Neuroendocrinimmune modulation of secretory component production by rat lacrimal, salivary, and intestinal epithelial cells

Purpose. To evaluate the kinetics, receptor specificity, molecular basis, and site selectivity of the endocrine and neural regulation of secretory component (SC) synthesis by rat lacrimal gland acinar cells. Methods. Acinar cells from male rat lacrimal and submandibular glands, as well as epithelial cells (IEC-6) from the rat small intestine, were cultured in supplemented, serum-free media and treated with dihydrotesterone, cholera toxin, carbachol, vehicle, or other agents for varying time periods. Media SC levels were measured by radioimmunoassay. Results. The authors' findings with lacrimal gland acinar cells demonstrate that: a significant, temporal delay exists between the initiation of stimulatory or inhibitory signals and the eventual cellular SC response to regulatory compounds; the parasympathetic analogue, carbachol, exerts a dual effect on SC output, i.e., an early stimulation (hours) followed by an extended suppression (days); the androgen and cholinergic control of SC is receptor-mediated; and the androgen modulation of SC may involve the induction of gene expression. In addition, the authors' results show that distinct, tissue-specific variations occur in the nature of SC regulation: Compounds that control SC output by lacrimal acinar cells do not necessarily alter SC production by epithelial cells from the rat submandibular gland or small intestine. Conclusions. These findings advance the authors' understanding of the neuroendocrine regulation of SC synthesis in acinar cells from the lacrimal gland. Moreover, the authors' results indicate that the nature of the neural, endocrine, and immune control of lacrimal SC may be unique