Effects of Longmu Guizhi Decoction on learning and memory ability and hippocampal-HPA axis of ADHD rats with chronic stress
Objective:To investigate the effects of Longmu Guizhi Decoction on learning and memory and hippocampal-attention deficit hyperactivity disorder(HPA)axis with chronic stress in the hypothalamic-pituitary-adrenal(ADHD)model rats.Methods:A total of 32 Juvenile spontaneously hypertensive rats were randomly divided into blank group,chronic stress group,methylphenidate hydrochloride group and Longmu Guizhi Decoction group,with 8 rats in each group.The Morris water maze test was used to evaluate the learning and memory ability of rats.The levels of adrenocorticotropin hormone(ACTH),corticosterone(CORT)and corticotropin releasing hormone(CRH)in serum were detected by ELISA.The mRNA expressions of CRH,corticotropin releasing hormone receptor 1(CRHR1)and CRH binding protein(CRH-BP)in hypothalamus,CRHR1 and CRH-BP in pituitary were detected by RT-PCR method.The protein expression of glucocorticoid receptor(GR)and mineralocorticoid receptor(MR)in hippocampus were detected by immunohistochemistry method.Results:Compared with the blank group,the incubation period for finding the platform in the model group was significantly longer(P＜0.01),and the residence time in the target quadrant and the times of entering the platform quadrant were reduced(P＜0.05).The levels of serum CORT,CRH and ACTH were significantly increased(P＜0.01,P＜0.05),the mRNA expressions of CRH,CRHR1,CRH-BP in the hypothalamus,CRHR1 and CRH-BP in the pituitary were increased(P＜0.05),GR protein expression was decreased and MR protein expression was increased in hippocampus(P＜0.05).Compared with the chronic stress group,the time to find the platform in Longmu Guizhi decoction group and the methylphenidate hydrochloride group were decreased(P＜0.01),and the time in the target quadrant and the numbers of crossing the platform were increased(P＜0.05),the serum levels of CORT,ACTH,and CRH were significantly decreased(P＜0.01),the mRNA expression of CRH,CRHR1,CRH-BP in the hypothalamus and CRHR1 and CRH-BP in the pituitary were decreased(P＜0.05,P＜0.01),while GR protein expression was increased and MR protein expression was decreased in the hippocampus(P＜0.05,P＜0.01).Conclusion:Chronic stress can lead to hyperfunction of HPA axis and decrease the ability of learning and memory in ADHD.Longmu Guizhi Decoction can reduce the mRNA expression of CRH,CRHR1,CRH-BP in the hypothalamus and CRHR1 and CRH-BP in the pituitary,regulate the expression of GR and MR in the hippocampus,so as to improve the learning and memory ability of ADHD under chronic stress.
Attention deficit hyperactivity disorder(ADHD)Chronic stressLongmu Guizhi DecoctionLearning and memory abilityHypothalamic-pituitary-adrenal(HPA)axisHippocampus
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