Z-Guggulsterone Produces Antidepressant-Like Effects in Mice through Activation of the BDNF Signaling Pathway

Abstract

Background: Z-guggulsterone, an active compound extracted from the gum resin of the tree Commiphora mukul, has been shown to improve animal memory deficits via activating the brain-derived neurotrophic factor signaling pathway. Here, we investigated the antidepressant-like effect of Z-guggulsterone in a chronic unpredictable stress mouse model of depression.

Methods: The effects of Z-guggulsterone were assessed in mice with the tail suspension test and forced swimming test. Z-guggulsterone was also investigated in the chronic unpredictable stress model of depression with fluoxetine as the positive control. Changes in hippocampal neurogenesis as well as the brain-derived neurotrophic factor signaling pathway after chronic unpredictable stress/Z-guggulsterone treatment were investigated. The tryptophan hydroxylase inhibitor and the tyrosine kinase B inhibitor were also used to explore the antidepressant-like mechanisms of Z-guggulsterone.

Results: Z-guggulsterone (10, 30 mg/kg) administration protected the mice against the chronic unpredictable stress-induced increases in the immobile time in the tail suspension test and forced swimming test and also reversed the reduction in sucrose intake in sucrose preference experiment. Z-guggulsterone (10, 30 mg/kg) administration prevented the reductions in brain-derived neurotrophic factor protein expression levels as well as the phosphorylation levels of cAMP response element binding protein, extracellular signal-regulated kinase 1/2, and protein kinase B in the hippocampus and cortex induced by chronic unpredictable stress. Z-guggulsterone (10, 30 mg/kg) treatment also improved hippocampal neurogenesis in chronic unpredictable stress-treated mice. Blockade of the brain-derived neurotrophic factor signal, but not the monoaminergic system, attenuated the antidepressant-like effects of Z-guggulsterone.

Conclusions: Z-guggulsterone exhibits antidepressant activity via activation of the brain-derived neurotrophic factor signaling pathway and upregulation of hippocampal neurogenesis.

Keywords: BDNF; CREB; CUS; Z-guggulsterone; major depression.

Figure 1.

Z-Guggulsterone produces antidepressant-like effects in the tail suspension test (TST) and forced swimming test (FST). (A) Z-Guggulsterone (10, 30 mg/kg) treatment significantly decreased the immobile time of C57BL/6J mice in the TST. (B) Z-Guggulsterone (10, 30 mg/kg) treatment decreased the immobile time of C57BL/6J mice in the FST. (C) Z-Guggulsterone (10, 30 mg/kg) treatment had no effects on the spontaneous locomotor activity of C57BL/6J mice in the open-field test. Fluoxetine (20 mg/kg) was used as a positive control. All these behavioral tests were conducted 30 minutes after the injection. All data were expressed as mean ± SEM.

Figure 2.

Effects of Z-guggulsterone on chronic unpredictable stress (CUS)-induced behavioral abnormalities. (A) The schematic diagram for the experimental timeline and tissue preparation in the present study. (B-C) Quantitative analysis showing the inhibitory effect of Z-guggulsterone (10 or 30 mg/kg) on CUS-induced increase in the immobile time in the TST (A, n = 10, *P<.05, **P<.01 vs control; #P<.05, ##P<.01 vs vehicle + CUS) and FST (B, n = 10, *P<.05, **P<.01 vs control; ##P<.01 vs vehicle + CUS). (D) Quantitative analysis showing the inhibitory effect of Z-guggulsterone (10 or 30 mg/kg) on CUS-induced decrease in sucrose intake (n = 10, **P<.01 vs control; #P<.05, ##P<.01 vs vehicle + CUS). The fluoxetine administration (20 mg/kg) was used as a positive control, and all data were shown as mean ± SEM.

Figure 3.

Effects of Z-guggulsterone on chronic unpredictable stress (CUS)-induced impairments of the hippocampal and cortical cAMP response element binding protein- brain-derived neurotrophic factor (CREB-BDNF) signals. (A) Representative images showing the restoration effects of Z-guggulsterone (10 or mg/kg) on CUS-induced decreases in the protein expression level of BDNF as well as the phosphorylation levels of extracellular-signal related kinase 1/2 (ERK1/2), CREB, and protein kinase B (Akt) in mice hippocampus. (B) Quantitative analysis showing the restoration effect of Z-guggulsterone on CUS-induced decrease in hippocampal BDNF protein expression (n=5, *P<.05 vs control; #P<.05 vs vehicle + CUS). (C) Quantitative analysis showing the restoration effects of Z-guggulsterone on CUS-induced decreases in hippocampal ERK1/2, CREB, and Akt phosphorylation levels (n = 5, *P<.05, **P<.01 vs control; #P<.05, ##P<.01 vs vehicle + CUS). (D) Representative images showing the restoration effects of Z-guggulsterone (10, 30 mg/kg) on CUS-induced decreases in the protein expression level of BDNF as well as the phosphorylation levels of ERK1/2, CREB, and Akt in medial prefrontal cortex (mPFC). (E) Quantitative analysis showing the restoration effect of Z-guggulsterone on CUS-induced decrease in cortical BDNF protein expression (n = 5, *P<.05 vs control; #P<.05 vs vehicle + CUS). (F) Quantitative analysis showing the restoration effects of Z-guggulsterone on CUS-induced decreases in cortical ERK1/2, CREB, and Akt phosphorylation levels (n = 5, *P<.05 vs control; #P<.05, ##P<.01 vs vehicle + CUS). The fluoxetine administration (20 mg/kg) was used as a positive control, and all data were shown as mean ± SEM.

Figure 4.

Effects of Z-guggulsterone on chronic unpredictable stress (CUS)-induced impairments of the hippocampal neurogenesis. (A) Representative images showing the restoration effect of Z-guggulsterone (10 or 30 mg/kg) on CUS-induced decrease in hippocampal doublecortin (DCX)⁺ cells. (B) Quantitative analysis showing the restoration effect of Z-guggulsterone on CUS-induced decrease in hippocampal DCX⁺ cells (n = 5, **P<.01 vs control; #P<.05, ##P<.01 vs vehicle + CUS). (C) Representative images showing the restoration effect of Z-guggulsterone on CUS-induced decrease in the protein expression level of hippocampal DCX. (D) Quantitative analysis showing the restoration effect of Z-guggulsterone on CUS-induced decrease in hippocampal DCX protein expression (n = 5, *P<.05 vs control; #P<.05 vs vehicle + CUS). The fluoxetine administration (20 mg/kg) was used as a positive control, and all data were shown as mean ± SEM.

Figure 5.

Effects of the inhibitor of brain-derived neurotrophic factor (BDNF), K252a, on Z-guggulsterone-mediated restoration of behavioral abnormalities induced by chronic unpredictable stress (CUS). (A) Quantitative analysis showing that K252a co-administration (25 μg/kg) attenuated the restoration effect of Z-guggulsterone (30 mg/kg) on CUS-induced increase in the immobile time in the tail suspension test (TST) (n = 10, **P<.01 vs control; ##P<.01 vs vehicle + CUS). (B) Quantitative analysis showing that K252a co-administration (25 μg/kg) attenuated the restoration effect of Z-guggulsterone (30 mg/kg) on CUS-induced increase in the immobile time in the forced swim test (FST) (n = 10; **P<.01 vs control; ##P<.01 vs vehicle + CUS). (C) Quantitative analysis showing that K252a co-administration (25 μg/kg) attenuated the restoration effect of Z-guggulsterone (30 mg/kg) on CUS-induced decrease in sucrose intake (n = 10; **P<.01 vs control; ##P<.01 vs vehicle + CUS). All data were shown as mean ± SEM.

Figure 6.

Effects of K252a on Z-guggulsterone-mediated restoration of the impairments of the hippocampal and cortical cAMP response element binding protein- brain-derived neurotrophic factor (CREB-BDNF) signals induced by chronic unpredictable stress (CUS). (A) Representative images showing that K252a co-administration (25 μg/kg) attenuated the restoration effect of Z-guggulsterone (30 mg/kg) on CUS-induced decreases in the protein expression level of BDNF as well as the phosphorylation levels of extracellular-signal related kinase 1/2 (ERK1/2), CREB, and protein kinase B (Akt) in the hippocampus. (B) Quantitative analysis that K252a co-administration attenuated the restoration effect of Z-guggulsterone on CUS-induced decrease in hippocampal BDNF protein expression (n = 5; *P<.05 vs control; #P<.05 vs vehicle + CUS). (C) Quantitative analysis that K252a co-administration attenuated the restoration effects of Z-guggulsterone on CUS-induced decreases in hippocampal ERK1/2, CREB, and Akt phosphorylation levels (n = 5; *P<.05, **P<.01 vs control; #P<.05, ##P<.01 vs vehicle + CUS). (D) Representative images showing that K252a co-administration (25 μg/kg) attenuated the restoration effect of Z-guggulsterone (30 mg/kg) on CUS-induced decreases in the protein expression level of BDNF as well as the phosphorylation levels of ERK1/2, CREB, and Akt in mouse medial prefrontal cortex (mPFC). (E) Quantitative analysis that K252a co-administration attenuated the restoration effect of Z-guggulsterone on CUS-induced decrease in cortical BDNF protein expression (n = 5; *P<.05, **P<.01 vs control; #P<.05 vs vehicle + CUS). (F) Quantitative analysis that K252a co-administration attenuated the restoration effect of Z-guggulsterone on CUS-induced decreases in cortical ERK1/2, CREB, and Akt phosphorylation levels (n = 5; *P<.05, **P<.01 vs control; #P<.05, ##P<.01 vs vehicle + CUS). All data were shown as mean ± SEM.

Figure 7.

Effects of K252a on Z-guggulsterone-mediated restoration of the impairment of hippocampal neurogenesis induced by chronic unpredictable stress (CUS). (A) Representative images showing that K252a co-administration (25 μg/kg) attenuated the restoration effect of Z-guggulsterone (30 mg/kg) on CUS-induced decrease in hippocampal doublecortin (DCX)⁺ cells. (B) Quantitative analysis showing that K252a co-administration attenuated the restoration effect of Z-guggulsterone on CUS-induced decrease in hippocampal DCX⁺ cells (n = 5; **P<.01 vs control; ##P<.01 vs vehicle + CUS). (C) Representative images showing that K252a co-administration (25 μg/kg) attenuated the restoration effect of Z-guggulsterone (30 mg/kg) on CUS-induced decrease in the protein expression level of hippocampal DCX. (D) Quantitative analysis showing that K252a co-administration attenuated the restoration effect of Z-guggulsterone on CUS-induced decrease in the protein expression level of hippocampal DCX (n = 5; **P<.01 vs control; #P<.05 vs vehicle + CUS). All data were shown as mean ± SEM.

Figure 8.

Effects of brain-derived neurotrophic factor (BDNF) antibody on the antidepressant-like effect of Z-guggulsterone. (A) Preinfusion of anti-BDNF antibody blocked the Z-guggulsterone-induced decrease in the immobile time of C57BL/6J mice in the tail suspension test (TST) and forced swim test (FST) (n = 10, *P<.05, **P<.01 vs control or IgY alone-treated group). (B-C) Preinfusion of anti-BDNF antibody prevented the Z-guggulsterone-induced decrease in the immobile time of C57BL/GJ mice in the TST (B, n = 10, *P<.05 vs control, ##P<.01 vs vehicle, vehicle + CUS, or IgY + CUS) and FST (C, n = 10, *P<.05 or **P<.01 vs control, #P<.05 or ##P<.01 vs vehicle + CUS or IgY + CUS). (D) CUS-treated mice were co-treated with Z-guggulsterone and anti-BDNF antibody for 12 days. CUS + Z-guggulsterone + anti-BDNF mice displayed significantly lower sucrose consumption than CUS + Z-guggulsterone + IgY mice (n = 10, **P<.01 vs control, #P<.05 or ##P<.01 vs vehicle + CUS or IgY + CUS). All results were expressed as means ± SEM.