Effect Of Morphine Addiction And Withdrawal In Parents Prior To Mating On The Anxiety-like Behavior And Spatial Learning-memory In Adult Offspring Rats

Objective The intent of this study was observing the impact of morphine addiction and withdrawal prior to mating to the anxiety-like behaviour and spatial learning-memory function in adult offspring rats. To analysis mRNA expression in rat hippocampus profile alterations by means of microarry technique and to provide molecular basis for further study.Methods 40 rats(20 female and 20 male) were used.10 males and 10 females were intraperitoneally injected with morphine twice a day for 10 days in ascending dosage schedule,accordingly.The rest of rats were injected with saline of the same volume.Twenty one days after morphine withdrawal,rats were mated.Then each one male with one female were housed(coupled) per cage as four groups for coupling: (Group 1) addicted males+addicted females;(Group 2) addicted males +saline females;(Group 3) saline males+addicted females;(Group 4) saline males+saline females.When the offspring is 8 weeks old,the anxiety-like behavior and spatial learning-memory were assessed in the elevated-plus maze test,the open-field test and morris water maze respectively.After behavioral tests,the animals were sacrificed,the hippocampus tissues were prepared for the microarray assay,probe mark the control and the experiment,hybridization and fluorescent scanning to screen out the different expression genes with the ratio of experiment to control being more than 2.0 or lower than 0.5.Results Compared with the female and male's offspring in group 4[(10.41±2.64,9.32±1.63)%],the female and male's offspring in group 1,2,3 exhibited the percent of time spent in open arms[(2.49±0.91, 0.45±0.10)%,(3.34±1.12,5.51±1.60)%,(3.15±0.52,2.09±0.70) %]were reduced obviously in the elevated plus maze(P＜0.01).Similarly, Compared with the female and male's offspring in group 4[(13.97±0.61,7.71±0.21)%],the female and male's offspring in group1,2,3 exhibited the percent of time spent in the center zone[(3.91±0.82,2.63±0.41)%,(4.31±0.62,2.75±0.72)%,(3.71±0.41,2.04±0.39) %]were reduced significantly in the open field test(P＜0.001).But the offspring in group 1,2,3,4 exhibited the escape latency and the percent of time spent in the target quadrant were no difference in the morris water maze(P＞0.05).Using gene chips,compared with the male's offspring in group 4, 663 genes upregulated and 449 genes downregulated in the male's offspring in group 1,2,3.Compared with the female's offspring in group 4,350 genes upregulated and 188 genes downregulated in the female's offspring in group 1,2,3.These genes are involved in the functions of mental health disorders and epigenetics(such us Htr2c,Gabra3,Gabra6, Crhr1,reelin,Hdac4_pre,Hdac5,Igf2,Mbd3_pre,etal.).Conclusion These findings suggest that parents experiencing morphine addiction and withdrawal prior to mating can result in the offsprings anxiety-like behavior,but have no obvious effect on spatial-memory learning.The microarray results indicated the anxiety-like behavior in offspring may involve in the differentially expressed gene in rat hippocampus.The achievement of differentially expression genes had provided useful clues to study the molecular mechanisms of the ethology alterations.