# STUDIES ON THE OVARIAN-HYPOTHALAMIC-HYPOPHYSEAL AXIS

> **NIH NIH R01** · UNIVERSITY OF CALIFORNIA LOS ANGELES · 1994 · $193,701

## Abstract

The sexual differentiation of the mammalian brain is of basic importance
to reproductive biology and developmental neuroscience.  Since the
discovery of structural sex differences in the brain and their
modification by the gonadal hormonal environment perinatally, it has been
assumed that structural sex differences underlie one or more of the
functional sex differences.  This laboratory has focused on two of the
structural sex differences in the rat brain, the Sexually Dimorphic
Nucleus of the Preoptic Area (SDN) and the Anteroventral Periventricular
Nucleus (AVPV), the SDN because it is one of the most marked sex
differences and the AVPV because it responds to gonadal hormones in a
direction opposite to that exhibited by the SDN.  Recent evidence,
however, suggests that the AVPV differentiates much later, perhaps due to
the activity of postpubertal gonads.  One study (Specific Aim IV) is
proposed to determine when the AVPV does become sexually dimorphic and if
postpubertal hormonal activity is responsible for its differentiation.
The other aims relate to the SDN, its function, developmental hormonal
sensitivity and the question whether growth factors mediate steroid
action on its differentiation. A unique animal preparation has been
developed - an animal with a unilaterally masculinized SDN.  Although
thus far documented only in the genetic male, it is likely that we can
produce a genetic female with one SDN feminine and the other
masculinized.  First, we will determine the reproductive physiological
and behavioral potential of these unique animals through classical
techniques of reproductive neuroendocrinology and then include these
animals in electrical stimulation and in some cases, lesion studies to
elucidate the possible function(s) of the SDN with particular emphasis on
prolactin (Specific Aim I).  Although the rat with the unilaterally
masculinized SDN offers a unique model for functional studies, the
nucleus still has to be further characterized (Specific Aim II).  Since
it is possible that there may be two critical periods for the
masculinization of the SDN, we plan to study the SDN and the reproductive
function of animals subjected to hormonal manipulations prenatally and
late-postnatally (Specific Aim III).  Finally, we plan using the
unilaterally modified SDN as a model, to determine whether specific
growth factors play a role in masculinization of the brain (Specific Aim
V).  Recently, the concept of sexual differentiation has been extended to
the structure of the human brain and even to gender orientation.  It is
only by a clear understanding of this process in laboratory animals that
sound conclusions can be made about our own species.

## Key facts

- **NIH application ID:** 2194763
- **Project number:** 5R01HD001182-32
- **Recipient organization:** UNIVERSITY OF CALIFORNIA LOS ANGELES
- **SAM.gov UEI:** RN64EPNH8JC6
- **Principal Investigator:** ROGER A GORSKI
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1994
- **Award amount:** $193,701
- **Award type:** 5
- **Project period:** 1976-12-01 → 1996-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/2194763

## Citation

> US National Institutes of Health, RePORTER application 2194763, STUDIES ON THE OVARIAN-HYPOTHALAMIC-HYPOPHYSEAL AXIS (5R01HD001182-32). Retrieved via MORVS 2026-10-25 from https://api.morvs.ai/grant/nih/2194763. Licensed CC0.

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