The Way To A Zebrafish’s Heart Is Through Its Nose

As part of their courtship and mating rituals, female zebrafish release a pheromone that activates the males’ brains through their smell receptors.

AsianScientist (Jun. 3, 2016) – Researchers in Japan have found that during zebrafish courtship and mating, a molecule released by female zebrafish activates male sense receptors via their noses.

The research team from the RIKEN Brain Science Institute also identified the neural pathway and brain areas involved in transforming this molecular messenger into courtship behavior in fish. Their findings are published in Nature Neuroscience.

In fish, the reproductive hormone prostaglandin F (PGF) involved in ovulation and uterine contraction also acts as a pheromone—a social and sexual signaling molecule used to attract the opposite sex. Pheromone signaling works hand in hand with other senses like vision to bring about the courtship dance that increases a fish’s chances of mating.

Released in the females’ urine, males will normally swim toward even small concentrations of the molecule, but the researchers, led by senior team leader Dr. Yoshihiro Yoshihara, found that male fish without a sense of smell were indifferent when PGF was added to their tank.

Through their experiments, the researchers found that PGF only bound to olfactory receptors, a different class of receptors from the prostaglandin receptors they had expected. Via these olfactory receptors, PGF activates a direct, dedicated neural ‘smell pathway’ to the areas of the brain that are responsible for eliciting courtship behavior in male fish.

As a final step, the researchers tested the response to PGF in male fish that were lacking the genes for one of the previously identified olfactory receptors. These fish weren’t drawn to PGF in their tank; spent less time chasing female fish; and were less successful at spawning. A smell receptor thus seems to be the gateway for PGF into the male fish brain.

As the same or corresponding olfactory receptor genes are present in other fish and mice, a similar mechanism for reproductive communication might be present within other species, the researchers say.

The article can be found at: Yabuki et al. (2016) Olfactory Receptor for Prostaglandin F Mediates Male Fish Courtship Behavior.


Source: RIKEN; Photo: Shutterstock.
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