Paolo Forni, University at Albany – From the Nose to the Brain

We all remember going through puberty.

Paolo Forni, assistant professor of biological sciences at the University at Albany, explores why this rite of passage is delayed for some.

2008                                       Ph.D. Biochemistry/Cellular Biotechnology, University of Turin, Italy.

2006-2011                            Visiting Fellow, NINDS, NIH, Bethesda, MD, USA.

2011-2013                            Research Fellow, NINDS, NIH, Bethesda, MD, USA.

2014-Present                     Assistant Professor, University at Albany, SUNY, NY, USA.

From the Nose to the Brain


Puberty is the process of physical changes that allows our body to reach sexual maturity in our younger years. The hormonal changes that trigger puberty are controlled by the brain, where there is a specialized population of neurons that produces the gonadotropin releasing hormone also known as GnRH. These neurons, called GnRH neurons, modulate the release of signaling molecules, from the brain, that instruct the ovaries, in females, and testes, in males, to produce sex hormones.

During embryonic development, the GnRH neurons first form in the nose and then they migrate into the brain.

Unusual migration of the GnRH neurons to the brain can negatively affect the production of sex hormones and therefore the onset of puberty.

Delayed or absence of puberty can be related to having a defective sense of smell.  In humans, this is called the Kallmann syndrome. 

The formation of the GnRH neurons in the nose and the reduced sense of smell in individuals affected by Kallmann syndrome led to the prevailing idea that the GnRH neurons migrate from the nose to the brain along the olfactory neurons.

Using mouse models with defective development of the olfactory system in combination with transgenic mouse lines that allow us to discriminate between different cell types, my research team has recently discovered that the connections of the olfactory neurons to the brain are not required for GnRH neuronal migration. In fact, we determined that the GnRH neurons travel to the brain on a small cranial nerve called the terminal nerve.  It’s still unknown what the function of the terminal nerve is. However, we found that the terminal nerve is not formed by olfactory neurons. Whether the GnRH neurons themselves or the terminal nerve play roles in the sense of smell is something that we still need to explore.

Read More:

Biology Open:     The terminal nerve plays a prominent role in GnRH-1 neuronal migration independent from proper olfactory and vomeronasal connections to the olfactory bulbs

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