Does dad’s ‘cologne’ make baby mice smarter?

"We found that male pheromones seem to influence the nutritional environment following birth, resulting in changes to the brain that could extend to future generations," says Sachiko Koyama. (Credit: iStockphoto)

Father mice may play a positive role in the development of their babies’ brains even before pregnancy, a new study suggests.

When female mice were exposed to male pheromones, they later gave birth to smarter babies.

“This is the first study to show that pheromone exposure exerts an influence across generations in mammals,” says Sachiko Koyama, associate research scientist at the Indiana University Bloomington Medical Sciences Program. “We found that male pheromones seem to influence the nutritional environment following birth, resulting in changes to the brain that could extend to future generations.”

Better breast milk?

Pheromones are chemical signals used to communicate between organisms of the same species. The connection between male pheromones and offspring’s brain development seems to stem from the influence of male pheromones on the nursing ability of mother mice.

Specifically, scientists measured greater mammary gland development in mice exposed to male pheromones a week after exposure, which may have led to greater volumes or improved quality of milk production. These mother mice also showed lengthier nursing periods compared to mice not exposed to the male pheromone.

To measure the intelligence of the offspring, researchers placed mice in a water maze with a hidden platform. The mice born of mothers exposed to male pheromones learned the location of the hidden platform much faster, suggesting quicker learning and stronger spatial memory compared to the control group.

These improvements in brain development and cognitive function may stem from specific “neuro-enhancing” chemicals in breast milk, such as sialic acid, a component of breast milk also found at high levels in the brain during early development. Researchers found higher levels of polysialyltransferase—an enzyme that requires sialic acid to produce a molecule involved in neural cell development—in the brains of the offspring of female mice exposed to male pheromones compared to the control group.

Power of scent

A synthetic version of the male mouse pheromone “SBT” was used in the study.

“This publication represents an important addition to the field of animal communication and the effects of mammalian pheromones,” says Miles Novotny, distinguished professor emeritus of chemistry and Lilly Chemistry Alumni Chair.

“It shows that the effect of the male mouse pheromone SBT not only transmits an important olfactory message to the recipient females but, through some as-yet-unknown molecular signaling mechanisms, brings apparent benefits to their offspring.”

Previous pheromone research has primarily focused on the influence of chemicals on animals within the same generational group, such as on mating behaviors, including the ability to suppress or encourage mammalian mating activity, as well as to attract females or stimulate aggression in males.

The power of scents has also been shown in humans through research showing that women who spend a long time together synchronize menstrual cycles.

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By focusing on pheromone effects across generations, researchers say the new study contributes to the growing field of epigenetics, which studies the influence of the environment on genetics, such as when nutrition creates changes in the body that may be passed on to the next generation.

“If we can find the specific milk ‘ingredients’ that affect cognitive function in the offspring, for example, we may eventually be able to use them as supplements to enhance brain development,” Koyama says.

The researchers next plan conduct a more complete chemical analysis of the milk of the mother mice, as well as to track the mental development of their offspring across future generations.

The IU Lilly Chemistry Alumni Chair and the National Institutes of Health supported the work.

Source: Indiana University