RecruitingNot ApplicableInterventional

Investigating the role of nitric oxide on reproductive hormones in humans

This research investigates how a natural chemical called nitric oxide (NO) influences hormones that control fertility. Fertility relies on hormones like GnRH and kisspeptin, which are crucial for reproductive health. While kisspeptin is known to safely boost hormone levels, we don't fully understand nitric oxide's role or how it interacts with these other hormones in people. This study aims to discover how nitric oxide affects reproductive hormones, both on its own and when given with kisspeptin or GnRH. The findings could lead to better ways to diagnose and treat fertility problems. We are looking for healthy adults and adults with reduced fertility to take part.

At a glance

Status

Recruiting

Phase

Not Applicable

Sponsor

Imperial College London

Enrolment target

Start

21 Jul 2025

Estimated completion

21 Jul 2028

The role of nitric oxide on reproductive hormone responses in healthy individuals and individuals with reproductive disorders.

What is this study about?

This research is looking into a natural molecule in the body called nitric oxide (NO) and how it affects the hormones that control our fertility. Fertility is a complex process, and it's mainly managed by hormones. In our brain, there's a key hormone called GnRH which kick-starts the release of other important reproductive hormones. Another hormone, called kisspeptin, also plays a crucial role in fertility and has been safely used in other studies to boost hormone levels in both men and women.

Early studies suggest that nitric oxide might help control these fertility hormones and could even work alongside kisspeptin. However, we don't yet know exactly how nitric oxide affects hormone levels in people. This study is designed to answer that question: we want to understand how nitric oxide influences our reproductive hormones, both by itself and when combined with kisspeptin or GnRH.

The main goal of this research is to improve how we understand, diagnose, and treat problems with fertility. By learning more about nitric oxide's role, we hope to open doors to new and more effective treatments for people struggling to conceive.

Key takeaways

This study explores how a natural substance, nitric oxide, affects fertility hormones.
It aims to improve diagnosis and treatment for fertility problems.
Participation involves multiple visits over time, including blood tests and different treatments.
You might not directly benefit, but your contribution helps future fertility research.
The study includes healthy people and those with reduced fertility.
You can withdraw from the study at any point.

Who may be eligible?

This study is looking for adults aged 18 and over. There are two main groups being recruited. The first group is for people with normal fertility – this means women who have regular periods and men who don't show signs of low testosterone or have known fertility problems.

The second group is for people who have reduced fertility. This could include women who have irregular periods or no periods at all, and men who have low testosterone levels or other known fertility issues.

You would not be able to take part if you have certain medical or mental health conditions, severe allergies to the medications used (like sildenafil or nitroglycerine), severe anaemia, or if you are pregnant. You also can't have participated in another research study in the last two weeks.

Could this study suit you?

Answer these quick questions to see if you may be eligible. This is a guide only — the research team makes the final call.

Are you 18 years old or older?
Do you have normal fertility (regular periods for women, no low testosterone for men)? OR Do you have reduced fertility (irregular/no periods for women, low testosterone for men)?
Are you able to give your informed consent to take part?
Do you have any severe allergies to sildenafil or nitroglycerine?
Are you pregnant or trying to get pregnant?
Have you participated in any other research study in the last two weeks?

Answer every question to see your result.

What does participation involve?

If you're interested in taking part, you'll first answer a short questionnaire. If it seems you might be a good fit, you'll be invited to Charing Cross Hospital for a screening visit. This visit involves a physical check-up, blood tests, an ECG (a check of your heart), and a chance to ask any questions you have.

If you're eligible after the screening, you'll then attend six study visits. Each of these visits will last about 5 to 8 hours and needs to be at least two days apart. During these visits, you'll receive different combinations of treatments. These might include nitric oxide (given through a patch on your skin), kisspeptin, GnRH, or a placebo (an inactive treatment). Neither you nor the researchers will know which treatment you are receiving at each visit.

Some people may also be asked to come for three extra visits where a different type of nitric oxide medication, like sildenafil tablets, will be used. At each visit, blood samples will be taken, you'll fill out questionnaires about how you're feeling, and your heart rate and blood pressure will be checked. Women will also need to take a pregnancy test before each visit. The study is expected to run from July 2025 to July 2029.

Potential risks and benefits

You might not personally benefit directly from taking part in this study. However, your involvement is very important as it will help researchers understand more about how nitric oxide affects fertility, which could lead to better treatments for fertility problems in the future. Some of the blood tests might also give you useful information about your general health, which can be shared with your GP if you agree. As with any medical study, there are potential risks, but these will be fully explained to you before you agree to participate. You are free to withdraw from the study at any time, for any reason, without it affecting your medical care.

Locations (1)

Imperial College London
Approximate
London, United Kingdom

Common questions

What is nitric oxide and why is it important?

Nitric oxide is a natural molecule in your body that helps regulate many processes, including blood flow and potentially hormone activity related to fertility.

What is a placebo?

A placebo is a treatment that looks like the real medication but doesn't contain any active drug. It helps researchers compare the effects of the actual treatment.

Will I know which treatment I am receiving?

No, neither you nor the researchers will know which treatment you are getting at each visit. This is a common practice in research to ensure fair results.

What happens if I decide to stop participating?

You can withdraw from the study at any time, for any reason, without it affecting your usual medical care.

Who is funding this research?

The study is funded by the NIHR Biomedical Research Centre at Imperial College London in the UK.

How to find out more

Jovanna Tsoutsouki

jt722@ic.ac.uk +44 (0)207 594 3487 Official trial record

Always speak to your GP or specialist before deciding to take part in a study.