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Tsui KC, Roy J, Chau SC, Wong KH, Shi L, Poon CH, Wang Y, Strekalova T, Aquili L, Chang RCC, Fung ML, Song YQ, Lim LW. Distribution and inter-regional relationship of amyloid-beta plaque deposition in a 5xFAD mouse model of Alzheimer’s disease. Front Aging Neurosci 2022; 14:964336. [PMID: 35966777 PMCID: PMC9371463 DOI: 10.3389/fnagi.2022.964336] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Accepted: 06/28/2022] [Indexed: 11/13/2022] Open
Abstract
Alzheimer’s disease (AD) is the most common form of dementia. Although previous studies have selectively investigated the localization of amyloid-beta (Aβ) deposition in certain brain regions, a comprehensive characterization of the rostro-caudal distribution of Aβ plaques in the brain and their inter-regional correlation remain unexplored. Our results demonstrated remarkable working and spatial memory deficits in 9-month-old 5xFAD mice compared to wildtype mice. High Aβ plaque load was detected in the somatosensory cortex, piriform cortex, thalamus, and dorsal/ventral hippocampus; moderate levels of Aβ plaques were observed in the motor cortex, orbital cortex, visual cortex, and retrosplenial dysgranular cortex; and low levels of Aβ plaques were located in the amygdala, and the cerebellum; but no Aβ plaques were found in the hypothalamus, raphe nuclei, vestibular nucleus, and cuneate nucleus. Interestingly, the deposition of Aβ plaques was positively associated with brain inter-regions including the prefrontal cortex, somatosensory cortex, medial amygdala, thalamus, and the hippocampus. In conclusion, this study provides a comprehensive morphological profile of Aβ deposition in the brain and its inter-regional correlation. This suggests an association between Aβ plaque deposition and specific brain regions in AD pathogenesis.
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Affiliation(s)
- Ka Chun Tsui
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Jaydeep Roy
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Sze Chun Chau
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Kah Hui Wong
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
- Department of Anatomy, Faculty of Medicine, Universiti Malaya, Kuala Lumpur, Malaysia
| | - Lei Shi
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Chi Him Poon
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Yingyi Wang
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Tatyana Strekalova
- Department of Neuroscience, Maastricht University, Maastricht, Netherlands
- Department of Normal Physiology and Laboratory of Psychiatric Neurobiology, Sechenov First Moscow State Medical University, Moscow, Russia
| | - Luca Aquili
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
- Discipline of Psychology, College of Science, Health, Engineering, and Education, Murdoch University, Perth, WA, Australia
| | - Raymond Chuen-Chung Chang
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Man-Lung Fung
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
- *Correspondence: Man-Lung Fung,
| | - You-qiang Song
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
- The State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
- You-qiang Song,
| | - Lee Wei Lim
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
- Lee Wei Lim,
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The Protective Effects of Escitalopram on Chronic Restraint Stress-Induced Memory Deficits in Adult Rats. PHYSIOLOGY AND PHARMACOLOGY 2021. [DOI: 10.52547/phypha.26.1.9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Tan SZK, Poon CH, Chan YS, Lim LW. Prelimbic cortical stimulation disrupts fear memory consolidation through ventral hippocampal dopamine D 2 receptors. Br J Pharmacol 2021; 178:3587-3601. [PMID: 33899943 DOI: 10.1111/bph.15505] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Accepted: 04/18/2021] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND AND PURPOSE Anxiety disorders pose one of the biggest threats to mental health worldwide, yet current therapeutics have been mostly ineffective due to issues with relapse, efficacy and toxicity of the medications. Deep brain stimulation (DBS) is a promising therapy for treatment-resistant psychiatric disorders including anxiety, but very little is known about the effects of deep brain stimulation on fear memories. EXPERIMENTAL APPROACH In this study, we employed a standard tone-footshock fear conditioning paradigm and modified plus maze discriminative avoidance task to probe the effects of prelimbic cortex deep brain stimulation on various stages of memory. KEY RESULTS We identified memory consolidation stage as a critical time point to disrupt fear memory via prelimbic cortex deep brain stimulation. The observed disruption was partially modulated by the inactivation of the ventral hippocampus and the transient changes in ventral hippocampus dopamine (D2 ) receptors expression upon prelimbic cortex deep brain stimulation. We also observed wide-scale changes of various neurotransmitters and their metabolites in ventral hippocampus, confirming its important role in response to prelimbic cortex deep brain stimulation. CONCLUSION AND IMPLICATIONS These findings highlight the molecular mechanism in the ventral hippocampus in response to prelimbic cortex stimulation and may have translational value, indicating that targeting the prelimbic cortex in the memory consolidation stage via non-invasive neuromodulation techniques may be a feasible therapeutic strategy against anxiety disorders.
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Affiliation(s)
- Shawn Zheng Kai Tan
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
| | - Chi Him Poon
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
| | - Ying-Shing Chan
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
| | - Lee Wei Lim
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
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Yoshioka D, Iwata M, Kaneko K. Case Report: GABAergic and Serotoninergic Agents for the Treatment and Prevention of Prolonged Dissociative Stupor. Front Psychiatry 2021; 12:641474. [PMID: 34093264 PMCID: PMC8169974 DOI: 10.3389/fpsyt.2021.641474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Accepted: 04/20/2021] [Indexed: 11/13/2022] Open
Abstract
Dissociative stupor is a common psychiatric disease lacking an established standard treatment. The lack of therapeutic options may be due to the spontaneous and quick complete remission of most patients. However, since some patients experience multiple relapses and prolonged stupor, investigating potential prevention and treatment options is critical. We reported the case of a 61-year-old Japanese woman who presented with intermittent dissociative stupor for several months. Despite her prolonged symptoms, the administration of lorazepam, escitalopram, and aripiprazole, which selectively enhance GABAergic and serotoninergic activity, improved her stupor and prevented relapse. These findings may help with the treatment of persistent dissociative stupor.
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Affiliation(s)
- Daisuke Yoshioka
- Division of Neuropsychiatry, Faculty of Medicine, Tottori University, Yonago, Japan.,Department of Psychiatry, National Hospital Organization Tottori Medical Center, Tottori, Japan
| | - Masaaki Iwata
- Division of Neuropsychiatry, Faculty of Medicine, Tottori University, Yonago, Japan
| | - Koichi Kaneko
- Division of Neuropsychiatry, Faculty of Medicine, Tottori University, Yonago, Japan
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Azizi SA. Monoamines: Dopamine, Norepinephrine, and Serotonin, Beyond Modulation, "Switches" That Alter the State of Target Networks. Neuroscientist 2020; 28:121-143. [PMID: 33292070 DOI: 10.1177/1073858420974336] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
How do monoamines influence the perceptual and behavioral aspects of brain function? A library of information regarding the genetic, molecular, cellular, and function of monoamines in the nervous system and other organs has accumulated. We briefly review monoamines' anatomy and physiology and discuss their effects on the target neurons and circuits. Monoaminergic cells in the brain stem receive inputs from sensory, limbic, and prefrontal areas and project extensively to the forebrain and hindbrain. We review selected studies on molecular, cellular, and electrophysiological effects of monoamines on the brain's target areas. The idea is that monoamines, by reversibly modulating the "primary" information processing circuits, regulate and switch the functions of brain networks and can reversibly alter the "brain states," such as consciousness, emotions, and movements. Monoamines, as the drivers of normal motor and sensory brain operations, including housekeeping, play essential roles in pathogenesis of neuropsychiatric diseases.
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Affiliation(s)
- Sayed Ausim Azizi
- Department of Neurology, Global Neuroscience Institute, Chester, PA, USA
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Serotonergic treatment normalizes midbrain dopaminergic neuron increase after periaqueductal gray stimulation. Brain Struct Funct 2020; 225:1957-1966. [PMID: 32594260 DOI: 10.1007/s00429-020-02102-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Accepted: 06/15/2020] [Indexed: 12/23/2022]
Abstract
Electrical stimulation of the dorsolateral periaqueductal gray (dlPAG) in rats has been shown to elicit panic-like behaviour and can be a useful as an unconditioned stimulus for modelling anticipatory fear and agoraphobia in a contextual fear conditioning paradigm. In this study, we further analysed our previous data on the effects of escitalopram (a selective serotonin reuptake inhibitor, SSRI) and buspirone (a 5-HT1A receptor partial agonist) on dlPAG-induced anticipatory fear behaviour in a rat model using freezing as a measure. We then attempted to unravel some of the interactions with dopamine signalling using tyrosine hydroxylase (TH) immunohistochemistry to probe the effects on dopaminergic neurons. We showed that acute treatment of escitalopram, but not buspirone, was effective in reducing anticipatory freezing behaviour, while chronic administrations of both drugs were effective. We found that the dlPAG stimulation induced increase number of dopaminergic neurons in the ventral tegmental area (VTA) which was reversed in both chronic buspirone and escitalopram groups. We further found a strong positive correlation between the number of dopaminergic neurons and freezing in the VTA and showed positive correlations between dopaminergic neurons in the VTA and substantia nigra pars compacta (SNpc) in escitalopram and buspirone groups, respectively. Overall, we showed that chronic treatment with an SSRI and a 5-HT1A agonist reduced anticipatory freezing behaviour which seems to be associated, through correlative studies, with a reversal of dlPAG stimulation induced increase in number of dopaminergic neurons in the VTA and/or SNpc.
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Huguet G, Kadar E, Temel Y, Lim LW. Electrical Stimulation Normalizes c-Fos Expression in the Deep Cerebellar Nuclei of Depressive-like Rats: Implication of Antidepressant Activity. THE CEREBELLUM 2017; 16:398-410. [PMID: 27435250 DOI: 10.1007/s12311-016-0812-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The electrical stimulation of specific brain targets has been shown to induce striking antidepressant effects. Despite that recent data have indicated that cerebellum is involved in emotional regulation, the mechanisms by which stimulation improved mood-related behaviors in the cerebellum remained largely obscure. Here, we investigated the stimulation effects of the ventromedial prefrontal cortex (vmPFC), nucleus accumbens (NAc), and lateral habenular nucleus on the c-Fos neuronal activity in various deep cerebellar and vestibular nuclei using the unpredictable chronic mild stress (CMS) animal model of depression. Our results showed that stressed animals had increased number of c-Fos cells in the cerebellar dentate and fastigial nuclei, as well as in the spinal vestibular nucleus. To examine the stimulation effects, we found that vmPFC stimulation significantly decreased the c-Fos activity within the cerebellar fastigial nucleus as compared to the CMS sham. Similarly, there was also a reduction of c-Fos expression in the magnocellular part of the medial vestibular nucleus in vmPFC- and NAc core-stimulated animals when compared to the CMS sham. Correlational analyses showed that the anxiety measure of home-cage emergence escape latency was positively correlated with the c-Fos neuronal activity of the cerebellar fastigial and magnocellular and parvicellular parts of the interposed nuclei in CMS vmPFC-stimulated animals. Interestingly, there was a strong correlation among activation in these cerebellar nuclei, indicating that the antidepressant-like behaviors were possibly mediated by the vmPFC stimulation-induced remodeling within the forebrain-cerebellar neurocircuitry.
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Affiliation(s)
- Gemma Huguet
- Department of Biology, University of Girona, Girona, Spain
| | - Elisabet Kadar
- Department of Biology, University of Girona, Girona, Spain.
| | - Yasin Temel
- Departments of Neuroscience and Neurosurgery, Maastricht University, Maastricht, The Netherlands
| | - Lee Wei Lim
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong, China. .,Department of Biological Sciences, Sunway University, Bandar Sunway, Malaysia.
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Tetratricopeptide repeat domain 9A modulates anxiety-like behavior in female mice. Sci Rep 2016; 6:37568. [PMID: 27869229 PMCID: PMC5116628 DOI: 10.1038/srep37568] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Accepted: 10/31/2016] [Indexed: 12/17/2022] Open
Abstract
Tetratricopeptide repeat domain 9A (TTC9A) expression is abundantly expressed in the brain. Previous studies in TTC9A knockout (TTC9A-/-) mice have indicated that TTC9A negatively regulates the action of estrogen. In this study we investigated the role of TTC9A on anxiety-like behavior through its functional interaction with estrogen using the TTC9A-/- mice model. A battery of tests on anxiety-related behaviors was conducted. Our results demonstrated that TTC9A-/- mice exhibited an increase in anxiety-like behaviors compared to the wild type TTC9A+/+ mice. This difference was abolished after ovariectomy, and administration of 17-β-estradiol benzoate (EB) restored this escalated anxiety-like behavior in TTC9A-/- mice. Since serotonin is well-known to be the key neuromodulator involved in anxiety behaviors, the mRNA levels of tryptophan hydroxylase (TPH) 1, TPH2 (both are involved in serotonin synthesis), and serotonin transporter (5-HTT) were measured in the ventromedial prefrontal cortex (vmPFC) and dorsal raphe nucleus (DRN). Interestingly, the heightened anxiety in TTC9A-/- mice under EB influence is consistent with a greater induction of TPH 2, and 5-HTT by EB in DRN that play key roles in emotion regulation. In conclusion, our data indicate that TTC9A modulates the anxiety-related behaviors through modulation of estrogen action on the serotonergic system in the DRN.
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Liu A, Jain N, Vyas A, Lim LW. Ventromedial prefrontal cortex stimulation enhances memory and hippocampal neurogenesis in the middle-aged rats. eLife 2015; 4. [PMID: 25768425 PMCID: PMC4381300 DOI: 10.7554/elife.04803] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Accepted: 03/11/2015] [Indexed: 12/11/2022] Open
Abstract
Memory dysfunction is a key symptom of age-related dementia. Although recent studies have suggested positive effects of electrical stimulation for memory enhancement, its potential targets remain largely unknown. In this study, we hypothesized that spatially targeted deep brain stimulation of ventromedial prefrontal cortex enhanced memory functions in a middle-aged rat model. Our results show that acute stimulation enhanced the short-, but not the long-term memory in the novel-object recognition task. Interestingly, after chronic high-frequency stimulation, both the short- and long-term memories were robustly improved in the novel-object recognition test and Morris water-maze spatial task compared to sham. Our results also demonstrated that chronic ventromedial prefrontal cortex high-frequency stimulation upregulated neurogenesis-associated genes along with enhanced hippocampal cell proliferation. Importantly, these memory behaviors were strongly correlated with the hippocampal neurogenesis. Overall, these findings suggest that chronic ventromedial prefrontal cortex high-frequency stimulation may serve as a novel effective therapeutic target for dementia-related disorders. DOI:http://dx.doi.org/10.7554/eLife.04803.001 Memory loss in older people is a serious and widespread problem that affects up to 50% of those over the age of 85. It is a key symptom of dementia, but despite the growing impact of this disease on society, there are no treatments currently available that can effectively stop or delay the progression of the symptoms. One therapy that may reduce memory loss is called deep brain stimulation. Electrodes are implanted into the brain and used to stimulate brain cells in particular areas of the brain to alter mental and emotional processes. Deep brain stimulation is already used to treat Parkinson's disease, depression and other conditions that affect how the brain works. Liu et al. studied the effect of deep brain stimulation on memory in rats. The experiments show that middle-aged rats performed less well in short- and long-term memory tests than young rats. Next, Liu et al. investigated whether deep brain stimulation could improve memory in the middle-aged rats. The electrodes were positioned to stimulate a region near the front of the brain called the ‘ventromedial prefrontal cortex’; this region is important for the formation and recall of memories. Liu et al. then gave the rats a series of memory tasks that tested their recall after 90 minutes (to test their short-term memory), and after 24 hours (to test long-term memory). The experiments reveal that a brief stimulation of brain cells in this region of the brain improved the rats' short-term memory, but not their long-term memory. However, more sustained stimulation of this region of the brain improved both the short-term and long-term memory of the rats. Furthermore, deep brain stimulation led to the formation of new brain cells in another region of the brain called the hippocampus, which is also involved in memory. The hippocampus had not been in direct contact with the electrodes so the increase in brain cells was due to its connections with the stimulated ventromedial prefrontal cortex. Liu et al.'s findings suggest that deep brain stimulation of the ventromedial prefrontal cortex has the potential to be developed into a therapy to treat dementia and other conditions that lead to memory loss in humans. DOI:http://dx.doi.org/10.7554/eLife.04803.002
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Affiliation(s)
- Albert Liu
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Neeraj Jain
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Ajai Vyas
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Lee Wei Lim
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
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Electrical stimulation alleviates depressive-like behaviors of rats: investigation of brain targets and potential mechanisms. Transl Psychiatry 2015; 5:e535. [PMID: 25826110 PMCID: PMC4354354 DOI: 10.1038/tp.2015.24] [Citation(s) in RCA: 86] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Revised: 01/16/2015] [Accepted: 01/20/2015] [Indexed: 02/06/2023] Open
Abstract
Deep brain stimulation (DBS) is a promising therapy for patients with refractory depression. However, key questions remain with regard to which brain target(s) should be used for stimulation, and which mechanisms underlie the therapeutic effects. Here, we investigated the effect of DBS, with low- and high-frequency stimulation (LFS, HFS), in different brain regions (ventromedial prefrontal cortex, vmPFC; cingulate cortex, Cg; nucleus accumbens (NAc) core or shell; lateral habenula, LHb; and ventral tegmental area) on a variety of depressive-like behaviors using rat models. In the naive animal study, we found that HFS of the Cg, vmPFC, NAc core and LHb reduced anxiety levels and increased motivation for food. In the chronic unpredictable stress model, there was a robust depressive-like behavioral phenotype. Moreover, vmPFC HFS, in a comparison of all stimulated targets, produced the most profound antidepressant effects with enhanced hedonia, reduced anxiety and decreased forced-swim immobility. In the following set of electrophysiological and histochemical experiments designed to unravel some of the underlying mechanisms, we found that vmPFC HFS evoked a specific modulation of the serotonergic neurons in the dorsal raphe nucleus (DRN), which have long been linked to mood. Finally, using a neuronal mapping approach by means of c-Fos expression, we found that vmPFC HFS modulated a brain circuit linked to the DRN and known to be involved in affect. In conclusion, HFS of the vmPFC produced the most potent antidepressant effects in naive rats and rats subjected to stress by mechanisms also including the DRN.
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Hestermann D, Temel Y, Blokland A, Lim LW. Acute serotonergic treatment changes the relation between anxiety and HPA-axis functioning and periaqueductal gray activation. Behav Brain Res 2014; 273:155-65. [DOI: 10.1016/j.bbr.2014.07.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Revised: 06/28/2014] [Accepted: 07/01/2014] [Indexed: 10/25/2022]
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Brown HD, Amodeo DA, Sweeney JA, Ragozzino ME. The selective serotonin reuptake inhibitor, escitalopram, enhances inhibition of prepotent responding and spatial reversal learning. J Psychopharmacol 2012; 26:1443-55. [PMID: 22219222 PMCID: PMC3345307 DOI: 10.1177/0269881111430749] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Previous findings indicate treatment with a selective serotonin reuptake inhibitor (SSRI) facilitates behavioral flexibility when conditions require inhibition of a learned response pattern. The present experiment investigated whether acute treatment with the SSRI, escitalopram, affects behavioral flexibility when conditions require inhibition of a naturally biased response pattern (elevated conflict test) and/or reversal of a learned response pattern (spatial reversal learning). An additional experiment was carried out to determine whether escitalopram, at doses that affected behavioral flexibility, also reduced anxiety as tested in the elevated plus-maze. In each experiment, Long-Evans rats received an intraperitoneal injection of either saline or escitalopram (0.03, 0.3 or 1.0 mg/kg) 30 min prior to behavioral testing. Escitalopram, at all doses tested, enhanced acquisition in the elevated conflict test, but did not affect performance in the elevated plus-maze. Escitalopram (0.3 and 1.0 mg/kg) did not alter acquisition of the spatial discrimination, but facilitated reversal learning. In the elevated conflict and spatial reversal learning test, escitalopram enhanced the ability to maintain the relevant strategy after being initially selected. The present findings suggest that enhancing serotonin transmission with an SSRI facilitates inhibitory processes when conditions require a shift away from either a naturally biased response pattern or a learned choice pattern.
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Affiliation(s)
- Holden D. Brown
- Department of Psychology, University of Illinois at Chicago, Chicago, IL 60607,Graduate Program in Neuroscience, University of Illinois at Chicago, Chicago, IL 60607
| | - Dionisio A. Amodeo
- Department of Psychology, University of Illinois at Chicago, Chicago, IL 60607
| | - John A. Sweeney
- Department of Psychology, University of Illinois at Chicago, Chicago, IL 60607,Center for Cognitive Medicine, University of Illinois at Chicago, Chicago, IL 60607
| | - Michael E. Ragozzino
- Department of Psychology, University of Illinois at Chicago, Chicago, IL 60607,Center for Cognitive Medicine, University of Illinois at Chicago, Chicago, IL 60607
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Temel Y, Blokland A, Lim LW. Deactivation of the parvalbumin-positive interneurons in the hippocampus after fear-like behaviour following electrical stimulation of the dorsolateral periaqueductal gray of rats. Behav Brain Res 2012; 233:322-5. [DOI: 10.1016/j.bbr.2012.05.029] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2012] [Revised: 05/11/2012] [Accepted: 05/16/2012] [Indexed: 11/28/2022]
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Hescham S, Lim LW, Jahanshahi A, Steinbusch HWM, Prickaerts J, Blokland A, Temel Y. Deep brain stimulation of the forniceal area enhances memory functions in experimental dementia: the role of stimulation parameters. Brain Stimul 2012; 6:72-7. [PMID: 22405739 DOI: 10.1016/j.brs.2012.01.008] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2011] [Revised: 01/20/2012] [Accepted: 01/24/2012] [Indexed: 01/10/2023] Open
Abstract
Deep brain stimulation (DBS) is currently being evaluated as a potential therapy in improving memory functions in Alzheimer's disease. The target for DBS and the stimulation parameters to be used are unknown. Here, we implanted bilateral electrodes in the vicinity of the fornix, a key element of the memory circuitry, and applied DBS with different stimulation frequencies and amplitudes in an experimental model of dementia. Rats received scopolamine, a muscarinic acetylcholine receptor antagonist, to mimic memory impairment. Rats were then tested in the object location task with the following conditions: (i) with attachment of stimulation cable (off stimulation), and (ii) with DBS at various amplitudes (50 μA, 100 μA and 200 μA), 100 μs pulse width and 100 Hz or 10 Hz stimulation frequency. DBS reversed the memory impairing effects of scopolamine when compared to sham rats. We found that the fornix is not sensitive to the frequency of stimulation, but rather to current levels. With the most optimal stimulation parameter, we found no side-effects on anxiety levels and general motor activity. These findings identify the fornix as a key region in controlling spatial memory functions. DBS of this region, using tailored stimulation parameters, has the potential to improve memory functions in conditions characterised by memory impairment.
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Affiliation(s)
- Sarah Hescham
- Department of Neuroscience, Maastricht University Medical Center, Maastricht, PO Box 5800, 6202 AZ Maastricht, The Netherlands
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Increased plasma corticosterone levels after periaqueductal gray stimulation-induced escape reaction or panic attacks in rats. Behav Brain Res 2010; 218:301-7. [PMID: 21185871 DOI: 10.1016/j.bbr.2010.12.026] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2010] [Revised: 12/12/2010] [Accepted: 12/16/2010] [Indexed: 11/21/2022]
Abstract
The hypothalamo-pituitary-adrenal (HPA) axis is involved in stress, depression and anxiety. Controversy exists on HPA axis activation during panic attacks (PAs). We examined whether the HPA axis is involved in the escape or panic-like response in an animal model of PAs induced by electrical stimulation of the dorsolateral periaqueductal gray (dlPAG) in rats. Additionally, rats were also treated with chronic administration of buspirone (BUSP) and escitalopram (ESCIT), respectively; and they were stimulated in the open-field arena for panic-like reaction. Levels of stress hormone corticosterone were measured following 30 min after escape or panic condition. Our results demonstrated that the levels of plasma corticosterone were significantly increased after the induction of escape or panic-like response in comparison with the sham animals. The levels of corticosterone were significantly decreased in the dlPAG stimulated groups after rats were treated chronically with the ESCIT but not the BUSP as compared to the saline treated animals. Importantly, the increase of corticosterone level after escape or panic-like response was paralleled by an increase of neuronal activation of c-Fos in both the parvocellular and magnocellular paraventricular nucleus of the hypothalamus. Moreover, the c-Fos data also showed a decrease in the number of positive cells particularly for the ESCIT as well as the BUSP in comparison with the saline stimulated animals. In conclusion, the present study clearly demonstrated that PA or escape response activates the HPA axis and it remains difficult to anticipate the mechanism underlying HPA axis during PAs and its relationship with 5-HT drugs.
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