Regulation of the level of epidermal growth factor by oestrogen in the submandibular gland of female mice.

The concentration of epidermal growth factor (EGF) in the submandibular gland of immature female mice (less than 6 weeks old) was low, ranging from 0.07 to 0.17 pmol (0.4 to 1.0 ng)/mg wet wt, but increasing to 7.61 pmol/mg wet wt by 8 weeks of age. It remained relatively constant up to 24 weeks of age, but thereafter the glandular EGF concentration increased again during the post-reproductive period to reach 62.9 pmol/mg wet wt. In contrast, the glandular EGF content in male mice increased greatly during the first 17 weeks of age to about 310 pmol/mg wet wt, and thereafter remained relatively constant up to 48 weeks of age. Ovariectomy of mature virgin mice markedly increased the glandular concentration of EGF to about 74.4 pmol/mg wet wt 4 weeks after the operation. This increase was suppressed by oestradiol-17 beta administered to ovariectomized mice at a dose of 1 microgram/mouse per day but not by 1 mg progesterone. Histological studies indicated that granular convoluted tubular cells that produced EGF in the submandibular gland were much less abundant in 12-week-old female and in oestrogen-treated ovariectomized mature mice than in 40-week-old female and ovariectomized mature mice. We conclude that oestrogen suppresses the concentration of EGF in the submandibular gland of female mice.