Abstract
The mesocorticolimbic system contains dopamine (DA)-producing neurons in the ventral tegmental area (VTA) and their projection targets, including the medial prefrontal cortex (mPFC), amygdala (AMY) and nucleus accumbens (NAc). Disruption of this system might attribute to mental illnesses. In the present study, we adopted the postweaning social isolation paradigm to model neuropsychiatric disorders and studied the functional and structural changes of the mesocorticolimbic system. After 8–9 weeks of isolation, rats exhibited hyperlocomotor activity and impaired sensorimotor gating compared to group-reared controls. However, the number of tyrosine hydroxylase-positive VTA neurons and the volume of VTA were not affected. Comparing with group-reared controls, the DA levels in the isolation-reared were not altered in the VTA, mPFC and NAc but decreased in the AMY. In the structural aspect, dendritic features of layer II/III pyramidal mPFC neurons; pyramidal neurons in the basolateral nucleus of amygdala (BLA) and medium spiny neurons in the core region of the NAc (NAcc) were examined. Interestingly, the neuronal changes were region-specific. The mPFC neurons had reduced dendritic complexity, spine density and elongated terminal branches. The BLA neurons had extensive dendritic arbors with short branches but unchanged spine density. The NAcc neurons had reduced total dendritic length but the segment length and spine density remained the same. Together, the results demonstrated the structural and functional changes in the mesocorticolimbic DA system of socially isolated rats. These changes may account for the behavioral impairments in these rats and attribute to the susceptibility to mental disorders related to schizophrenia and depression.
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Abbreviations
- AMY:
-
Amygdala
- BLA:
-
Basolateral nucleus of amygdala
- CE:
-
Coefficient of error
- DA:
-
Dopamine
- DOPAC:
-
3,4-Dihydroxy-phenylacetic acid
- HPLC:
-
High performance liquid chromatography
- mPFC:
-
Medial prefrontal cortex
- NAc:
-
Nucleus accumbens
- NAcc:
-
Core region of the nucleus accumbens
- P:
-
Postnatal day
- PBS:
-
Phosphate-buffered saline
- PPI:
-
Prepulse inhibition
- SD:
-
Sprague-Dawley
- TH:
-
Tyrosine hydroxylase
- VTA:
-
Ventral tegmental area
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Acknowledgments
This work was supported by National Science Council of the Republic of China (Grant numbers: NSC 98-2410-H-002-033-, NSC 96-2628-B-002-053-MY3 and NSC 99-2628-B-002-052-MY3) and National Taiwan University.
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Y.-C. Wang and U.-C. Ho contributed equally to this work.
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Wang, YC., Ho, UC., Ko, MC. et al. Differential neuronal changes in medial prefrontal cortex, basolateral amygdala and nucleus accumbens after postweaning social isolation. Brain Struct Funct 217, 337–351 (2012). https://doi.org/10.1007/s00429-011-0355-4
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DOI: https://doi.org/10.1007/s00429-011-0355-4