# Reversible Contraception by Selective Silencing of GnRH-II

> **NIH NIH R01** · OREGON HEALTH & SCIENCE UNIVERSITY · 2021 · $500,826

## Abstract

PROJECT SUMMARY
The overall goal of this proposal is to upgrade our understanding of the primate neuroendocrine reproductive
axis, and thereby to lay a foundation for the development of novel contraceptives and to gain new insights
about the etiology of idiopathic human reproductive disorders. This goal is thus responsive to one of NICHD's
new Research Priorities: “To Encourage the Development of Innovative Technologies and Model Systems to
Study Fertility and Infertility.” Specifically, the proposed research will empirically test the hypothesis that active
immunization against GnRH-II can provide safe and effective long-term contraception - by selectively silencing
the LH surge mechanism, while leaving the rest of the neuroendocrine reproductive axis intact.
 In humans, gonadotropin-releasing hormone (GnRH) neurons represent the primary neuroendocrine link
between the brain and the rest of the reproductive axis, yet the mechanism by which these neurons trigger
ovulation is poorly understood. Recently, however, human and rhesus macaques (but not rodents) were found
to express two different molecular forms of GnRH (GnRH-I and GnRH-II). Furthermore, only the GnRH-II
neurons were found to respond positively to estrogen feedback, suggesting that GnRH-II neurons serve as the
primary trigger of the mid-cycle preovulatory LH surge. We therefore hypothesize that selective silencing of
GnRH-II neurons will block ovulation without perturbing ovarian steroidogenesis or affecting negative feedback
of estrogen on GnRH-I neurons. This hypothesis will be empirically tested using the female rhesus macaque, a
highly translational nonhuman primate animal model that shows human-like menstrual cycles and similar
organization of its reproductive neuroendocrine axis. Specific Aim 1: To test the hypothesize that active
immunization against GnRH-II will selectively block ovulation without impacting ovarian steroidogenesis. We
will test this hypothesis by immunizing adult female rhesus macaques against unique non-conserved regions of
the GnRH-II neuropeptide; control animals will be immunized against a unique non-conserved region of GnRH-
I. After immunization, the animals will be examined daily for signs of menstruation and circulating levels of
reproductive hormones (i.e., LH, FSH, estradiol, progesterone, anti-Müllerian hormone) will be monitored in bi-
weekly blood samples. We expect to show that selective immunization against GnRH-II will block development
of the mid-cycle LH surge and corpus luteum formation (i.e., inferred by maintenance of low circulating
progesterone levels). Specific Aim 2: To elucidate the neuroendocrine mechanism that underlies the
contraceptive potential of GnRH-II silencing. Using remote serial blood sampling we will examine the dynamic
relationships between reproductive hormone levels in the circulation after immunization (1) in ovary-intact
animals, (2) after ovariectomy, and (3) after estrogen induction of an LH surge. We expect to show ...

## Key facts

- **NIH application ID:** 10140396
- **Project number:** 5R01HD098200-03
- **Recipient organization:** OREGON HEALTH & SCIENCE UNIVERSITY
- **Principal Investigator:** HENRYK F URBANSKI
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $500,826
- **Award type:** 5
- **Project period:** 2019-04-15 → 2023-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10140396

## Citation

> US National Institutes of Health, RePORTER application 10140396, Reversible Contraception by Selective Silencing of GnRH-II (5R01HD098200-03). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10140396. Licensed CC0.

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