Immunocytochemical detection of estrogen and progesterone receptors in the rabbit submandibular gland.

Rabbit submandibular glands produce secretions involved in olfactory communication. The histology of these glands and their secretory activity are: sexually dimorphic; vary across the female reproductive cycle; and are modified by gonadectomy. This suggests that gonadal steroids regulate the structure and function of such glands. To further support this idea we assessed by immunocytochemistry the presence of estrogen and progesterone receptors in male and female rabbit submandibular glands. Immunoreactivity was detected only in the nucleus of acini cells. The number of estrogen receptor-immunoreactive cells/field varied among estrus (26 +/- 6; mean +/- S.E.), ovariectomized (19 +/- 2), and ovariectomized-estrogen-treated animals (13 +/- 3). Intact males showed a significantly smaller number of estrogen receptor-immunoreactive cells/field (12 +/- 1) than estrous females. Interestingly, progesterone receptor-immunoreactive cells were more abundant in estrous (32 +/- 7) than in ovariectomized animals (7 +/- 1). Estradiol benzoate (5 micrograms daily for 5 days) increased the number of progesterone receptor-immunoreactive cells/field in ovariectomized females (17 +/- 1). Intact males showed fewer progesterone receptor-immunoreactive cells/field (16 +/- 2) than estrous females. Results show that the rabbit submandibular gland is a target for estrogen and progesterone and support the idea that these hormones participate in regulating the physiology of this gland.