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.
Hui
Jiao-Jie
JJ
Department of Neurology, Affiliated ZhongDa Hospital and the Institution Neuropsychiatry of Southeast University, Nanjing, Jiangsu, China.
Zhang
Zhi-Jun
ZJ
Liu
Shan-Shan
SS
Xi
Guang-Jun
GJ
Zhang
Xiang-Rong
XR
Teng
Gao-Jun
GJ
Chan
Kevin C
KC
Wu
Ed X
EX
Nie
Bin-Bin
BB
Shan
Bao-Ci
BC
Li
Ling-Jiang
LJ
Reynolds
Gavin P
GP
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