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Sex Differences in Dopamine Receptor Signaling in Fmr1 Knockout Mice: A Pilot Study
Anlong Jiang1, Le Wang1, Justin Y D Lu1
1Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON M5T 1R8, Canada.
Abstract:
Fragile X syndrome (FXS) is an X-chromosome-linked dominant genetic disorder that causes a variable degree of cognitive dysfunction and developmental disability. Current treatment is symptomatic and no existing medications target the specific cause of FXS. As with other X-linked disorders, FXS manifests differently in males and females, including abnormalities in the dopamine system that are also seen in Fmr1-knockout (KO) mice. We investigated sex differences in dopamine signaling in Fmr1-KO mice in response to L-stepholidine, a dopamine D1 receptor agonist and D2 receptor antagonist. We found significant sex differences in basal levels of phosphorylated protein kinase A (p-PKA) and glycogen synthase kinase (GSK)-3β in wild type mice that were absent in Fmr1-KO mice. In wild-type mice, L-stepholidine increased p-PKA in males but not female mice, decreased p-GSK-3 in female mice and increased p-GSK-3 in male mice. Conversely, in Fmr1-KO mice, L-stepholidine increased p-PKA and p-GSK-3β in females, and decreased p-PKA and p-GSK-3β in males.
Insights
Fragile X syndrome (FXS) research reveals sex-specific dopamine signaling differences in Fmr1-knockout mice. L-stepholidine impacts protein kinase A and glycogen synthase kinase-3β differently in males and females, offering potential therapeutic insights.
Area of Science:
- Neuroscience
- Genetics
- Pharmacology
Background:
- Fragile X syndrome (FXS) is an X-linked genetic disorder causing cognitive and developmental issues.
- Current FXS treatments are symptomatic, lacking targeted therapies for the underlying cause.
- FXS exhibits sex-specific manifestations, including dopamine system abnormalities, observed in Fmr1-knockout (KO) mouse models.
Purpose of the Study:
- To investigate sex differences in dopamine signaling pathways in Fmr1-KO mice.
- To examine the effects of L-stepholidine, a dopamine receptor agonist/antagonist, on these pathways.
- To identify potential sex-specific therapeutic targets for FXS.
Main Methods:
- Utilized Fmr1-KO mice and wild-type littermates.
- Administered L-stepholidine, a dopamine D1 receptor agonist and D2 receptor antagonist.
- Measured basal and drug-induced levels of phosphorylated protein kinase A (p-PKA) and glycogen synthase kinase (GSK)-3β.
Main Results:
- Wild-type mice showed sex differences in basal p-PKA and p-GSK-3β, absent in Fmr1-KO mice.
- L-stepholidine differentially affected p-PKA and p-GSK-3β in male and female wild-type mice.
- In Fmr1-KO mice, L-stepholidine increased p-PKA and p-GSK-3β in females, while decreasing them in males.
Conclusions:
- FXS is associated with sex-specific alterations in dopamine signaling pathways.
- L-stepholidine's effects on key signaling molecules are sex-dependent in both wild-type and Fmr1-KO mice.
- These findings highlight potential sex-specific therapeutic strategies for Fragile X syndrome.
