Effects of Electroacupuncture on Chronic Unpredictable Mild Stress Rats Depression-Like Behavior and Expression of p-ERK/ERK and p-P38/P38

Abstract

We investigate the antidepressant-like effect and mechanism of electroacupuncture (EA) on a chronic unpredictable mild stress rats depression-like behavior. In our study, depression in rats was induced by unpredictable chronic mild stress (UCMS) and isolation for four weeks. Male Sprague-Dawley rats were randomly divided into four groups: Normal, Model, EA, and Sham EA. EA treatment was administered for two weeks, once a day for five days a week. Two acupoints, Yintang (EX-HN3) and Baihui (GV20), were selected. For sham EA, acupuncture needles were inserted shallowly into the acupoints: EX-HN3 and GV20. No electrostimulator was connected. The antidepressant-like effect of the electroacupuncture treatment was measured by sucrose intake test, open field test, and forced swimming test in rats. The protein levels of phosphorylated extracellular regulated protein kinases (p-ERK1/2)/ERK1/2 and p-P38/P38 in the hippocampus (HP) were examined by Western blot analysis. Our data demonstrate that EA treatment decreased the immobility time of forced swimming test and improved the sucrose solution intake in comparison to unpredictable chronic mild stress and placebo sham control. Electroacupuncture may act on depression by enhancing p-ERK1/2 and p-p38 in the hippocampus.

Figure 1

Timeline for all procedures.

Figure 2

Immobility time (in seconds) of forced swimming test in the following groups (n = 7 per group): Normal, Model, EA, and Sham EA. ^∗∗ P < 0.01.

Figure 3

Open field test scores in the following groups (n = 7 per group): Normal, Model, EA, and Sham EA. (a) Total distance, (b) distance in the central area, (c) time in central area, and (d) rearing and grooming incidents. ^∗ P < 0.05. There was no significant difference between EA and Sham EA in all parameters of OFT.

Figure 4

Sucrose solution intake in the following groups (n = 7 per group): Normal, Model, EA, and Sham EA. ^∗ P < 0.05, ^∗∗ P < 0.01.

Figure 5

ERK and p-ERK protein expression in the hippocampus in the following groups (n = 6 per group): Normal, Model, EA, and Sham EA. ^∗ P < 0.05, ^∗∗ P < 0.01.

Figure 6

Representative Western blots showing levels of p-ERK, ERK in the hippocampus of the following groups (n = 6 per group): Normal, Model, EA, and Sham EA.

Figure 7

P38 and p-P38 protein expression in the hippocampus in the following groups (n = 6 per group): Normal, Model, EA, and Sham EA. ^∗ P < 0.05, ^∗∗ P < 0.01.

Figure 8

Representative Western blots showing levels of p-P38, P38 in the hippocampus of the following groups (n = 6 per group): Normal, Model, EA, and Sham EA.