Commonly called the “happiness hormone”, serotonin plays a central role in our body. This neurotransmitter present in our brain – but not only – is involved in regulating our mood, but also our appetite or our sleep. It contributes in some way to our feeling of well-being. Moreover, a dysfunction of the serotoninergic system has been observed in several psychiatric disorders such as depression but also anxiety disorders, anorexia or even schizophrenia. This is why anti-depressants generally have an action on serotonin.
If serotonin is synthesized in the brain, it is found throughout the body. The different actions it exerts are governed by 14 receptors on which serotonin binds, and which are called serotonergic receptors. Each receptor is associated with various functions in the body. ” Serotonin is a sort of master key explains Violette Richin, who studies a particular type of serotonin receptor. The problem: as many receptors for serotonin, there is an even greater risk of seeing other molecules – in particular medicinal ones – settling there instead of serotonin. Gold, ” it is still difficult to have antidepressants specific enough to bind only to the target receptors responsible for the therapeutic action. This is one of the causes of adverse drug reactions. Sometimes with significant consequences for patients “, explains this doctoral student, pharmacist by training.
Thus, in the plectrum scandal, the anti-diabetic molecule used was fixed in particular on serotonin receptors, 5-HT receptors2b. And in 2000, an article highlighted the role of these receptors in pulmonary arterial hypertension and heart valve damage (heart valve disease).
Today, research is moving towards the formulation of new, more targeted drugs to further limit the side effects of drugs. In the field of psychiatric diseases, it is essential to better understand the functioning of serotonin receptors, most of which are still poorly understood. This is precisely the subject of Violette Richin’s thesis at Cermep, a research platform in life imaging in Lyon.
But studying serotonin receptors is not easy. There are techniques in vitro to study the receptors (in cell culture), some studies are carried out post-mortem, but they do not reflect the physiological functioning of the organism. This is why this doctoral student uses another method: radiotracers. These molecules, combined with PET (Positron Emission Tomography) medical imaging techniques, make brain chemistry visible in a non-invasive way.
« The aim of my thesis is to synthesize new radiotracers of serotoninergic receptors, in order to be able to study their functioning in the body. “, she explains.
For this pharmacist, there is still a long way to go before arriving at new drugs. But the stakes are high in the field of psychiatry. The anti-depressants still in use are old, and have been little renewed over the past fifty years. A context conducive to drug resistance, adverse effects and, ultimately, non-compliance with treatment by patients.