Hippocampal neurochemistry is involved in the behavioural effects of neonatal maternal separation and their reversal by post-weaning environmental enrichment: a magnetic resonance study.
Exposure to early life stress results in behavioural changes, and these dysfunctions may persist throughout adulthood. In this study, we investigated whether hippocampus volume and neurochemical changes were involved in the appearance of these effects in the maternal separation (MS) animal model using the noninvasive techniques of structural magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS). Sprague-Dawley rats exposed to MS for 180 min from postnatal days (PND) 2-14 demonstrated decreased sucrose preference, increased immobility in the forced swimming test (FST), and impaired memory in the Morris water maze in adulthood. Environmental enrichment (EE) (PND 21-60) could ameliorate the effects of MS on sucrose preference and learning and memory but not on immobility in the FST. In addition, EE significantly increased N-acetylaspartate (NAA) of MS animals. However, we did not find an effect of MS or EE on hippocampal volume. These results indicate the involvement of hippocampal neurochemistry in the behavioural changes that result from early stressful life events and their modification by post-weaning EE. Thus changes in NAA, as a measure of neuronal integrity, appear to be a sensitive correlate of these behavioural effects.
Department of Neurology, Affiliated ZhongDa Hospital and the Institution Neuropsychiatry of Southeast University, Nanjing, Jiangsu, China.
Jiao-Jie
JJ
Hui
Zhi-Jun
ZJ
Zhang
Shan-Shan
SS
Liu
Guang-Jun
GJ
Xi
Xiang-Rong
XR
Zhang
Gao-Jun
GJ
Teng
Kevin C
KC
Chan
Ed X
EX
Wu
Bin-Bin
BB
Nie
Bao-Ci
BC
Shan
Ling-Jiang
LJ
Li
Gavin P
GP
Reynolds
D000818:Animals; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D001284:Atrophy / Q000523:psychology; D002755:Choice Behavior / Q000502:physiology; D004777:Environment; D005260:Female; D006624:Hippocampus / Q000378:metabolism* / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D008426:Maternal Deprivation; D018782:Maze Learning / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013315:Stress, Psychological / Q000378:metabolism* / Q000503:physiopathology / Q000523:psychology*; D013550:Swimming
D001224:Aspartic Acid; C000179:N-acetylaspartate