ANDROGEN SUPPORT OF LACRIMAL GLAND-FUNCTION

The effects of dihydrotestosterone (DHT) (1 mg/kg) on biochemical para meters related to lacrimal secretion, basal tear flow rate, and piloca rpine-stimulated lacrimal gland fluid secretion, in mature ovariectomi zed rabbits were studied. The effects of the synthetic estrogen, dieth ylstilbestrol (DES) (100 mu g/kg), on lacrimal gland biochemical param eters in normal mature female rabbits was also studied. Ovariectomy de creased the total serum levels of testosterone (T) by 88.5% and andros tenedione by 35.9%, without changing the levels of dehydroepiandroster one (DHEA) or its sulfate. Ovariectomy caused a significant regression of the lacrimal glands, decreasing total DNA by 35%, and total protei n by 22%. DHT treatment of ovariectomized animals prevented lacrimal g land regression, increasing total gland DNA (31%) and total protein (1 8%). DHT treatment also increases Na+,K+-ATPase activity (29%) and bet a-adrenergic receptor binding sites (23%) compared to the ovariectomiz ed group. DHT increased pilocarpine stimulated lacrimal gland fluid se cretion (13.26 +/- 1.47 mu L/min) compared to the ovariectomized group (7.72 +/- 0.41 mu L/min), but DHT treatment paradoxically decreased b asal tear flow rate (1.02 +/- 0.04 mu L/min) as compared to the ovarie ctomized rabbits (1.96 +/- 0.12 mu L/min). DES decreased the total ser um T from 59.33 +/- 10.54 pg/mL to 21.5 +/- 6.06 pg/mL. DES decreased total Na+,K+-ATPase by 12% and increased beta-adrenergic receptor bind ing sites by 83.3%. These results suggest that androgens play a major role in supporting lacrimal gland secretory function. Additionally, th ey suggest that estrogens may influence certain aspects of lacrimal fu nctions, although it is not clear to what extent those actions are eli cited directly or indirectly.