Men’s Sweat May Soothe a Woman’s Soul

WebMD Medical NewsMarch 19, 2003 — The scent of a good man may be music to a woman’s nose. Researchers say the odorless pheromones found in male perspiration can have a dramatic effect on both a woman’s mind and body. A new study found exposure to male pheromones can boost a woman’s mood and stimulate the release of a hormone that regulates the menstrual cycle.

In the study, researchers applied extracts of underarm secretions from male volunteers to the upper lips of 18 women between the ages of 25 and 45. None of the women knew that male sweat had been applied to their lips, and some thought they were involved in a study of alcohol or perfume or even lemon floor wax. The women then rated their moods over six hours of exposure; they consistently reported feeling less tension and more relaxed.

“Much to our surprise, the women reported feeling less tense and more relaxed during exposure to the male extract,” says researcher Charles J. Wysocki of the University of Pennsylvania, in a news release. “This suggests that there may be much more going on in social settings like singles bars than meets the eye.”

Each of the women received three applications of the underarm extract during the six-hour evaluation period, followed by three doses of exposure to ethanol (alcohol) over another six-hour period.

Researchers also found that exposure to the male pheromones also prompted a shift in blood levels of a reproductive hormone called luteinizing hormone. Levels of this hormone typically surge before ovulation, but women also experience small surges during other times in the menstrual cycle.

The study found that the male pheromone extract hastened the onset of these smaller surges and shortened the pauses between surges by 20%.

Researchers are now looking at individual compound that are found in male perspiration in hopes of identifying the elements responsible for these psychological and hormonal changes.

“This may open the door to pharmacological approaches to manage onset of ovulation or the effects of premenstrual syndrome or even natural products to aid relaxation,” says Wysocki. “By determining how pheromones impact mood and endocrine response, we might be able to build a better male odor: molecules that more effectively manipulate the effects we observed.”

SOURCE: Biology of Reproduction, June 2003. News release, University of Pennsylvania.

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The first quantitative study of protein complexes that transmit pheromone signals in living yeast cells sheds light on a crucial signalling process also found in humans.

New insights into the cellular signal chain through which pheromones stimulate mating in yeast have been gained by scientists at the European Molecular Biology Laboratory (EMBL). Similar signal chains are found in humans, where they are involved in many important processes such as the differentiation of nerve cells and the development of cancer. A sophisticated microscopy technique allowed the researchers to observe for the first time the interplay of signalling molecules in living yeast cells, and to work out how they pass on a signal through the cell.

Upon release of a pheromone – a chemical signal stimulating mating behaviour – by a nearby cell, yeast cells form a projection that serves as a mating organ and brings about the fusion of two cells. The pheromone binds to a receptor on the cell’s exterior – in the same way as many growth hormones in humans do – which then sets off a signalling chain inside the cell.

This chain consists of a series of proteins called MAP kinases, which pass on the signal by interacting with each other and activating the next downstream member of the chain by adding on phosphate residues. At the end of the chain are those molecules that bring about the changes that underpin the formation of the mating organ and the fusion of the cells.

Scientists in the groups of Michael Knop and Philippe Bastiaens at EMBL labelled members of the MAP kinase signalling chain with fluorescent molecules and observed their diffusion and interaction in living yeast cells stimulated with pheromones using a novel microscopic approach that does not disturb the natural state of the cell.

“Our method is so precise that we could virtually count the molecules and the interactions between chain components,” says Knop. “To our surprise, the observed proteins in the cell’s interior did not interact more after stimulation by the pheromone. This means changes in interaction are not the way by which the signal is transmitted through the interior of the cell.”

Knop and his team revealed that the actual signal is not produced uniformly throughout the cell but only by the few chain components found in the mating projection. They activate a protein called Fus3, which diffuses into the centre of the cell to spread the signal. While travelling, however, Fus3 is constantly inactivated by proteins found in the interior of the cell.

“We found that the concentration of Fus3 activity is very high at the tip of the developing mating organ and then gradually gets less towards the centre of the cell,” says Celine Maeder, who carried out the research in Knop’s lab. “This sets up a gradient of Fus3 activity, which might allow the signal to have different effects in different parts of the cell.”

“This result is exciting,” concludes former EMBL group leader Philippe Bastiaens, who now is a director at the Max Planck Institute of Molecular Physiology. “It revolutionizes our understanding of signalling processes and the way we need to study them.” The MAP kinase signalling chain is conserved across species, and the insights gained in yeast contribute to a better understanding of a pathway also relevant to human biology and disease.

Reference: C.I. Maeder, M.A. Hink, A. Kinkhabwala, R. Mayr, P.I.H. Bastiaens and M. Knop, Spatial regulation of Fus3 MAP kinase activity through a reaction-diffusion mechanism in yeast pheromone signalling, Nature Cell Biology, 21 October 2007

Adapted from materials provided by European Molecular Biology Laboratory.

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