| ObjectiveTo observe the behavioral characterization of adult male rats after experiencing neonatal maternal deprivation and the effect of maternal deprivation on the expression of dopmine transporter (DAT) mRNA in adult male rats' striatum and explore whether DNA methylation was involved in its expression regulatory mechanism.MethodsNewborn male rats were randomly divided into two groups, the maternal deprivation group (n=16) and the control group (n= 14).Beginning on post-natal days(PND) 1 through 14, each pup designated for deprivation was placed in an individual round plastic container with no bedding and remained isolated for 6 hours(9:00-15:00) per day in constant temperature (25℃),while the controls without any treatment. When both groups grew up to ten weeks old, their spatial learning and memory, exploratory ability in novel environments spontaneous and anxiety levels were assessed by Morris water maze,an open field test and an elevated plus maze. DAT mRNA expression level in striatum was detected by Reverse Transcription-PCR, and its DNA methylation levels were measured by bisulfite genomic sequencing PCR(BSP).ResultsTwo groups are significantly different in mean latency to reach the platform : maternal deprivation group(83.66±22.91s);control group(56.98±20.89s) in the Morris water maze experiment. (t=-2.39, p＜0.05) .The number crossing the paltform has significant difference between maternal deprivation group (2.56±1.55) and control group(4.21±1.58) (t=-2.89, p＜0.05) .The total time spent in the quadrant previously associated with the platform was significantly different:maternal deprivation group((25±9.52s);controlgroup(32,87±8.27s) (t=-2.39, p＜0.05) .Open-field test revealed that the exploratory ability decreased compared to the controls: maternal deprivation group(17.41±2.24m); control group(22.86±2.89m) (t=-5.81, p＜0.001) .The total time stayed in the centre squares was no great different: maternal deprivation group (13.13±5.22s) ; control group(9.42±5.16s) (t=-2.38, p＞0.05) .The elevated plus maze experiment showed that maternal deprivation group spent a greater amount of time in the open arms(u=2.35, p＜0.05).The number of entries into the open arms was not significant different (u=-0.99, p＞0.05) ;The number of entries into the closed arms Of maternal deprivation group was more than control group (u=2.351, p＜0.05) .The expression level of DATmRNA in the striatum of the maternal separation group (0.24±0.04) was significantly lower than that of the control group (0.48±0.11)(t=-4.76, P＜0.05). The DNA methylation levels in the promoter region of DAT were not significantly different between the maternal deprivation group (0.29±0.42) and the control group (0.29±0.20) (t=-0.18, P＞0.05).ConclusionAdult male rats that experienced neonatal maternal deprivation showed impairment in spatial learning and memory, exploratory ability in novel environments and spontaneous anxiety levels.We conclude that maternal deprivation could influence the expression of DAT mRNA in striatum. However, DNA methylation may not be involved. |
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