Androgen Support of Lacrimal Gland Function in the Female Rabbit

Abstract

Dry eye is a major reason for visits to an ophthalmologist’s office. The most probable cause for dry eye is primary lacrimal deficiency (PLD).¹ PLD is usually detected in women, most frequently after menopause, during pregnancy or lactation, or when taking estrogen-containing oral contraceptives. These various endocrine states exhibit a complete range of plasma estrogen levels from very low to very high. Thus, plasma estrogen concentrations do not appear to be a common variable in PLD. However, plasma free androgen levels are potentially decreased in all of these states. We have previously demonstrated that ovariectomy of female rabbits² and hypophysectomy of female rats³ result in a decrease in biochemical correlates of lacrimal gland function. Treatment of these endocrinectomized animals with the potent androgen dihydrotestosterone (DHT) restores the decreases in the biochemical markers of secretion,^2,3 specifically, lacrimal gland protein, DNA, Na,K-ATPase, and ß-adrenergic receptors. Androgens have been shown to be responsible for the male-like morphological and functional characteristics of the gland, including larger acini,⁴ greater secretion of IgA,⁵ and greater production of polymeric IgA receptor, measured as secretory component (SC).⁶ When female rats are treated with androgens, the morphology of the lacrimal gland changes and resembles the male lacrimal gland.⁷ However, the major neurotransmitter receptor coupled to secretion in the lacrimal gland, the muscarinic cholinergic receptor, is regulated by circulating levels of prolactin, not androgens.³