Effect of hydrocortisone on the extra-adrenal intensely fluorescent chromaffin and non-chromaffin cells in stretch preparations of the newborn rat

Air-dried stretch preparations were used to study adrenergic nerve fibres and catecholamine-containing cells with the formaldehyde-induced fluorescence method in the abdominal tissue block containing the para-aortic paraganglia, in the neurovascular structures of the cervical region including the carotid body, in the bladder, in the ileum, in the mesentery, in the vagus nerve and in the sympathetic ganglia of 5- or 15-day-old rats. The adrenergic nerves and the catecholamine-containing cells were well preserved and showed little or no diffusion of amines. While most intensely fluorescent cells of the main para-aortic body disappeared during the first two postnatal weeks, some such cells survived and they showed long, slender fluorescent processes. Administration of 20 mg/kg of hydrocortisone acetate daily for 5 days after birth caused a striking increase in the number and size of the clusters of the intensely fluorescent cells in the organ of Zuckerkandl, in the sympathetic ganglia and in the bladder, as well as an increase in the fluorescence intensity of the carotid body. In rats treated with hydrocortisone for 5 days and left to recover for 10 days an increased fluorescence was still observed. However, in the organ of Zuckerkandl the intensely fluorescent cells of hydrocortisone-treated 15-day-old rats showed less processes than those of the control rats of the same age.