Effects of Hypericum scabrum extract on dentate gyrus synaptic plasticity in high fat diet-fed rats

Ghazaleh Omidi,Ahmad Ganji,Somayeh Komaki,Farshid Etaee,Masoumeh Asadbegi,Alireza Komaki,Arezoo Rezvani-Kamran

doi:10.1186/s12576-020-00747-0

Ghazaleh Omidi, Ahmad Ganji + Show 5 more

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https://doi.org/10.1186/s12576-020-00747-0

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Abstract

High-fat diet (HFD) can induce deficits in neural function, oxidative stress, and decrease hippocampal neurogenesis. Hypericum (H.) scabrum extract (Ext) contains compounds that could treat neurological disorders. This study aimed to examine the neuroprotective impacts of the H. scabrum Ext on hippocampal synaptic plasticity in rats that were fed HFD. Fifty-four male Wistar rats (220 ± 10 g) were randomly arranged in six groups: (1) HFD group; (2) HFD + Ext300 group; (3) HFD + Ext100 group; (4) Control group; (5) Ext 300 mg/kg group; (6) Ext 100 mg/kg group. These protocols were administrated for 3 months. After this stage, a stimulating electrode was implanted in the perforant pathway (PP), and a bipolar recording electrode was embedded into the dentate gyrus (DG). Long-term potentiation (LTP) was provoked by high-frequency stimulation (HFS) of the PP. Field excitatory postsynaptic potentials (EPSP) and population spikes (PS) were recorded at 5, 30, and 60 min after HFS. The HFD group exhibited a large and significant decrease in their PS amplitude and EPSP slope as compared to the control and extract groups. In reverse, H. scabrum administration in the HFD + Ext rats reversed the effect of HFD on the PS amplitude and EPSP slope. The results of the study support that H. scabrum Ext can inhibit diminished synaptic plasticity caused by the HFD. These effects are probably due to the extreme antioxidant impacts of the Ext and its capability to scavenge free radicals.

Highlights

Modifications in diet and lifestyle, which may have happened with industrialization, urbanization, economic development, and market globalization have occurred previously [1]
Fifty-four rats were divided into 6 groups (n = 9): (1) high-fat diet (HFD) group, given an HFD with 45% energy from fat; (2) HFD + Ext300 group, given an HFD supplemented with H. scabrum extract (300 mg/ kg); (3) HFD + Ext100 group, given an HFD supplemented with H. scabrum extract (100 mg/kg); (4) control group, given a normal diet with 10% energy from fat and received the saline through oral gavage once a day for 3 months; (5) H. scabrum 300 mg/kg (Ext300) group, given the standard diet supplemented with H. scabrum (300 mg/kg); (6) H. scabrum 100 mg/kg (Ext100) group, given the standard diet supplemented with H. scabrum (100 mg/kg)
Effects of H. scabrum extract supplementation on the excitatory postsynaptic potentials (EPSP) slopes of granular cells in the dentate gyrus (DG) of rats fed with HFD Field potential recordings were obtained in the granular cells in the DG following stimulation of the perforant pathway (PP)

Summary

Introduction

Modifications in diet and lifestyle, which may have happened with industrialization, urbanization, economic development, and market globalization have occurred previously [1]. It is assumed that lifestyle plays an essential role in maintaining neural function [2]. The continuous and long-term consumption of a high-fat diet (HFD) leads to weight gain and obesity [3]. The adverse effects of obesity in the brain are unclear, studies have suggested that obesity and body fat deposition play an essential role in the pathogenesis of certain brain-related disorders [3, 5, 6]. Recent studies have demonstrated that HFD consumption and obesity are correlated with cognitive damage and a raised chance of expanding dementia [7, 8]

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