DIFFERENTIAL DISTRIBUTION OF AN ESTROGEN-RECEPTOR IN THE SUBMANDIBULAR AND PAROTID SALIVARY-GLANDS OF FEMALE RATS

The purpose of this study was to measure the availability of the estrogen receptor in submandibular and parotid salivary glands in female rats. The presence of a specific, competitive, and saturable estrogen binder in rat salivary gland tissue was determined by saturation analysis and steroid competition in cell-free homogenates of salivary gland tissue from adult ovariectomized females. Scatchard analysis of the data indicated an estrogen receptor content of 1971.1 +/- 651.4 femtomoles/gm of tissue in submandibular salivary gland. This was significantly (p < 0.01) greater than the number of estrogen binding sites in the parotid gland (457.1 +/- 123.4 femtomoles/gm tissue). Thus, there is a differential distribution in estrogen receptor content between parotid and submandibular salivary glands. The presence of an estrogen receptor in salivary gland tissue may serve to promote gender differences in submandibular salivary gland EGF content, to mediate changes in saliva composition during the female reproductive cycle and to regulate EGF release for cyclic uterine growth.