How a hormone could boost men's sexual appetite

Anxiety can be a driving force for sexual dysfunction in men. A new study reveals that there may be an effective treatment for both, in the form of a hormone called kisspeptin.

Sexual dysfunction is defined as low sexual satisfaction as a result of physical or psychological issues.

In men, common forms of sexual dysfunction include erectile dysfunction, premature ejaculation, and reduced sexual desire.

It is estimated that around 30 million men in the United States experience erectile dysfunction, and estimates suggest that around 1 in 3 men in the U.S. experience premature ejaculation at some point in their lives.

For many men, anxiety can be a trigger for sexual dysfunction. Some men worry about erectile response and maintenance, which can have negative implications for sexual function; others may be concerned about body image, or they may be experiencing psychological stress due to work, money, or health problems.

The new study suggests that increasing activity of the hormone kisspeptin in a specific area of the brain has the potential to reduce anxiety in men and boost sexual behavior.

Study co-author Dr. Daniel Adekunbi, of King's College London in the United Kingdom, and colleagues are due to present their findings today at the Society for Endocrinology Annual Conference, held in Harrogate, U.K.

Kisspeptin, anxiety, and sexual behavior

Kisspeptin is a hormone produced by a section of the brain called the hypothalamus.

Named after Hershey's chocolate "Kisses" — due to the first gene for the hormone being discovered by a research team working in Hershey, PA, where the product is produced — kisspeptin is known for its crucial roles in puberty and fertility.

The hormone interacts with receptors in the pituitary gland, which is connected to the bottom of the hypothalamus. This prompts a signaling cascade that fuels the production of the sex hormones testosterone and estradiol.  

Previous research from Dr. Adekunbi and team revealed that nerve cells, or neurons, that respond to kisspeptin are also present in the amygdala, which is a brain region that plays a role in emotional processing.

Specifically, the team identified these neurons in the posterodorsal medial area of the amygdala (MePD). This is an area strongly linked to the response to pheromones, which are chemicals that can alter behavior – including sexual behavior.

With all of these factors in mind, Dr. Adekunbi and colleagues investigated whether increasing kisspeptin activity in the MePD might influence anxiety and sexual behavior.

Anxiety reduced, social behavior increased

To reach their findings, the researchers manipulated kisspeptin-responsive neurons in the MePD of male mice.

The team used a series of drugs to activate or deactivate these neurons in rodents, and their anxiety and social and sexual behaviors were monitored in response.

The study revealed that when kisspeptin-responsive neurons were activated, the male mice demonstrated fewer indicators of anxiety, they were more willing to have social interaction with other mice, and they gave greater attention to female mice.

Further studies are needed to confirm the findings, but Dr. Adekunbi and team believe their results hold promise for a new treatment for anxiety-related sexual dysfunction in men.

"In men, anxiety-related disorders occur in tandem with sexual dysfunction," notes Dr. Adekunbi.

"The findings of our study suggest that activation of MePD kisspeptin neurons coordinates sexual preference and anxiety behavior towards copulation, indicating that amygdala kisspeptin functionally promotes maximal reproductive success in the male."

Dr. Daniel Adekunbi

Going forward, the team plans to take a closer look at how activating and deactivating kisspeptin neurons in the MePD affects sexual behavior and anxiety in rodents.

"We can speculate that kisspeptin may modulate sexual orientation but this needs further confirmation," says Dr. Adekunbi. "[O]ur planned work to silence the MePD kisspeptin neurons may provide some insight into this. For example, when the neurons are inactivated, will the male mouse prefer to interact with a male mouse over a female?"