Luteinizing hormone, sex, and smell (18 years later)

By: James V. Kohl | Published on: December 4, 2009

12-04-2009 12:05 AM
Abstract: Pheromones have been shown to induce sexually dimorphic responses in LH secretion. Here we asked whether the sexually dimorphic population of kisspeptin neurons in the rostral periventricular area of the third ventricle(RP3V) could relay sexually dimorphic information from the olfactory systems tothe GnRH system. Furthermore, we analyzed the effects of aromatase mutation(ArKO) and thus the role of estradiol on RP3V kisspeptin neuronal numbers and on the response of these kisspeptin neurons to same- versus opposite-sex urinary pheromones. Exposure to male but not female urinary odors induced Fos protein in kisspeptin neurons in the RP3V of female wildtype (WT) mice, suggesting that these kisspeptin neurons may be part of the neural circuitry that relays information from the olfactory brain to the GnRH system in a sexually dimorphic manner. Male pheromones induced Fos in kisspeptin neurons in ArKO females,albeit significantly less compared to WT females. The sexual differentiation of kisspeptin neuronal number was lost in ArKO mice, i.e. the number of kisspeptin-immunoreactive neurons in the RP3V of ArKO females was as low as in male mice, whereas male ArKO mice had somewhat increased numbers of kisspeptin neurons. These results suggest that the sex difference in kisspeptin neuronal number in WT mice reflects an organizational action of estradiol in females. By contrast, the ability of male urinary pheromones to activate kisspeptin neurons in WT females may not depend on the organizational action of estradiol since ArKO females still showed some Fos/kisspeptin co-activation.
Effects of aromatase mutation (ArKO) on the sexual differentiation of kisspeptin neuronal numbers and their activation by same versus opposite sex urinary pheromones
InPress, Uncorrected Proof Available online 27 November 2009
Julie Bakker, Sylvie Pierman, David González-Martínez
The first line of the abstract (above) is: “Pheromones have been shown to induce sexually dimorphic responses in LH secretion.” my emphasis added. This article, when published, will help to further establish the credibility of the model I’ve been presenting since the early 1990’s.
The title of my first presentation to a scientific congress was Luteinizing hormone: (LH) the link between sex and the sense of smell? The question mark in my title was suggested by a reviewer because — at that time — no one could be sure that LH was the link. It is!
Julie Bakker’s group has helped to detail a sexually dimorphic pathway from pheromones to hormones (and thus to behavior) in mammals, which we can be relatively sure includes humans. I met Julie at a conference in 1995. At the last two scientific conferences I attended, the presentations on kisspeptin assured me it would be part of the big picture. Even though the abstract may not make sense to most people, you can expect some journalistic liberties to betaken in order to help more people understand after the article is published.
Meanwhile, as some of you already know, androstenol alters LH in women. That’s one reason why androstenol is in Scent of Eros products.

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