The Inmed team is working on to offspring

French neurobiologists began the year by fanfare. Two teams of CNRS and Inserm come to present original advances in knowledge of the embryonic brain. An area of interest at the highest point of booming discipline specialists: the biology of development. The objective of this work is twofold. First, unlocking the secrets of the construction of "the most complex organ of the universe". At the same time, researchers hope to develop the pattern of development of the cognitive functions in the infant. Queries and research tracks are not missing. "Before the birth, the brain of the fetus is immature." This is not an adult organ reduction. "It has its own rules of operation", summarizes Yehezkel Ben - Ari, who heads the Institute of Neurobiology of the Mediterranean (Inmed) in Marseille.

At birth, the baby brain is as a "cluster of cells become". Over time, neurons proliferate and connect with each other, a process whose productivity and complexity are whirling disease. In the phase of maximum proliferation brain plant produces up to 250,000 neurons per minute. The adult State, it is an inextricable tangle with nearly 1 million billion connections wiring the 100 billion neurons between them.

A page opens

The Inmed team attempts to answer the questions that arise in all the world couples waiting for a child: how the fetus prepares for delivery That the mother or the child sign release form What are the signals that mark out the roadmap of the birth "A few hours before delivery, under the action of a series of events and the decline in the rate of progesterone circulating in the mother, the hypothalamus makes and releases a hormone: oxytocin.". "It is on the uterus by promoting contractions, breasts at the level of responsible channels of lactation and would promote even maternal feeling" reported Yehezkel Ben - Ari.

The embryologists use a colourful term to depict the environment of the baby in the maternal belly: "It swims in a bath of hormones". In fact, the world of the living is regulated by a series of orders and contre-ordres by chemical messengers. Certain hormones trigger function and other repressed. A brain cell is lit permanently (excited) or hydrated (inhibited) by molecular ballet. More than 100 neurotransmitters providing this function of biological switch have been identified in the human brain. Acetylcholine, glutamate, Adrenaline and dopamine are are exciting. Others inhibit signals: Gaba (gamma aminobutyric acid), glycine.

The Inmed team is working on to offspring. These rodents, biologists know blocking the expression of a specific gene using a technique called "knock" out A mouse of the gene of the maternal instinct thus neglects its small, eventually dying unnecessarily. The OM team has focused on two genes that control the most common neurotransmitter regulation: Gaba. During childbirth.

the Gaba levels drop sharply.

But it is by the regulation of the uterus that the mother prepares the fetus to the trauma of birth. This operation is in fact a kind of anaesthesia in the brains of the unborn child. "Under the action of this hormone, fetal neurons are preparing to confront the lack of inherent birth oxygen" indicates the marseillais biologist. According to him, many neurological diseases of genetic origin begin in utero and the in-depth knowledge of these hormonal exchanges could explain the appearance of neurological pathologies. "Sometimes, the migration of a neuron development occurs as expected and this can lead to disaster," said Yehezkel Ben - Ari.

The team of Jacques Mallet, the laboratory of molecular genetics of CNRS Paris 6 (NGL) became interested in an another neurotransmitter: serotonin. This compound in the blood and central nervous system regulates the cycle sleep, body temperature and blood pressure. It also raises a series of actions or reactions: food, sexual behaviour. But it also has a major role in the initial development of the nervous system central.

The Parisian team, who also works in mice, just to demonstrate that the fetus uses serotonin of maternal origin rather than to appeal to its own production. "It is the first example of displacement of the embryonic gene by maternal gene expression," said Jacques Mallet. In fact, the fetus has all the genetic material to ensure its own production, but it rests on the maternal supply. "It is the genotype of the mother determines the phenotype of the child." In reality, the baby has the genes and do not express and it is not known why. This is a new page in the genetics that opens. "Should stimulate research to identify all other genes involved in the phenomenon of displacement", note, enthusiastic, Jacques Mallet.

This work could help explain the mother-child transmission of hereditary neurological diseases. According to Parisian researchers, an abnormal serotonin levels in mothers could explain some diseases of development such as schizophrenia or autism. The Parisian researcher, the serotonin levels in the blood of pregnant women suffering from neuropsychiatric disorders and receiving serotonin should be placed under surveillance.