Atrophy of Rat Exorbital Lacrimal Glands Induced by Atropine

To assess the morphological changes of the lacrimal gland after cholinergic suppression, we performed light- and transmission-electron microscopic examinations on the exorbital lacrimal glands in rats after intragastric intubation of atropine, a nonselective antimuscarinic compound with a high affinity for M3 muscarinic subtype receptors. In addition, areas of acinar cells were measured by an image processor. The weights of the lacrimal gland were decreased at hours 36 and 48 after atropine single administration at 250 mg/kg. Areas of acinar cells, measured by an image processor, were also decreased. Electron-microscopic examination demonstrated decreased number of secretory granules in the apical cytoplasm of acinar cells in all rats on days 7 and 28 of repeated atropine treatment. No changes were evident in other cytoplasmic organelles. Four- and even thirteen-week repeated administration studies revealed no progression in lacrimal acinar cell atrophy. The present findings demonstrate that an antimuscarinic compound that has high affinity for M3 muscarinic subtype receptors induces lacrimal gland acinar cell atrophy caused by a decrease in secretory granules, and that the repeated administration is not associated with any progression or any other changes.