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Liiver K, Imbeault S, Školnaja M, Kaart T, Kanarik M, Laugus K, De Wettinck J, Pulver A, Shimmo R, Harro J. Active vs passive novelty-related strategies: Sex differences in exploratory behaviour and monoaminergic systems. Behav Brain Res 2023; 441:114297. [PMID: 36641084 DOI: 10.1016/j.bbr.2023.114297] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Revised: 01/02/2023] [Accepted: 01/10/2023] [Indexed: 01/13/2023]
Abstract
Sex differences are apparent in numerous behavioural characteristics. In order to compare and characterise male and female variability of exploratory behaviour, 365 male and 401 female rats were assessed in a task where a bimodal response distribution had previously been established in males. Female rats had significantly higher exploratory activity, and presented normal distribution of the behaviour, very differently from the bimodal distribution of males. No major effect of litter or oestrous cycle was detected. Several differences between male and female rats were found in monoamine metabolism measured ex vivo. Male rats had lower levels of dopamine (DA) in frontal cortex, and higher levels of 3,4-dihydroxyphenylacetic acid (DOPAC) in raphe area; higher levels of serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) in dorsal striatum but lower levels of 5-HT and 5-HIAA in locus coeruleus area, 5-HIAA levels were also lower in hippocampus as compared to females. Males had higher noradrenaline (NA) levels in hippocampus and lower normetanephrine (NMN) levels in striatum, in both brain regions male animals had lower NMN/NA ratio. No sex difference was found in accumbens. The only brain region with an interaction between sex and the expression of exploratory activity was raphe: Here 5-HT levels were lower, and DOPAC levels and DOPAC/DA and 5-HIAA/5-HT ratios higher in low exploring male but not female rats. Conclusively, female rats not only display higher levels of exploration but the population distribution of this behaviour is distinct; this may be related to differences in the monoaminergic systems between female and male animals.
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Affiliation(s)
- Kristi Liiver
- School of Natural Sciences and Health, Tallinn University, Narva Road 25, 10120 Tallinn, Estonia
| | - Sophie Imbeault
- School of Natural Sciences and Health, Tallinn University, Narva Road 25, 10120 Tallinn, Estonia
| | - Marianna Školnaja
- School of Natural Sciences and Health, Tallinn University, Narva Road 25, 10120 Tallinn, Estonia; Laboratory Animal Centre, Tallinn University of Technology, Akadeemia Road 15, 12618 Tallinn, Estonia
| | - Tanel Kaart
- Institute of Veterinary Medicine and Animal Science, Estonian University of Life Sciences, 51006 Tartu, Estonia
| | - Margus Kanarik
- Division of Neuropsychopharmacology, Institute of Chemistry, University of Tartu, Ravila 14A, 50411 Tartu, Estonia
| | - Karita Laugus
- Division of Neuropsychopharmacology, Institute of Chemistry, University of Tartu, Ravila 14A, 50411 Tartu, Estonia
| | - Jade De Wettinck
- School of Natural Sciences and Health, Tallinn University, Narva Road 25, 10120 Tallinn, Estonia
| | - Aleksander Pulver
- School of Natural Sciences and Health, Tallinn University, Narva Road 25, 10120 Tallinn, Estonia
| | - Ruth Shimmo
- School of Natural Sciences and Health, Tallinn University, Narva Road 25, 10120 Tallinn, Estonia
| | - Jaanus Harro
- School of Natural Sciences and Health, Tallinn University, Narva Road 25, 10120 Tallinn, Estonia; Division of Neuropsychopharmacology, Institute of Chemistry, University of Tartu, Ravila 14A, 50411 Tartu, Estonia; Institute of Biotechnology, HiLIFE, University of Helsinki, Viikinkaari 5D, 00014 Helsinki, Finland.
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Varela AJ, Melvin A. The theatre of depression: a role for physical therapy. Physiother Theory Pract 2022:1-17. [DOI: 10.1080/09593985.2022.2041136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Antonio J Varela
- School of Physical Therapy, Arkansas College of Health Education, Fort Smith, AR, USA
| | - Ann Melvin
- School of Social and Behavioral Sciences, Capella University, Minneapolis, MN, USA
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3
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van der Goot MH, Kooij M, Stolte S, Baars A, Arndt SS, van Lith HA. Incorporating inter-individual variability in experimental design improves the quality of results of animal experiments. PLoS One 2021; 16:e0255521. [PMID: 34351958 PMCID: PMC8341614 DOI: 10.1371/journal.pone.0255521] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Accepted: 07/16/2021] [Indexed: 11/19/2022] Open
Abstract
Inter-individual variability in quantitative traits is believed to potentially inflate the quality of results in animal experimentation. Yet, to our knowledge this effect has not been empirically tested. Here we test whether inter-individual variability in emotional response within mouse inbred strains affects the outcome of a pharmacological experiment. Three mouse inbred strains (BALB/c, C57BL/6 and 129S2) were behaviorally characterized through repeated exposure to a mild aversive stimulus (modified Hole Board, five consecutive trials). A multivariate clustering procedure yielded two multidimensional response types which were displayed by individuals of all three strains. We show that systematic incorporation of these individual response types in the design of a pharmacological experiment produces different results from an experimental pool in which this variation was not accounted for. To our knowledge, this is the first study that empirically confirms that inter-individual variability affects the interpretation of behavioral phenotypes and may obscure experimental results in a pharmacological experiment.
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Affiliation(s)
- Marloes H. van der Goot
- Faculty of Veterinary Medicine, Department Population Health Sciences, Section Animals in Science and Society, Utrecht University, Utrecht, the Netherlands
| | - Marieke Kooij
- Faculty of Veterinary Medicine, Department Population Health Sciences, Section Animals in Science and Society, Utrecht University, Utrecht, the Netherlands
| | - Suzanne Stolte
- Faculty of Veterinary Medicine, Department Population Health Sciences, Section Animals in Science and Society, Utrecht University, Utrecht, the Netherlands
| | - Annemarie Baars
- Faculty of Veterinary Medicine, Department Population Health Sciences, Section Animals in Science and Society, Utrecht University, Utrecht, the Netherlands
| | - Saskia S. Arndt
- Faculty of Veterinary Medicine, Department Population Health Sciences, Section Animals in Science and Society, Utrecht University, Utrecht, the Netherlands
| | - Hein A. van Lith
- Faculty of Veterinary Medicine, Department Population Health Sciences, Section Animals in Science and Society, Utrecht University, Utrecht, the Netherlands
- Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, the Netherlands
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Effect of Neuropeptide S Administration on Ultrasonic Vocalizations and Behaviour in Rats with Low vs. High Exploratory Activity. Pharmaceuticals (Basel) 2021; 14:ph14060524. [PMID: 34070724 PMCID: PMC8229755 DOI: 10.3390/ph14060524] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 05/26/2021] [Accepted: 05/27/2021] [Indexed: 12/20/2022] Open
Abstract
Neuropeptide S (NPS) is a peptide neurotransmitter that in animal studies promotes wakefulness and arousal with simultaneous anxiety reduction, in some inconsistency with results in humans. We examined the effect of NPS on rat ultrasonic vocalizations (USV) as an index of affective state and on behaviour in novel environments in rats with persistent inter-individual differences in exploratory activity. Adult male Wistar rats were categorised as of high (HE) or low (LE) exploratory activity and NPS was administered intracerebroventricularly (i.c.v.) at a dose of 1.0 nmol/5 µL, after which USVs were recorded in the home-cage and a novel standard housing cage, and behaviour evaluated in exploration/anxiety tests. NPS induced a massive production of long and short 22 kHz USVs in the home cage that continued later in the novel environment; no effect on 50 kHz USVs were found. In LE-rats, the long 22 kHz calls were emitted at lower frequencies and were louder. The effects of NPS on behaviour appeared novelty- and test-dependent. NPS had an anxiolytic-like effect in LE-rats only in the elevated zero-maze, whereas in HE-rats, locomotor activity in the zero-maze and in a novel standard cage was increased. Thus NPS appears as a psychostimulant peptide but with a complex effect on dimensions of affect.
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Vaher K, Anier K, Jürgenson M, Harro J, Kalda A. Cocaine-induced changes in behaviour and DNA methylation in rats are influenced by inter-individual differences in spontaneous exploratory activity. J Psychopharmacol 2020; 34:680-692. [PMID: 32338111 DOI: 10.1177/0269881120916137] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
BACKGROUND Individual differences in behavioural traits influence susceptibility to addictive disorders. Drug addiction involves changes in gene expression, proposed to occur via DNA methylation (DNAm). AIMS To investigate DNAm changes in reward-related brain structures (nucleus accumbens (NAc), lateral habenula (LHb)) in response to cocaine exposure in rats differing in spontaneous exploratory activity. METHODS Rats were observed in the exploration box and categorised as high- (HE) or low explorers (LE). Rats were administered vehicle or cocaine (12 mg/kg, i.p.) for 7 days, followed by a 14-day withdrawal period and cocaine challenge (7 mg/kg); horizontal locomotor activity was recorded. Brain tissue was dissected after 24 h; we analysed messenger RNA (mRNA) and activity levels of epigenetic DNA modifiers (DNMTs and TETs) as well as mRNA and promoter methylation levels at selected genes previously linked to addictive behaviours. RESULTS The cocaine challenge dose stimulated locomotor activity in both LE- and HE rats only when administered after a repeated cocaine schedule, suggesting development of behavioural sensitisation. Quantitative polymerase chain reaction analyses demonstrated higher basal expression of Dnmt3a, Tet2 and Tet3 in the LHb of HE- vs. LE rats, and we observed differential effects of cocaine exposure on the expression and activity of epigenetic DNA modifiers in the NAc and LHb of HE- and LE rats. Furthermore, cocaine exposure differentially altered promoter methylation levels of A2AR, Ppp1cc, and Taar7b in the NAc and LHb of HE- and LE rats. CONCLUSIONS DNAm might play a role in the HE- and LE phenotypes as well as mediate behavioural effects of LE- and HE rats in response to drugs of abuse.
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Affiliation(s)
- Kadi Vaher
- Department of Psychology, University of Tartu, Tartu, Estonia
| | - Kaili Anier
- Department of Pharmacology, University of Tartu, Tartu, Estonia
| | | | - Jaanus Harro
- Department of Psychology, University of Tartu, Tartu, Estonia
| | - Anti Kalda
- Department of Pharmacology, University of Tartu, Tartu, Estonia
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Nitric oxide synthase genotype interacts with stressful life events to increase aggression in male subjects in a population-representative sample. Eur Neuropsychopharmacol 2020; 30:56-65. [PMID: 31405541 DOI: 10.1016/j.euroneuro.2019.07.241] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Revised: 06/14/2019] [Accepted: 07/27/2019] [Indexed: 01/02/2023]
Abstract
Nitric oxide signalling has been implicated in impulsive and aggressive traits and behaviours in both animals and humans. In the present study, we investigated the effects of a functional variable number of tandem repeats (VNTR) polymorphism in exon 1f (ex1f) of the nitric oxide synthase 1 (NOS1) gene (NOS1 ex1f-VNTR) and stressful life events on aggressive behaviour in population representative sample of adolescents followed up from third grade to 25 years of age. We studied the younger cohort of the longitudinal Estonian Children Personality, Behaviour and Health Study (subjects in the last study wave n = 437, males n = 193; mean age 24.8 ± 0.5 years). Aggressive behaviour was rated at age 25 with the Illinois Bully Scale and Buss-Perry Aggression Questionnaire. Life history of aggression was evaluated in a structured interview. Stressful life events and family relationships were self-reported at age 15. The hypothesized risk genotype (homozygosity for the short allele) was associated with higher levels of aggression in males (statistical significance withstanding the multiple correction procedure). Exposure to stressful life events or adverse family relationships was associated with increased aggressive behaviour in subjects homozygous for either of the alleles, and these associations were mostly observed in males. However, these associations in these stratified analyses did not survive correction for multiple testing. Aggressiveness was relatively unaffected by the NOS1 ex1f-VNTR genotype in the female subjects even when taking exposure to childhood adversity into account. Our findings support the hypothesized involvement of a functional NOS1 polymorphism on aggression in a population representative sample of young adults.
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Kõiv K, Vares M, Kroon C, Metelitsa M, Tiitsaar K, Laugus K, Jaako K, Harro J. Effect of chronic variable stress on sensitization to amphetamine in high and low sucrose-consuming rats. J Psychopharmacol 2019; 33:1512-1523. [PMID: 31208275 DOI: 10.1177/0269881119856000] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Individual vulnerability to stress manifests in the interaction of innate properties and environment. There is a growing interest in the individual variability in vulnerability to stress and how it contributes to the development of psychiatric disorders. Intake of palatable substances is often measured in animal models. We have previously demonstrated that the consumption of sucrose solution is a stable trait in rats. AIMS The present study aimed to compare the sensitivity of rats with high vs low liquid sucrose consumption to chronic variable stress and the stress effect on behavioural sensitization to amphetamine. METHODS Male Wistar rats were subjected to a chronic stress regimen and subsequent repeated treatment with amphetamine (1 mg/kg, intraperitoneally). Fifty-kHz ultrasonic vocalizations, locomotor activity and stereotypies were measured. RESULTS In no-stress baseline conditions, the behavioural response to acute amphetamine was similar in rats with high vs low sucrose consumption. Prior chronic stress potentiated the effect of amphetamine only in rats with high sucrose consumption. Behavioural sensitization to repeated administration of amphetamine was observed in non-stressed rats with lower sucrose preference, but not in the respective stressed group that had increased monoamine turnover in the nucleus accumbens. In contrast, in rats with high sucrose preference the amphetamine sensitization effect was prevalent in stressed rats, but not in non-stressed animals. INTERPRETATION Chronic stress can change the psychostimulant effect but this depends on the inherent reward sensitivity of the animal. Trait-wise, sucrose intake reflects vulnerability to chronic stress and may interact with the development of addiction.
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Affiliation(s)
- Kadri Kõiv
- Department of Psychology, University of Tartu, Tartu, Estonia
| | - Marten Vares
- Department of Psychology, University of Tartu, Tartu, Estonia
| | - Cristina Kroon
- Department of Psychology, University of Tartu, Tartu, Estonia
| | - Mait Metelitsa
- Department of Psychology, University of Tartu, Tartu, Estonia
| | - Kai Tiitsaar
- Department of Psychology, University of Tartu, Tartu, Estonia
| | - Karita Laugus
- Department of Psychology, University of Tartu, Tartu, Estonia
| | - Külli Jaako
- Department of Pharmacology, University of Tartu, Tartu, Estonia
| | - Jaanus Harro
- Department of Psychology, University of Tartu, Tartu, Estonia
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Reisinger SN, Kong E, Molz B, Humberg T, Sideromenos S, Cicvaric A, Steinkellner T, Yang J, Cabatic M, Monje FJ, Sitte HH, Nichols BJ, Pollak DD. Flotillin-1 interacts with the serotonin transporter and modulates chronic corticosterone response. GENES, BRAIN, AND BEHAVIOR 2019; 18:e12482. [PMID: 29667320 PMCID: PMC6392109 DOI: 10.1111/gbb.12482] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/13/2018] [Revised: 04/05/2018] [Accepted: 04/12/2018] [Indexed: 01/08/2023]
Abstract
Aberrant serotonergic neurotransmission in the brain is considered at the core of the pathophysiological mechanisms involved in neuropsychiatric disorders. Gene by environment interactions contribute to the development of depression and involve modulation of the availability and functional activity of the serotonin transporter (SERT). Using behavioral and in vivo electrophysiological approaches together with biochemical, molecular-biological and molecular imaging tools we establish Flotillin-1 (Flot1) as a novel protein interacting with SERT and demonstrate its involvement in the response to chronic corticosterone (CORT) treatment. We show that genetic Flot1 depletion augments chronic CORT-induced behavioral despair and describe concomitant alterations in the expression of SERT, activity of serotonergic neurons and alterations of the glucocorticoid receptor transport machinery. Hence, we propose a role for Flot1 as modulatory factor for the depressogenic consequences of chronic CORT exposure and suggest Flotillin-1-dependent regulation of SERT expression and activity of serotonergic neurotransmission at the core of the molecular mechanisms involved.
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Affiliation(s)
- S. N. Reisinger
- Department of Neurophysiology and NeuropharmacologyCenter for Physiology and Pharmacology, Medical University of ViennaViennaAustria
| | - E. Kong
- Department of Neurophysiology and NeuropharmacologyCenter for Physiology and Pharmacology, Medical University of ViennaViennaAustria
| | - B. Molz
- Department of Neurophysiology and NeuropharmacologyCenter for Physiology and Pharmacology, Medical University of ViennaViennaAustria
| | - T. Humberg
- Department of Neurophysiology and NeuropharmacologyCenter for Physiology and Pharmacology, Medical University of ViennaViennaAustria
| | - S. Sideromenos
- Department of Neurophysiology and NeuropharmacologyCenter for Physiology and Pharmacology, Medical University of ViennaViennaAustria
| | - A. Cicvaric
- Department of Neurophysiology and NeuropharmacologyCenter for Physiology and Pharmacology, Medical University of ViennaViennaAustria
| | - T. Steinkellner
- Department of PharmacologyCenter for Physiology and Pharmacology, Medical University of ViennaViennaAustria
| | - J.‐W. Yang
- Department of PharmacologyCenter for Physiology and Pharmacology, Medical University of ViennaViennaAustria
| | - M. Cabatic
- Department of Neurophysiology and NeuropharmacologyCenter for Physiology and Pharmacology, Medical University of ViennaViennaAustria
| | - F. J. Monje
- Department of Neurophysiology and NeuropharmacologyCenter for Physiology and Pharmacology, Medical University of ViennaViennaAustria
| | - H. H. Sitte
- Department of PharmacologyCenter for Physiology and Pharmacology, Medical University of ViennaViennaAustria
| | | | - D. D. Pollak
- Department of Neurophysiology and NeuropharmacologyCenter for Physiology and Pharmacology, Medical University of ViennaViennaAustria
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Harro J. Animal models of depression: pros and cons. Cell Tissue Res 2018; 377:5-20. [PMID: 30560458 DOI: 10.1007/s00441-018-2973-0] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Accepted: 11/23/2018] [Indexed: 12/11/2022]
Abstract
Animal models of depression are certainly needed but the question in the title has been raised owing to the controversies in the interpretation of the readout in a number of tests, to the perceived lack of progress in the development of novel treatments and to the expressed doubts in whether animal models can offer anything to make a true breakthrough in understanding the neurobiology of depression and producing novel drugs against depression. Herewith, it is argued that if anything is wrong with animal models, including those for depression, it is not about the principle of modelling complex human disorder in animals but in the way the tests are selected, conducted and interpreted. Further progress in the study of depression and in developing new treatments, will be supported by animal models of depression if these were more critically targeted to drug screening vs. studies of underlying neurobiology, clearly stratified to vulnerability and pathogenetic models, focused on well-defined endophenotypes and validated for each setting while bearing the existing limits to validation in mind. Animal models of depression need not to rely merely on behavioural readouts but increasingly incorporate neurobiological measures as the understanding of depression as human brain disorder advances. Further developments would be fostered by cross-fertilizinga translational approach that is bidirectional, research on humans making more use of neurobiological findings in animals.
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Affiliation(s)
- Jaanus Harro
- Division of Neuropsychopharmacology, Department of Psychology, Estonian Centre of Behavioural and Health Sciences, University of Tartu, Ravila 14A Chemicum, 50411, Tartu, Estonia.
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Animals, anxiety, and anxiety disorders: How to measure anxiety in rodents and why. Behav Brain Res 2018; 352:81-93. [DOI: 10.1016/j.bbr.2017.10.016] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Revised: 10/12/2017] [Accepted: 10/14/2017] [Indexed: 12/31/2022]
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Kurrikoff T, Kaarma K, Tooding LM, Vaht M, Tulviste T, Veidebaum T, Harro J. Association of the COMT Val108/158Met genotype with professional career and education: The Val-allele is more frequent in managers and in enterprising occupations. PERSONALITY AND INDIVIDUAL DIFFERENCES 2018. [DOI: 10.1016/j.paid.2017.05.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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12
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Sociability trait and regional cerebral oxidative metabolism in rats: Predominantly nonlinear relations. Behav Brain Res 2018; 337:186-192. [DOI: 10.1016/j.bbr.2017.08.049] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2017] [Revised: 08/25/2017] [Accepted: 08/28/2017] [Indexed: 12/15/2022]
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Lehner M, Gryz M, Wisłowska-Stanek A, Turzyńska D, Sobolewska A, Skórzewska A, Płaźnik A. The amphetamine-associated context exerts a stronger motivational effect in low-anxiety rats than in high-anxiety rats. Behav Brain Res 2017; 330:97-107. [PMID: 28479265 DOI: 10.1016/j.bbr.2017.05.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Revised: 04/27/2017] [Accepted: 05/03/2017] [Indexed: 11/28/2022]
Abstract
This study used the conditioned place preference test to explore the effects of subchronic amphetamine administration on drug-associated cues in rats with different emotional reactivity. We also examined the changes in markers of dopaminergic activity in brain regions in response to the amphetamine-paired context, after a withdrawal period preceded by subchronic amphetamine treatment. We used low-anxiety (LR) and high-anxiety (HR) rats, which are known to exhibit distinct levels of susceptibility to amphetamine. Compared to HR rats, LR rats spent significantly more time in the amphetamine-paired compartment after the withdrawal period preceded by subchronic amphetamine treatment. Compared to HR control rats, LR control rats showed higher expression of the D1 receptor in the nucleus accumbens core (NAC core) and basolateral amygdala and higher expression of the D2 receptor in the NAC core. After the amphetamine treatment and withdrawal period, the LR rats showed higher D1 receptor expression in the NAC core, an increased level of homovanilic acid (HVA) in the prefrontal cortex, the NAC and the central amygdala than HR rats, as well as lower D2 receptor expression in the NAC core and the amygdala than LR control rats. These results indicate that the differences in the activity of the dopaminergic mesolimbic system in the HR and LR rats are maintained and even enhanced after a multi-day break in the use of the drug, indicating the occurrence of sensitisation. These findings show that the innate reactivity of the limbic dopaminergic innervations, dependent on the level of emotional reactivity, may significantly and chronically modify the development and maintenance of sensitisation to amphetamine.
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Affiliation(s)
- Małgorzata Lehner
- Department of Neurochemistry, Institute of Psychiatry and Neurology, 9 Sobieskiego Street, 02-957 Warsaw, Poland.
| | - Marek Gryz
- Department of Neurochemistry, Institute of Psychiatry and Neurology, 9 Sobieskiego Street, 02-957 Warsaw, Poland
| | - Aleksandra Wisłowska-Stanek
- Department of Experimental and Clinical Pharmacology, Medical University of Warsaw, Centre for Preclinical Research and Technology CEPT, 1B Banacha Streeet, 02-097 Warsaw, Poland
| | - Danuta Turzyńska
- Department of Neurochemistry, Institute of Psychiatry and Neurology, 9 Sobieskiego Street, 02-957 Warsaw, Poland
| | - Alicja Sobolewska
- Department of Neurochemistry, Institute of Psychiatry and Neurology, 9 Sobieskiego Street, 02-957 Warsaw, Poland
| | - Anna Skórzewska
- Department of Neurochemistry, Institute of Psychiatry and Neurology, 9 Sobieskiego Street, 02-957 Warsaw, Poland
| | - Adam Płaźnik
- Department of Neurochemistry, Institute of Psychiatry and Neurology, 9 Sobieskiego Street, 02-957 Warsaw, Poland; Department of Experimental and Clinical Pharmacology, Medical University of Warsaw, Centre for Preclinical Research and Technology CEPT, 1B Banacha Streeet, 02-097 Warsaw, Poland
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Carreira MB, Cossio R, Britton GB. Individual and sex differences in high and low responder phenotypes. Behav Processes 2017; 136:20-27. [DOI: 10.1016/j.beproc.2017.01.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 01/03/2017] [Accepted: 01/09/2017] [Indexed: 11/29/2022]
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15
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Kaska S, Brunk R, Bali V, Kechner M, Mazei-Robison MS. Deletion of Rictor in catecholaminergic neurons alters locomotor activity and ingestive behavior. Neuropharmacology 2017; 117:158-170. [PMID: 28167137 DOI: 10.1016/j.neuropharm.2017.02.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 01/31/2017] [Accepted: 02/02/2017] [Indexed: 01/09/2023]
Abstract
While the etiology of depression is not fully understood, increasing evidence from animal models suggests a role for the ventral tegmental area (VTA) in pathogenesis. In this paper, we investigate the potential role of VTA mechanistic target of rapamycin 2 (TORC2) signaling in mediating susceptibility to chronic social defeat stress (CSDS), a well-established mouse model of depression. Utilizing genetic and viral knockout of Rictor (rapamycin-insensitive companion of target of rapamycin), a requisite component of TORC2, we demonstrate that decreasing Rictor-dependent TORC2 signaling in catecholaminergic neurons, or within the VTA specifically, does not alter susceptibility to CSDS. Opiate abuse and mood disorders are often comorbid, and previous data demonstrate a role for VTA TORC2 in mediating opiate reward. Thus, we also investigated its potential role in mediating changes in opiate reward following CSDS. Catecholaminergic deletion of Rictor increases water, sucrose, and morphine intake but not preference in a two-bottle choice assay in stress-naïve mice, and these effects are maintained after stress. VTA-specific knockout of Rictor increases water and sucrose intake after physical CSDS, but does not alter consummatory behavior in the absence of stress. These findings suggest a novel role for TORC2 in mediating stress-induced changes in consummatory behaviors that may contribute to some aspects of mood disorders.
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Affiliation(s)
- Sophia Kaska
- Dept. of Pharmacology and Toxicology, Michigan State University, East Lansing, MI 48824, United States
| | - Rebecca Brunk
- Neuroscience Program, Michigan State University, East Lansing, MI 48824, United States
| | - Vedrana Bali
- Dept. of Physiology, Michigan State University, East Lansing, MI 48824, United States
| | - Megan Kechner
- Neuroscience Program, Michigan State University, East Lansing, MI 48824, United States
| | - Michelle S Mazei-Robison
- Neuroscience Program, Michigan State University, East Lansing, MI 48824, United States; Dept. of Physiology, Michigan State University, East Lansing, MI 48824, United States.
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Vasconcelos M, Stein DJ, de Almeida RMM. Social defeat protocol and relevant biomarkers, implications for stress response physiology, drug abuse, mood disorders and individual stress vulnerability: a systematic review of the last decade. TRENDS IN PSYCHIATRY AND PSYCHOTHERAPY 2016. [PMID: 26222297 DOI: 10.1590/2237-6089-2014-0034] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
INTRODUCTION Social defeat (SD) in rats, which results from male intraspecific confrontations, is ethologically relevant and useful to understand stress effects on physiology and behavior. METHODS A systematic review of studies about biomarkers induced by the SD protocol and published from 2002 to 2013 was carried out in the electronic databases PubMed, Web of Knowledge and ScienceDirect. The search terms were: social defeat, rat, neurotrophins, neuroinflammatory markers, and transcriptional factors. RESULTS Classical and recently discovered biomarkers were found to be relevant in stress-induced states. Findings were summarized in accordance to the length of exposure to stress: single, repeated, intermittent and continuous SD. This review found that the brain-derived neurotrophic factor (BDNF) is a distinct marker of stress adaptation. Along with glucocorticoids and catecholamines, BDNF seems to be important in understanding stress physiology. CONCLUSION The SD model provides a relevant tool to study stress response features, development of addictive behaviors, clinic depression and anxiety, as well as individual differences in vulnerability and resilience to stress.
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Affiliation(s)
- Mailton Vasconcelos
- Instituto de Psicologia, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Dirson João Stein
- Hospital de Clínicas de Porto Alegre, UFRGS, Porto Alegre, RS, Brazil
| | - Rosa Maria M de Almeida
- Instituto de Psicologia, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
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O’Leary A, Kõiv K, Raudkivi K, Harro J. Antidepressants differentially affect striatal amphetamine-stimulated dopamine and serotonin release in rats with high and low novelty-oriented behaviour. Pharmacol Res 2016; 113:739-746. [DOI: 10.1016/j.phrs.2016.02.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/25/2015] [Revised: 02/01/2016] [Accepted: 02/01/2016] [Indexed: 11/24/2022]
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Harro J, Oreland L. The role of MAO in personality and drug use. Prog Neuropsychopharmacol Biol Psychiatry 2016; 69:101-11. [PMID: 26964906 DOI: 10.1016/j.pnpbp.2016.02.013] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Revised: 02/16/2016] [Accepted: 02/17/2016] [Indexed: 02/04/2023]
Abstract
Monoamine oxidases, both MAO-A and MAO-B, have been implicated in personality traits and complex behaviour, including drug use. Findings supporting the involvement of MAO-A and MAO-B in shaping personality and in the development of strategies of making behavioural choices come from a variety of studies that have examined either prevalence of gene variants in clinical groups or population-derived samples, estimates of enzyme activity in blood or, by positron emission tomography, in the brain and, most recently, measurement of methylation of the gene. Most of the studies converge in associating MAO-A and MAO-B with impulsive, aggressive or antisocial personality traits or behaviours, including alcohol-related problems, and for MAO-A available evidence strongly supports interaction with adverse environmental exposures in childhood. What is known about genotype effects, and on expression and activity of the enzyme in the brain and in blood has not yet been possible to unite into a mechanistic model of the role of monoamine systems, but the reason for this low degree of generalization is likely caused by the cross-sectional nature of investigation that has not incorporated the developmental effects of MAO-s in critical time windows, including the foetal period. The "risk variants" of both MAO-s appear to increase behavioural plasticity, as supportive environments may particularly well enhance the hidden potential of their carriers. Importantly, male and female brain and behaviours have been found very different with regard to MAO×life events interaction. Future studies need to take into consideration these developmental aspects and sex/gender, as well as to specify the role of different types of environmental factors.
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Affiliation(s)
- Jaanus Harro
- Division of Neuropsychopharmacology, Department of Psychology, Estonian Centre of Behavioural and Health Sciences, University of Tartu, Estonia; Psychiatry Clinic, North Estonia Medical Centre, Tallinn, Estonia.
| | - Lars Oreland
- Department of Neuroscience, Pharmacology, University of Uppsala, Biomedical Centre, Uppsala, Sweden
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Vaht M, Kiive E, Veidebaum T, Harro J. A Functional Vesicular Monoamine Transporter 1 (VMAT1) Gene Variant Is Associated with Affect and the Prevalence of Anxiety, Affective, and Alcohol Use Disorders in a Longitudinal Population-Representative Birth Cohort Study. Int J Neuropsychopharmacol 2016; 19:pyw013. [PMID: 26861143 PMCID: PMC4966275 DOI: 10.1093/ijnp/pyw013] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Accepted: 02/04/2016] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Inter-individual differences in the monoaminergic systems have been shown to moderate the risk for a lifetime history of anxiety, affective, and alcohol use disorders. A common single nucleotide polymorphism in the vesicular monoamine transporter 1 gene (VMAT1 rs1390938 G/A; Thr136Ile) has been reported as functional in vitro and associated with bipolar disorder and anxiety. We aimed at assessing the association between the VMAT1 genotype, affect, and affect-related psychiatric disorders in a longitudinal population-representative study. METHODS We used the database of the Estonian Children Personality Behaviour and Health Study (beginning in 1998). Cohorts of initially 9- (recalled at ages 15 and 18 years, n=579) and 15- (recalled at ages 18 and 25 years; n=654) year-old children provided self-reports on impulsivity, anxiety, depressiveness, neuroticism, and alcohol use. In addition, psychiatric assessment based on DSM-IV was carried out in the older cohort at age 25 years. RESULTS Subjects homozygous for the less prevalent A (136Ile) allele reported lower maladaptive impulsivity, state and trait anxiety, depressiveness, and neuroticism and were less likely to have been diagnosed with an affective, anxiety, and/or alcohol use disorder by young adulthood. While in the younger cohort alcohol use started at younger age, this birth cohort effect was dependent on genotype: only G allele carriers and in particular the GG homozygotes started alcohol use earlier. CONCLUSIONS VMAT1 rs1390938/Thr136Ile is associated with mood, personality, and alcohol use in the general population. Subjects homozygous for the "hyperfunction" allele (AA; Ile/Ile) appear to be more resilient to these disorders.
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Affiliation(s)
- Mariliis Vaht
- Division of Neuropsychopharmacology, Department of Psychology, Estonian Centre of Behavioural and Health Sciences (Ms Vaht and Dr Harro), and Department of Educational Science, Faculty of Social Sciences and Education, University of Tartu, Tartu, Estonia (Dr Kiive); National Institute for Health Development, Estonian Centre of Behavioural and Health Sciences, Tallinn, Estonia (Dr Veidebaum)
| | - Evelyn Kiive
- Division of Neuropsychopharmacology, Department of Psychology, Estonian Centre of Behavioural and Health Sciences (Ms Vaht and Dr Harro), and Department of Educational Science, Faculty of Social Sciences and Education, University of Tartu, Tartu, Estonia (Dr Kiive); National Institute for Health Development, Estonian Centre of Behavioural and Health Sciences, Tallinn, Estonia (Dr Veidebaum)
| | - Toomas Veidebaum
- Division of Neuropsychopharmacology, Department of Psychology, Estonian Centre of Behavioural and Health Sciences (Ms Vaht and Dr Harro), and Department of Educational Science, Faculty of Social Sciences and Education, University of Tartu, Tartu, Estonia (Dr Kiive); National Institute for Health Development, Estonian Centre of Behavioural and Health Sciences, Tallinn, Estonia (Dr Veidebaum)
| | - Jaanus Harro
- Division of Neuropsychopharmacology, Department of Psychology, Estonian Centre of Behavioural and Health Sciences (Ms Vaht and Dr Harro), and Department of Educational Science, Faculty of Social Sciences and Education, University of Tartu, Tartu, Estonia (Dr Kiive); National Institute for Health Development, Estonian Centre of Behavioural and Health Sciences, Tallinn, Estonia (Dr Veidebaum).
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Middle-range exploratory activity in adult rats suggests higher resilience to chronic social defeat. Acta Neuropsychiatr 2016; 28:125-40. [PMID: 26669552 DOI: 10.1017/neu.2015.64] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
OBJECTIVE Stressful life events play an important role in the aetiology of human mood disorders and are frequently modelled by chronic social defeat (SD) in rodents. Exploratory phenotype in rats is a stable trait that is likely related to inter-individual differences in reactivity to stress. The aim of the study was to confirm that low levels of exploratory activity (LE) are, in rodents, a risk factor for passive stress coping, and to clarify the role of medium (ME) and high (HE) exploratory disposition in the sensitivity to SD. METHODS We examined the effect of SD on male Wistar rats with LE, ME, and HE activity levels as measured in the exploration box. After SD, the rats were evaluated in social preference, elevated zero maze, and open-field tests. Brain tissue levels of monoamines were measured by high-performance liquid chromatography. RESULTS Rats submitted to SD exhibited lower weight gain, higher sucrose consumption, showed larger stress-induced hyperthermia, lower levels of homovanillic acid in the frontal cortex, and higher levels of noradrenaline in the amygdala and hippocampus. Open-field, elevated zero maze, and social preference tests revealed the interaction between stress and phenotype, as only LE-rats were further inhibited by SD. ME-rats exhibited the least reactivity to stress in terms of changes in body weight, stress-induced hyperthermia, and sucrose intake. CONCLUSION Both low and high novelty-related activity, especially the former, are associated with elevated sensitivity to social stress. This study shows that both tails of a behavioural dimension can produce stress-related vulnerability.
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Rao RM, Sadananda M. Influence of State and/or Trait Anxieties of Wistar Rats in an Anxiety Paradigm. Ann Neurosci 2016; 23:44-50. [PMID: 27536021 PMCID: PMC4934415 DOI: 10.1159/000443555] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2015] [Accepted: 11/24/2015] [Indexed: 11/19/2022] Open
Abstract
Systematic individual differences between male Wistar rats can be detected in paradigms such as the elevated plus maze (EPM), which is a widely used behavioral paradigm that measures fear-motivated avoidance behavior. It has been extensively used to assess anxiety profiles with face, construct and predictive validities. During a typical EPM test, animals actively avoid the open arms in favour of the closed arms. We investigated whether individuals carry inherent trait anxiety profiles and whether perturbations of different intensities influence anxiety measures. Inherent anxiety levels and coping strategies following stress have become critical determinants in pre-disposition to other neuropsychiatric disorders and affect biomedical interventions in individuals. One group of rats was screened on EPM and in the activity box. Another set of rats were randomly divided into groups and subjected to perturbations of acute and sub-chronic isolation or restraint and tested in the EPM. Based on open-arm time in the EPM, low or high anxiety profiles were identified with significant differences in all measures. Perturbations of different intensities induced differential anxiety measures as expressed in the EPM. Anxiety levels were significantly reduced in sub-chronic restrained subjects, while isolation did not show marked difference. Anxiety profiles become evident from broad sample sizes and could constitute a critical limiting factor in personalized treatments. Stress-induced anxiety disorders could implicate comorbidity to other neuropsychiatric disorders in individuals. Coping strategies come to the fore in repeated sub-chronic perturbations indicating adaptive responses to the stressor, while acute perturbation enhances expression of anxiety behaviors.
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Affiliation(s)
- Rashmi Madhava Rao
- Brain Research Laboratory, Biotechnology Division, Department of Biosciences, Mangalore University, Mangalagangothri, Mangalore, India
| | - Monika Sadananda
- Brain Research Laboratory, Biotechnology Division, Department of Biosciences, Mangalore University, Mangalagangothri, Mangalore, India
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Lehto K, Mäestu J, Kiive E, Veidebaum T, Harro J. BDNF Val66Met genotype and neuroticism predict life stress: A longitudinal study from childhood to adulthood. Eur Neuropsychopharmacol 2016; 26:562-9. [PMID: 26738427 DOI: 10.1016/j.euroneuro.2015.12.029] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Revised: 11/17/2015] [Accepted: 12/14/2015] [Indexed: 11/25/2022]
Abstract
The brain-derived neurotrophic factor gene (BDNF) Val66Met polymorphism and life stress have been associated with negative emotionality (e.g., neuroticism), but relevant evidence is far from unequivocal. Possible confounding factors include the type and timing of stressful events measured, such as childhood adversity vs. recent stressful events, and variable gene × environment interactions. The aim of this study was to longitudinally assess the BDNF Val66Met polymorphism and environment interaction effect on neuroticism in a population representative sample, depending upon the type of stress, gender and family relations. In the original older cohort of the Estonian Children Personality Behavior and Health Study (ECPBHS, n=593), neuroticism was measured at age 15 (parental assessment), 18 and 25 (self-assessments). Childhood stress was reported at age 15, quality of family relations was measured at age 18, and recent stressful life events at age 25. The BDNF Val66Met polymorphism interacted with recent stressful life events, but not with childhood adversities, to impact neuroticism. Interestingly, in female participants, neuroticism at age 18 predicted future stressful life events dependent upon genotype: individuals with Val/Val genotype and high neuroticism experienced higher, but Met-allele carriers with high neuroticism lower stress exposure at age 25. Similar tendencies were observed using parental assessments at age 15. The protective effect of Met-allele in the high stress exposure group could result from better early family environment. In conclusion, we herewith provide further evidence for a role of BDNF gene variance contributing to plasticity in response to environmental demands.
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Affiliation(s)
- Kelli Lehto
- Division of Neuropsychopharmacology, Department of Psychology, Estonian Centre of Behavioural and Health Sciences, University of Tartu, Ravila 14A, 50411 Tartu, Estonia; National Institute for Health Development, Estonian Centre of Behavioural and Health Sciences, Tallinn, Estonia
| | - Jarek Mäestu
- Department of Sports Biology and Physiotherapy, Estonian Centre of Behavioural and Health Sciences, University of Tartu, Tartu, Estonia
| | - Evelyn Kiive
- Division of Neuropsychopharmacology, Department of Psychology, Estonian Centre of Behavioural and Health Sciences, University of Tartu, Ravila 14A, 50411 Tartu, Estonia
| | - Toomas Veidebaum
- National Institute for Health Development, Estonian Centre of Behavioural and Health Sciences, Tallinn, Estonia
| | - Jaanus Harro
- Division of Neuropsychopharmacology, Department of Psychology, Estonian Centre of Behavioural and Health Sciences, University of Tartu, Ravila 14A, 50411 Tartu, Estonia.
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Tulviste T, Kiive E, Akkermann K, Harro J. Fears in the General Population: More Frequent in Females and Associated With the Serotonin Transporter Promoter Polymorphism and Perceived Relationship With Mothers. J Child Neurol 2015; 30:1459-65. [PMID: 25688072 DOI: 10.1177/0883073815570151] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Accepted: 01/04/2015] [Indexed: 02/03/2023]
Abstract
This study aimed to examine the structure of fears of youth, and its associations with gender, genetic variation of the serotonin transporter (5-HTTLPR), and perceived maternal acceptance/rejection and control, in a population-representative sample. Participants were 453 adolescents and 540 young adults. Fears were assessed by a 18-item Fear Questionnaire, and perceived maternal relationships by the Mother Acceptance-Rejection/Control Questionnaire. A structured psychiatric interview was used to assess current and lifetime psychiatric disorders in participants from the older cohort. A principal component analyses indicated 2 components, named Fear/Phobia and Panic/Despair. Females expressed higher level of fears and symptoms of despair regardless of the serotonin transporter genotype. The 5-HTTLPR genotype nevertheless played a role in the association between fears and perceived relationships: in S/S-genotype, more Fear/Phobia was reported by the participants who perceived greater maternal acceptance in combination with strict maternal control, and had a history of psychiatric disorder.
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Affiliation(s)
- Tiia Tulviste
- Centre of Behavioral and Health Sciences, University of Tartu, Tartu, Estonia
| | - Evelyn Kiive
- Centre of Behavioral and Health Sciences, University of Tartu, Tartu, Estonia
| | - Kirsti Akkermann
- Centre of Behavioral and Health Sciences, University of Tartu, Tartu, Estonia
| | - Jaanus Harro
- Centre of Behavioral and Health Sciences, University of Tartu, Tartu, Estonia
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Raudkivi K, Alttoa A, Leito I, Harro J. Differences in extracellular glutamate levels in striatum of rats with high and low exploratory activity. Pharmacol Rep 2015; 67:858-65. [DOI: 10.1016/j.pharep.2015.02.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Revised: 01/06/2015] [Accepted: 02/02/2015] [Indexed: 11/25/2022]
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Immobility time during the forced swimming test predicts sensitivity to amitriptyline, whereas traveled distance in the circular corridor indicates resistance to treatment in female Wistar rats. Neuroreport 2015; 26:233-8. [DOI: 10.1097/wnr.0000000000000324] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Harro J, Kanarik M, Kaart T, Matrov D, Kõiv K, Mällo T, Del Río J, Tordera RM, Ramirez MJ. Revealing the cerebral regions and networks mediating vulnerability to depression: oxidative metabolism mapping of rat brain. Behav Brain Res 2014; 267:83-94. [PMID: 24662150 DOI: 10.1016/j.bbr.2014.03.019] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2013] [Revised: 03/09/2014] [Accepted: 03/13/2014] [Indexed: 01/13/2023]
Abstract
The large variety of available animal models has revealed much on the neurobiology of depression, but each model appears as specific to a significant extent, and distinction between stress response, pathogenesis of depression and underlying vulnerability is difficult to make. Evidence from epidemiological studies suggests that depression occurs in biologically predisposed subjects under impact of adverse life events. We applied the diathesis-stress concept to reveal brain regions and functional networks that mediate vulnerability to depression and response to chronic stress by collapsing data on cerebral long term neuronal activity as measured by cytochrome c oxidase histochemistry in distinct animal models. Rats were rendered vulnerable to depression either by partial serotonergic lesion or by maternal deprivation, or selected for a vulnerable phenotype (low positive affect, low novelty-related activity or high hedonic response). Environmental adversity was brought about by applying chronic variable stress or chronic social defeat. Several brain regions, most significantly median raphe, habenula, retrosplenial cortex and reticular thalamus, were universally implicated in long-term metabolic stress response, vulnerability to depression, or both. Vulnerability was associated with higher oxidative metabolism levels as compared to resilience to chronic stress. Chronic stress, in contrast, had three distinct patterns of effect on oxidative metabolism in vulnerable vs. resilient animals. In general, associations between regional activities in several brain circuits were strongest in vulnerable animals, and chronic stress disrupted this interrelatedness. These findings highlight networks that underlie resilience to stress, and the distinct response to stress that occurs in vulnerable subjects.
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Affiliation(s)
- Jaanus Harro
- Department of Psychology, Estonian Centre of Behavioural and Health Sciences, University of Tartu, Ravila 14A, 50411 Tartu, Estonia.
| | - Margus Kanarik
- Department of Psychology, Estonian Centre of Behavioural and Health Sciences, University of Tartu, Ravila 14A, 50411 Tartu, Estonia
| | - Tanel Kaart
- Institute of Veterinary Medicine and Animal Sciences, Estonian University of Life Sciences, Kreutzwaldi 1, 51014 Tartu, Estonia
| | - Denis Matrov
- Department of Psychology, Estonian Centre of Behavioural and Health Sciences, University of Tartu, Ravila 14A, 50411 Tartu, Estonia
| | - Kadri Kõiv
- Department of Psychology, Estonian Centre of Behavioural and Health Sciences, University of Tartu, Ravila 14A, 50411 Tartu, Estonia
| | - Tanel Mällo
- Department of Psychology, Estonian Centre of Behavioural and Health Sciences, University of Tartu, Ravila 14A, 50411 Tartu, Estonia
| | - Joaquin Del Río
- Department of Pharmacology, School of Medicine, University of Navarra, Irunlarrea 1, 31008 Pamplona, Spain
| | - Rosa M Tordera
- Department of Pharmacology, School of Medicine, University of Navarra, Irunlarrea 1, 31008 Pamplona, Spain
| | - Maria J Ramirez
- Department of Pharmacology, School of Medicine, University of Navarra, Irunlarrea 1, 31008 Pamplona, Spain
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Laas K, Reif A, Kiive E, Domschke K, Lesch KP, Veidebaum T, Harro J. A functional NPSR1 gene variant and environment shape personality and impulsive action: a longitudinal study. J Psychopharmacol 2014; 28:227-36. [PMID: 23325374 DOI: 10.1177/0269881112472562] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Neuropeptide S and its receptor NPSR1 are involved in the regulation of arousal, attention and anxiety. We examined whether the NPSR1 gene functional polymorphism Asn¹⁰⁷Ile (rs324981, A>T) influences personality, impulsivity, and attention-deficit/hyperactivity disorder (ADHD)-related symptoms in a population-representative sample, and whether any eventual associations depend on age, sex, family relations and stressful life events (SLE). We used self-reports or teachers' ratings for both the younger (n=593) and older (n=583) cohort of the longitudinal Estonian Children Personality, Behaviour and Health Study. Males with the TT genotype displayed more ADHD-related symptoms. Adaptive impulsivity and Extraversion increased the most from age 18 to 25. While highest increases were observed in AA men, TT women exhibited the largest decreases. For participants with the AA genotype, Warmth in family was inversely associated with Neuroticism, and positively associated with Extraversion and Adaptive impulsivity. High exposure to SLE increased impulsivity and ADHD scores in TT genotype subjects. We conclude that the NPSR1 A/T polymorphism is associated with impulsivity, ADHD symptoms and personality, mirroring the activity- and anxiety-mediating role of NPSR1. Heterozygous individuals were the least sensitive to environmental factors, whereas subjects with the AA genotype and TT genotype reacted to different types of environmental adversities.
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Affiliation(s)
- Kariina Laas
- 1Department of Psychology, University of Tartu, Estonian Centre of Behavioural and Health Sciences, Tartu, Estonia
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Pitychoutis PM, Sanoudou D, Papandreou M, Nasias D, Kouskou M, Tomlinson CR, Tsonis PA, Papadopoulou-Daifoti Z. Forced swim test induces divergent global transcriptomic alterations in the hippocampus of high versus low novelty-seeker rats. Hum Genomics 2014; 8:4. [PMID: 24568636 PMCID: PMC3941591 DOI: 10.1186/1479-7364-8-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Accepted: 02/14/2014] [Indexed: 01/17/2023] Open
Abstract
BACKGROUND Many neuropsychiatric disorders, including stress-related mood disorders, are complex multi-parametric syndromes. Susceptibility to stress and depression is individually different. The best animal model of individual differences that can be used to study the neurobiology of affect regards spontaneous reactions to novelty. Experimentally, when naive rats are exposed to the stress of a novel environment, they display a highly variable exploratory activity and are classified as high or low responders (HR or LR, respectively). Importantly, HR and LR rats do not seem to exhibit a substantial differentiation in relation to their 'depressive-like' status in the forced swim test (FST), a widely used animal model of 'behavioral despair'. In the present study, we investigated whether FST exposure would be accompanied by phenotype-dependent differences in hippocampal gene expression in HR and LR rats. RESULTS HR and LR rats present a distinct behavioral pattern in the pre-test session but develop comparable depressive-like status in the second FST session. At 24 h following the second FST session, HR and LR rats (stressed and unstressed controls) were sacrificed and hippocampal samples were independently analyzed on whole rat genome Illumina arrays. Functional analysis into pathways and networks was performed using Ingenuity Pathway Analysis (IPA) software. Notably, hippocampal gene expression signatures between HR and LR rats were markedly divergent, despite their comparable depressive-like status in the FST. These molecular differences are reflected in both the extent of transcriptional remodeling (number of significantly changed genes) and the types of molecular pathways affected following FST exposure. A markedly higher number of genes (i.e., 2.28-fold) were statistically significantly changed following FST in LR rats, as compared to their HR counterparts. Notably, genes associated with neurogenesis and synaptic plasticity were induced in the hippocampus of LR rats in response to FST, whereas in HR rats, FST induced pathways directly or indirectly associated with induction of apoptotic mechanisms. CONCLUSIONS The markedly divergent gene expression signatures exposed herein support the notion that the hippocampus of HR and LR rats undergoes distinct transcriptional remodeling in response to the same stress regimen, thus yielding a different FST-related 'endophenotype', despite the seemingly similar depressive-like phenotype.
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Affiliation(s)
- Pothitos M Pitychoutis
- Department of Biology & Center for Tissue Regeneration and Engineering (TREND), University of Dayton, 300 College Park, Dayton, OH 45469-2320, USA.
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Mitigating aggressiveness through education? The monoamine oxidase A genotype and mental health in general population. Acta Neuropsychiatr 2014; 26:19-28. [PMID: 25142096 DOI: 10.1017/neu.2013.34] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
OBJECTIVE Monoamine oxidase A (MAOA) gene promoter region includes a variable number of tandem repeat (VNTR) associated with antisocial behaviour in adverse environment. We have examined the effect of the MAOA-uVNTR on mental health and academic success by using a population representative sample and a longitudinal design. METHODS The data of the older cohort (n = 593, aged 15 years at the original sampling) of the longitudinal Estonian Children Personality, Behaviour and Health Study (ECPBHS) were used. Follow-ups were conducted at ages 18 and 25 years. Aggressiveness, inattention and hyperactivity were reported by class teachers or, at older age, self-reported. Stressful life events, psychological environment in the family and interactions between family members were self-reported. Data of general mental abilities and education were obtained at the age of 25, and lifetime psychiatric disorder assessment was carried out with the Mini-International Neuropsychiatric Interview (MINI) interview. RESULTS MAOA-uVNTR genotype had no independent effect on aggressiveness, hyperactive and inattentive symptoms, and neither was there a genotype interaction with adverse life events. Interestingly, the proportion of male subjects with higher education by the age of 25 was significantly larger among those with MAOA low-activity alleles (χ² = 7.13; p = 0.008). Logistic regression revealed that MAOA low-activity alleles, higher mental abilities, occurrence of anxiety disorders and absence of substance-use disorder were significant independent predictors for higher education in male subjects. CONCLUSIONS In a population representative sample of young subjects, the MAOA-uVNTR 'risk genotype' predicted better life outcomes as expressed in higher level of education.
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Association of a functional variant of the nitric oxide synthase 1 gene with personality, anxiety, and depressiveness. Dev Psychopathol 2013; 24:1225-35. [PMID: 23062293 DOI: 10.1017/s0954579412000661] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
A functional promoter polymorphism of the nitric oxide synthase 1 gene first exon 1f variable number tandem repeat (NOS1 ex1f-VNTR) is associated with impulsivity and related psychopathology. Facets of impulsivity are strongly associated with personality traits; maladaptive impulsivity with neuroticism; and adaptive impulsivity with extraversion. Both high neuroticism and low extraversion predict anxiety and depressive symptoms. The aim of the present study was to evaluate the effect of the NOS1 ex1f-VNTR genotype and possible interaction with environmental factors on personality, anxiety, and depressiveness in a population-representative sample. Short allele carriers had higher neuroticism and anxiety than individuals with the long/long (l/l) genotype. Male short/short homozygotes also had higher extraversion. In the face of environmental adversity, females with a short allele had higher scores of neuroticism, anxiety, and depressiveness compared to the l/l genotype. Males were more sensitive to environmental conditions when they had the l/l genotype and low extraversion. In conclusion, the NOS1 ex1f-VNTR influences personality and emotional regulation dependent on gender and environment. Together with previous findings on the effect of the NOS1 genotype on impulse control, these data suggest that NOS1 should be considered another plasticity gene, because its variants are associated with different coping strategies.
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Raudkivi K, Mällo T, Harro J. Effect of chronic variable stress on corticosterone levels and hippocampal extracellular 5-HT in rats with persistent differences in positive affectivity. Acta Neuropsychiatr 2012; 24:208-14. [PMID: 25286813 DOI: 10.1111/j.1601-5215.2011.00619.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Objective:The trait of experiencing positive affect could make a unique contribution to the pathogenesis of affective disorders. Animal models of positive emotionality are scarce but 50-kHz ultrasonic vocalizations (USVs) in rats have been associated with rewarding experience. We have previously reported that persistent inter-individual differences in expression of 50-kHz USVs (chirps) exist, and that male rats producing fewer 50-kHz USVs are more sensitive to chronic variable stress (CVS). In this study we examined the effect of CVS on extracellular serotonin (5-HT) levels in hippocampus, comparing high-chirping (HC) and low-chirping (LC) rats.Methods:Male rats were classified as HC- and LC-rats on the basis of stable levels of USV response using sessions of tickling-like stimulation. CVS procedure lasted 4 weeks. The administration of citalopram (1 μM) and measurements of levels of 5-HT were done by microdialysis. Corticosterone levels were also measured from trunk blood.Results:Male LC-rats were more sensitive to CVS: the effect of stress on body weight gain was larger and corticosterone levels from full blood were higher in the stressed LC animals as compared to both the unstressed groups and the stressed HC animals. While no baseline differences in extracellular 5-HT levels in hippocampus were found between groups, the increase in extracellular 5-HT levels induced by citalopram was much higher in LC-rats.Conclusion:Chronic stress appears to modify hippocampal 5-HT overflow in rats with low positive affectivity. This finding supports the notion of greater vulnerability to CVS in male rats with low positive affectivity.
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Affiliation(s)
- Karita Raudkivi
- Department of Psychology, Estonian Centre of Behavioural and Health Sciences, University of Tartu, Tiigi 78, 50410, Tartu, Estonia
| | - Tanel Mällo
- Department of Psychology, Estonian Centre of Behavioural and Health Sciences, University of Tartu, Tiigi 78, 50410, Tartu, Estonia
| | - Jaanus Harro
- Department of Psychology, Estonian Centre of Behavioural and Health Sciences, University of Tartu, Tiigi 78, 50410, Tartu, Estonia
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Walker QD, Johnson ML, Van Swearingen AED, Arrant AE, Caster JM, Kuhn CM. Individual differences in psychostimulant responses of female rats are associated with ovarian hormones and dopamine neuroanatomy. Neuropharmacology 2012; 62:2267-77. [PMID: 22342988 DOI: 10.1016/j.neuropharm.2012.01.029] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2011] [Revised: 01/26/2012] [Accepted: 01/30/2012] [Indexed: 10/14/2022]
Abstract
Ovarian hormones modulate the pharmacological effects of psychostimulants and may enhance vulnerability to drug addiction. Female rats have more midbrain dopamine neurons than males and greater dopamine uptake and release rates. Cocaine stimulates motor behavior and dopamine efflux more in female than male rats, but the mediating mechanisms are unknown. This study investigated individual differences in anatomic, neurochemical, and behavioral measures in female rats to understand how ovarian hormones affect the relatedness of these endpoints. Ovarian hormone effects were assessed by comparing individual responses in ovariectomized (OVX) and sham adult female rats. Locomotion was determined before and following 10mg/kg cocaine. Electrically-stimulated dopamine efflux was assessed using fast cyclic voltammetry in vivo. Dopamine neuron number and density in substantia nigra (SN) and ventral tegmental area (VTA) were determined in the same animals using tyrosine-hydroxylase immunohistochemistry and unbiased stereology. Locomotor behavior and dopamine efflux did not differ at baseline but were greater in sham than OVX following cocaine. Cocaine increased dopamine release rates in both groups but uptake inhibition (K(m)) was greater in sham than OVX. Dopamine neuron number and density in SN and VTA were greater in shams. Sham females with the largest uterine weights exhibited the highest density of dopamine neurons in the SN, and the most cocaine-stimulated behavior and dopamine efflux. Ovariectomy eliminated these relationships. We postulate that SN density could link ovarian hormones and high-psychostimulant responses in females. Similar mechanisms may be involved in individual differences in the addiction vulnerability of women.
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Affiliation(s)
- Q David Walker
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC 27710, USA.
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Edwards S, Koob GF. Experimental psychiatric illness and drug abuse models: from human to animal, an overview. Methods Mol Biol 2012; 829:31-48. [PMID: 22231805 DOI: 10.1007/978-1-61779-458-2_2] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Preclinical animal models have supported much of the recent rapid expansion of neuroscience research and have facilitated critical discoveries that undoubtedly benefit patients suffering from psychiatric disorders. This overview serves as an introduction for the following chapters describing both in vivo and in vitro preclinical models of psychiatric disease components and briefly describes models related to drug dependence and affective disorders. Although there are no perfect animal models of any psychiatric disorder, models do exist for many elements of each disease state or stage. In many cases, the development of certain models is essentially restricted to the human clinical laboratory domain for the purpose of maximizing validity, whereas the use of in vitro models may best represent an adjunctive, well-controlled means to model specific signaling mechanisms associated with psychiatric disease states. The data generated by preclinical models are only as valid as the model itself, and the development and refinement of animal models for human psychiatric disorders continues to be an important challenge. Collaborative relationships between basic neuroscience and clinical modeling could greatly benefit the development of new and better models, in addition to facilitating medications development.
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Affiliation(s)
- Scott Edwards
- Committee on the Neurobiology of Addictive Disorders, Pearson Center for Alcoholism and Addiction Research, The Scripps Research Institute, La Jolla, CA, USA
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Abstract
The rapid increase in the number of proposed animal models of depression reflects the dissatisfaction with our current state of knowledge on neurobiology of depression and unsuccessful drug development. Results obtained with even the best validated models can be difficult to compare. Because evidence from epidemiological studies suggests that depression occurs in biologically predisposed subjects under the impact of adverse life events, increasing attempts have been made to use the diathesis-stress concept in animal models. In this way, factors underpinning vulnerability to depression have been identified by measuring behavioural traits analogous to facets of human personality, or created by inducing neurochemical lesions. Stressful interventions administered prenatally, in early life or in adulthood have been combined with other vulnerability factors including genetic changes. As a result, several putative animal models of endophenotypes of depression or depression vulnerability have been proposed. Diathesis-stress models may aid in separating adaptive and maladaptive strategies in coping with stress, and understanding the relevant neurobiology. Studies comparing effects of stress on males and females should reveal to which extent the pathogenetic processes leading to depression can be specific to sex/gender.
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Affiliation(s)
- Jaanus Harro
- Unit of Psychophysiology, Department of Psychology, Estonian Centre of Behavioural and Health Sciences, University of Tartu, Estonia.
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Pitychoutis PM, Pallis EG, Mikail HG, Papadopoulou-Daifoti Z. Individual differences in novelty-seeking predict differential responses to chronic antidepressant treatment through sex- and phenotype-dependent neurochemical signatures. Behav Brain Res 2011; 223:154-68. [DOI: 10.1016/j.bbr.2011.04.036] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2011] [Revised: 04/12/2011] [Accepted: 04/18/2011] [Indexed: 01/05/2023]
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Radley JJ, Kabbaj M, Jacobson L, Heydendael W, Yehuda R, Herman JP. Stress risk factors and stress-related pathology: neuroplasticity, epigenetics and endophenotypes. Stress 2011; 14:481-97. [PMID: 21848436 PMCID: PMC3641164 DOI: 10.3109/10253890.2011.604751] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
This paper highlights a symposium on stress risk factors and stress susceptibility, presented at the Neurobiology of Stress workshop in Boulder, CO, in June 2010. This symposium addressed factors linking stress plasticity and reactivity to stress pathology in animal models and in humans. Dr. J. Radley discussed studies demonstrating prefrontal cortical neuroplasticity and prefrontal control of hypothalamo-pituitary-adrenocortical axis function in rats, highlighting the emerging evidence of the critical role that this region plays in normal and pathological stress integration. Dr. M. Kabbaj summarized his studies of possible epigenetic mechanisms underlying behavioral differences in rat populations bred for differential stress reactivity. Dr. L. Jacobson described studies using a mouse model to explore the diverse actions of antidepressants in brain, suggesting mechanisms whereby antidepressants may be differentially effective in treating specific depression endophenotypes. Dr. R. Yehuda discussed the role of glucocorticoids in post-traumatic stress disorder (PTSD), indicating that low cortisol level may be a trait that predisposes the individual to development of the disorder. Furthermore, she presented evidence indicating that traumatic events can have transgenerational impact on cortisol reactivity and development of PTSD symptoms. Together, the symposium highlighted emerging themes regarding the role of brain reorganization, individual differences, and epigenetics in determining stress plasticity and pathology.
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Affiliation(s)
- Jason J. Radley
- Department of Psychology, University of Iowa, Iowa City, IA 52242
| | - Mohamed Kabbaj
- Biomedical Sciences Department, Program in Neurosciences, Florida State University, Tallahassee, FL 32306
| | - Lauren Jacobson
- Center for Neuropharmacology and Neuroscience, Albany Medical College, Albany, NY 12208
| | - Willem Heydendael
- Center for Neuropharmacology and Neuroscience, Albany Medical College, Albany, NY 12208
| | - Rachel Yehuda
- James J. Peters VA Medical Center and Mount Sinai School of Medicine
| | - James P. Herman
- Department of Psychiatry, University of Cincinnati, Cincinnati, OH 45237
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Harro J, Kiive E. Droplets of black bile? Development of vulnerability and resilience to depression in young age. Psychoneuroendocrinology 2011; 36:380-92. [PMID: 20206449 DOI: 10.1016/j.psyneuen.2010.02.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/02/2010] [Revised: 02/07/2010] [Accepted: 02/08/2010] [Indexed: 11/19/2022]
Abstract
Major depressive disorder is predicted by enduring anxiety-related personality traits, in particular by neuroticism, which have genetic foundations. Neuroticism in turn is strongly related with the genetic risk for depression. Search for gene variants associated with neuroticism and depression has led to some good candidates, but the consistency of findings is very far from ideal. Adverse life events are causal to development of mood disorders, and often the vulnerability genes can be detected only when environmental impact has been objectively assessed. Yet the continuity of depression diagnosis from early childhood to adulthood is limited, while childhood depression increases odds of other affect-related disorders such as substance abuse and personality disorders. Whether specific genes have an impact seems to depend on the period of life both because of biological maturation and differences in major environmental factors, but also active engagement--or the failure to do so--of the vulnerable subjects with their environment. It is proposed that subjects with genetically determined neurotic tendencies are likely to attempt to select coping strategies that reduce events perceived as harmful and can by this means develop resilience towards affective disorders.
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Affiliation(s)
- Jaanus Harro
- Department of Psychology, Estonian Centre of Behavioural and Health Sciences, University of Tartu, Tiigi 78, Tartu, 50410, Estonia.
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Kanarik M, Alttoa A, Matrov D, Kõiv K, Sharp T, Panksepp J, Harro J. Brain responses to chronic social defeat stress: effects on regional oxidative metabolism as a function of a hedonic trait, and gene expression in susceptible and resilient rats. Eur Neuropsychopharmacol 2011; 21:92-107. [PMID: 20656462 DOI: 10.1016/j.euroneuro.2010.06.015] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2010] [Revised: 06/21/2010] [Accepted: 06/27/2010] [Indexed: 12/17/2022]
Abstract
Chronic social defeat stress, a depression model in rats, reduced struggling in the forced swimming test dependent on a hedonic trait-stressed rats with high sucrose intake struggled less. Social defeat reduced brain regional energy metabolism, and this effect was also more pronounced in rats with high sucrose intake. A number of changes in gene expression were identified after social defeat stress, most notably the down-regulation of Gsk3b and Map1b. The majority of differences were between stress-susceptible and resilient rats. Conclusively, correlates of inter-individual differences in stress resilience can be identified both at gene expression and oxidative metabolism levels.
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Affiliation(s)
- Margus Kanarik
- Department of Psychology, Estonian Centre of Behavioural and Health Sciences, University of Tartu, Tiigi 78, 50410 Tartu, Estonia
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Duclot F, Hollis F, Darcy MJ, Kabbaj M. Individual differences in novelty-seeking behavior in rats as a model for psychosocial stress-related mood disorders. Physiol Behav 2010; 104:296-305. [PMID: 21172365 DOI: 10.1016/j.physbeh.2010.12.014] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2010] [Revised: 11/12/2010] [Accepted: 12/13/2010] [Indexed: 01/09/2023]
Abstract
Most neuropsychiatric disorders, including stress-related mood disorders, are complex multi-parametric syndromes. Diagnoses are therefore hard to establish and current therapeutic strategies suffer from significant variability in effectiveness, making the understanding of inter-individual variations crucial to unveiling effective new treatments. In rats, such individual differences are observed during exposure to a novel environment, where individuals will exhibit either high or low locomotor activity and can thus be separated into high (HR) and low (LR) responders, respectively. In rodents, a long-lasting, psychosocial, stress-induced depressive state can be triggered by exposure to a social defeat procedure. We therefore analyzed the respective vulnerabilities of HR and LR animals to long-lasting, social defeat-induced behavioral alterations relevant to mood disorders. Two weeks after four daily consecutive social defeat exposures, HR animals exhibit higher anxiety levels, reduced body weight gain, sucrose preference, and a marked social avoidance. LR animals, however, remain unaffected. Moreover, while repeated social defeat exposure induces long-lasting contextual fear memory in both HR and LR animals, only HR individuals exhibit marked freezing behavior four weeks after a single social defeat. Combined, these findings highlight the critical involvement of inter-individual variations in novelty-seeking behavior in the vulnerability to stress-related mood disorders, and uncover a promising model for posttraumatic stress disorder.
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Affiliation(s)
- Florian Duclot
- Department of Biomedical Sciences, Florida State University College of Medicine, Tallahassee, FL 32306, USA
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