Increased uptake of [3H]choline by rat superior cervical ganglion: an effect of dexamethasone.

The high affinity uptake of [3H]choline by the superior cervical ganglion, isolated from the rat, was found to be increased by dexamethasone. Maximal increase (60-65% above control values) occurred at the steroid concentration of 5 X 10(-5) M. Other glucocorticoids (triamcinolone, corticosterone and hydrocortisone) were without an effect on the [3H]choline uptake. Following administration of dexamethasone (25 mg/kg, i.p.), there was a marked increase in the level of choline in the ganglion. The increase was 3-fold at 1 hr and 10-fold at 6 hr, and by 24 hr the choline levels still remained higher in the steroid-treated animals than in the controls. Levels of acetylcholine in the ganglion were also increased, beginning at 1 hr after the injection of steroid. The increase was 85% by 3 hr and 60% by 6 hr. Triamcinolone, a glucocorticoid that was without an effect on [3H]choline uptake in vitro, was also ineffective in altering the levels of choline and acetylcholine in vivo. It seems probable that the increase of choline uptake in the ganglion induced by dexamethasone may, at least in part, occur in the preganglionic cholinergic terminals, leading to increased synthesis of acetylcholine. Such an effect of dexamethasone provides another case of a selective steroid acting directly on nerve terminals by altering a transport mechanism.