Washington, June 6 : Experts at the Medical College of Georgia Schools of Medicine and Graduate Studies have revealed that they are using zebrafish as a live model to study the migration of neurons necessary for sexual maturity and fertility, from the region of their formation near the developing nose to deep inside the brain.
The researchers are hopeful that their study would enable better ways to help children who do not mature sexually.
"They can go to the right place but take too long; delayed puberty suggests they got there late," says Dr. David J. Kozlowski, developmental geneticist in the Medical College of Georgia Schools of Medicine and Graduate Studies.
"They can go to the wrong place. They can go to the right place and make the wrong connections, or not enough of them go to the right place. All sorts of things can go wrong and result in clinical defects," he adds.
Dr. Lawrence C. Layman, an expert on delayed puberty, believes that improved understanding and treatment may help scores of people who have to face puberty problems due to central nervous system abnormalities.
It may be crucial to improving birth control and fertility treatments, he says.
The researchers have revealed that puberty begins when the hypothalamus in the brain begins releasing more gonadotropin releasing hormone (GnRH).
This hormone stimulates the pituitary gland to make follicle stimulating hormone, and luteinizing hormone that prompt ovaries to produce oestrogen and eggs, and testes to produce testosterone and sperm.
According to them, first necessity for all that is that GnRH neurons must get to the brain, which is what they would be studying using zebrafish as a model.
"This occurs very early in the life of a zebrafish, probably after the heart forms, at about 48 to 72 hours of life," says Dr. Kozlowski.
"One class of patients Dr. Layman sees has Kallmann syndrome in which there is evidence that the GnRH neurons gets stuck about halfway. People want to know the molecular mechanism that allows these neurons to find the right place," he adds.
He says that zebrafish was chosen for this study because their embryos are transparent, and develop outside the mother.
For their study, the researchers have made a transgenic fish whose GnRH neurons turn fluorescent green at birth for easy tracking.
"We can put them under the microscope and image them for as long as it takes for these cells to get from point A to point B and ask how they got there. Do they go straight there or take the long way? Then we can start asking questions about the signals that direct them and dissect out the genes expressed along the route which may function as road signs," says Dr. Kozlowski.
He says that the live embryos would enable his team to watch GnRH neurons as they first appear near the developing nose, and then migrate with nearby olfactory neurons.
The researchers are also looking at genetic mutations to see what role they may play in misrouting neurons.
"A mechanic has to know how a car works to fix it. We want to understand what is under the hood that gets the neurons from point A to B. We want to know the mechanisms because that helps you understand how you might be able to fix it. It will also help you diagnose patients who have mutations in the road signs," says Dr. Kozlowski.
Dr. Layman says that since the understanding of what initiates puberty in humans is still not really known, finding more genes involved in directing migration will help.