3 GROWTH HORMONE Produced in the anterior pituitary Been shown to influence mammary development even in the fetal stagesMammary parenchyma: + correlated to GHReceptors on epithelial / stromal tissueMOST EFFECTS MEDIATED THROUGH LOCAL STROMAL FACTORS (IGF)
4 GLUCOCORTICOIDS (C) Produced in the adrenal glands Involved in nutrient metabolismShown to be involved in both:- ductal development: with GH and E2- lobulo/alveolar growth: GH, PRL, E2, P4DIRECT vs. INDIRECT EFFECTS?
5 Produced in the ovary (placenta) ESTROGEN (E2)Produced in the ovary (placenta)SPECIES SPECIFICITY!!!!!Parenchymal development even very early- rodents, bovine : essential- sheep: ovex and still get developmentParenchymal development: species specific- rodents: duct / stroma bovine: ductMediated through local factors: IGF
8 PROGESTERONE (P4) Produced in the ovary ( placenta) Lobulo-alveolar dev:Lactogenesis-stage 1Function of high E2 and P4 ( GH, PL, C)- luteal phase: some dev./ milk synthesis?- pregnancy: massive development P4/E2** especially late pregnancyInhibitory to lactogenesis (Stage 2)?
12 PROLACTIN Produced in the anterior pituitary SPECIES SPECIFIC!! Bovine: Permissive effect for steroidsRodents: ESSENTIAL for mammo.* Regression of elongated terminal end buds* Promotes ductular side branches* Direct effect on lobulo- alveolar development
14 PLACENTAL LACTOGEN Growth hormone and prolactin-like activities Produced by the placenta (fetal originGrowth hormone and prolactin-like activitiesLinkage to calf size / future milk production?Mediated by local factors (IGF)?
15 MAMMOGENIC HORMONE ACTIONS Related to hormone concentrationsRelated to tissue sensitivity- increase in receptors / late pregnancyHormone biological availability- Steroid hormones bound to transport proteins : glucocorticoids
36 What prevents milk letdown? STRESS!!!Sympathetic innervation: vasoconstrictionCentral InhibitionFailure of oxytocin to be releasedPeripheral InhibitionFailure of oxytocin to reach myoepithelial cells- Failure of oxytocin receptorsOxytocin-short 1/2 life~5 minutes
39 ARTIFICIAL INDUCTION OF LACTATION WHAT HORMONESAREINVOLVED?
40 ARTIFICIAL INDUCTION OF LACTATION Estrogen: .1 mg/kg/day in oil 2X/12 hr.Progesterone: .25 mg/kg/day “ “ “*** E2 and P4 given for 7 days ( days 1-7)Dexamethasone: 20 mg/d (day 18, 19-20?)Milk on day 21 or when engorged w/milkReserpine: tranquilizer that prolactin(days 8, 10, 12, 14)
41 EXTRA CREDIT # 2 QUESTION (10 PTS) AS 337 LACTATION BIOLOGYEXTRA CREDIT # 2 QUESTION (10 PTS)How can lactation be induced (how was Tom Cruise going to nurse his baby or an animal who is not pregnant initiate a new lactation)? Look for strategies, products, organizations, or interesting information about induction of lactation in any species and/or male lactation. Share what you find and where you found it.DUE ON/ BEFORE CLASS Th 2/5 (Th before exam)Can give to Sarah, Erin, Kevin or me in class or send via .HAVE A FANTASTIC WEEKEND!!!