# CONTROL OF CALCIUM METABOLISM IN AGING AND OSTEOPOROSIS

> **NIH NIH R01** · DUKE UNIVERSITY · 1989 · $89,026

## Abstract

Osteoporosis is a major health problem in the elderly population.  Affected
subjects suffer fractures of the vertebrae, distal forearm and hip.  While
the frequency with which osteoporosis occurs in the aged has made research
into its pathogenesis and treatment of high priority, routine, efficacious
therapy for improvement of the underlying skeletal abnormalities of
osteoporosis (both bone fragility and volume deficit) remains unrealized.
The present application outlines research aimed at generating information
on the pathogenesis of osteoporosis, an understanding of which must be
obtained if the means for abatement or cure of the debilitating symptoms is
to be found.  The primary objective is to characterize and compare the
endocrine control of bone and mineral metabolism in aging and
osteoporosis.  Since a thorough knowledge of the changes in calcium
homeostasis which accompany normal aging is necessary to recognize any
changes which occur uniquely in osteoporosis, initially, the effects of age
and dietary calcium on the metabolism of vitamin D and the secretion of
parathyroid hormone (PTH) and calcitonin (CT) in the Fisher F-344 rat model
of human aging will be studied utilizing a longitudinal design.  This
approach will eliminate much of the variation that has plagued earlier
experiments of cross-sectional design and may integrate apparently
conflicting previous data obtained from animals in which the level of
dietary calcium was not considered as a cofactor.  Circulating
concentrations of 25(OH)D, 24,25(OH)2D and 1,25(OH)2D, the vitamin D
binding protein (as an index of free 1,25(OH)2D), immunoreactive CT and PTH
will be serially determined and bioactive PTH-like activity (using a
cytochemical bioassay technique domestically available only in our
laboratory) will be measured.  Further, gastrointestinal calcium
absorption, metabolic clearance of 1,25(OH)2D, and 250HD-1- and
24-hydroxylase activities (using an in vitro assay) will be assessed at
each age and dietary calcium level.  These experiments will be supplemented
with human studies in which the same metabolites are measured in plasmas of
osteoporotics and age-matched controls.  In addition, the association of
any alterations in the hormonal milieu in individual affected subjects with
the nature of the bone histomorphological abnormalities that are manifest
will be explored.  These studies will yield significant new insight into:
1) age-related changes in the control of bone and mineral metabolism in
human and rats; 2) the adequacy of the F-344 rat as a model of human aging;
and 3) whether unique abnormalities of vitamin D metabolism and/or PTH or
CT secretion exist in osteoporotics.

## Key facts

- **NIH application ID:** 3157812
- **Project number:** 5R01AR036903-03
- **Recipient organization:** DUKE UNIVERSITY
- **SAM.gov UEI:** TP7EK8DZV6N5
- **Principal Investigator:** BRUCE LOBAUGH
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1989
- **Award amount:** $89,026
- **Award type:** 5
- **Project period:** 1987-01-01 → 1989-12-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/3157812

## Citation

> US National Institutes of Health, RePORTER application 3157812, CONTROL OF CALCIUM METABOLISM IN AGING AND OSTEOPOROSIS (5R01AR036903-03). Retrieved via MORVS 2026-10-25 from https://api.morvs.ai/grant/nih/3157812. Licensed CC0.

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