A fluorescence study on the ability of the notochord to synthesize and store catecholamines in early chick embryos

摘要

AbstractThe role that catecholamines play in presympathetic embryogenesis is relatively unknown. All catecholamine‐producing cells develop both the enzymes needed for catecholamine synthesis and an amine pump for the uptake of extraneous catecholamines. This investigation was undertaken to define areas which are able to produce and store catecholamines in the presympathetic chick embryo. Embryonic chicks between two and four days of incubation (stages 11 to 23) were incubated in a medium containing norepinephrine, dopa or dopa with cocaine, and treated for fluorescence according to the method of Falck and Owman. Norepinephrine uptake was considered to be evidence of the presence of an amine pump. The conversion of dopa, a nonfluorescent precursor of dopamine, to dopamine which is fluorescent was considered to be an indication that the enzyme dopa decarboxylase was present. Cocaine, an amine pump inhibitor, applied simultaneously with dopa would prevent dopamine synthesized in one site from entering other cells. It was found that the notochord was intensely fluorescent in the presence of norepinephrine. No other sites of norepinephrine uptake were seen. The notochord could also convert dopa to dopamine indicating the presence of dopa decarboxylase in notochordal cells. Similar results were obtained when cocaine was added to the incubation medium. It is concluded that the notochord is a possible site of catecholamine synthesis and storage in presympathetic chick embryo