title: Influence of melatonin on mammary gland growth: in vivo and in vitro studies.
abstract: Our objective was to determine whether melatonin influenced mammary growth in response to mammogenic hormones. Prepubertal female BALB/c mice were injected for 9 days with 1 microgram of 17 beta-estradiol and 1 mg of progesterone or 17 beta-estradiol/progesterone plus 50, 100, or 200 micrograms of melatonin. Area of the parenchyma and total DNA content of the second thoracic gland were similar between controls and melatonin-injected mice. However, micrograms of DNA/100 mg of mammary tissue were lower in animals treated with 17 beta-estradiol/progesterone plus 200 micrograms of melatonin than in controls. Triglyceride content of mammary glands from animals treated with 100 or 200 micrograms of melatonin/day increased relative to controls. In an in vitro experiment, thoracic mammary glands of 21-day-old mice were cultured for 6 days in a mammogenic milieu of hormones (17 beta-estradiol/progesterone, aldosterone, bovine prolactin, growth hormone, and insulin) with 0 (control), 10(-6), 10(-9), or 10(-12) M melatonin. Relative to controls, 10(-12) M melatonin increased and 10(-6) M melatonin decreased mammary DNA and uptake of [methyl-3H]thymidine. We conclude that high doses of melatonin reduce mammary development in normal mice and that some of this effect may be mediated directly at the mammary tissue.
authors.affiliation: Department of Animal Science, Michigan State University, East Lansing 48824.
authors.forename: E J
authors.initials: EJ
authors.lastname: Sanchez-Barcelo
authors.forename: M D
authors.initials: MD
authors.lastname: Mediavilla
authors.forename: H A
authors.initials: HA
authors.lastname: Tucker
mesh_terms: D000818:Animals; D002452:Cell Count; D002455:Cell Division / Q000187:drug effects; D004247:DNA / Q000032:analysis; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D008321:Mammary Glands, Animal / Q000166:cytology / Q000187:drug effects* / Q000254:growth & development; D008550:Melatonin / Q000494:pharmacology*; D051379:Mice; D008807:Mice, Inbred BALB C; D009924:Organ Culture Techniques; D011374:Progesterone / Q000494:pharmacology*; D014280:Triglycerides / Q000032:analysis
chemical_list: D014280:Triglycerides; D011374:Progesterone; D004958:Estradiol; D004247:DNA; D008550:Melatonin