Study: Stress hormone blocks testosterone's effects

Sep 29, 2010

High levels of the stress hormone cortisol play a critical role in blocking testosterone's influence on competition and domination, according to new psychology research at The University of Texas at Austin.

The study, led by Robert Josephs, professor of psychology at The University of Texas at Austin, and Pranjal Mehta, assistant professor of psychology at the University of Oregon, is the first to show that two hormones—testosterone and cortisol—jointly regulate dominance.

The findings, available online in Hormones and Behavior, show that when cortisol—a hormone released in the body in response to threat—increases, the body is mobilized to escape danger, rather than respond to any influence that testosterone is having on behavior.

The study provides new evidence that hormonal axes (complex feedback networks between hormones and particular brain areas that regulate and cortisol) work against each other to regulate dominant and competitive behaviors.

"It makes good adaptive sense that testosterone's behavioral influence during an emergency situation gets blocked because engaging in behaviors that are encouraged by testosterone, such as mating, competition and aggression, during an imminent survival situation could be fatal," Josephs said. "On the other hand, fight or flight behaviors encouraged by cortisol become more likely during an emergency situation when are high. Thus, it makes sense that the hormonal axes that regulate testosterone levels and cortisol levels are antagonistic."

As part of the study, the researchers measured hormone levels of saliva samples provided by 57 subjects. The respondents participated in a one-on-one competition and were given the opportunity to compete again after winning or losing. Among those who lost, 100 percent of the subjects with high testosterone and low cortisol requested a rematch to recapture their lost status. However, 100 percent of participants with high testosterone and high cortisol declined to compete again. All subjects who declined a rematch experienced a significant drop in testosterone after defeat, which may help to explain their unwillingness to compete again, Josephs said.

The researchers suggest these findings reveal new insights into the physiological effects of stress and how they may play a role in fertility problems. According to research, chronically elevated cortisol levels can produce impotence and loss of libido by inhibiting production in men. In women, chronically high levels of cortisol can produce severe fertility problems and result in an abnormal menstrual cycle.

"When cortisol levels remain elevated, as is the case with so many people who are under constant stress, the ability to reproduce can suffer greatly," Josephs said. "However, these effects of in both men and women are reversed when stress levels go down."

Explore further: Platelets modulate clotting behavior by 'feeling' their surroundings

Related Stories

Men's testosterone levels predict competitiveness

Dec 04, 2006

After a man loses a challenge, whether or not he is willing to get back into the game depends on changes in his testosterone levels, according to new research at The University of Texas at Austin.

Scientists study loneliness

Oct 31, 2006

A U.S. scientist studying physiological dynamics of day-to-day experiences say older adults who go to bed lonely have higher cortisol levels the next day.

Victory and defeat: Are you a wolf or a sheep?

Jun 19, 2006

Are all people stressed out by a defeat or does it hurt some more than others? It may depend on whether you're a power-hungry wolf or a sheep, according to University of Michigan psychology researchers.

Recommended for you

A better way to track emerging cell therapies using MRIs

Sep 19, 2014

Cellular therapeutics – using intact cells to treat and cure disease – is a hugely promising new approach in medicine but it is hindered by the inability of doctors and scientists to effectively track the movements, destination ...

User comments : 0