Deferred Administration of Afobazole Induces Sigma1R-Dependent Restoration of Striatal Dopamine Content in a Mouse Model of Parkinson's Disease

Abstract

Previously, we demonstrated that the immediate administration of multitarget anxiolytic afobazole slows down the progression of neuronal damage in a 6-hydroxidodamine (6-OHDA) model of Parkinson's disease due to the activation of chaperone Sigma1R. The aim of the present study is to evaluate the therapeutic potential of deferred afobazole administration in this model. Male ICR mice received a unilateral 6-OHDA lesion of the striatum. Fourteen days after the surgery, mice were treated with afobazole, selective Sigma1R agonist PRE-084, selective Sigma1R antagonist BD-1047, and a combination of BD-1047 with afobazole or PRE-084 for another 14 days. The deferred administration of afobazole restored the intrastriatal dopamine content in the 6-OHDA-lesioned striatum and facilitated motor behavior in rotarod tests. The action of afobazole accorded with the effect of Sigma1R selective agonist PRE-084 and was blocked by Sigma1R selective antagonist BD-1047. The present study illustrates the Sigma1R-dependent effects of afobazole in a 6-OHDA model of Parkinson's disease and reveals the therapeutic potential of Sigma1R agonists in treatment of the condition.

Keywords: 6-OHDA; BD-1047; PRE-084; Parkinson’s disease; afobazole; chaperone Sigma1R; dopamine; rotarod; tyrosine hydroxylase.

Figure 1

Influence of deferred administration of afobazole over 14 days on dopamine content in 6-hydroxidodamine (6-OHDA)-lesioned ICR mice striata. Data are presented as mean ± S.D. Sham-operated—ipsilateral striatum of sham-operated animals. 6-OHDA—ipsilateral striatum of animals with 6-OHDA lesion. Experimental groups divided by treatment, tissue harvesting, and last drug administration were spaced 1 h apart: 1 vehicle. 2 BD-1047 3.0 mg/kg. 3 afobazole 2.5 mg/kg. 4 PRE-084 1.0 mg/kg. 5 BD-1047 3.0 mg/kg and afobazole 2.5 mg/kg. 6 BD-1047 3.0 mg/kg and PRE-084 1.0 mg/kg. Two-way ANOVA, Tukey multiple comparison test: A significant difference (p < 0.01) was observed in 6-OHDA-lesioned mice within all experimental groups except for afobazole (3) and PRE-084 (4). Statistical significance: * p < 0.01 vs. sham-operated vehicle-treated mice. # p < 0.01 vs. 6-OHDA-lesioned vehicle-treated mice. a p < 0.01 vs. 6-OHDA-lesioned afobazole-treated mice. p p < 0.05 vs. 6-OHDA-lesioned PRE-084-treated mice. n.s.—no statistical significance between compared groups. Paired t-test: A significant difference (p < 0.001) was observed between the contralateral and ipsilateral striata of 6-OHDA-lesioned mice for all groups.

Figure 2

Influence of deferred administration of afobazole over 14 days on DOPAC content in 6-OHDA-lesioned ICR mice striata. Data are presented as mean ± S.D. Sham-operated—ipsilateral striatum of sham-operated animals. 6-OHDA—ipsilateral striatum of animals with 6-OHDA lesion. Experimental groups were divided by treatment, tissue harvesting, and last drug administration and spaced 1 h apart: 1 vehicle. 2 BD-1047 3.0 mg/kg. 3 afobazole2.5 mg/kg. 4 PRE-084 1.0 mg/kg. 5 BD-1047 3.0 mg/kg and afobazole 2.5 mg/kg. 6 BD-1047 3.0 mg/kg and PRE-084 1.0 mg/kg. Two-way ANOVA, Tukey multiple comparison test: A significant difference (p < 0.05) was observed within all experimental groups except for afobazole (3) and PRE-084 (4). Statistical significance: * p < 0.01 vs. sham-operated vehicle-treated mice. # p < 0.01 vs. 6-OHDA-lesioned vehicle-treated mice. a p < 0.01 vs. 6-OHDA-lesioned afobazole-treated mice. p p < 0.05 vs. 6-OHDA-lesioned PRE-084-treated mice. n.s.—no statistical significance between compared groups. Paired t-test: A significant difference (p < 0.001) was observed between the contralateral and ipsilateral striata of 6-OHDA-lesioned mice for all groups except for afobazole and PRE-084.

Figure 3

Influence of deferred administration of afobazole over 14 days on HVA content in 6-OHDA-lesioned ICR mice striata. Data are presented as mean ± S.D. Sham-operated—ipsilateral striatum of sham-operated animals. 6-OHDA—ipsilateral striatum of animals with 6-OHDA lesion. Experimental groups were divided by treatment, tissue harvesting and last drug administration were 1-h spaced apart: 1 vehicle. 2 BD-1047 3.0 mg/kg. 3 afobazole 2.5 mg/kg. 4 PRE-084 1.0 mg/kg. 5 BD-1047 3.0 mg/kg and afobazole 2.5 mg/kg. 6 BD-1047 3.0 mg/kg and PRE-084 1.0 mg/kg. Two-way ANOVA, Tukey multiple comparison test: A significant difference (p < 0.05) was observed within all experimental groups except for afobazole (3) and PRE-084 (4). Statistical significance: * p < 0.01 vs. sham-operated vehicle-treated mice. # p < 0.01 vs. 6-OHDA-lesioned vehicle-treated mice. a p < 0.01 vs. 6-OHDA-lesioned afobazole-treated mice. p p < 0.05 vs. 6-OHDA-lesioned PRE-084-treated mice. n.s.—no statistical significance between compared groups.

Figure 4

The influence of deferred administration of afobazole over 14 days on latency to fall during fixed-speed rotarod test (FSRR) in 6-OHDA-lesioned and sham-operated ICR mice. Data are presented as median with interquartile range. Sham-operated—sham-operated animals. 6-OHDA—animals with 6-OHDA lesion. Experimental groups were divided by treatment, drugs were administered 20 h prior to the test: 1 vehicle. 2 BD-1047 3.0 mg/kg. 3 afobazole 2.5 mg/kg. 4 PRE-084 1.0 mg/kg. 5 BD-1047 3.0 mg/kg and afobazole 2.5 mg/kg. 6 BD-1047 3.0 mg/kg and PRE-084 1.0 mg/kg. Kruskal‒Wallis test, Dunn’s multiple comparison test: A significant difference (p < 0.05) was observed within all experimental groups except for afobazole (3) and PRE-084 (4). Statistical significance: * p < 0.01 vs. sham-operated vehicle-treated mice. # p < 0.01 vs. 6-OHDA-lesioned vehicle-treated mice. a p < 0.01 vs. 6-OHDA-lesioned afobazole-treated mice. p p < 0.05 vs. 6-OHDA-lesioned PRE-084-treated mice. n.s.—no statistical significance between compared groups.

Figure 5

The influence of deferred administration of afobazole over 14 days on latency to fall during accelerated rotarod test (ARR) in 6-OHDA-lesioned and sham-operated ICR mice. Data are presented as median with interquartile range. Sham-operated—sham-operated animals. 6-OHDA—animals with 6-OHDA lesion. Experimental groups were divided by treatment, drugs were administered 20 h prior to the test: 1 vehicle. 2 BD-1047 3.0 mg/kg. 3 afobazole 2.5 mg/kg. 4 PRE-084 1.0 mg/kg. 5 BD-1047 3.0 mg/kg and afobazole 2.5 mg/kg. 6 BD-1047 3.0 mg/kg and PRE-084 1.0 mg/kg. Kruskal‒Wallis test, Dunn’s multiple comparison test: A significant difference (p < 0.05) was observed within all experimental groups except for afobazole (3) and PRE-084 (4). Statistical significance: * p < 0.01 vs. sham-operated vehicle-treated mice. # p < 0.05 vs. 6-OHDA-lesioned vehicle-treated mice. a p < 0.01 vs. 6-OHDA-lesioned afobazole-treated mice. p p < 0.05 vs. 6-OHDA-lesioned PRE-084-treated mice. n.s.—no statistical significance between compared groups.

Figure 6

Correlation between striatal dopamine content of 6-OHDA-lesioned mice and their latency to fall in a fixed-speed rotarod test (FSRR). Gray dot—vehicle. Black circle—BD-1047 3.0 mg/kg. Red dot—afobazole 2.5 mg/kg. Blue dot—PRE-084 1.0 mg/kg. Red circle—BD-1047 3.0 mg/kg and afobazole 2.5 mg/kg. Blue circle—BD-1047 3.0 mg/kg and PRE-084 1.0 mg/kg. R = 0.6, p < 0.0001; line of best fit equation DA = 0.3518*X + 39.11.

Figure 7

Correlation between striatal dopamine content of 6-OHDA-lesioned mice and their latency to fall in accelerated rotarod test (ARR). Gray dot—vehicle. Black circle—BD-1047 3.0 mg/kg. Red dot—afobazole 2.5 mg/kg. Blue dot—PRE-084 1.0 mg/kg. Red circle—BD-1047 3.0 mg/kg and afobazole 2.5 mg/kg. Blue circle—BD-1047 3.0 mg/kg and PRE-084 1.0 mg/kg. R = 0.6, p < 0.0001; line of best fit equation DA = 0.2822*X + 29.05.