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Lipska BK. A neonatal hippocampal disconnection model; testing a neurodevelopmental hypothesis of schizophrenia. ACTA ACUST UNITED AC 2003. [DOI: 10.1016/s1566-2772(03)00097-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Le Pen G, Grottick AJ, Higgins GA, Moreau JL. Phencyclidine exacerbates attentional deficits in a neurodevelopmental rat model of schizophrenia. Neuropsychopharmacology 2003; 28:1799-809. [PMID: 12784101 DOI: 10.1038/sj.npp.1300208] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Schizophrenia is characterized by severe abnormalities in cognition, including disordered attention. In the rat, neonatal ventral hippocampal (NVH) lesions induce behavioral abnormalities at adulthood thought to simulate some aspects of the symptomatology of schizophrenia. Here, we compared the effects of NVH and adult ventral hippocampal (AVH) lesions on attentional performance as assessed by the five-choice serial reaction time task (5-CSRTT). NVH-lesioned rats were slower to acquire the task than AVH-lesioned and control animals. When training was complete, NVH- and AVH-lesioned animals exhibited stable but disrupted performance under standard conditions, thus emphasizing an implication of VH in visual attentional processes. Variations in task parameters induced a significantly greater disruption in NVH- and AVH-lesioned groups as compared to controls. NVH-lesioned rats were also hyper-responsive to the disruptive effects of a high dose of phencyclidine (PCP) (3 mg/kg). In contrast, amphetamine (0.4-0.8 mg/kg) had a similar effect in control and VH-lesioned rats. Thus, NVH-lesioned rats were impaired in the acquisition of stable performance in the 5-CSRTT, and were hypersensitive to the cognitive-impairing effects of PCP.
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Lipska BK, Lerman DN, Khaing ZZ, Weickert CS, Weinberger DR. Gene expression in dopamine and GABA systems in an animal model of schizophrenia: effects of antipsychotic drugs. Eur J Neurosci 2003; 18:391-402. [PMID: 12887421 DOI: 10.1046/j.1460-9568.2003.02738.x] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We used in situ hybridization histochemistry to assess expression of dopamine receptors (D1R, D2R and D3R), neurotensin, proenkephalin and glutamate decarboxylase-67 (GAD67) in the prefrontal cortex, striatum, and/or nucleus accumbens in adult rats with neonatal ventral hippocampal (VH) lesions and in control animals after acute and chronic treatment with antipsychotic drugs clozapine and haloperidol. We also acquired these measures in a separate cohort of treatment-naïve sham and neonatally VH-lesioned rats used as an animal model of schizophrenia. Our results indicate that the neonatal VH lesion did not alter expression of D1R, D3R, neurotensin or proenkephalin expression in any brain region examined. However, D2R mRNA expression was down-regulated in the striatum, GAD67 mRNA was down-regulated in the prefrontal cortex and prodynorphin mRNA was up-regulated in the striatum of the VH-lesioned rats as compared with sham controls. Antipsychotic drugs did not alter expression of D1R, D2R or D3R receptor mRNAs but elevated neurotensin and proenkephalin expression in both groups of rats; patterns of changes were dependent on the duration of treatment and brain area examined. GAD67 mRNA was up-regulated by chronic antispychotics in the nucleus accumbens and the striatum and by chronic haloperidol in the prefrontal cortex in both sham and lesioned rats. These results indicate that the developmental VH lesion changed the striatal expression of D2R and prodynorphin and robustly compromised prefrontal GAD67 expression but did not modify drug-induced expression of any genes examined in this study.
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Affiliation(s)
- Barbara K Lipska
- Clinical Brain Disorders Branch, Intramural Research Program, National Institute of Mental Health, NIH, Bldg.10, Rm. 4N306, Bethesda, MD 20892-1385, USA.
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Lipska BK, Luu S, Halim ND, Weinberger DR. Behavioral effects of neonatal and adult excitotoxic lesions of the mediodorsal thalamus in the adult rat. Behav Brain Res 2003; 141:105-11. [PMID: 12742246 DOI: 10.1016/s0166-4328(03)00027-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
We examined in the rat, the effects of neonatal (postnatal Day 7) and adult excitotoxic lesions of the mediodorsal thalamus (MDT), a brain area innervating the prefrontal cortex and implicated as a site of neuropathology in schizophrenia. Previous studies showed that rats with neonatal excitotoxic damage of the ventral hippocampus (VH), used as an animal model of this disorder, display in young adulthood a variety of abnormalities reminiscent of schizophrenia, including hyperactivity to stressful stimuli and amphetamine. It has been speculated that behavioral abnormalities of the neonatally VH lesioned animals are mediated through MDT projections to the prefrontal cortex. We tested if rats with ibotenic acid (1.5 microg per hemisphere in neonates, 2 microg in adults) lesions of MDT exhibited motor hyperactivity in the same experimental conditions (i.e. in response to novelty, saline injections and amphetamine administration) as rats with the VH lesions. We found that, in contrast to rats with VH lesions, neonatally lesioned MDT rats showed reduced vertical activity in response to amphetamine and no changes in locomotor activity to novelty, saline or amphetamine injections 7 weeks postlesion. Adult lesioned MDT rats exhibited no changes in motor activity as compared to controls at 7 weeks postlesion. These results indicate that neonatal or adult excitotoxic lesions of MDT do not produce behavioral changes analogous to those seen after neonatal VH lesions and do not appear to reproduce animal model-like features of schizophrenia.
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Affiliation(s)
- Barbara K Lipska
- Intramural Research Program, Clinical Brain Disorders Branch, National Institute of Mental Health, National Institutes of Health, 10 Center Drive, Bldg. 10, Rm. 4N306, Bethesda, MD 20892-1385, USA.
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55
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Lipska BK, Weinberger DR. A neurodevelopmental model of schizophrenia: neonatal disconnection of the hippocampus. Neurotox Res 2002; 4:469-475. [PMID: 12754160 DOI: 10.1080/1029842021000022089] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
In the context of our current knowledge about schizophrenia, heuristic models of psychiatric disorders may be used to test the plausibility of theories developed on the basis of new emerging biological findings, explore mechanisms of schizophrenia-like phenomena, and develop potential new treatments. In a series of studies, we have shown that neonatal excitotoxic lesions of the rat ventral hippocampus (VH) may serve as a heuristic model. The model appears to mimic a spectrum of neurobiological and behavioral features of schizophrenia, including functional pathology in presumably critical brain regions interconnected with the hippocampal formation and targeted by antipsychotic drugs - the striatum/nucleus accumbens and the prefrontal cortex, and leads in adolescence or early adulthood to the emergence of abnormalities in a number of dopamine related behaviors. Moreover, our data show that even transient inactivation of the ventral hippocampus during a critical period of development, that produces subtle, if any, anatomical changes in the hippocampus, may be sufficient to disrupt normal maturation of the prefrontal cortex (and perhaps, other interconnected late maturing regions) and trigger behavioral changes similar to those observed in animals with the permanent excitotoxic lesion. These results represent a potential new model of aspects of schizophrenia without a gross anatomical lesion.
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Affiliation(s)
- Barbara K. Lipska
- Clinical Brain Disorders Branch, Intramural Research Program, National Institute of Mental Health, NIH, IRP, 10 Center Drive, Bldg.10, Rm. 4N306, Bethesda, MD 20892
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Daenen EWPM, Wolterink G, Gerrits MAFM, Van Ree JM. Amygdala or ventral hippocampal lesions at two early stages of life differentially affect open field behaviour later in life; an animal model of neurodevelopmental psychopathological disorders. Behav Brain Res 2002; 131:67-78. [PMID: 11844573 DOI: 10.1016/s0166-4328(01)00350-3] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Psychiatric disorders like schizophrenia or autism are thought to result from disruption of the normal pattern of brain development. Abnormalities in the amygdaloid complex and hippocampus have been reported in these disorders. In the present study rats were lesioned in the amygdala or ventral hippocampus on day 7 of life (immature brain) or day 21 of life (almost mature brain) and open field behaviour was determined later in life before and after puberty. Lesioning on day 7 resulted in behavioural changes, interpreted as locomotor stereotypy and decreased anxiety in case of amygdala or hippocampus, respectively. These effects were more profoundly present after puberty. Lesioning on day 21 did not result in these behavioural changes, which subscribes to the importance of the stage of brain maturation on functional development. The results suggest that the behavioural changes in rats lesioned on day 7 may due to a malfunctioning of structures connected to the amygdala or ventral hippocampus. Brain lesions made on day 7 of life may serve as a potential model of psychopathological neurodevelopmental disorders.
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Affiliation(s)
- Elisabeth W P M Daenen
- Department of Pharmacology, Division of Pharmacology and Anatomy Rudolf Magnus Institute for Neurosciences, University Medical Center Utrecht, PO Box 85060, 3508, AB, Utrecht, The Netherlands
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Daenen EW, Van der Heyden JA, Kruse CG, Wolterink G, Van Ree JM. Adaptation and habituation to an open field and responses to various stressful events in animals with neonatal lesions in the amygdala or ventral hippocampus. Brain Res 2001; 918:153-65. [PMID: 11684053 DOI: 10.1016/s0006-8993(01)02987-0] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
A rat model of neurodevelopmental psychopathological disorders, designed to determine neurodevelopmental deficits following damage to the brain early in life, was used to investigate behavioural changes in adaptation and habituation to an open field and responses to different kinds of stressful events. Animals with bilateral ibotenic acid lesions in the amygdala or ventral hippocampus on day 7 or 21 of life were compared to sham-operated animals. According to the model it was assumed that behavioural changes in animals lesioned on day 7, but not in animals lesioned on day 21 of life, were caused by maldevelopment of one or more structures connected to the damaged area. Animals lesioned in the amygdala or ventral hippocampus on day 7, but not animals lesioned in these structures on day 21 of life, displayed decreased (within-session) adaptation and (between-session) habituation to the open field and a decrease in immobility in the forced swim test, whereas only animals lesioned in the amygdala displayed enhanced general activity. These results were indicative of neurodevelopmental deficits. No changes in stress-induced hyperthermia were found, while animals lesioned in the amygdala both on day 7 or 21 of life exhibited decreased conditioned ultrasonic vocalizations. These latter results suggest that the amygdala is implicated in the conditioned stress-induced response. The contribution of the present findings to the animal model of neurodevelopmental disorders like schizophrenia and possible brain structures and neurotransmitter systems involved in the neurodevelopmental deficits are discussed.
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Affiliation(s)
- E W Daenen
- Division of Pharmacology and Anatomy, University Medical Center Utrecht, Rudolf Magnus Institute for Neurosciences, P.O. Box 85060, 3508 AB Utrecht, The Netherlands
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58
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Al-Amin HA, Shannon Weickert C, Weinberger DR, Lipska BK. Delayed onset of enhanced MK-801-induced motor hyperactivity after neonatal lesions of the rat ventral hippocampus. Biol Psychiatry 2001; 49:528-39. [PMID: 11257238 DOI: 10.1016/s0006-3223(00)00968-9] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
BACKGROUND Abnormalities in the glutamatergic system, glutamate/dopamine/gamma-aminobutyric acid interactions, and cortical development are implicated in schizophrenia. Moreover, patients with schizophrenia show symptom exacerbation in response to N-methyl-D-aspartate (NMDA) antagonist drugs. Using an animal model of schizophrenia, we compared the impact of neonatal and adult hippocampal lesions on behavioral responses to MK-801, a noncompetitive NMDA antagonist. METHODS Neonatal rats were lesioned on postnatal day 7. Their motor activity in response to MK-801 was tested at a juvenile age, in adolescence, and in adulthood. We also measured binding of [(3)H]MK-801 and the expression of NR1 messenger RNA (mRNA) in the medial prefrontal cortex and nucleus accumbens. Adult rats received similar lesions and were tested 4 and 8 weeks after the lesion. RESULTS As juveniles, neonatally lesioned rats did not differ from control rats in responsiveness to MK-801, whereas in adolescence and adulthood they showed more pronounced hyperactivity than control rats. The adult lesion did not alter behaviors elicited by MK-801. Neonatally lesioned rats showed no apparent changes in [(3)H]MK-801 binding or expression of the NR1 mRNA. CONCLUSIONS These results suggest that an early lesion of the ventral hippocampus affects development of neural systems involved in MK-801 action without changes at the NMDA receptor level, and they show that the behavioral changes manifest first in early adulthood.
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Affiliation(s)
- H A Al-Amin
- Clinical Brain Disorders Branch, Intramural Research Programs, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892, USA
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59
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Hori T, Subramaniam S, Srivastava LK, Quirion R. Behavioral and neurochemical alterations following repeated phencyclidine administration in rats with neonatal ventral hippocampal lesions. Neuropharmacology 2000; 39:2478-91. [PMID: 10974332 DOI: 10.1016/s0028-3908(00)00059-9] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Exposure to chronic phencyclidine (PCP) has been reported to mimic certain aspects of schizophrenia in normal subjects as well as to exacerbate symptoms in schizophrenic patients. Analogous to schizophrenics, adult rats with neonatal ventral hippocampal (VH) lesions have been shown to display enhanced sensitivity to both stress and psychostimulants. In order to examine whether repeated PCP treatment can modulate behavior when administered to neonatal VH-lesioned animals, we examined locomotor activity and immobility time in the forced swimming test (FST) in neonatal VH-lesioned rats following repeated PCP treatment. Receptor autoradiography studies were also performed for dopamine (DA) and N-methyl-D-aspartate (NMDA) receptors to identify neurochemical correlates of the altered behavior in these animals. Though repeated PCP administration resulted in increased levels of locomotor activity and rearing in both VH-lesioned as well as sham rats, the effects were much more enhanced in the lesioned rats compared to sham. However, repeated PCP treatment induced hypolocomotion during the habituation period in both sham and lesioned rats. In the FST paradigm, lesioned rats displayed an altered retention of acquired immobility. Repeated PCP administration increased DA D1-like receptors in the caudate-putamen in lesioned rats and decreased striatal D2-like receptors in both sham and lesioned rats. Moreover, repeated PCP administration in lesioned rats decreased NMDA binding sites in the prefrontal cortex while increasing labelling in the subcortical regions. These results suggest that repeated administration of PCP can qualitatively and quantitatively affect behaviors in neonatal VH-lesioned rats related to abnormal neurodevelopmental processes presumably via prefrontal glutamatergic and subcortical dopaminergic dysfunctions.
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Affiliation(s)
- T Hori
- Douglas Hospital Research Centre and Department of Psychiatry, McGill University, Québec, H4H 1R3, Montréal, Canada
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60
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Le Pen G, Grottick AJ, Higgins GA, Martin JR, Jenck F, Moreau JL. Spatial and associative learning deficits induced by neonatal excitotoxic hippocampal damage in rats: further evaluation of an animal model of schizophrenia. Behav Pharmacol 2000; 11:257-68. [PMID: 11103880 DOI: 10.1097/00008877-200006000-00009] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Neonatal ventral hippocampal lesions in the rat result in post-pubertal onset of behavioural abnormalities, modelling some aspects of schizophrenia. We further assessed the behavioural effects of neonatal lesions in rats in a variety of cognitive tasks and in the prepulse inhibition (PPI) of startle response paradigm. Prepubescent, lesioned rats exhibited startle responses and PPI similar to controls whereas, at adulthood, they showed a deficit in PPI. Lesioned rats acquired both passive and active avoidance responses. However, compared to controls, they showed a deficit in passive avoidance retention and in acquisition of active avoidance responses. In a cued Morris water-maze task, lesioned rats demonstrated adequate sensorimotor functions and appropriate motivation to escape from water. However, they were impaired in place learning and in remembering the location of a submerged platform. In conclusion, neonatal ventral hippocampal lesions result in the post-pubertal emergence of long-lasting deficits in sensorimotor gating and in the capacity to acquire and retain information in tests of spatial and avoidance learning. Therefore, this neurodevelopmental model of schizophrenia seems to exhibit an interesting degree of validity in possibly simulating some cognitive impairments and sensorimotor gating deficits frequently observed in psychotic patients.
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Affiliation(s)
- G Le Pen
- Pharma Division, Preclinical CNS Research, F-Hoffmann-La Roche Ltd, Basel, Switzerland.
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61
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Al-Amin HA, Weinberger DR, Lipska BK. Exaggerated MK-801-induced motor hyperactivity in rats with the neonatal lesion of the ventral hippocampus. Behav Pharmacol 2000; 11:269-78. [PMID: 11103881 DOI: 10.1097/00008877-200006000-00010] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Neonatal lesions of the ventral hippocampus in rats produce changes in spontaneous and pharmacologically induced dopamine-dependent behaviors that emerge in early adulthood. Neural mechanisms underlying these changes may have implications for understanding the neurobiology of schizophrenia, putatively a neurodevelopmental disorder. In this study, we evaluated the effects of MK-801 (dizocilpine), on automated measures of distance traveled and stereotypies in adult rats with neonatal (postnatal day 7) lesions, and tested the effects of haloperidol, clozapine and an alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic (AMPA) antagonist LY293558 on the MK-801-induced behaviors. The lesioned rats showed significantly greater increases in motor activity after 0.05 and O.1 mg/kg of MK-801 than did controls. Both haloperidol (0.1 and 0.4 mg/kg) and clozapine (4 and 10 mg/kg) reduced hyperlocomotion elicited by 0.2 mg/kg MK-801 in the ventral hippocampus (VH)-lesioned and sham rats. Haloperidol was more potent than clozapine in decreasing MK-801-induced stereotypy, especially in the lesioned rats. Moreover, an AMPA antagonist normalized exaggerated MK-801-induced hyperolocomotion in the lesioned rats at doses that had no effect in controls. These results demonstrate that the lesioned rats are more sensitive to MK-801 during adulthood than control rats, and that antidopaminergic drugs as well as AMPA antagonists antagonize the MK-801-induced behaviors. The neonatal lesion rat model may be useful to further our understanding of the interactions between dopamine and glutamate and their role in the pathophysiology of schizophrenia.
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Affiliation(s)
- H A Al-Amin
- Clinical Brain Disorders Branch, Intramural Research Programs, National Institute of Mental Health, Bethesda 20892-1385, USA
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62
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Uehara T, Tanii Y, Sumiyoshi T, Kurachi M. Neonatal lesions of the left entorhinal cortex affect dopamine metabolism in the rat brain. Brain Res 2000; 860:77-86. [PMID: 10727625 DOI: 10.1016/s0006-8993(00)01985-5] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The present study was performed to determine the effects of neonatal excitotoxic lesions of the left entorhinal cortex on dopamine (DA) metabolism and release in limbic regions of the rat brain. Quinolinic acid or phosphate buffered saline was infused into the left entorhinal cortex of rat pups on postnatal day 7 (PD7). Concentrations of DA,3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) in the lateral amygdala, nucleus accumbens, caudate-putamen, and medial prefrontal cortex were determined in the postmortem brains of lesioned and sham-operated rats on PD35 and PD56. On PD35, concentrations of DA in the bilateral lateral amygdala and HVA in the left lateral amygdala were significantly increased in lesioned rats compared with sham-operated animals, while no significant change was observed in the other three brain areas. On PD56, in addition to the increased concentration of DA in the left lateral amygdala, those of DA, DOPAC and HVA in the caudate-putamen, and DA in the nucleus accumbens were found to be increased, but DA concentrations in the right medial prefrontal cortex were decreased. The DOPAC/DA concentration ratio was, however, decreased in the amygdala and nucleus accumbens of the lesioned rats. In an in vivo microdialysis study, methamphetamine (MAP: 2 mg/kg, i.p.)-induced DA release in the amygdala of lesioned rats was significantly enhanced compared with sham-operated rats on both PD35 and PD56. There were no significant differences in MAP-induced DA release in the caudate-putamen between the sham-operated and lesioned rats at any time point. These findings provide evidence that neonatally induced structural abnormalities in the entorhinal cortex affect DA transmission in the limbic regions at the adolescent stage.
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Affiliation(s)
- T Uehara
- Department of Neuropsychiatry, Faculty of Medicine, Toyama Medical and Pharmaceutical University, 2630, Sugitani, Toyama, Japan.
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63
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Miele M, Mura MA, Enrico P, Esposito G, Serra PA, Migheli R, Zangani D, Miele E, Desole MS. On the mechanism of d-amphetamine-induced changes in glutamate, ascorbic acid and uric acid release in the striatum of freely moving rats. Br J Pharmacol 2000; 129:582-8. [PMID: 10711358 PMCID: PMC1571853 DOI: 10.1038/sj.bjp.0703066] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
1. The effects of systemic, intrastriatal or intranigral administration of d-amphetamine on glutamate, aspartate, ascorbic acid (AA), uric acid, dopamine (DA), dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA) concentrations in dialysates from the striatum of freely-moving rats were evaluated using microdialysis. 2. d-Amphetamine (2 mg kg-1) given subcutaneously (s.c.) increased DA, AA and uric acid and decreased DOPAC + HVA, glutamate and aspartate dialysate concentrations over a 3 h period after d-amphetamine. 5-HIAA concentrations were unaffected. Individual changes in glutamate and AA dialysate concentrations were negatively correlated. 3. d-Amphetamine (0.2 mM), given intrastriatally, increased DA and decreased DOPAC + HVA and aspartate dialysate concentrations, but failed to change those of glutamate, AA uric acid or 5-HIAA, over a 2 h period after d-amphetamine. Haloperidol (0.1 mM), given intrastriatally, increased aspartate concentrations without affecting those of glutamate or AA. 4. d-Amphetamine (0.2 mM), given intranigrally, increased AA and uric acid dialysate concentrations and decreased those of glutamate, aspartate and DA; DOPAC + HVA and 5-HIAA concentrations were unaffected. 5. These results suggest that d-amphetamine-induced increases in AA and uric acid and decreases in glutamate concentrations are triggered at nigral sites. The changes in aspartate levels may be evoked by at least two mechanisms: striatal (mediated by inhibitory dopaminergic receptors) and nigral (activation of amino acid carrier-mediated uptake).
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Affiliation(s)
- Maddalena Miele
- Department of Pharmacology, University of Sassari, Viale S. Pietro 43/B, 07100 Sassari, Italy
| | - Maria A Mura
- Department of Pharmacology, University of Sassari, Viale S. Pietro 43/B, 07100 Sassari, Italy
| | - Paolo Enrico
- Department of Pharmacology, University of Sassari, Viale S. Pietro 43/B, 07100 Sassari, Italy
| | - Giovanni Esposito
- Department of Pharmacology, University of Sassari, Viale S. Pietro 43/B, 07100 Sassari, Italy
| | - Pier A Serra
- Department of Pharmacology, University of Sassari, Viale S. Pietro 43/B, 07100 Sassari, Italy
| | - Rossana Migheli
- Department of Pharmacology, University of Sassari, Viale S. Pietro 43/B, 07100 Sassari, Italy
| | - Danilo Zangani
- Department of Pharmacology, University of Sassari, Viale S. Pietro 43/B, 07100 Sassari, Italy
| | - Egidio Miele
- Department of Pharmacology, University of Sassari, Viale S. Pietro 43/B, 07100 Sassari, Italy
| | - Maria S Desole
- Department of Pharmacology, University of Sassari, Viale S. Pietro 43/B, 07100 Sassari, Italy
- Author for correspondence:
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64
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El-Khodor BF, Boksa P. Transient birth hypoxia increases behavioral responses to repeated stress in the adult rat. Behav Brain Res 2000; 107:171-5. [PMID: 10628741 DOI: 10.1016/s0166-4328(99)00119-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
The aim of this study was to test if two birth complications, namely, transient global hypoxia during Caesarean section (C-section) birth or C-section birth per se, produce long-term changes in behavioral responses to repeated stress. Adult rats, that had been born vaginally, by C-section or by C-section with 10 min of global anoxia, were stressed for 8 days (15 min tail pinch daily) followed by challenge with the same stressor 2 weeks later. The main finding is that adult rats born by C-section + 10 min of anoxia showed enhanced locomotor activity on days 5 and 6 of the repeated stress period and at stress challenge 2 weeks later, compared to animals born vaginally or by C-section. It is concluded that transient global birth hypoxia can render the adult rat behaviorally hyper-responsive to repeated stress.
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Affiliation(s)
- B F El-Khodor
- Department of Psychiatry and of Neurology and Neurosurgery, McGill University, Douglas Hospital Research Centre, Montreal, Qué, Canada
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65
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Bachevalier J, Alvarado MC, Malkova L. Memory and socioemotional behavior in monkeys after hippocampal damage incurred in infancy or in adulthood. Biol Psychiatry 1999; 46:329-39. [PMID: 10435198 DOI: 10.1016/s0006-3223(99)00123-7] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The present study reviews the long-term effects of neonatal hippocampal damage in monkeys on the development of memory functions and socioemotional behavior. The results showed that neonatal damage to the hippocampal formation impairs specific memory processes, such as those subserving automatic (as opposed to effortful) recognition memory and relational learning, while sparing the abilities to acquire skills, such as object discriminations. Furthermore, the neonatal hippocampectomy led to a progressive loss of social affiliation and a protracted emergence of locomotor stereotypies. While the memory losses following neonatal hippocampal lesions resemble those found after similar lesions acquired in adulthood, only the neonatal lesions resulted in a protracted emergence of abnormal behaviors. These later findings suggested that, presumably, the neonatal lesions impacted on neural systems remote from the site of damage. This was confirmed by our more recent neurobiological studies, demonstrating that neonatal, but not late, lesions of the medial temporal lobe region, disrupt the normal behavioral and cognitive processes subserved by the prefrontal cortex and the caudate nucleus. All together the data support the neurodevelopmental hypothesis viewing early insult to the medial temporal region as the origin of developmental psychosis in humans, such as schizophrenia.
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Affiliation(s)
- J Bachevalier
- University of Texas Health Science Center, Houston 77030, USA
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66
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Brake WG, Sullivan RM, Flores G, Srivastava LK, Gratton A. Neonatal ventral hippocampal lesions attenuate the nucleus accumbens dopamine response to stress: an electrochemical study in the adult rat. Brain Res 1999; 831:25-32. [PMID: 10411980 DOI: 10.1016/s0006-8993(99)01477-8] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Neonatal damage to the ventral hippocampus (VH) can lead, during adulthood, to behaviours that are believed to reflect enhanced mesocorticolimbic dopamine (DA) transmission. In the present study, the effects of neonatal excitotoxic lesions to the VH on spontaneous locomotor activity and stress-elicited increases in extracellular nucleus accumbens (NAcc) DA levels were examined in adult rats. Male pups received, on postnatal day 7, bilateral injections of either an ibotenic acid solution (lesioned) or vehicle (sham-lesioned) into the VH. At 3-4 months of age, animals were assessed during five daily sessions for changes in spontaneous locomotor activity associated with habituation to a novel environment. Voltammetry was used in separate groups of sham- and VH-lesioned animals to monitor the NAcc DA response to each of five once-daily exposures to tail-pinch stress. The results indicate that while VH-lesioned animals seem to habituate to novelty, they remain hyperactive relative to sham-lesioned controls. In contrast, however, stress consistently elicited in VH-lesioned animals smaller and shorter-lasting increases in NAcc DA than in sham-lesioned controls. These data suggest that neonatal excitotoxic damage to VH leads to changes in DA function that persist into adulthood. The blunted response to stress seen in VH-lesioned animals indicates that one consequence of such damage is a functional hyporeactivity in meso-NAcc DA neurons. The fact that these animals are spontaneously more active suggests compensatory changes in DA function that are efferent to DA terminals in NAcc.
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Affiliation(s)
- W G Brake
- Douglas Hospital Research Centre, McGill University, Department of Psychiatry, 6875 LaSalle Blvd., Verdun, Quebec, Canada
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67
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Varty GB, Marsden CA, Higgins GA. Reduced synaptophysin immunoreactivity in the dentate gyrus of prepulse inhibition-impaired isolation-reared rats. Brain Res 1999; 824:197-203. [PMID: 10196449 DOI: 10.1016/s0006-8993(99)01173-7] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Isolation rearing of rat pups from weaning produces neurochemical and behavioural changes that may have relevance to the neurodevelopmental basis of neuropsychiatric disorders such as schizophrenia. Although limited, studies have begun to probe for neuroanatomical changes produced by isolation rearing. In the present study, rat pups were reared in isolation, i.e., housed one per cage, from weaning. After 8 weeks of isolation, 'isolates' were compared to their socially reared controls (housed three per cage) in two behavioural paradigms: locomotor activity in a novel open field and prepulse inhibition (PPI) of the acoustic startle response. Subsequently, all rats were sacrificed and their brains removed. The hippocampus was sectioned and analysed immunohistochemically using an antibody to the synapse-specific protein synaptophysin, to gain an estimate of the synaptic content of selected hippocampal subfields. Isolates demonstrated locomotor hyperactivity and deficits in PPI relative to socially reared controls. Analysis of synaptophysin immunoreactivity suggested that isolates had significantly reduced synaptic content in the hippocampal dentate gyrus molecular layer, with smaller, non-significant reductions in the CA1 and CA3 regions. This pattern of change may be consistent with reduced neuronal input to the dentate gyrus via the entorhinal cortex, suggesting developmental changes in hippocampal-cortical circuitry. These preliminary studies extend the characterisation of isolation rearing as a model for the investigation of neurodevelopmental diseases such as schizophrenia.
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Affiliation(s)
- G B Varty
- Glaxo Unit of Behavioural Psychopharmacology, Division of Biosciences, University of Hertfordshire, Hatfield, Herts, UK.
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68
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Frantz K, Van Hartesveldt C. The locomotor effects of MK801 in the nucleus accumbens of developing and adult rats. Eur J Pharmacol 1999; 368:125-35. [PMID: 10193648 DOI: 10.1016/s0014-2999(99)00009-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
This developmental study was an investigation of locomotion induced by the NMDA receptor antagonist, (+)MK-801 hydrogen maleate [(5R,10S)-(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5, 10-imine], at doses of 0, 3 or 10 microg injected bilaterally into the nucleus accumbens of rats at 11, 21, 31, or 61-66 days of age. During a 2-h test session, only a few 11-day-old pups responded to either dose of MK801; they displayed short bouts of obstinate progression. In contrast, 21- and 31-day-olds were not affected by 3 microg MK801 but exhibited robust activation after 10 microg MK801. The activation was greatest in 21-day-olds and also occurred after mid-striatal injections in 21- but not 31-day-old rats. Adult rats injected with MK801 were not robustly activated, but they maintained their initial level of activity throughout the test session, instead of habituating to the test monitor, as controls did. Ontological changes in MK801-induced activity are likely to reflect maturation of glutamate transmission in the nucleus accumbens.
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Affiliation(s)
- K Frantz
- Department of Psychology, University of Florida, Gainesville 32611-2250, USA.
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69
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Lipska BK, Khaing ZZ, Weinberger DR. Neonatal Hippocampal Damage in the Rat: A Heuristic Model of Schizophrenia. Psychiatr Ann 1999. [DOI: 10.3928/0048-5713-19990301-12] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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70
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Wan RQ, Hartman H, Corbett R. Alteration of dopamine metabolites in CSF and behavioral impairments induced by neonatal hippocampal lesions. Physiol Behav 1998; 65:429-36. [PMID: 9877408 DOI: 10.1016/s0031-9384(98)00179-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Alterations of monoamine metabolites in CSF and behavioral abnormalities were studied in rats with neonatal hippocampal lesions and controls. Lesions of the ventral hippocampus were produced bilaterally by ibotenic acid on postnatal day 7. Lesion-induced neurochemical alterations and behavioral impairments were examined concurrently when rats were 12 weeks old. CSF from the cisterna magna was sampled repeatedly from freely moving rats. The levels of free 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), and 5-hydroxyindoleacetic acid (5-HIAA) in CSF were determined. An exposure to a novel environment induced hyperexploratory behavior and elevated the level of free DOPAC in CSF in lesioned rats. Although a swim stress increased the levels of free DOPAC and 5-HIAA in CSF in both control and lesioned groups, rats with hippocampal lesions had a further elevation of free DOPAC in CSF and greater spontaneous activity relative to controls shortly after stress. Amphetamine (1.5 mg/kg, i.p.) induced hyperlocomotion in lesioned rats compared to controls. For the control group, the levels of the three monoamine metabolites in CSF were not significantly influenced by amphetamine. However, for the lesioned group, the level of DOPAC significantly decreased compared to preinjection of amphetamine. The results indicate that neonatal hippocampal lesion-induced impairments can be manifested by behavioral and neurochemical abnormalities. Alterations of monoamine metabolites in CSF may be determined quantitatively and used as indices for monitoring lesion-impaired monoaminergic function in the central nervous system.
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Affiliation(s)
- R Q Wan
- Neuroscience PGU, Hoechst Marion Roussel, Inc., Somerville, NJ 08876, USA
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71
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Mittleman G, Bratt AM, Chase R. Heterogeneity of the hippocampus: effects of subfield lesions on locomotion elicited by dopaminergic agonists. Behav Brain Res 1998; 92:31-45. [PMID: 9588683 DOI: 10.1016/s0166-4328(97)00124-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Structural abnormalities in the hippocampal formation and overactive dopamine neurotransmission in the ventral striatum are thought to be key pathologies in schizophrenia. This experiment examined the functional contribution of different hippocampal subfields to locomotion elicited by D-amphetamine (0.32-3.2 mg/kg) and the direct agonists quinpirole (0.025-0.5 mg/kg) and SKF 38393 (2.5-15.0 mg/kg). Male rats served as unoperated controls or received one of six different lesions (hippocampal formation, fimbria-fornix, subiculum, CA3-4, entorhinal cortex or dentate gyrus (DG)). The main results indicated that extensive ibotenic acid-induced lesions of the hippocampal formation, or colchicine-induced lesions of the DG enhanced locomotion elicited by the D2 agonist quinpirole. Electrolytic lesions of the fimbria-fornix, in comparison, had much larger effects and resulted in increases in the locomotor response to amphetamine and quinpirole. These results extend previous demonstrations of hippocampal modulation of the ventral striatum by showing that this modulatory influence is dependent on both the location and total extent of cell loss within the hippocampal formation. The results are discussed in relation to the causes of and neurophysiological mechanisms involved in enhanced drug-induced locomotion and in terms of their implications for mental diseases including schizophrenia.
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72
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Abstract
Research on spatial problem-solving over the past two years has linked the hippocampus to path integration, that is, the use of movement-related cues to guide spatial behavior. Path integration may underlie the forms of place learning that are impaired by hippocampal damage. It remains a challenge to determine whether path integration is the central function of the hippocampus or but one of many.
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Affiliation(s)
- I Q Whishaw
- Department of Psychology and Neuroscience, The University of Lethbridge, 4401 University Drive, Lethbridge, Alberta, Canada T1K 3M4.
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