Adenosine A2 receptor presence and synergy with cholinergic stimulation in rabbit lacrimal gland.
OBJECTIVE
Secretion from the lacrimal gland is an important part of the well-being of the eye, and a central part in the search for treatment of dry eye syndrome. Adenosine has stimulatory effects on the lacrimal gland, and can potentiate the effect of the cholinergic agonist carbachol (Cch). The aim of the present study is to investigate the presence of the adenosine A(2) receptor subtypes A(2A) and A(2B) in the rabbit lacrimal gland, and to characterize their role in regulated acinar cell secretion.


METHODS
Expression of the receptors was investigated using reverse transcriptase-PCR (RT-PCR) and immunofluorescence, and secretion effects were studied using a secretion assay in isolated lacrimal gland acinar cells.


RESULTS
Presence of both receptors was detected by RT-PCR and immunofluorescence. The secretion assay revealed a minor effect of stimulation of the A(2) receptors, and a strong synergistic effect with the cholinergic agonist Cch. The synergistic effect was significantly reduced by the A(2B) antagonist PSB 1115, but not by the A(2A) antagonist SCH 58261, indicating that A(2B) is the receptor responsible for this potentiation.


CONCLUSIONS
The study reveals the presence of the adenosine A(2) receptor subtypes as well as a role for them in lacrimal gland secretion, and especially in the synergy with purinergic and cholinergic stimulation.
Carlsson
Stina K
SK
School of Natural Sciences, Linnaeus University, Kalmar, Sweden.
Edman
Maria C
MC
Delbro
Dick
D
Gierow
J Peter
JP
D000818:Animals; D002217:Carbachol / Q000494:pharmacology*; D002478:Cells, Cultured; D018678:Cholinergic Agents / Q000494:pharmacology*; D004357:Drug Synergism; D005455:Fluorescent Antibody Technique; D007765:Lacrimal Apparatus / Q000187:drug effects* / Q000378:metabolism*; D011817:Rabbits; D043705:Receptor, Adenosine A2A / Q000378:metabolism*; D043704:Receptor, Adenosine A2B / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013194:Staining and Labeling
D018678:Cholinergic Agents; D043705:Receptor, Adenosine A2A; D043704:Receptor, Adenosine A2B; D002217:Carbachol