Lithium ameliorates altered glycogen synthase kinase-3 and behavior in a mouse model of fragile X syndrome - PubMed (original) (raw)

Comparative Study

Lithium ameliorates altered glycogen synthase kinase-3 and behavior in a mouse model of fragile X syndrome

Christopher J Yuskaitis et al. Biochem Pharmacol. 2010.

Abstract

Fragile X syndrome (FXS), the most common form of inherited mental retardation and a genetic cause of autism, results from mutated fragile X mental retardation-1 (Fmr1). This study examined the effects on glycogen synthase kinase-3 (GSK3) of treatment with a metabotropic glutamate receptor (mGluR) antagonist, MPEP, and the GSK3 inhibitor, lithium, in C57Bl/6 Fmr1 knockout mice. Increased mGluR signaling may contribute to the pathology of FXS, and the mGluR5 antagonist MPEP increased inhibitory serine-phosphorylation of brain GSK3 selectively in Fmr1 knockout mice but not in wild-type mice. Inhibitory serine-phosphorylation of GSK3 was lower in Fmr1 knockout, than wild-type, mouse brain regions and was increased by acute or chronic lithium treatment, which also increased hippocampal brain-derived neurotrophic factor levels. Fmr1 knockout mice displayed alterations in open-field activity, elevated plus-maze, and passive avoidance, and these differences were ameliorated by chronic lithium treatment. These findings support the hypothesis that impaired inhibition of GSK3 contributes to the pathogenesis of FXS and support GSK3 as a potential therapeutic target.

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Figures

Fig. 1

Fig. 1

Acute MPEP administration increases GSK3 serine-phosphorylation selectively in Fmr1 knockout mice. Fmr1 knockout mice were administered MPEP (30 mg/kg; ip) or vehicle 30 or 90 min prior to sacrifice. Extracts of striatum, hippocampus, cerebral cortex, and cerebellum were probed with antibodies to (A–D) phospho-Ser21-GSK3α or total GSK3α, and (E–H) phospho-Ser9-GSK3β or total GSK3β. Shown are representative immunoblots and quantitative values presented as the percent of values from untreated mice analyzed on the same gel. n = 6 mice for control and 30 min groups, and n = 3 for 90 min group; *p < 0.05; †p < 0.06 compared to untreated values.

Fig. 2

Fig. 2

Acute MPEP administration does not change GSK3 serine-phosphorylation in wild-type mice. Wild-type mice were administered MPEP (30 mg/kg; ip) or vehicle 30 or 90 min prior to sacrifice. Extracts of striatum, hippocampus, cerebral cortex, and cerebellum were probed with antibodies to (A–D) phospho-Ser21-GSK3α or total GSK3α, and (E–H,) phospho-Ser9-GSK3β or total GSK3β. Shown are representative immunoblots and quantitative values presented as the percent of values from untreated mice analyzed on the same gel. n = 6 mice for control and 30 min groups, and n = 3 for 90 min group; *p < 0.05 compared to untreated values.

Fig. 3

Fig. 3

GSK3 serine-phosphorylation modulated by acute lithium administration. (A) Fmr1 knockout and (B) wild-type mice were administered lithium chloride (ip; 4 mmole/kg) in PBS for 30, 60, or 180 min. Extracts of striatum, hippocampus, cerebral cortex, and cerebellum were immunoblotted for phospho-Ser21-GSK3α, phospho-Ser9-GSK3β, total GSK3α, or total GSK3β. Shown are representative immunoblots and quantitative values presented as the percent of values from untreated mice analyzed on the same gel. n = 4 mice per group; *p < 0.05 compared to untreated values.

Fig. 3

Fig. 3

GSK3 serine-phosphorylation modulated by acute lithium administration. (A) Fmr1 knockout and (B) wild-type mice were administered lithium chloride (ip; 4 mmole/kg) in PBS for 30, 60, or 180 min. Extracts of striatum, hippocampus, cerebral cortex, and cerebellum were immunoblotted for phospho-Ser21-GSK3α, phospho-Ser9-GSK3β, total GSK3α, or total GSK3β. Shown are representative immunoblots and quantitative values presented as the percent of values from untreated mice analyzed on the same gel. n = 4 mice per group; *p < 0.05 compared to untreated values.

Fig. 4

Fig. 4

Chronic lithium treatment rescues hyperactive GSK3 in Fmr1 knockout mice. Fmr1 knockout (Fragile X) and wild-type mice were treated with lithium for 3–4 weeks prior to sacrifice and compared to untreated littermates. Homogenates of the striatum, hippocampus, cerebral cortex, and cerebellum were probed with antibodies to (A–D) phospho-Ser21-GSK3α, (E–H) total GSK3α, (I–L) phospho-Ser9-GSK3β, (M-P) or total GSK3β. Immunoblots were quantified by densitometry and are presented as the percents of values from untreated wild-type mice. n = 10 mice per group; **p < 0.05 comparing untreated Fragile X and wild-type values; *p < 0.05 compared with matched sample without lithium treatment.

Fig. 4

Fig. 4

Chronic lithium treatment rescues hyperactive GSK3 in Fmr1 knockout mice. Fmr1 knockout (Fragile X) and wild-type mice were treated with lithium for 3–4 weeks prior to sacrifice and compared to untreated littermates. Homogenates of the striatum, hippocampus, cerebral cortex, and cerebellum were probed with antibodies to (A–D) phospho-Ser21-GSK3α, (E–H) total GSK3α, (I–L) phospho-Ser9-GSK3β, (M-P) or total GSK3β. Immunoblots were quantified by densitometry and are presented as the percents of values from untreated wild-type mice. n = 10 mice per group; **p < 0.05 comparing untreated Fragile X and wild-type values; *p < 0.05 compared with matched sample without lithium treatment.

Fig. 5

Fig. 5

Chronic lithium treatment increases hippocampal BDNF levels. Fmr1 knockout and wild-type mice were treated with lithium for 3–4 weeks prior to sacrifice and compared to untreated littermates. BDNF levels were measured in hippocampal extracts by ELISA. Results are expressed as a percent of values in untreated wild-type controls; n = 10 mice per group; *p < 0.05 compared with matched sample without lithium treatment.

Fig. 6

Fig. 6

Chronic lithium treatment rescues hyperactive behavior of Fmr1 knockout mice. Fmr1 knockout (FX) and wild-type (WT) mice were treated with lithium for 3–4 weeks prior to 30 min open-field testing of activity. (A) Distance traveled was analyzed in 5 min bins. (B) Total, cumulative distance traveled during the 30 min test. (C) Center-square behavior, defined as the central zone of the open-field, was measured as distance traveled in the central area in 5 min bins. (D) Average center-square distance per 5 min bin. n = 5 mice per group. **p < 0.05 compared to untreated, wild-type values; *p < 0.05 compared with matched sample without lithium treatment.

Fig. 7

Fig. 7

Lithium partially rescues altered elevated plus-maze behavior of Fmr1 knockout mice, and Fmr1 knockout mice do not display depressive-like behaviors. Fmr1 knockout (FX) and wild-type (WT) mice were treated with lithium for 3–4 weeks prior to testing. Behavior in the 5 min elevated plus-maze test was analyzed as (A) total time in the open arms, (B) percentage of time spent in the open arms compared with total time spent in all arms, (C) closed arm entries, (D) open arm entries, and (E) open arm explorations. (F) Immobility time was measured during the last 4 min of the 6 min tail suspension test. (G) Immobility time was measured by beam breaks in the forced swim test. n = 10 mice per group; *p < 0.05 compared to untreated, wild-type values.

Fig. 8

Fig. 8

Chronic lithium treatment rescues impaired passive avoidance behavior of Fmr1 knockout mice. Fmr1 knockout and wild-type mice were treated with lithium for 3–4 weeks prior to behavioral assessment. (A) On training day, the latency to enter the dark chamber was measured during a 60 s test. Mice remaining in the light chamber for 60 s were excluded from further analysis. (B) Latency to enter the dark chamber 24 h after training was measured, with a cutoff time of 9 min. (C) Percentage of mice in each group crossing into the dark chamber within the 9 min cutoff time. n = 15 mice per group; **p < 0.05 compared to untreated, wild-type values; *p < 0.05 compared with matched sample without lithium treatment.

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