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Giordano GM, Caporusso E, Pezzella P, Galderisi S. Updated perspectives on the clinical significance of negative symptoms in patients with schizophrenia. Expert Rev Neurother 2022; 22:541-555. [PMID: 35758871 DOI: 10.1080/14737175.2022.2092402] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
INTRODUCTION Negative symptoms in schizophrenia are associated with poor response to available treatments, poor quality of life, and functional outcome. Therefore, they represent a substantial burden for people with schizophrenia, their families, and health-care systems. AREAS COVERED In this manuscript, we will provide an update on the conceptualization, assessment, and treatment of this complex psychopathological dimension of schizophrenia. EXPERT OPINION Despite the progress in the conceptualization of negative symptoms and in the development of state-of-the-art assessment instruments made in the last decades, these symptoms are still poorly recognized, and not always assessed in line with current conceptualization. Every effort should be made to disseminate the current knowledge on negative symptoms, on their assessment instruments and available treatments whose efficacy is supported by research evidence. Longitudinal studies should be promoted to evaluate the natural course of negative symptoms, improve our ability to identify the different sources of secondary negative symptoms, provide effective interventions, and target primary and persistent negative symptoms with innovative treatment strategies. Further research is needed to identify pathophysiological mechanisms of primary negative symptoms and foster the development of new treatments.
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Seo S, Sizemore RJ, Reader KL, Smither RA, Wicky HE, Hughes SM, Bilkey DK, Parr-Brownlie LC, Oorschot DE. A schizophrenia risk factor induces marked anatomical deficits at GABAergic-dopaminergic synapses in the rat ventral tegmental area: Essential evidence for new targeted therapies. J Comp Neurol 2021; 529:3946-3973. [PMID: 34338311 DOI: 10.1002/cne.25225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 06/07/2021] [Accepted: 07/26/2021] [Indexed: 11/09/2022]
Abstract
To develop new therapies for schizophrenia, evidence accumulated over decades highlights the essential need to investigate the GABAergic synapses that presynaptically influence midbrain dopaminergic neurons. Since current technology restricts these studies to animals, and evidence accumulated in recent decades indicates a developmental origin of schizophrenia, we investigated synaptic changes in male rat offspring exposed to maternal immune activation (MIA), a schizophrenia risk factor. Using a novel combination of lentiviruses, peroxidase-immunogold double labeling, three-dimensional serial section transmission electron microscopy and stereology, we observed clear anatomical alterations in synaptic inputs on dopaminergic neurons in the midbrain posterior ventral tegmental area (pVTA). These changes relate directly to a characteristic feature of schizophrenia: increased dopamine release. In 3-month-old and 14-month-old MIA rats, we found a marked decrease in the volume of presynaptic GABAergic terminals from the rostromedial tegmental nucleus (RMTg) and in the length of the synapses they made, when innervating pVTA dopaminergic neurons. In MIA rats in the long-term, we also discovered a decrease in the volume of the postsynaptic density (PSD) and in the maximum thickness of the PSD at the same synapses. These marked deficits were evident in conventional GABA-dopamine synapses and in synaptic triads that we discovered involving asymmetric synapses that innervated RMTg GABAergic presynaptic terminals, which in turn innervated pVTA dopaminergic neurons. In triads, the PSD thickness of asymmetric synapses was significantly decreased in MIA rats in the long-term cohort. The extensive anatomical deficits provide a potential basis for new therapies targeted at synaptic inputs on midbrain pVTA dopaminergic neurons, in contrast to current striatum-targeted antipsychotic drugs.
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Affiliation(s)
- Steve Seo
- Department of Anatomy, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand.,Brain Health Research Centre, University of Otago, Dunedin, New Zealand
| | - Rachel J Sizemore
- Department of Anatomy, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand.,Brain Health Research Centre, University of Otago, Dunedin, New Zealand
| | - Karen L Reader
- Department of Anatomy, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand.,Brain Health Research Centre, University of Otago, Dunedin, New Zealand
| | - Roseanna A Smither
- Department of Anatomy, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand.,Brain Health Research Centre, University of Otago, Dunedin, New Zealand.,Brain Research, New Zealand
| | - Hollie E Wicky
- Brain Health Research Centre, University of Otago, Dunedin, New Zealand.,Brain Research, New Zealand.,Department of Biochemistry, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Stephanie M Hughes
- Brain Health Research Centre, University of Otago, Dunedin, New Zealand.,Brain Research, New Zealand.,Department of Biochemistry, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - David K Bilkey
- Brain Health Research Centre, University of Otago, Dunedin, New Zealand.,Department of Psychology, University of Otago, Dunedin, New Zealand
| | - Louise C Parr-Brownlie
- Department of Anatomy, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand.,Brain Health Research Centre, University of Otago, Dunedin, New Zealand.,Brain Research, New Zealand
| | - Dorothy E Oorschot
- Department of Anatomy, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand.,Brain Health Research Centre, University of Otago, Dunedin, New Zealand
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