title: Transport of 125I-EGF into milk and effect of sialoadenectomy on milk EGF in mice.
abstract: Epidermal growth factor (EGF) (urogastrone) is found in high concentrations in mouse and human milk. The origin of milk EGF is unknown. Milk samples were collected from lactating mice 2-6 h after the intravenous administration of a tracer dose of 125I-labeled EGF. The milk contained relatively high levels of radioactivity of which 35-46% was precipitated by trichloroacetic acid-phosphotungstic acid (TCA-PTA) and 26% by a specific antimouse EGF antiserum. Part of the radioactivity in milk was eluted from a Bio-Gel P-10 column at the point at which pure standard 125I-EGF was eluted. These data indicate that the mammary gland of the lactating mouse is capable of sequestering and transporting 125I-EGF into milk. Administration of a thousand-fold excess of unlabeled EGF caused no reduction in TCA-PTA-precipitable radioactivity in milk samples of mice given 125I-EGF. When mice were given 10 micrograms of unlabeled EGF and milk was collected 4 h later, compared with controls the EGF level in milk was doubled. Administration of EGF had no effect on lactose and protein concentrations in the milk, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed no qualitative or quantitative changes in the major milk proteins. Milk collected from lactating mice that were sialoadenectomized 6 mo earlier contained about 50% less EGF compared with controls. After the administration of 125I-EGF high concentrations of radioactivity were also found in the mammary and submandibular glands and in the stomach. In the latter organs, however, 95-96% of the radioactivity was in the acid-soluble fraction.(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D000818:Animals; D001692:Biological Transport; D004591:Electrophoresis, Polyacrylamide Gel; D004815:Epidermal Growth Factor / Q000032:analysis / Q000378:metabolism*; D005260:Female; D007457:Iodine Radioisotopes; D007774:Lactation; D008321:Mammary Glands, Animal / Q000378:metabolism*; D051379:Mice; D008892:Milk / Q000032:analysis / Q000378:metabolism*; D011247:Pregnancy; D012469:Salivary Glands / Q000502:physiology*; D013361:Sublingual Gland / Q000502:physiology; D013363:Submandibular Gland / Q000502:physiology; D013997:Time Factors
chemical_list: D007457:Iodine Radioisotopes; D004815:Epidermal Growth Factor