title: Effects of adenosine on cAMP production during early development in the optic tectum of chicks.
abstract: Accumulation of cyclic adenosine monophosphate (cAMP) elicited by adenosine was studied in slices and membrane preparations of optic tectum from chicks aged 1-13 days post-hatch. Accumulation of cAMP promoted by adenosine declined with age, the highest value being observed in three-day-old chicks and the lowest in 11-day-old chicks. However, when the slices were incubated with adenosine and the phosphodiesterase inhibitor-Ro 20-1724 the differences between the two ages were abolished, suggesting a higher phosphodiesterase activity in 11-day-old chicks. In membrane preparations, although basal adenylate cyclase activity was lower in three-day-old chicks, the guanylyl-imidodiphosphate (Gpp(NH)p) concentration curves for stimulation of adenylate cyclase activity indicated a higher sensitivity of G protein to Gpp(NH)p at this age. This hypothesis was reinforced by the observation that the binding of [3H]Gpp(NH)p to the membrane preparation was greater in three-day-old animals. In spite of these differences, the percentage of adenylate cyclase activity stimulation by 2-chloroadenosine (2CADO)+Gpp(NH)p was the same at both ages. These findings suggest that the decreased response evoked by adenosine during development is probably due to increased phosphodiesterase activity and a lower sensitivity of adenylate cyclase activity to Gpp(NH)p.
authors.affiliation: Department of Biochemistry, Federal University of Rio Grande do Sul, Porto Alegre, Brazil.
authors.forename: C I
authors.initials: CI
authors.lastname: Tasca
authors.forename: D
authors.initials: D
authors.lastname: Vendite
authors.forename: K L
authors.initials: KL
authors.lastname: Garcia
authors.forename: D O
authors.initials: DO
authors.lastname: Souza
mesh_terms: D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000037:antagonists & inhibitors; D000241:Adenosine / Q000494:pharmacology*; D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D002645:Chickens; D000242:Cyclic AMP / Q000096:biosynthesis*; D006165:Guanylyl Imidodiphosphate / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D008566:Membranes / Q000187:drug effects / Q000378:metabolism; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D011869:Radioligand Assay; D015398:Signal Transduction / Q000187:drug effects*; D013477:Superior Colliculi / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism
chemical_list: D010726:Phosphodiesterase Inhibitors; D006165:Guanylyl Imidodiphosphate; D000242:Cyclic AMP; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D000262:Adenylyl Cyclases; D000241:Adenosine