The WOW! Factor
By VIRGINIA WINDER – Taranaki Daily News
July 9, 2009
Otago University researchers have made a major breakthrough in finding out how a group of important fertility-controlling neurons communicate, despite being scattered throughout the brain.
Most people think people’s sexual organs, like ovaries, just sit there and do their own thing, Allan Herbison says. But these organs are controlled by brain neurons that trigger the release of hormones, which then tell different parts of the body what to do.
“What my group is doing is trying to understand how the brain controls fertility.”
The latest findings are focused on a unique population of cells known as gonadotropin-releasing hormone (GnRH) neurons. The professor and Rebecca Campbell from the university’s Centre for Neuroendocrinology have just published a paper about how these strange neurons communicate.
“A fascinating thing about GnRH neurons is that unlike all other nice self-respecting neurons, they aren’t actually born in the brain,” Herbison says.
They are made in a part of the nose called the olfactory placode during a foetus’s first trimester. About 2000 are made, but only about 1000 survive the migration to the brain, where they travel to an area called the hypothalamus “That’s your one shot at getting your GnRH neurons,” Herbison says. “There are some gene mutations that cause malfunctioning of the nose and so you get individuals who have no sense of smell and who are infertile.”
If these neurons don’t develop, people simply won’t go through puberty. However, hormone treatment can help this problem. But for those who have GnRH neurons, these work like a relay, passing messages like batons. The neurons spray the gonadotropin-releasing hormone on to the pituitary gland, which releases two types of gonadotropin.
The other, called the follicle- stimulating hormone, regulates and maintains sperm and egg production. Herbison says that these gonadotropins are released in pulses about every hour. “In men, that’s very continuous. It just continues one pulse an hour for all of our lives.”
For women it’s a different story.
“In females, it changes throughout the menstrual cycle.
“So to generate a pulse of hormones, you need to have generated a pulse of GnRH on to the pituitary gland.”
For this to happen, the 1000 neurons responsible have to be synchronised so they all release GnRH together as a pulse. This is where the Otago researchers have made their breakthrough. Up until now, nobody knew how these neurons communicated.
“In basic understanding of how these neurons work, it’s one of the biggest findings for a long time,” Herbison says.