Steroid Transport, Local Synthesis, and Signaling within the Brain: Roles in Neurogenesis, Neuroprotection, and Sexual Behaviors

• Published in: Frontiers in neuroscience Vol. 12; p. 84
• Main Authors: Diotel, Nicolas, Charlier, Thierry D, Lefebvre d'Hellencourt, Christian, Couret, David, Trudeau, Vance L, Nicolau, Joel C, Meilhac, Olivier, Kah, Olivier, Pellegrini, Elisabeth
• Format: Journal Article
• Language: English
• Published: Switzerland Frontiers Research Foundation 20.02.2018; Frontiers; Frontiers Media S.A
• Subjects: Androgens; aromatase; Blood-brain barrier; Brain injury; Central nervous system; Cholesterol; Endocrinology and metabolism; Estrogens; Evolutionary conservation; Excitability; HDL; High density lipoprotein; Human health and pathology; Inflammation; Ischemia; Life Sciences; Lipoproteins; Membrane permeability; Menopause; Neurobiology; Neurogenesis; Neurons and Cognition; Neuroprotection; Neuroscience; Neurosteroidogenesis; Neurosteroids; Sex; Sexual behavior; Steroid hormones; Steroids; blood-brain barrier; HDL; progestins; aromatase; estrogens; cholesterol; stroke; lipoproteins
• ISSN: 1662-4548; 1662-453X; 1662-453X
• DOI: 10.3389/fnins.2018.00084

Sex steroid hormones are synthesized from cholesterol and exert pleiotropic effects notably in the central nervous system. Pioneering studies from Baulieu and colleagues have suggested that steroids are also locally-synthesized in the brain. Such steroids, called neurosteroids, can rapidly modulate neuronal excitability and functions, brain plasticity, and behavior. Accumulating data obtained on a wide variety of species demonstrate that neurosteroidogenesis is an evolutionary conserved feature across fish, birds, and mammals. In this review, we will first document neurosteroidogenesis and steroid signaling for estrogens, progestagens, and androgens in the brain of teleost fish, birds, and mammals. We will next consider the effects of sex steroids in homeostatic and regenerative neurogenesis, in neuroprotection, and in sexual behaviors. In a last part, we will discuss the transport of steroids and lipoproteins from the periphery within the brain (and vice-versa) and document their effects on the blood-brain barrier (BBB) permeability and on neuroprotection. We will emphasize the potential interaction between lipoproteins and sex steroids, addressing the beneficial effects of steroids and lipoproteins, particularly HDL-cholesterol, against the breakdown of the BBB reported to occur during brain ischemic stroke. We will consequently highlight the potential anti-inflammatory, anti-oxidant, and neuroprotective properties of sex steroid and lipoproteins, these latest improving cholesterol and steroid ester transport within the brain after insults.