How adenosine and dopamine receptors work together to control light-sensing cell connections in the mouse eye

Adenosine and dopamine may coregulate photoreceptor coupling through opposing effects on the PKA pathway and Cx36 phosphorylation.

• Gap junctions in retinal photoreceptors help reduce voltage noise and integrate rod signals during mesopic vision.
• Dopamine, acting through D4 receptors, may uncouple photoreceptors by inhibiting adenylyl cyclase and reducing PKA activity.
• Adenosine levels increase in darkness and could serve as a signal to regulate photoreceptor coupling by affecting gap junction phosphorylation.
• Pharmacological activation of A2a receptors or inhibition of D4 receptors in light-adapted retinas enhanced photoreceptor coupling.
• In dark-adapted retinas, inhibiting A2a receptors or activating D4 receptors decreased Cx36 phosphorylation, indicating a PKA-dependent mechanism.
• A2a-deficient retinas displayed impaired regulation of photoreceptor gap junction phosphorylation and altered expression of D4 receptor and adenylyl cyclase mRNAs.

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