Estrogen stimulates microglia and brain recovery from hypoxia-ischemia in normoglycemic but not diabetic female mice.
Diabetic hyperglycemia increases ischemic brain damage in experimental animals and humans. The mechanisms are unclear but may involve enhanced apoptosis in penumbral regions. Estrogen is an established neuroprotectant in experimental stroke. Our previous study demonstrated that female diabetic db/db mice suffered less damage following cerebral hypoxia-ischemia (H/I) than male db/db mice. Here we investigated the effects of diabetes and estrogen apoptotic gene expression following H/I. Female db/db and nondiabetic (+/?) mice were ovariectomized (OVX) and treated with estrogen or vehicle prior to H/I; brains were analyzed for damage and bcl-2 family gene expression. OVX increased ischemic damage in +/? mice; estrogen reduced tissue injury and enhanced antiapoptotic gene expression (bcl-2 and bfl-1). db/db mice demonstrated more damage, without increased bcl-2 mRNA; bfl-1 expression appeared at 48 hours of recovery associated with infarction. To our knowledge, this is the first description of bfl-1 in the brain with localization to microglia and macrophages. Early induction of bfl-1 expression in +/? mouse brain was associated with microglia; delayed bfl-1 expression in diabetic brain was in macrophages bordering the infarct. Furthermore, estrogen replacement stimulated early postischemic expression of bcl-2 and bfl-1 and reduced damage in normoglycemic animals but failed to protect the diabetic brain.
Zhang
Liqun
L
Department of Pediatrics, Morgan Stanley Children's Hospital of New York, Columbia University College of Physicians and Surgeons, New York, New York 10032, USA.
Nair
Aji
A
Krady
Kyle
K
Corpe
Christopher
C
Bonneau
Robert H
RH
Simpson
Ian A
IA
Vannucci
Susan J
SJ
D000818:Animals; D001786:Blood Glucose / Q000378:metabolism*; D001921:Brain / Q000187:drug effects / Q000473:pathology*; D002545:Brain Ischemia / Q000235:genetics / Q000517:prevention & control*; D003922:Diabetes Mellitus, Type 1 / Q000150:complications*; D003925:Diabetic Angiopathies / Q000150:complications* / Q000235:genetics; D004967:Estrogens / Q000502:physiology*; D005260:Female; D005786:Gene Expression Regulation; D002534:Hypoxia, Brain / Q000235:genetics / Q000517:prevention & control*; D051379:Mice; D008810:Mice, Inbred C57BL; D008815:Mice, Inbred Strains; D008817:Mice, Mutant Strains; D017628:Microglia / Q000187:drug effects / Q000473:pathology*; D015778:Minor Histocompatibility Antigens; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D014158:Transcription, Genetic
C096816:BCL2-related protein A1; D001786:Blood Glucose; D004967:Estrogens; D015778:Minor Histocompatibility Antigens; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger