# STEROIDS AS TROPHIC FACTORS--AGING NEUROMUSCULAR SYSTEM

> **NIH NIH R01** · TRUSTEES OF INDIANA UNIVERSITY · 1992 · $135,525

## Abstract

Using a simple neuromuscular system, this proposal focuses on the
influence of androgens in the maintenance of motoneuron number,
morphology, and function in aging.  This system consists of two sexually
dimorphic nuclei in the rat spinal cord, the spinal nucleus of the
bulbocavernosus (SNB) and the dorsolateral nucleus (DLN) and the muscles
of the perineum they innervate.  While present in males these nuclei and
their target muscles are reduced or absent in females.  Androgens serve a
trophic function in the development and adult maintenance of this system,
for example regulating neuron number and dendritic growth during
development, and maintaining motoneuron morphology and
synaptology in adulthood.  The experiments proposed examine the effect of
the declines in androgen levels that occur with advancing age on these
steroid-sensitive motoneurons.  Three different features of these
motoneuron populations will be examined: motoneuron number, morphology,
and function.  Motoneuron number will be assessed at a series of time
points corresponding to the natural changes in circulating androgen in
both sexually dimorphic and nondimorphic steroid-sensitive populations, to
determine whether declines in androgen are reflected in the loss of
motoneurons.  By maintaining androgen levels or accelerating their
decline, the influence of androgens on motoneuron survival will be
directly assessed.  The normal time course of regressive changes and the
causal relation with age-related declines in androgens will be tested.
The retention of structural plasticity in motoneuron morphology will also
be determined.  Finally, functional aspects of steroid accumulation and
excitability will be assessed with regard to changes with age and hormonal
condition.  Because neurons can not be replaced in mature mammalian
nervous systems, understanding the factors which control the death of
neurons in aging is critical for our understanding of the aging process
and age-related declines in neurobehavioral function.

## Key facts

- **NIH application ID:** 3121152
- **Project number:** 5R01AG009309-03
- **Recipient organization:** TRUSTEES OF INDIANA UNIVERSITY
- **SAM.gov UEI:** YH86RTW2YVJ4
- **Principal Investigator:** DALE R SENGELAUB
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1992
- **Award amount:** $135,525
- **Award type:** 5
- **Project period:** 1990-08-01 → 1995-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/3121152

## Citation

> US National Institutes of Health, RePORTER application 3121152, STEROIDS AS TROPHIC FACTORS--AGING NEUROMUSCULAR SYSTEM (5R01AG009309-03). Retrieved via MORVS 2026-10-25 from https://api.morvs.ai/grant/nih/3121152. Licensed CC0.

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