Lieu: Brunoy.

Abstract: The hypothalamus is a highly plastic structure that integrates regulatory homeostatic and external factors to control key physiological functions such as energy homeostasis, reproductive function, thermoregulation, and circadian rhythms. The reproductive function is orchestrated by a small population of hypothalamic neurons that produce the neurohormone Gonadotropin-Releasing Hormone (GnRH). While these neurons are in place at birth, they need a post-natal maturation to increase their pulsatile secretion of GnRH and initiate puberty. Using a combination of neuroanatomy, physiology, molecular & cellular biology approaches, we have shown that pubertal activation of GnRH secretion in female rats requires a dialogue between GnRH neurons and local progenitor cells: GnRH neurons attract in their immediate vicinity progenitors that differentiate into astrocytes, known to provide stimulatory inputs to GnRH neurons. As development proceeds, the population of neural stem/progenitor cells (NPC) sharply decreases and is retained in adulthood in a few restricted brain locations called niches. Recent work, mainly performed in rodents, has shown that the adult hypothalamus hosts NPC that produce new neurons and glial cells throughout life. In order to explore whether the hypothalamus of adult primates contains a NPC niche, we performed a neuroanatomical study and compared the human, grey mouse lemur, rat and mouse hypothalamus for the expression of NPC markers. Our work suggests that the human hypothalamus contains an extended population of NPC compared to other species.