1
|
Aksic M, Poleksic J, Aleksic D, Petronijevic N, Radonjic NV, Jakovcevski M, Kapor S, Divac N, Filipovic BR, Jakovcevski I. Maternal Deprivation in Rats Decreases the Expression of Interneuron Markers in the Neocortex and Hippocampus. Front Neuroanat 2021; 15:670766. [PMID: 34168541 PMCID: PMC8217609 DOI: 10.3389/fnana.2021.670766] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Accepted: 05/07/2021] [Indexed: 12/12/2022] Open
Abstract
Early life stress has profound effects on the development of the central nervous system. We exposed 9-day-old rat pups to a 24 h maternal deprivation (MD) and sacrificed them as young adults (60-day-old), with the aim to study the effects of early stress on forebrain circuitry. We estimated numbers of various immunohistochemically defined interneuron subpopulations in several neocortical regions and in the hippocampus. MD rats showed reduced numbers of parvalbumin-expressing interneurons in the CA1 region of the hippocampus and in the prefrontal cortex, compared with controls. Numbers of reelin-expressing and calretinin-expressing interneurons were also reduced in the CA1 and CA3 hippocampal areas, but unaltered in the neocortex of MD rats. The number of calbinin-expressing interneurons in the neocortex was similar in the MD rats compared with controls. We analyzed cell death in 15-day-old rats after MD and found no difference compared to control rats. Thus, our results more likely reflect the downregulation of markers than the actual loss of interneurons. To investigate synaptic activity in the hippocampus we immunostained for glutamatergic and inhibitory vesicular transporters. The number of inhibitory synapses was decreased in the CA1 and CA3 regions of the hippocampus in MD rats, with the normal number of excitatory synapses. Our results indicate complex, cell type-specific, and region-specific alterations in the inhibitory circuitry induced by maternal deprivation. Such alterations may underlie symptoms of MD at the behavioral level and possibly contribute to mechanisms by which early life stress causes neuropsychiatric disorders, such as schizophrenia.
Collapse
Affiliation(s)
- Milan Aksic
- Institute of Anatomy Niko Miljanić, School of Medicine, University of Belgrade, Belgrade, Serbia
| | - Joko Poleksic
- Institute of Anatomy Niko Miljanić, School of Medicine, University of Belgrade, Belgrade, Serbia
| | - Dubravka Aleksic
- Institute of Anatomy Niko Miljanić, School of Medicine, University of Belgrade, Belgrade, Serbia
| | - Natasa Petronijevic
- Institute of Medical and Clinical Biochemistry, School of Medicine, University of Belgrade, Belgrade, Serbia
| | - Nevena V Radonjic
- Department of Psychiatry, University of Connecticut School of Medicine, Farmington, CT, United States
| | - Maja Jakovcevski
- Department of Anatomy, Faculty of Medical Sciences, University of Kragujevac, Kragujevac, Serbia
| | - Slobodan Kapor
- Institute of Anatomy Niko Miljanić, School of Medicine, University of Belgrade, Belgrade, Serbia
| | - Nevena Divac
- Department of Pharmacology, Clinical Pharmacology and Toxicology, School of Medicine, University of Belgrade, Belgrade, Serbia
| | - Branislav R Filipovic
- Institute of Anatomy Niko Miljanić, School of Medicine, University of Belgrade, Belgrade, Serbia
| | - Igor Jakovcevski
- Abteilung für Neuroanatomie und Molekulare Hirnforschung, Ruhr-Universität Bochum, Bochum, Germany.,Institut für Anatomie und Klinische Morphologie, Universität Witten/Herdecke, Witten, Germany
| |
Collapse
|
2
|
Increased Basolateral Amygdala Pyramidal Cell Excitability May Contribute to the Anxiogenic Phenotype Induced by Chronic Early-Life Stress. J Neurosci 2015; 35:9730-40. [PMID: 26134655 DOI: 10.1523/jneurosci.0384-15.2015] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
UNLABELLED Adolescence represents a particularly vulnerable period during which exposure to stressors can precipitate the onset of psychiatric disorders and addiction. The basolateral amygdala (BLA) plays an integral role in the pathophysiology of anxiety and addiction. Acute and chronic stress promote increases in BLA pyramidal cell firing, and decreasing BLA excitability alleviates anxiety measures in humans and rodents. Notably, the impact of early-life stress on the mechanisms that govern BLA excitability is unknown. To address this gap in our knowledge, we used a rodent model of chronic early-life stress that engenders robust and enduring increases in anxiety-like behaviors and ethanol intake and examined the impact of this model on the intrinsic excitability of BLA pyramidal cells. Adolescent social isolation was associated with a significant increase in the intrinsic excitability of BLA pyramidal cells and a blunting of the medium component of the afterhyperpolarization potential, a voltage signature of calcium-activated potassium (Kca) channel activity. Western blot analysis revealed reduced expression of small-conductance Kca (SK) channel protein in the BLA of socially isolated (SI) rats. Bath application of a positive SK channel modulator (1-EBIO) normalized firing in ex vivo recordings from SI rats, and in vivo intra-BLA 1-EBIO infusion reduced anxiety-like behaviors. These findings reveal that chronic adolescent stress impairs SK channel function, which contributes to an increase in BLA pyramidal cell excitability and highlights BLA SK channels as promising targets for the treatment of anxiety disorders and comorbid addiction. SIGNIFICANCE STATEMENT Although anxiety disorders and alcohol addiction frequently co-occur, the mechanisms that contribute to this comorbidity are poorly understood. Here, we used a rodent early-life stress model that leads to robust and longlasting increases in behaviors associated with elevated risk of anxiety disorders and addiction to identify novel neurobiological substrates that may underlie these behaviors. Our studies focused on the primary output neurons of the basolateral amygdala, a brain region that plays a key role in anxiety and addiction. We discovered that early-life stress decreases the activity of a specific class of potassium channels and increases the intrinsic excitability of BLA neurons and present evidence that enhancing the function of these channels normalizes BLA excitability and attenuates anxiety-like behaviors.
Collapse
|
3
|
Hong YP, Lee HC, Kim HT. Treadmill exercise after social isolation increases the levels of NGF, BDNF, and synapsin I to induce survival of neurons in the hippocampus, and improves depression-like behavior. J Exerc Nutrition Biochem 2015; 19:11-8. [PMID: 25960950 PMCID: PMC4424441 DOI: 10.5717/jenb.2015.19.1.11] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Revised: 02/01/2015] [Accepted: 02/05/2015] [Indexed: 11/16/2022] Open
Abstract
[Purpose] We investigated the effects of 8 weeks of treadmill exercise on nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and synapsin I protein expression and on the number of 5-bromo-2'-deoxyuridine-5'-mono-phosphate (BrdU)-positive cells in the dentate gyrus of the hippocampus in socially isolated rats. Additionally, we examined the effects of exercise on the number of serotonin (5-HT)- and tryptophan hydroxylase (TPH)-positive cells in the raphe nuclei and on depression behaviors induced by social isolation. [Methods] Forty male Sprague-Dawley rats were divided into four groups: (1) group housing and control group (GCG, n = 10); (2) group housing and exercise group (GEG, n = 10); (3) isolated housing and control group (ICG, n = 10); and (4) isolated housing and exercise group (IEG, n = 10). After 1 week of housing under the normal condition of 3 animals per cage, rats were socially isolated via transfer to individual cages for 8 weeks. Rats were then subjected to treadmill exercise for 5 days per week for 8 weeks during which time the speed of the treadmill was gradually increased. [Results] Compared to the GCG, levels of NGF, BDNF, and synapsin I were significantly decreased in the ICG and significantly increased in the IEG (p < 0.001 respectively). Significantly more BrdU-positive cells in the GEG were present as compared to the GCG and ICG, and more BrdU-positive cells were found in the IEG as compared to the ICG (p < 0.001). 5-HT-positive cells in the GEG were significantly increased compared to the GCG and ICG, and more of these cells were found in the IEG as compared to the ICG (p < 0.01). TPH-positive cells in the GEG were significantly increased compared to those in the GCG and ICG (p < 0.05). In the forced swim test, immobility time was significantly increased in the ICG and significantly decreased in the IEG as compared to the ICG (p < 0.01). [Conclusion] These results showed that regular treadmill exercise following social isolation not only increased the levels of NGF, BDNF, and synapsin I to induce survival of neurons in the hippocampus but also improved depression by increasing the number of serotonergic cells in the raphe nuclei.
Collapse
Affiliation(s)
- Young-Pyo Hong
- Department of Health and Sport Science, Korea National Sport University, Seoul, Korea
| | - Hyo-Chul Lee
- Department of Health and Sport Science, Korea National Sport University, Seoul, Korea
| | - Hyun-Tae Kim
- Department of Health and Sport Science, Korea National Sport University, Seoul, Korea
| |
Collapse
|
4
|
Segura B, Melo AI, Fleming AS, Mendoza-Garrido ME, González del Pliego M, Aguirre-Benitez EL, Hernández-Falcón J, Jiménez-Estrada I. Early social isolation provokes electrophysiological and structural changes in cutaneous sensory nerves of adult male rats. Dev Neurobiol 2014; 74:1184-93. [DOI: 10.1002/dneu.22197] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Revised: 05/14/2014] [Accepted: 06/02/2014] [Indexed: 11/10/2022]
Affiliation(s)
- Bertha Segura
- Department of Biology, FES Iztacala; UNAM. Av. de los Barrios 1 Col. Los Reyes Iztacala; Tlanepantla de Baz Estado de México CP 54090 México
| | - Angel I. Melo
- Centro de Investigación en Reproducción Animal; CINVESTAV Laboratorio Tlaxcala. Universidad Autónoma de Tlaxcala; A.P. 62. C.P. 90000 Tlaxcala México
| | - Alison S. Fleming
- Department of Psychology; University of Toronto at Mississauga; Mississauga, Ontario 5L 1C6 Canada
| | - Maria Eugenia Mendoza-Garrido
- Department of Physiology, Biophysics and Neurosciences; CINVESTAV, IPN Av. Instituto Politécnico Nacional 2508 Col. San Pedro Zacatenco, Del. Gustavo A. Madero; C.P. 07360 México D.F México
| | | | | | - Jesús Hernández-Falcón
- Laboratorio de Redes Neuronales, Departamento de Fisiología; Facultad de Medicina, UNAM; Mexico
| | - Ismael Jiménez-Estrada
- Department of Physiology, Biophysics and Neurosciences; CINVESTAV, IPN Av. Instituto Politécnico Nacional 2508 Col. San Pedro Zacatenco, Del. Gustavo A. Madero; C.P. 07360 México D.F México
| |
Collapse
|
5
|
Gaskin PLR, Alexander SPH, Fone KCF. Neonatal phencyclidine administration and post-weaning social isolation as a dual-hit model of 'schizophrenia-like' behaviour in the rat. Psychopharmacology (Berl) 2014; 231:2533-45. [PMID: 24402141 DOI: 10.1007/s00213-013-3424-y] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Accepted: 12/16/2013] [Indexed: 01/07/2023]
Abstract
RATIONALE Schizophrenia is a debilitating disorder comprising positive, negative and cognitive deficits with a poorly defined neurobiological aetiology; therefore, animal models with greater translational reliability are essential to develop improved therapies. OBJECTIVES This study combines two developmental challenges in rats, neonatal phencyclidine (PCP) injection and subsequent rearing in social isolation from weaning, to attempt to produce more robust behavioural deficits with greater translational relevance to schizophrenia than either challenge alone. METHODS Forty-two male Lister-hooded rat pups received the N-methyl-D-aspartate (NMDA) receptor antagonist, phencyclidine (PCP, 10 mg/kg, s.c.), or vehicle on post-natal day (PND) 7, 9 and 11 and were weaned on PND 23 into group housing (saline-treated n = 11 or PCP-treated n = 10) or isolation (saline n = 10 or PCP n = 11). Six weeks post-weaning, novelty- and PCP-induced (3.2 mg/kg) locomotor activity, novel object discrimination, prepulse inhibition of acoustic startle and contextual memory in a conditioned emotion response (CER) were recorded. RESULTS Isolation rearing alone significantly elevated baseline locomotor activity and induced visual recognition memory impairment in novel object discrimination. Neonatal PCP treatment did not induce locomotor sensitisation to a subsequent acute PCP injection, but it impaired prepulse inhibition when combined with isolation rearing. CER freezing behaviour was significantly reduced by isolation rearing but an even greater effect occurred when combined with neonatal PCP treatment. CONCLUSIONS Neonatal PCP and isolation rearing both produce behavioural deficits in adult rats, but combined treatment caused a wider range of more severe cognitive impairments, providing a more comprehensive preclinical model to determine the neurobiological aetiology of schizophrenia than either treatment alone.
Collapse
Affiliation(s)
- Philip L R Gaskin
- School of Life Sciences, Medical School, Queen's Medical Centre, University of Nottingham, Nottingham, NG7 2UH, UK
| | | | | |
Collapse
|
6
|
Swerdlow NR, Light GA, Trim RS, Breier MR, Hines SR, Powell SB. Forebrain gene expression predicts deficits in sensorimotor gating after isolation rearing in male rats. Behav Brain Res 2013; 257:118-28. [PMID: 24076151 DOI: 10.1016/j.bbr.2013.09.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2013] [Revised: 08/28/2013] [Accepted: 09/01/2013] [Indexed: 01/01/2023]
Abstract
Compared to socially housed (SH) rats, adult isolation-reared (IR) rats exhibit phenotypes relevant to schizophrenia (SZ), including reduced prepulse inhibition (PPI) of startle. PPI is normally regulated by the medial prefrontal cortex (mPFC) and nucleus accumbens (NAC). We assessed PPI, auditory-evoked local field potentials (LFPs) and expression of seven PPI- and SZ-related genes in the mPFC and NAC, in IR and SH rats. Buffalo (BUF) rats were raised in same-sex groups of 2-3 (SH) or in isolation (IR). PPI was measured early (d53) and later in adulthood (d74); LFPs were measured approximately on d66. Brains were processed for RT-PCR measures of mPFC and NAC expression of Comt, Erbb4, Grid2, Ncam1, Slc1a2, Nrg1 and Reln. Male IR rats exhibited PPI deficits, most pronounced at d53; male and female IR rats had significantly elevated startle magnitude on both test days. Gene expression levels were not significantly altered by IR. PPI levels (d53) were positively correlated with mPFC expression of several genes, and negatively correlated with NAC expression of several genes, in male IR but not SH rats. Late (P90) LFP amplitudes correlated significantly with expression levels of 6/7 mPFC genes in male rats, independent of rearing. After IR that disrupts early adult PPI in male BUF rats, expression levels of PPI- and SZ-associated genes in the mPFC correlate positively with PPI, and levels in the NAC correlate negatively with PPI. These results support the model that specific gene-behavior relationships moderate the impact of early-life experience on SZ-linked behavioral and neurophysiological markers.
Collapse
Affiliation(s)
- Neal R Swerdlow
- Department of Psychiatry, UCSD School of Medicine, 9500 Gilman Dr., La Jolla, CA 92093-0804, USA.
| | | | | | | | | | | |
Collapse
|
7
|
Lim AL, Taylor DA, Malone DT. A two-hit model: behavioural investigation of the effect of combined neonatal MK-801 administration and isolation rearing in the rat. J Psychopharmacol 2012; 26:1252-64. [PMID: 22361477 DOI: 10.1177/0269881111430751] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
This study combined two neurodevelopmental manipulations, neonatal MK-801 treatment and isolation rearing, to produce a 'two-hit' model and determine whether two hits induce a more robust behavioural phenotype of an animal model of aspects of schizophrenia compared with individual manipulations alone. The effect of clozapine was also assessed. Male Sprague-Dawley rats received 0.2 mg/kg MK-801 or saline intraperitoneally (i.p.) once daily on postnatal days (PNDs) 7-10 and were assigned to group or isolation rearing at weaning (PND 21). From PND 77, they received a vehicle or 5 mg/kg clozapine (i.p.) treatment regimen and were subjected to three prepulse inhibition (PPI) tests, a locomotor activity assessment and a novel object recognition task. MK-801-treated rats reared in isolation displayed robust PPI disruptions which were consistently manifested in all three tests. PPI deficits were also detected in saline-treated rats reared in isolation but not in all tests. Only the two-hit rats demonstrated hyperlocomotion and impaired object recognition memory. Clozapine restored PPI anomalies in the two-hit rats. The two-hit model showed greater psychotic-like effects than either neonatal MK-801 or isolation rearing alone. The preliminary predictive validity shown with clozapine suggests this model may be useful for predicting the efficacy of putative antipsychotics.
Collapse
Affiliation(s)
- Ann Li Lim
- Medicinal Chemistry and Drug Action, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia.
| | | | | |
Collapse
|
8
|
Chappell AM, Carter E, McCool BA, Weiner JL. Adolescent rearing conditions influence the relationship between initial anxiety-like behavior and ethanol drinking in male Long Evans rats. Alcohol Clin Exp Res 2012; 37 Suppl 1:E394-403. [PMID: 22924742 DOI: 10.1111/j.1530-0277.2012.01926.x] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2012] [Accepted: 06/21/2012] [Indexed: 01/25/2023]
Abstract
BACKGROUND Rodent studies have demonstrated that adolescent social isolation results in many behavioral perturbations, including increases in anxiety-like behaviors. Socially isolated (SI) rats have also been shown to self-administer greater amounts ethanol (EtOH) in some, but not all, studies. Here, we tested whether juvenile social isolation increases EtOH drinking using an intermittent procedure that engenders relatively high intake in normally reared animals. We also compared the behavioral phenotype of rats reared under social isolation or group-housed conditions with adult rats housed under conditions commonly used in EtOH-drinking studies. METHODS Male Long Evans rats were procured immediately postweaning and were group housed for 1 week. Subjects were then randomly divided into 2 groups: SI rats, housed individually for 6 weeks and group-housed (GH) rats (4/cage). A third group was procured as young adults and was housed individually upon arrival for 1 week (standard housing condition). Rats were then tested in a plus-maze and novelty assay, and then, all subjects were singly housed and EtOH drinking was assessed. RESULTS SI rats displayed increased anxiety-like behaviors on the plus-maze, a greater locomotor response to a novel environment, and increased EtOH intake, relative to GH rats. Age-matched standard housed (STD) rats exhibited an anxiety-like behavioral profile on the plus-maze that was similar to SI, and not GH rats, and also drank EtOH at levels comparable with SI subjects. In addition, anxiety-like behavior on the plus-maze correlated with intermittent EtOH intake in SI and GH rats. CONCLUSIONS These data further support the validity of the rodent juvenile social isolation model for studies directed at elucidating behavioral and neurobiological mechanisms linking anxiety and EtOH drinking. These findings further suggest that housing conditions commonly employed in rodent drinking studies may recapitulate the anxiety-like and EtOH-drinking phenotype engendered by a juvenile social isolation procedure.
Collapse
Affiliation(s)
- Ann M Chappell
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, North Carolina 27157, USA
| | | | | | | |
Collapse
|
9
|
Post-weaning social isolation rearing influences the expression of molecules related to inhibitory neurotransmission and structural plasticity in the amygdala of adult rats. Brain Res 2012; 1448:129-36. [PMID: 22356888 DOI: 10.1016/j.brainres.2012.01.073] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2012] [Revised: 01/27/2012] [Accepted: 01/28/2012] [Indexed: 01/15/2023]
Abstract
Several lines of evidence indicate that alterations in the structure of neural circuits and inhibitory neurotransmission underlie the physiopathogenesis of schizophrenia. Most of the studies on these parameters have been focused on cortical regions and, despite the crucial role of the amygdala in this psychiatric disorder, there is less information on this region. In order to expand this knowledge, we have studied the expression of molecules related to inhibitory neurotransmission and structural plasticity in rats subjected to post-weaning isolation rearing, an animal model that reproduces several core symptoms of schizophrenia. We have analyzed, using qRT-PCR and immunohistochemistry, the expression of synaptophysin, GAD65, GAD67, the neural cell adhesion molecule (NCAM), its polysialylated form (PSA-NCAM) and its synthesizing enzymes (St8siaII and St8SiaIV). Isolation-reared rats showed significant increases in the expression of GAD67 protein in the centromedial, medial and basolateral amygdaloid nuclei, but no significant changes in GAD65 or synaptophysin expression were found in these regions. The expression of PSA-NCAM and NCAM was significantly increased in the basolateral and medial nuclei respectively. Our results indicate that isolation-rearing influences positively inhibitory neurotransmission and neuronal structural plasticity in the amygdala, probably through PSA-NCAM. These findings are in contrast to reports describing decreased expression of molecules related to inhibitory neurotransmission in the amygdala of schizophrenic patients. Consequently, although the social isolation rearing model can reproduce some of the behavioral traits of schizophrenics it may fail to reproduce some of the neurobiological features of this disorder, particularly in the amygdala.
Collapse
|