Hydrocortisone-induced increase in the number of small intensely fluorescent cells and their histochemically demonstrable catecholamine content in cultures of sympathetic ganglia of the newborn rat.

Synopsis  It is known that hydrocortisone causes a great increase in the number of small intensely fluorescent (SIF) cells in the sympathetic ganglia when injected into newborn rats. The effect of hydrocortisone on nervous tissuein vitro has not been studied previously.Pieces of newborn rat sympathetic ganglia were cultivated in Rose chambers. Hydrocortisone was dissolved in the medium in concentrations of 1–9 mg/l. Both control and hydrocortisone-containing cultures were examined daily by phase-contrast microscopy, and the catecholamines were demonstrated histochemically by formaldehyde-induced fluorescence after 7 days in culture.All cultures showed outgrowths of axons and supporting cells elements, although these were less extensive in the groups of cultures with hydrocortisone. After a week, SIF cells with a green fluorescence were observed in the control explants. In all cultures with hydrocortisone, a concentration-dependent increase was observed in the fluorescence intensity and the number of the SIF cells in the explant; numerous SIF cells were also seen in the outgrowth. Some SIF cells showed processes and the longest processes were seen in cultures with the highest concentration of hydrocortisone.It is concluded that hydrocortisone causes an increased synthesis of catecholamines in the SIF cellsin vitro, and an increase in their number by affecting either their division or their differentiation from a more immature form, or both. This effect was a direct one and not mediated by any system other than the ganglion itself. Induction of enzyme synthesis by hydrocortisone is proposed as an explanation of the increase in catecholamine concentration.