Source: UNIVERSITY OF NEBRASKA submitted to
ESTROGEN-CALCIUM RELATIONSHIPS DURING ONSET OF METABOLIC BONE DISEASE IN THE AGING HEN
 
PROJECT DIRECTOR: Beck, M. M.
 
PERFORMING ORGANIZATION
ANIMAL SCIENCE
UNIVERSITY OF NEBRASKA
LINCOLN,NE 68583
 
NON TECHNICAL SUMMARY: Laying hens show declines in egg production that are also associated with increasingly poor calcification of shells and depletion of calcium in bone. This project is designed to determine whether the declines in egg numbers and bone/shell calcification can be slowed or reversed by exogenous estrogen administration.
 
OBJECTIVES: 1. To continue investigations of exogenous estrogen administration to aging laying hens as a means of understanding estrogen/calcium relationships, with regard to plasma estradiol concentrations and duodenal calcium uptake. 2. To investigate cellular responses to exogenous estrogen dosage (as determined in #1), particularly estrogen receptor and calcium binding protein regulation.
 
APPROACH: Estrogen will be administered via subcutaneous implants to elevate plasma estrogen, LH, progesterone and also calcium uptake by duodenal cells. Hormones will be assayed by RIA; calcium uptake by radiolabeled calcium in vitro. As hens age, estrogen receptor populations in various tissues will be determined by immunocytochemistry. Exogenous estrogen administration will be used to determine whether receptors can be manipulated (increased) as the hen ages.
 
CRIS NUMBER: 0185073 SUBFILE: CRIS
PROJECT NUMBER: NEB-13-151 SPONSOR AGENCY: CSREES
PROJECT TYPE: ANIMAL HEALTH PROJECT STATUS: TERMINATED MULTI-STATE PROJECT NUMBER: (N/A)
START DATE: Oct 1, 1999 TERMINATION DATE: Sep 30, 2004

GRANT PROGRAM: (N/A)
GRANT PROGRAM AREA: (N/A)

CLASSIFICATION
Knowledge Area (KA)Subject (S)Science (F)Objective (G)Percent
305321010202.250%
306321010202.250%

CLASSIFICATION HEADINGS
KA305 - Animal Physiological Processes
KA306 - Environmental Stress in Animals
S3210 - Egg-type chicken, live animal
F1020 - Physiology
G2.2 - Increase Efficiency of Production and Marketing Systems


RESEARCH EFFORT CATEGORIES
BASIC 80%
APPLIED 20%
DEVELOPMENTAL (N/A)%

KEYWORDS: estrogens; layers; poultry; bone diseases; metabolic diseases; calcium; nutrient transport; egg production; animal physiology; environmental stress; receptors; exogenous hormones; skeleton; progesterone; hormones; aging; hens; estradiol; plasma levels; dosage; implants

PROGRESS: Oct 1, 1999 TO Sep 30, 2004
Extrogen receptor populations were characterized in laying hen, in various calcium-regulating tissues, over the productive lifetime of the hen. In all tissues studied (shellgland, kidney, duodenum, ER-alpha populations decreased with age. When tamoxifen was administered to block ER-alpha, it blocked progesterone release and increased calcium uptake by duodenal cells; these results suggest an antagonist action at the hypothalamus and an agonist action at the gut. It also suggests the presence of ER-alpha in duodenum of the chicken, a novel finding that indicates similarity with rat and that is the first such demonstration in birds.

IMPACT: 1999-10-01 TO 2004-09-30 The findings from this project establish new and exciting information about the status of estrogen regulating mechanisms in birds. They provide a clear basis on which to pursue molecular investigations of estrogen receptor regulation in aging hens.

PUBLICATION INFORMATION: 1999-10-01 TO 2004-09-30
Hansen, KK, RJ Kittok, G. Sarath, CF Toombs, N. Caceres, and MM Beck. 2003. Estrogen receptor-alpha populations change with age in commercial laying hens. Poultry Sci. 82:1624-1629.

PROJECT CONTACT INFORMATION
NAME: Beck, M. M.
PHONE: 402-472-6439
FAX: 402-472-6362