Modulation of lingual lipase development by glucocorticoid in the rat

Lingual lipase in the rat is present in the neonatal period and undergoes developmental increase during postnatal life. To evaluate the role of glucocorticoid in the control of lingual lipase during development, suckling rats were adrenalectomized at d 10 and various hormone replacements were performed. Adrenalectomy abolished the developmental increase of lingual lipase. Low doses of dexamethasone (0.2 and 0.5 microgram/100 g body wt) restored the lingual lipase to near normal level in adrenalectomized animals. High doses of dexamethasone (20 micrograms/100 g body wt), when given to similarly adrenalectomized animals, however, led to a reduction of lingual lipase levels. Inhibition by dexamethasone is through the action of the hormone inasmuch as the coadministration of RU38486, a glucocorticoid type II receptor antagonist, completely abolished the inhibitory action. Inhibition is also steroid specific, with dexamethasone and triamcinolone acetonide being more effective. The results suggest a unique bimodal regulation of lingual lipase by dexamethasone in the rat serous glands. Because of the possible importance of lingual lipase as an alternative enzyme for fat digestion in neonates, the inhibitory action of high doses of glucocorticoid on lingual lipase development may have important implications. The use of steroidal compounds in the hastening of lung maturation and treatment of inflammatory disease might conceivably compromise their lingual lipase development, hence their capacities of fat digestion and malabsorption in the same period.