The Ontogeny of Dopamine‐dependent Increase of Adenosine 3′,5′‐cyclic Monophosphate in the Chick Retina

The adenosine 3′,5′‐cyclic monophosphate level of chick embryonic retina changes during the course of development. In retinas from 6‐ to 15‐day‐old embryos the cAMP level is approximately 7 pmol/mg protein. A sharp 3‐fold increase is observed between the 16th and 18th embronic day and remains constant thereafter. A dopamine‐dependent increase in cAMP of the chick retina is already present in 7‐day‐old embryos, and by the 8th embryonic day maximal response is attained. Glutamate promotes a 2‐fold stimulation. Carbachol, γ‐aminobutyric acid and glycine do not cause any significant change in the level of cAMP of the embryonic tissue. Guanosine 3′,5′‐cyclic monophosphate also accumulates during development. Its concentration is approx 0.5 pmol/mg protein from the 8th to the 14th embryonic day, then increases gradually until the 19th day of development when the level observed is approx 14 pmol/mg protein.