Early life experience shapes physiological responses to internal and external cues later in adulthood and has a long lasting impact on health and behavior. Amongst the numerous factors important for development, exposure to steroid hormones, including androgens, estrogens and glucocorticoids, during a narrow window limited to the perinatal period or puberty, have been demonstrated to organize specific hypothalamic and telencephalic nuclei in most vertebrates and allow specific behaviors to be activated later in life. The changes triggered in these brain regions are permanent and will configure the nuclei to respond in adulthood to steroid hormones and thus shape social interactions, such as aggression, mate choice, sexual behavior, and parental behavior. Although the organizational and activational roles of steroid hormones were described several decades ago, numerous fundamental questions remain in order to understand the mechanisms underlying the permanent changes induced by early steroid hormone exposure
Our lab focuses on 2 main research lines
1- Neurosteroidogenesis and brain plasticity .
The brain of vertebrates expresses a variety of enzymes involved in the synthesis of endogenous steroids
2- The effects of Endocrine Disrupting Chemicals (EDCs) on neurogenesis and the neuroendocrine circuits.
An important aspect of our research is to understand whether chemicals present in our environment can affect the process of neurogenesis during early development. Indeed, why there is been a wealth of studies dedicated to the impact of EDCs on the peripheral organs such as the liver and the gonads, there are much less information regarding potential effects on the brain. We are particularly interested in the impact of steroid hormones such as estrogens and progestins that are widely present in the aquatic environment as a result of the massive use as contraceptives.In addition, we are also interested by the impact of several pesticides and plasticizers notably BPA and BPA-related chemicals.
Our goal is to investigate the effects of endocrine disrupting chemicals (EDCs) on neurogenesis and the neuroendocrine circuits. We also aim at developing techniques to identify such chemicals in vivo and in vitro. We have characterized the cyp19a1b gene as an outstanding biomarker of zenoestrogen exposure and we have developed in vivo and in vitro screening tests permitting to screen chemicals of complex mixtures for estrogenic activities. It is important to mention that the OECD selected embryos of fishes as potential alternatives that permit screening early EDC effects in vertebrate models.
We use a variety of techniques to understand how cell phenotypes are defined and how these cells are involved in the expression of complex behavior. These techniques include for example immunocytochemistry, in situ hybridization, Western blots, cell culture, cloning and plasmid construction, PCR, and surgery and behavioral analysis. In many studies, we use a multi-level approach ranging from examination of gene expression to behavioral analysis.
All together, this work aims at providing an integrated model of the different components modulating steroid action. The parallel study of all components of this regulation is critical to understand how hormones act in the brain to regulate complex normal and abnormal behaviors. Several aspects of this regulation are relevant for other types of steroid-dependent responses such as estrogen-dependent tumor growth.