Adenosine A1 receptors determine effects of caffeine on total fluid intake but not caffeine appetite.
Adenosine A1 receptor wild-type (+/+) and knockout (-/-) mice were used to elucidate the role of adenosine A1 receptors in caffeine self-administration in a two-bottle choice test and in the effect of caffeine on total fluid intake and plasma renin concentration. With access to water only, adenosine A1 receptor -/- mice showed greater basal fluid intake and greater plasma renin concentration than +/+ mice. Free access to both water and a caffeinated solution (30 mg/100 ml) for 14 days increased total fluid intake only in adenosine A1 receptor +/+ mice (by 23+/-3%), and both total fluid intake and plasma renin concentration were no longer different between genotypes. Mean intake of water and caffeinated solution was not different between adenosine A1 receptor +/+ and -/- mice. These data reveal that adenosine A1 receptors do not contribute to caffeine consumption, but determine the effects of caffeine on fluid intake and plasma renin concentration.
Rieg
Timo
T
Department of Medicine, University of California San Diego & VA San Diego Healthcare System, 3350 La Jolla Village Drive (9151), San Diego, CA 92161, USA.
Schnermann
Jürgen
J
Vallon
Volker
V
D000818:Animals; D001066:Appetite / Q000187:drug effects* / Q000502:physiology; D002110:Caffeine / Q000008:administration & dosage*; D000697:Central Nervous System Stimulants / Q000008:administration & dosage; D004327:Drinking Behavior / Q000187:drug effects* / Q000502:physiology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D043682:Receptor, Adenosine A1 / Q000235:genetics / Q000502:physiology*; D012083:Renin / Q000097:blood
D000697:Central Nervous System Stimulants; D043682:Receptor, Adenosine A1; D002110:Caffeine; D012083:Renin