Browsing by Subject "Norepinephrine"

Now showing 1 - 10 of 11
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    Attentional Disengagement and the Locus Coeruleus – Norepinephrine System in Children With Autism Spectrum Disorder
    (Frontiers Media, 2021-08-31) Keehn, Brandon; Kadlaskar, Girija; Bergmann, Sophia; McNally Keehn, Rebecca; Francis, Alexander; Pediatrics, School of Medicine
    Background: Differences in non-social attentional functions have been identified as among the earliest features that distinguish infants later diagnosed with autism spectrum disorder (ASD), and may contribute to the emergence of core ASD symptoms. Specifically, slowed attentional disengagement and difficulty reorienting attention have been found across the lifespan in those at risk for, or diagnosed with, ASD. Additionally, the locus coeruleus-norepinephrine (LC-NE) system, which plays a critical role in arousal regulation and selective attention, has been shown to function atypically in ASD. While activity of the LC-NE system is associated with attentional disengagement and reorienting in typically developing (TD) individuals, it has not been determined whether atypical LC-NE activity relates to attentional disengagement impairments observed in ASD. Objective: To examine the relationship between resting pupil diameter (an indirect measure of tonic LC-NE activation) and attentional disengagement in children with ASD. Methods: Participants were 21 school-aged children with ASD and 20 age- and IQ-matched TD children. The study consisted of three separate experiments: a resting eye-tracking task and visual and auditory gap-overlap paradigms. For the resting eye-tracking task, pupil diameter was monitored while participants fixated a central crosshair. In the gap-overlap paradigms, participants were instructed to fixate on a central stimulus and then move their eyes to peripherally presented visual or auditory targets. Saccadic reaction times (SRT), percentage of no-shift trials, and disengagement efficiency were measured. Results: Children with ASD had significantly larger resting pupil size compared to their TD peers. The groups did not differ for overall SRT, nor were there differences in SRT for overlap and gap conditions between groups. However, the ASD group did evidence impairments in disengagement (larger step/gap effects, higher percentage of no-shift trials, and reduced disengagement efficiency) compared to their TD peers. Correlational analyses showed that slower, less efficient disengagement was associated with increased pupil diameter. Conclusion: Consistent with prior reports, children with ASD show significantly larger resting pupil diameter, indicative of atypically elevated tonic LC-NE activity. Associations between pupil size and measures of attentional disengagement suggest that atypically increased tonic activation of the LC-NE system may be associated with poorer attentional disengagement in children with ASD.
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    Effects of Reducing Norepinephrine Levels via DSP4 Treatment on Amyloid-β Pathology in Female Rhesus Macaques (Macaca Mulatta)
    (IOS Press, 2019) Duffy, Kara B.; Ray, Balmiki; Lahiri, Debomoy K.; Tilmont, Edward M.; Tinkler, Gregory P.; Herbert, Richard L.; Greig, Nigel H.; Ingram, Donald K.; Ottinger, Mary Ann; Mattison, Julie A.; Psychiatry, School of Medicine
    The degeneration in the locus coeruleus associated with Alzheimer's disease suggests an involvement of the noradrenergic system in the disease pathogenesis. The role of depleted norepinephrine was tested in adult and aged rhesus macaques to develop a potential model for testing Alzheimer's disease interventions. Monkeys were injected with the noradrenergic neurotoxin N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP4) or vehicle at 0, 3, and 6 months; brains were harvested at 9 months. Reduced norepinephrine in the locus coeruleus was accompanied by decreased dopamine β-hydroxylase staining and increased amyloid-β load in the aged group, and the proportion of potentially toxic amyloid-β42 peptide was increased. Immunohistochemistry revealed no effects on microglia or astrocytes. DSP4 treatment altered amyloid processing, but these changes were not associated with the induction of chronic neuroinflammation. These findings suggest norepinephrine deregulation is an essential component of a nonhuman primate model of Alzheimer's disease, but further refinement is necessary.
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    Hypothalamic orexin’s role in exacerbated cutaneous vasodilation responses to an anxiogenic stimulus in a surgical menopause model
    (Elsevier, 2016-03) Federici, Lauren M.; Caliman, Izabela Facco; Molosh, Andrei I.; Fitz, Stephanie D.; Truitt, William A.; Bonaventure, Pascal; Carpenter, Janet S.; Shekhar, Anantha; Johnson, Philip L.; Department of Psychiatry, IU School of Medicine
    Distressing symptoms such as hot flashes and sleep disturbances affect over 70% of women approaching menopause for an average of 4-7 years, and recent large cohort studies have shown that anxiety and stress are strongly associated with more severe and persistent hot flashes and can induce hot flashes. Although high estrogen doses alleviate symptoms, extended use increases health risks, and current non-hormonal therapies are marginally better than placebo. The lack of effective non-hormonal treatments is largely due to the limited understanding of the mechanisms that underlie menopausal symptoms. One mechanistic pathway that has not been explored is the wake-promoting orexin neuropeptide system. Orexin is exclusively synthesized in the estrogen receptor rich perifornical hypothalamic region, and has an emerging role in anxiety and thermoregulation. In female rodents, estrogens tonically inhibit expression of orexin, and estrogen replacement normalizes severely elevated central orexin levels in postmenopausal women. Using an ovariectomy menopause model, we demonstrated that an anxiogenic compound elicited exacerbated hot flash-associated increases in tail skin temperature (TST, that is blocked with estrogen), and cellular responses in orexin neurons and efferent targets. Furthermore, systemic administration of centrally active, selective orexin 1 or 2 and dual receptor antagonists attenuated or blocked TST responses, respectively. This included the reformulated Suvorexant, which was recently FDA-approved for treating insomnia. Collectively, our data support the hypothesis that dramatic loss of estrogen tone during menopausal states leads to a hyperactive orexin system that contributes to symptoms such as anxiety, insomnia, and more severe hot flashes. Additionally, orexin receptor antagonists may represent a novel non-hormonal therapy for treating menopausal symptoms, with minimal side effects.
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    Measures of tonic and phasic activity of the locus coeruleus-norepinephrine system in children with autism spectrum disorder: An event-related potential and pupillometry study
    (Wiley, 2022) Kim, Yesol; Kadlaskar, Girija; McNally Keehn, Rebecca; Keehn, Brandon; Pediatrics, School of Medicine
    A growing body of research suggests that locus coeruleus‐norepinephrine (LC‐NE) system may function differently in individuals with autism spectrum disorder (ASD). Understanding the dynamics of both tonic (resting pupil diameter) and phasic (pupil dilation response [PDR] and event‐related potential [ERP]) indices may provide meaningful insights about the nature of LC‐NE function in ASD. Twenty‐four children with ASD and 27 age‐ and nonverbal‐IQ matched typically developing (TD) children completed two experiments: (1) a resting eye‐tracking task to measure tonic pupil diameter, and (2) a three‐stimulus oddball paradigm to measure phasic responsivity using PDR and ERP. Consistent with prior reports, our results indicate that children with ASD exhibit increased tonic (resting pupil diameter) and reduced phasic (PDR and ERP) activity of the LC‐NE system compared to their TD peers. For both groups, decreased phasic responsivity was associated with increased resting pupil diameter. Lastly, tonic and phasic LC‐NE indices were primarily related to measures of attention‐deficit/hyperactivity disorder (ADHD), and not ASD, symptomatology. These findings expand our understanding of neurophysiological differences present in ASD and demonstrate that aberrant LC‐NE activation may be associated with atypical arousal and decreased responsivity to behaviorally‐relevant information in ASD.
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    The role of anterior insula-brainstem projections and alpha-1 noradrenergic receptors for compulsion-like and alcohol-only drinking
    (Springer Nature, 2021) De Oliveira Sergio, Thatiane; Lei, Kelly; Kwok, Claudina; Ghotra, Shahbaj; Wegner, Scott A.; Walsh, Margaret; Waal, Jaclyn; Darevsky, David; Hopf, Frederic W.; Psychiatry, School of Medicine
    Compulsion-like alcohol drinking (CLAD), where consumption continues despite negative consequences, is a major obstacle to treating alcohol use disorder. The locus coeruleus area in the brainstem and norepinephrine receptor (NER) signaling in forebrain cortical regions have been implicated in adaptive responding under stress, which is conceptually similar to compulsion-like responding (adaptive responding despite the presence of stress or conflict). Thus, we examined whether anterior insula (aINS)-to-brainstem connections and alpha-1 NERs regulated compulsion-like intake and alcohol-only drinking (AOD). Halorhodopsin inhibition of aINS-brainstem significantly reduced CLAD, with no effect on alcohol-only or saccharin intake, suggesting a specific aINS-brainstem role in aversion-resistant drinking. In contrast, prazosin inhibition of alpha-1 NERs systemically reduced both CLAD and AOD. Similar to systemic inhibition, intra-aINS alpha-1-NER antagonism reduced both CLAD and AOD. Global aINS inhibition with GABAR agonists also strongly reduced both CLAD and AOD, without impacting saccharin intake or locomotion, while aINS inhibition of calcium-permeable AMPARs (with NASPM) reduced CLAD without impacting AOD. Finally, prazosin inhibition of CLAD and AOD was not correlated with each other, systemically or within aINS, suggesting the possibility that different aINS pathways regulate CLAD versus AOD, which will require further study to definitively address. Together, our results provide important new information showing that some aINS pathways (aINS-brainstem and NASPM-sensitive) specifically regulate compulsion-like alcohol consumption, while aINS more generally may contain parallel pathways promoting CLAD versus AOD. These findings also support the importance of the adaptive stress response system for multiple forms of alcohol drinking.
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    The role of beta- and alpha-adrenergic receptors on alcohol drinking
    (Elsevier, 2023) De Oliveira Sergio, Thatiane; Wean, Sarah; Katner, Simon Nicholas; Hopf, Frederic W.; Psychiatry, School of Medicine
    Alcohol Use Disorders (AUD) is characterized by compulsion-like alcohol drinking (CLAD), where intake despite negative consequences can be a major clinical obstacle. With few treatment options available for AUD, there is a significant need for novel therapies. The noradrenergic system is an important hub for regulating stress responses and maladaptive drives for alcohol. Studies have shown that drugs targeting α1 adrenenergic receptors (ARs) may represent a pharmacological treatment for pathological drinking. However, the involvement of β ARs for treating human drinking has received scant investigation, and thus we sought to provide pre-clinical validation for possible AR utility for CLAD by analyzing whether β AR antagonists propranolol (β1/2), betaxolol (β1), and ICI, 118,551 (β2) impacted CLAD and alcohol-only drinking (AOD) in male Wistar rats. We found that the highest dose of propranolol tested systemically (10 mg/kg) reduced alcohol drinking, while 5 mg/kg propranolol reduced drinking with a trend to impact CLAD more than AOD, and with no effects of 2.5 mg/kg. Betaxolol (2.5 mg/kg) also decreased drinking, while ICI 118.551 had no effects. Also, while AR compounds might have utility for AUD, they can also lead to undesirable side effects. Here, a combination of ineffective doses of propranolol and prazosin reduced both CLAD and AOD. Finally, we investigated the effect of propranolol and betaxolol in two brain areas related to pathological drinking, the anterior insula (aINS) and medial prefrontal cortex (mPFC). Surprisingly, propranolol (1-10 μg) in aINS or mPFC did not affect CLAD or AOD. Together, our findings provide new pharmacological insights into noradrenergic regulation of alcohol consumption, which may inform AUD therapy.