Reproductive hormones regulate the selective permeability of the blood-brain barrier.
Reproductive hormones have been demonstrated to modulate both gap and tight junction protein expression in the ovary and other reproductive tissues, however the effects of changes in reproductive hormones on the selective permeability of the blood-brain barrier (BBB) remain unclear. Age-related declines in BBB integrity correlate with the loss of serum sex steroids and increase in gonadotropins with menopause/andropause. To examine the effect of reproductive senescence on BBB permeability and gap and tight junction protein expression/localization, female mice at 3 months of age were either sham operated (normal serum E2 and gonadotropins), ovariectomized (low serum E2 and high serum gonadotropins) or ovariectomized and treated with the GnRH agonist leuprolide acetate (low serum E2 and gonadotropins). Ovariectomy induced a 2.2-fold increase in Evan's blue dye extravasation into the brain. The expression and localization of the cytoplasmic membrane-associated tight junction protein zona occludens 1 (ZO-1) in microvessels was not altered among groups indicating that the increased paracellular permeability was not due to changes in this tight junction protein. However, ovariectomy induced a redistribution of the gap junction protein connexin-43 (Cx43) such that immunoreactivity relocalized from along the extracellular microvascular endothelium to become associated with endothelial cells. An increase in Cx43 expression in the mouse brain following ovariectomy was suppressed in ovariectomized animals treated with leuprolide acetate, indicating that serum gonadotropins rather than sex steroids were modulating Cx43 expression. These results suggest that elevated serum gonadotropins following reproductive senescence may be one possible cause of the loss of selective permeability of the BBB at this time. Furthermore, these findings implicate Cx43 in mediating changes in BBB permeability, and serum gonadotropins in the cerebropathophysiology of age-related neurodegenerative diseases such as stroke and Alzheimer's disease.
Wilson
Andrea C
AC
Department of Medicine, University of Wisconsin-Madison and Geriatric Research, Education and Clinical Center, Veterans Administration Hospital, 2500 Overlook Terrace, Madison, WI 53705 USA.
Clemente
Luca
L
Liu
Tianbing
T
Bowen
Richard L
RL
Meethal
Sivan Vadakkadath
SV
Atwood
Craig S
CS
D000704:Analysis of Variance; D000818:Animals; D001812:Blood-Brain Barrier / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D018031:Connexin 43 / Q000378:metabolism; D005260:Female; D005640:Follicle Stimulating Hormone / Q000378:metabolism / Q000502:physiology; D017629:Gap Junctions / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D012739:Gonadal Steroid Hormones / Q000378:metabolism / Q000502:physiology*; D006062:Gonadotropins / Q000097:blood / Q000502:physiology; D015151:Immunoblotting; D007150:Immunohistochemistry; D016729:Leuprolide / Q000494:pharmacology; D007986:Luteinizing Hormone / Q000378:metabolism / Q000502:physiology; D051379:Mice; D008815:Mice, Inbred Strains; D010052:Ovariectomy; D010539:Permeability / Q000187:drug effects; D019108:Tight Junctions / Q000187:drug effects / Q000378:metabolism / Q000502:physiology
D018031:Connexin 43; D012739:Gonadal Steroid Hormones; D006062:Gonadotropins; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D016729:Leuprolide