Oral Herb Medicine Paste Improves Learning and Memory Function in Elderly Spontaneous Hypertensive Rats

Abstract

Background: Oral herb medicine paste (Gao-Zi-Yao) has long been a unique way for treating various diseases. The present study is to explore the effect of Gao-Zi-Yao on learning and memory function in elderly spontaneous hypertensive rats (SHR) and its possible mechanism. Methods: Male elderly SHR were received different doses of Gao-Zi-Yao for 4 weeks. Systolic blood pressure (SBP) and heart rate were monitored. Morris water maze was performed to test the learning and memory function of the rats. Number of neurons in hippocampus was counted by Nissl staining. Western blot was applied to detect the expressions of learning and memory function related proteins, N-methyl-d-aspartate receptor 2B (NMDAR 2B), glutamate receptor 1 (GluR1), phosphorylated-calmodulin-dependent protein kinase II (p-CaMK II), and phosphorylated-cAMP responsive element-binding protein (p-CREB) in rat hippocampus. Findings: Data showed that Gao-Zi-Yao reduced SBP in elderly SHR. The results of Morris water maze experiment showed that Gao-Zi-Yao dose-dependently improved learning and memory function. Number of neurons in the hippocampal dentate gyrus (DG) region of the elderly SHR was increased by Gao-Zi-Yao treatment. In addition, Gao-Zi-Yao elevated the protein expressions of NMDAR 2B, GluR1, p-CaMK II, and p-CREB in hippocampus. Interpretation: Gao-Zi-Yao decreases SBP and improves the learning and memory function of the elderly SHR by regulation of neuron number in hippocampal DG area and the expressions of learning and memory function related proteins. Funding Statement: This work was supported by the National Natural Science Foundation of China (81970422), Suzhou Municipal Science and Technology Bureau (SS201745, GSWS2019022, SYSD2020210), and 5th 333 Project of Jiangsu Province. Declaration of Interests: The authors stated 'not applicable.' Ethics Approval Statement: The experiments were performed in according with the National Institutes of Health Guidelines for the Use of Laboratory Animals (NIH, publication number 85-23, revised 1996.), which were approved by and performed according to guidelines for the care and use of animals established by Soochow University. All the herbs and other materials used in the preparation of Gao-Zi Yao were approved by National Health Commission of the People’s Republic of China.