Dionysia Theodosis #

Biography#

Dionysia Thodosis was born in Greece but grew up and studied in Montreal, Canada where she obtained her PhD from McGill University. Her postdoctorate took place at the Medical School of the University of Geneva in Switzerland. She has been in France as a tenured scientist in Inserm (The French National Institute of Health and Medical Research) since 1980 (presently, she is a senior Research Director). During her professional carreer, she has trained many graduate students and postdoctorate fellows who are now established scientists in various Neuroscience departments in European and American universities. Her major scientific interest has always revolved around the cell biology and morphology of the central nervous system. Initially trained as an electron microscopist, that vision of the natural world has continued to attract and fascinate her. Her work still revolves around a discovery she made about 20 years ago, namely, that the structure of the adult brain is not fixed but can be modified in response to purely physiological conditions. In the female brain, this is exemplified by maternity, which results in profound changes in the morphology of oxytocin neurons, their supportive cells, the astroglia, and the synapses that drive their activity. These changes are reversible and the part of the hypothalamus that undergoes such plasticity reverts to its 'virgin' condition once maternity is over; it will be reorganised in the course of another maternal period. Presently, her laboratory is active in the study of the cellular and molecular bases underlying this kind of neuronal plasticity.

Curriculum vitae#

Born on 25.07.1945 in Zakinthos, Greece

Degrees

• 1966 BSc, McGill University, Montreal
• 1969 MSc, Univ. Toronto, Toronto
• 1975 PhD McGill Univ, Montreal

Scientific positions and titles

• 1967-1969 Research Fellow, NRC, Canada, Dept of Zoology, Univ. of Toronto, Toronto
• 1969-1970 Technician, Dept. of Zoology, Univ. of Toronto, Toronto
• 1970-1971 Technician, Pathology Inst, McGill University , Montréal
• 1972-1974 Research Fellow, NRC, Dept. Biology, McGill Univ, Montreal
• 1974 Research Assistant, Dépt. de Pathologie, Ecole de Médecine, Geneva
• 1974-1978 Research Assistant, Dépt de Morphologie, Ecole de Médecine, Geneva
• 1978-1979 Chercheur Poste Orange INSERM, INSERM U.l76 (dir. Prof. J.D. Vincent), Bordeaux
• 1979-1980 Assistante, Dept. Physiologie, Univ Bordeaux II, Bordeaux
• 1980-1991 Chargée et Directeur de Recherches INSERM, U l76, Bordeaux

Presently

• Directeur de Recherches INSERM (1st class), working in the Laboratory of Morphofunctional Neurobiology INSERM U 378 associated with the University Victor Segalen-Bordeaux II, Bordeaux, France

Postodoctorate activities

• 1974-1978 Dépt de Morphologie (dir L Orci), Ecole de Médecine, Geneva

Research Activities

Cell biology of exo-endocytosis at neurosecretory terminals

Morphological analyses of the mechanisms controlling the activity of hypothalamic magnocellular neurons secreting oxytocin and vasopressin, neuropeptides intervening in the control of parturition, lactation, cardiovascular and osmotic regulatory mechanisms.

Morphological plasticity of the hypothalamo-neurohypophysial system

Our morphological studies established that the neurons, glia and synaptic inputs of the oxytocinergic system can undergo reversible remodelling in relation to particular physiological stages. Such plasticity modifies glial coverage of oxytocin neurons and the number of synapses driving their acitivity. We also demonstrated the importance of cell surface adhesion molecules in permitting such changes and that oxytocin itself is capable of inducing them. In recent studies, we provided direct evidence of the physiological consequences of such plasticity by showing that glial retraction during lactation affects the efficacy of glutamatergic transmission.

Teaching activities

• Director of 8 graduate students for the Thèse d'Université (equivalent to Ph.D) and 8 students for the degree of DEA (equivalent to M.Sc)
• Punctual teaching periods in the disciplines of neurocytology (electron microscopy, immunocytochemistry), neuroanatomy and neuroendocrinology
• Host to 7 postdoctoral fellows and 3 colleagues on sabbatical

Visiting scientist

• 1980 Dept of Biochemistry, Univ of Aarrhus, Aarrhus, Denmark (CNRS Fellowship)
• 1982 Inst für Zellbiologie, Univ of Munich, Munich, Germany (INSERM-DFG Fellowship)
• 1983 Univ. Inst. of Pathology, Copenhagen (Short-term Fellowship, EMBO)
• 1985 Inst. Animal Physiology, Babraham, Cambridge l985 (Short Term Fellowships, European Science and Nuffield Foundations)

Other activities

• 2000-2005 Founder and President of the International Neuroendocrine Federation
• 1998-2000 President of the International Society of Neuroendocrinology
• 1999-2001 Treasurer of the Société des Neurosciences
• 1996-1998 Treasurer of the Club des Cellules Gliales
• 1998-2000 President of the Club des Cellules Gliales

Memberships

• Member of the Société de Neuroendocrinologie Expérimentale and of the Society for Neuroscience
• Member of committees for the evaluation of theses
• Member of committes for the evaluation of theses and other research units in France
• External Evaluator: AFRC, Wellcome Foundation (U.K.), National Science Foundation(U.S.A.), Human Frontiers, Italian *Ministry of Education and Research, European Biomed Programme, European Science Foundation
• Receiving Editor (until 1996) of the Journal of Neuroendocrinology
• Reviewing Editor of Neuroscience
• Member of the Editorial Board of Frontiers of Neuroendocrinology
• Reviewer for Eur J Neurosci, J Neurosci, J Comp Neurol, Glia, Brain Res, J Neuroendocrinol, Neuroendocrinology, J Neurocytology etc
• Organiser of the 2nd European Meeting on Glial Cell Function, April 1996, Archachon, France
• Member of the Local Organising and/or the International Scientific Committee of the World Congress on Neurohypophysial Hormones WCNH, Bordeaux Sept 2001; Kyoto Sept 2003; Colorado July 2005; Regensburg Sept 2007
• The European Meeting on Glial Cell Function, Berlin Sept 2003; Amsterdam May 2005; London Sept 2007
• The Meeting of the Sociéte des Neurosciences, May 2001, Toulouse, France
• The FENS meeting, July 2002, Paris
• The Meeting of the International Neuroendocrine Federation, September 2002, Bristol, UK

Current Research Interests

Themes: Activity-dependent structural (neuronal-glial and synaptic) plasticity of the adult central nervous system, and in particular, of the hypothalamo-neurohypophysial system ; Mechanisms controlling the activity of hypothalamic magnocellular neurons secreting oxytocin and vasopressin, neuropeptides intervening in the control of parturition, lactation, cardiovascular and osmotic regulatory mechanisms