EFFECT OF GLUCOCORTICOIDS ON NERVE GROWTH FACTOR-MEDIATED ENZYME INDUCTION IN ORGAN CULTURES OF RAT SYMPATHETIC GANGLIA: ENHANCED RESPONSE AND REDUCED TIME REQUIREMENT TO INITIATE ENZYME INDUCTION

Abstract— After previous studies had shown that nerve growth factor produces a very similar change in the enzyme pattern of adrenergic neurons as does an increased activity of the preganglionic cholinergic nerves, the present experiments revealed that the nerve growth factor-mediated selective induction of TH and DBH is enhanced by glucocorticoids in a way similar to that mediated by acetylcholine via nicotinic receptors. Corticosterone (5 μM) produced not only an increase in the maximal response to NGF but shifted the concentration response curve of TH to NGF to the left. The potentiation effect was shown to be specific for glucocorticoids, since other steroid hormones like testosterone, β-estradiol and progesterone had no effect. Moreover, the glucocorticoid effect could be antagonized by cortexolone, suggesting an effect via glucocorticoid receptors. In addition to the potentiation of the nerve growth factor-mediated enzyme induction, glucocorticoids reduced the exposure time to NGF, necessary to initiate maximal TH induction, from 4 h to 10 min. The glucocorticoid potentiation of NGF-mediated specific enzyme induction is discussed in relation to the site and mechanism of action of NGF.