Korean J Physiol Pharmacol.  2010 Dec;14(6):371-376. 10.4196/kjpp.2010.14.6.371.

Effects of Glycyrrhizae Radix on Repeated Restraint Stress-induced Neurochemical and Behavioral Responses

• Park HJ
• Shim HS
• Kim H
• Kim KS
• Lee H
• Hahm DH
• Shim I

• KMID: 2071708
• DOI: http://doi.org/10.4196/kjpp.2010.14.6.371

Abstract

Glycyrrhizae radix (GR) is an herbal medicine that is commonly used in the East Asia for treating a variety of diseases, including stomach disorders. The objective of the present study was to examine the anti-stress effects of GR on repeated stress-induced alterations of anxiety, learning and memory in rats. Restraint stress was administered for 14 days (2 h/day) to the rats in the Control and GR groups (400 mg/kg/day, PO). Starting on the eighth day, the rats were tested for spatial memory on the Morris water maze test (MW) and for anxiety on the elevated plus maze (EPM). We studied the changes of the expressions of cholineacetyl transferase (ChAT) and tyrosine hydroxylase (TH) in the locus coerleus (LC) using immunohistochemistry. The results showed that the rats treated with GR had significantly reduced stress-induced deficits on their learning and memory on the spatial memory tasks. In addition, the ChAT immunoreactivities were increased. Gor the EPM, treatment with GR increased the time spent in the open arms (p<0.001) as compared to that of the control group. Moreover, GR treatment also normalized the increases of the TH expression in the LC (p<0.001). In conclusion, administration of GR improved spatial learning and memory and reduced stress-induced anxiety. Thus, the present results suggest that GR has the potential to attenuate the behavioral and neurochemical impairments caused by stress.

Keyword

Glycyrrhizae radix (GR); Morris water maze (WM); Elevated plus maze (EPM)

MeSH Terms

Animals
Anxiety
Arm
Far East
Glycyrrhiza
Herbal Medicine
Immunohistochemistry
Learning
Memory
Rats
Stomach
Transferases
Tyrosine 3-Monooxygenase
Transferases
Tyrosine 3-Monooxygenase

Figure

• 

  Fig. 1. Time spent in the open and closed arms in the elevated plus maze maze. The GR group was daily treated with the GR extract (400 mg/kg, p.o.) for 2 weeks, and other groups were given sterile saline. Immobilization began 30 min after the treatments. The results of elevated plus maze maze were analyzed by performing separate one-way ANOVA among the groups were followed by LSD test. Each value represents the mean±S.E.M. ∗∗∗p<0.001 compared to normal group and & #p<0.05 compared to control group, respectively.

• 

  Fig. 2. (A) Changes of the latency time during 6d of the acquisition test in the Morris water maze test. The AM group was daily treated with the GR extract (400 mg/kg, p.o.) for 2 weeks, and other groups were given sterile saline. Immobilization began 30 min after the treatments. Repeated measures of two-way ANOVA of swimming time among the groups following by LSD test. Each value represents the mean±S.E.M. ##p<0.01 compared to control group. (B) The latency time on the 7th day of the retention test in the Morris water maze test. The GR group was daily treated with the GR extract (400 mg/kg, p.o.) for 2 weeks, and other groups were given sterile saline. Immobilization began 30 min after the treatments. The results of retention test were analyzed by performing separate measures of one-way ANOVA of swimming time among the groups were followed by LSD test. Each value represents the mean±S.E.M. ∗∗∗p<0.001 compared to normal group and & #p<0.05 compared to control group, respectively.

• 

  Fig. 3. (A) Number of choline acetyltransferase (ChAT) immunostained nuclei in the different hippocampal areas of the experimental groups after 8d of the behavior test. The GR group was daily treated with the GR extract (400 mg/kg, p.o.) for 2 weeks, and other groups were given sterile saline. Immobilization began 30 min after the treatments. The results of ChAT-reactivity were analyzed by performing separate one-way ANOVA of neurons among the groups were followed by LSD test. Each value represents the mean±S.E.M. ∗∗∗p<0.001 compared to normal group and ++p <0.01 compared to control group. (B) Photographs showing the distribution of ChAT-immunoreactive cells in hippocampus of Normal group (A), Control group (B), GR group (C). Sections were cut coronally at 30μm and the scale bar represents 200μm (200×200).

• 

  Fig. 4. Number of Tyrosine hydroxylase (TH) immunostained nuclei in the locus coerleus areas of the experimental groups. The AM group was daily treated with the GR extract (400 mg/kg, p.o.) for 2 weeks, and other groups were given sterile saline. Immobilization began 30 min after the treatments. The results of TH-reactivity were analyzed by performing separate one-way ANOVA of neurons among the groups were followed by LSD test. Each value represents the mean±S.E.M. ∗p<0.05 compared to normal group and ++p<0.01 compared to control group. (B) Photographs showing the distribution of TH-immunoreactive cells in LC of Normal group (A), Control group (B), GR group (C). Sections were cut coronally at 30μm and the scale bar represents 200μm (200×200).

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