in women compared with men. One potential point of overlap in the physiological systems involved in anxiety response and reward processing is the amygdala. Here, a model of chronic stress in rodents was employed to probe changes in the electrophysiological and biochemical properties of the amygdala at a post-stress baseline and during a post-stress first exposure to alcohol. Electrophysiological data revealed that neurons in the centromedial amygdala were more responsive to stimulation in the basolateral amygdala in females compared with males, but a history of chronic stress altered the female response to match that of males with or without a history of chronic stress. Protein analysis of postsynaptic glutamatergic receptor expression and phosphorylation in the amygdala did not indicate any differences based on sex or exposure to stress or alcohol. These data demonstrate a sex difference in stress-induced alterations in amygdala circuitry and indicate a potential role for this circuitry in the comorbidity of anxiety disorders and alcoholism.
Effect of GABRA2 expression in the central nucleus of the amygdala on anxiety and alcohol's anxiolytic capacity in C57BL/6J mice
(2016) Smoker, Michael P.; Boehm, Stephen L.; Lapish, Christopher C.; Czachowski, Cristine Lynn; Grahame, Nicholas J.
The GABRA2 gene, which encodes the α2 subunit of GABAA receptors, is one of the genes most frequently associated with alcohol-related behavior in human studies (Demers, Bogdan, & Agrawal, 2014). Polymorphisms in GABRA2 have been found to be associated with alcohol dependence, changes in drinking frequency, and alcohol’s stimulating and euphoric effects (Arias et al., 2014; Dick et al., 2014; Edenberg et al., 2004). However, the GABRA2-alcohol relationship may not be direct, as anxiety and impulsiveness have been found to be mediating factors (Enoch, Schwartz, Albaugh, Virkkunen, & Goldman, 2006; Villafuerte, Strumba, Stoltenberg, Zucker, & Burmeister, 2013). Comorbidity of anxiety and alcohol use disorders is both prevalent and clinically relevant (J. P. Smith & Randall, 2012), and GABAA receptors play a significant role in each. Benzodiazepines, primary pharmacologic treatments for anxiety disorders and alcohol withdrawal, facilitate signaling at GABAA receptors, and their anxiolytic effects appear to depend on the presence of α2 subunits in these receptors (Low et al., 2000). The amygdala is widely implicated in both anxiety disorders as well as addiction (Janak & Tye, 2015), and its central nucleus is an important mediator of responses to both alcohol- and stress-related stimuli (Roberto, Gilpin, & Siggins, 2012), some of which may be related to GABRA2 expression within this region (Jin et al., 2014). The aim of the current study was to explore the role of Gabra2 (mouse ortholog of GABRA2) expression within the central nucleus of the amygdala (CeA) in anxiety-related behavior and alcohol’s anxiolytic effects in mice. C57BL/6J (B6) mice underwent surgery for bilateral infusion of GFP-tagged lentivirus targeting Gabra2 or a scramble control lentivirus into the CeA. Following 12-13 days of recovery, mice were assessed for anxiety-like behavior in the elevated plus maze (EPM) naïve or following IP injection of 0, 0.75, or 1.5 g/kg ethanol. After assessment, brains were extracted and sectioned through the CeA. Finally, GFP was quantified, the CeA was collected via laser microdissection, and α2 protein was quantified via ELISA. In mice expressing GFP in the CeA, α2 protein concentrations were lower for Virus mice relative to Control mice. The EPM was anxiogenic, and alcohol was found to be anxiolytic. In naïve mice, while there was no difference between Control mice and Virus mice on any behavioral measure, there were significant correlations between CeA α2 protein concentration and time spent in closed arms as well as both total and average time spent in open arms. In mice receiving injection of 0, 0.75, or 1.5 g/kg ethanol, there was a main effect of dose on several behavioral measures, but no interaction between viral condition and dose, and only a main effect of viral condition on average time spent in closed arms. There were no significant correlations between CeA α2 protein concentration and behavioral measures within any injected dose. These results are consistent with GABRA2-anxiety associations and effects of Gabra2 manipulation on anxiety-like behavior. Furthermore, they suggest that CeA α2 protein concentration is positively related to basal anxiety, which could affect alcohol use through various routes. However, these results also suggest that CeA α2 protein concentration is not related to alcohol’s anxiolytic capacity, at least when acutely administered in alcohol-naïve animals.
Effects of Chronic Alcohol and Repeated Deprivations on Dopamine D1 and D2 Receptor Levels in the Extended Amygdala of Inbred Alcohol-Preferring Rats
(Wiley Blackwell (Blackwell Publishing), 2006-01) Sari, Youssef; Bell, Richard L.; Zhou, Feng C.; Department of Anatomy & Cell Biology, IU School of Medicine
Background Dopaminergic (DA) activity in the extended amygdala (EA) has been known to play a pivotal role in mediating drug and alcohol addiction. Alterations of DA activity within the EA after chronic exposure to alcohol or substances of abuse are considered a major mechanism for the development of alcoholism and addiction. To date, it is not clear how different patterns of chronic alcohol drinking affect DA receptor levels. Therefore, the current studies investigated the effects of chronic ethanol consumption, with or without deprivations, on D1 and D2 receptor densities within the EA. Methods Inbred alcohol-preferring (iP) rats were divided into 3 groups with the following treatments: (1) water for 14 weeks; (2) continuous alcohol (C-Alc) for 14 weeks [24-hour concurrent access to 15 and 30% (v/v) ethanol]; or (3) repeatedly deprived of alcohol (RD-Alc) (24-hour concurrent access to 15 and 30% ethanol for 6 weeks, followed by 2 cycles of 2 weeks of deprivation of and 2 weeks of reexposure to ethanol access). At the end of 14 weeks, the rats were killed for autoradiographic labeling of D1 and D2 receptors. Results Compared with the water control group, both the C-Alc and the RD-Alc groups displayed increases in D1 receptor binding density in the anterior region of the Acb core, whereas the RD-Alc group displayed additional increases in D1 receptor binding density in anterior regions of the lateral and intercalated nuclei of the amygdala. Additionally, both C-Alc and RD-Alc rats displayed increases in D2 receptor binding density in anterior regions of the Acb shell and core, whereas RDAlc rats displayed additional increases in D2 receptor binding density in the dorsal striatum. Conclusion The results of this study indicate that 14-week extended alcohol drinking with continuous chronic or repeated deprivations increase binding sites of D1 and D2 receptors in specific regions of the EA with greater sensitivity in the anterior regions. The repeated deprivation has greater effect on altering D1 and D2 receptor binding sites in the Acb, dorsal striatum, and subamygdala regions. The current result indicates that the two drinking paradigms may have common as well as differential mechanisms on alteration of dopamine receptor–binding sites in specific regions of the EA.
Elucidating mechanisms that lead to persistent anxiety-like behavior in rats following repeated activation of corticotropin-releasing factor receptors in the basolateral amygdala
(2012-03-16) Gaskins, Denise; Shekhar, Anantha, 1957-; Harris, Robert A. (Robert Allison), 1939-; Hingtgen, Cynthia M., 1966-; Truitt, William A.
Anxiety disorders are estimated to impact 1 in 4 individuals within their lifetime. For some individuals, repeated episodes of the stress response leads to pathological anxiety and depression. The stress response is linked to increased levels of corticotropin-releasing factor (CRF) in the basolateral nucleus of the amygdala (BLA), a putative site for regulating anxiety and associative processes related to aversive emotional memories, and activation of CRF receptors in the BLA of rats produces anxiety-like behavior. Mimicking repeated episodes of the stress response, sub-anxiogenic doses of urocortin 1 (Ucn1), a CRF receptor agonist, are microinjected into the BLA of rats for five consecutive days, a procedure called priming. This results in 1) behavioral sensitization, such that a previously non-efficacious dose of Ucn1 will elicit anxiety-like response after the 3rd injection and 2) the development of a persistent anxiety-like phenotype that lasts at least five weeks after the last injection without any further treatment. Therefore, the purpose of this thesis was to identify mechanisms involved in the Ucn1-priming-induced anxiogenesis. The first a set of experiments revealed that the anxiety-like behavior was not due to aversive conditioning to the context or partner cues of the testing environment. Next, Ucn1-priming-induced gene expression changes in the BLA were identified: mRNA expression for Sst2, Sst4, Chrna4, Chrma4, and Gabrr1 was significantly reduced in Ucn1-primed compared to Vehicle-primed rats. Of these, Sst2 emerged as the primary receptor of interest. Subsequent studies found that antagonizing the Sstr2 resulted in anxiety-like behavior and activation of Sstr2 blocked acute Ucn1-induced anxiety-like responses. Furthermore, pretreatment with a Sstr2 agonist delayed the behavioral sensitization observed in Ucn1-induced priming but did not stop the development of persistent anxiety-like behavior or the Ucn1-priming-induced decrease in the Sstr2 mRNA. These results suggest that the decrease in Sstr2 mRNA is associated with the expression of persistent anxiety-like behavior but dissociated from the mechanisms causing the behavioral sensitization. Pharmacological studies confirmed that a reduced Sstr2 mediated effect in the BLA is likely to play a role in persistent anxiety and should be investigated further.
Enhanced amygdala-cingulate connectivity associates with better mood in both healthy and depressive individuals after sleep deprivation
(National Academy of Science, 2023) Chai, Ya; Gehrman, Philip; Yu, Meichen; Mao, Tianxin; Deng, Yao; Rao, Joy; Shi, Hui; Quan, Peng; Xu, Jing; Zhang, Xiaocui; Lei, Hui; Fang, Zhuo; Xu, Sihua; Boland, Elaine; Goldschmied, Jennifer R.; Barilla, Holly; Goel, Namni; Basner, Mathias; Thase, Michael E.; Sheline, Yvette I.; Dinges, David F.; Detre, John A.; Zhang, Xiaochu; Rao, Hengyi; Radiology and Imaging Sciences, School of Medicine
Sleep loss robustly disrupts mood and emotion regulation in healthy individuals but can have a transient antidepressant effect in a subset of patients with depression. The neural mechanisms underlying this paradoxical effect remain unclear. Previous studies suggest that the amygdala and dorsal nexus (DN) play key roles in depressive mood regulation. Here, we used functional MRI to examine associations between amygdala- and DN-related resting-state connectivity alterations and mood changes after one night of total sleep deprivation (TSD) in both healthy adults and patients with major depressive disorder using strictly controlled in-laboratory studies. Behavioral data showed that TSD increased negative mood in healthy participants but reduced depressive symptoms in 43% of patients. Imaging data showed that TSD enhanced both amygdala- and DN-related connectivity in healthy participants. Moreover, enhanced amygdala connectivity to the anterior cingulate cortex (ACC) after TSD associated with better mood in healthy participants and antidepressant effects in depressed patients. These findings support the key role of the amygdala-cingulate circuit in mood regulation in both healthy and depressed populations and suggest that rapid antidepressant treatment may target the enhancement of amygdala-ACC connectivity.

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