Involvement of adenosine A2a receptor in intraocular pressure decrease induced by 2-(1-octyn-1-yl)adenosine or...

Area of Science:

• Ophthalmology
• Pharmacology
• Neuroscience

Background:

• Glaucoma is a leading cause of irreversible blindness.
• Current treatments aim to reduce intraocular pressure (IOP), but novel mechanisms are needed.
• Adenosine receptors play roles in ocular physiology and may be therapeutic targets.

Purpose of the Study:

• To elucidate the mechanism by which 2-alkynyladenosine derivatives reduce IOP in rabbits.
• To investigate the specific adenosine receptor subtypes involved in the ocular hypotensive effects of these compounds.
• To assess the potential of these derivatives as therapeutic agents for glaucoma.

Main Methods:

• Receptor binding assays were performed to determine the affinity of 2-O-Ado and 2-CN-Ado for adenosine receptor subtypes.
• Ocular hypotensive responses were measured in rabbits following topical administration of the compounds.
• The effects of selective adenosine receptor antagonists (CSC, DPCPX, alloxazine) on IOP reduction and outflow facility were evaluated.
• Changes in cAMP levels in the aqueous humor were measured.

Main Results:

• 2-O-Ado and 2-CN-Ado demonstrated high affinity and selectivity for the adenosine A(2a) receptor.
• Both compounds significantly reduced IOP in rabbits.
• The ocular hypotensive effects were blocked by the A(2a) antagonist CSC, but not by A(1) or A(2b) antagonists.
• Treatment with 2-O-Ado and 2-CN-Ado increased aqueous humor cAMP levels and outflow facility, effects inhibited by CSC.

Conclusions:

• 2-O-Ado and 2-CN-Ado lower IOP by increasing aqueous humor outflow facility, primarily through activation of the adenosine A(2a) receptor.
• These findings highlight the therapeutic potential of selective adenosine A(2a) receptor agonists for glaucoma treatment.
• 2-O-Ado and 2-CN-Ado serve as promising lead compounds for developing new anti-glaucoma medications.