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Adenosine-elicited accumulation of adenosine 3', 5'-cyclic monophosphate in the chick embryo retina
Abstract:
The cyclic AMP level of 17-day-old chick embryo retina increased from 20 to 331 pmol/mg protein when the tissue was incubated for 20 min in the presence of 4-(3-butoxy-4-methoxybenzyl-2-imidozolinone) (RO 20-1724). The addition of 0.5 mM-3-isobutyl-1-methylxanthine (IBMX) or 0.5 units/ml of adenosine deaminase (EC 3.5.4.4) to the medium reduced the increase of cyclic AMP content from 20 to 100 pmol/mg protein. Dipyridamole did not interfere with the rise of the retinal cyclic AMP level observed with RO 20-1724. The EC50 of 6-amino-2-chloropurine riboside (2-chloroadenosine)-elicited accumulation of cyclic AMP of retinas incubated in the presence of RO 20-1724 plus adenosine deaminase was approximately 1 microM. When retina incubation was carried out in the presence of 0.5 mM-IBMX, the 2-chloroadenosine dose-response curve was shifted to the right two orders of magnitude. Maximal stimulation of the cyclic AMP level of 17-day-old chick embryo retina incubated in the presence of 0.5 mM-IBMX was observed at 1 mM-adenosine concentration. This effect was not blocked by dopamine antagonists. Guanosine and adenine did not affect the retinal cyclic AMP level. AMP and ATP had a slight stimulatory effect. Adenosine response of embryonic retina increased sharply from the 14th to the 17th embryonic day. A similar, but not identical adenosine effect was observed in cultured retina cells.
Insights
Cyclic AMP levels in chick embryo retinas significantly increase with RO 20-1724, a phosphodiesterase inhibitor. Adenosine also stimulates cyclic AMP, with this response intensifying during embryonic development.
Area of Science:
- Neuroscience
- Biochemistry
- Developmental Biology
Background:
- Cyclic AMP (cAMP) is a crucial second messenger in various cellular processes, including neuronal function.
- Understanding cAMP regulation in the developing retina is vital for comprehending visual system development and function.
Purpose of the Study:
- To investigate the effects of specific compounds on cyclic AMP levels in embryonic chick retinas.
- To explore the role of adenosine and phosphodiesterase inhibition in regulating retinal cAMP.
Main Methods:
- Incubation of 17-day-old chick embryo retina with RO 20-1724, a phosphodiesterase inhibitor.
- Assessment of cyclic AMP levels using biochemical assays.
- Dose-response studies with 2-chloroadenosine and adenosine in the presence of inhibitors and modulators.
Main Results:
- RO 20-1724 significantly increased retinal cyclic AMP levels.
- 3-isobutyl-1-methylxanthine (IBMX) and adenosine deaminase modulated the RO 20-1724-induced cAMP increase.
- Adenosine elicited a concentration-dependent stimulation of cAMP, with response increasing from day 14 to 17 of embryonic development.
Conclusions:
- Phosphodiesterase inhibition is a potent stimulator of cAMP in the embryonic chick retina.
- Adenosine plays a significant role in regulating cAMP levels in the developing retina.
- The sensitivity to adenosine increases during late embryonic development.