Quantitative fluorescence studies of the effects of catecholamines and hydrocortisone on endogenous amine levels in neurones and small intensely fluorescent cells of embryonic chick sympathetic ganglia in vivo and in vitro

Summary Chick embryo lumbar sympathetic ganglia (11 day) cultured for three days and uncultured (in vivo) ganglia of comparable age were freeze-dried and processed by the formaldehyde-induced fluorescence technique for the demonstration of biogenic monoamines. The catecholamine levels within principal neurone cell bodies and small intensely fluorescent (SIF) cells were then examined in plastic sections of the in vivo and in vitro ganglia by a quantitative fluorescence method under various experimental conditions. Culture of ganglia for three days in the presence of hydrocortisone acetate (10g/ml) resulted in an increased SIF cell fluorescence (P<0.001 compared to control) and a green to yellow colour shift in the fluorophore of SIF cells. No detectable alteration in the fluorescence level of neurones was observed. When neurones after three days in culture were incubated for 1 h in exogenous catecholamines, a significant increase in fluorescence levels (interpreted as an increase in catecholamine content) occurred with noradrenaline (2×10^–6 M; 2×10^–5 M). SIF cells in ganglia removed directly from 14-day old chicks similarly took up noradrenaline and dopamine, and also adrenaline (2×10^–5 M). Morphological results are presented which indicate that the cellular appearances and architecture of cultured ganglion explants are very similar to those in comparable ganglia in vivo.This work was supported by a grant from the Medical Research Council. We thank Mrs. G. O'Shea, Mr. T.T. Lee and Mr. P.F. Hire for their valuable technical assistance