Mineralocorticoid and glucocorticoid receptor expressions in astrocytes and microglia in the gerbil hippocampal CA1 region after ischemic insult.
In the present study, we observed expression and changes of mineralocorticoid receptor (MR) and glucocorticoid receptor (GR) in the gerbil hippocampal CA1 region, but not in the CA2/3 region, after 5 min of transient forebrain ischemia. In blood, corticosterone levels were increased biphasically at 30 min and 12 h after ischemia/reperfusion, and thereafter its levels were decreased. In the sham-operated group, MR and GR immunoreactivities were weakly detected in the CA1 region. By 3 days after ischemia, MR and GR were not significantly altered in the CA1 region: at 12 h after ischemia, GR was expressed in a few neurons in the CA1 region, whereas MR was not expressed in any neurons after ischemic insult. From 4 days after ischemia, MR and GR immunoreactivities were detected in astrocytes and microglia in the CA1 region, and at 7 days after ischemia, MR and GR immunoreactivities peaked in the hippocampal CA1 region. At this time, 55% of astrocytes and 30% of microglia showed MR immunoreactivity, and 20% of astrocytes and 40% of microglia showed GR immunoreactivity. Western blot analyses showed that the pattern of changes in MR and GR protein levels was similar to the immunohistochemical changes observed after transient forebrain ischemia. From 4 days after ischemia, MR and GR protein levels were increased time-dependently after ischemia. In conclusion, enhanced MR and GR expressions in astrocytes and microglia were detected in the hippocampal CA1 region 4-7 days after ischemia/reperfusion. At this time, GR immunoreactivity was abundant in microglia, whereas MR immunoreactivity was prominent in astrocytes. The specific distribution of corticosteroid receptors in the astrocytes and microglia may be associated with the differences of MR and GR functions against ischemic damage.
Hwang
In Koo
IK
Department of Anatomy, College of Medicine, Hallym University, Chunchon, South Korea.
Yoo
Ki-Yeon
KY
Nam
Young Sam
YS
Choi
Jung Hoon
JH
Lee
In Se
IS
Kwon
Young-Guen
YG
Kang
Tae-Cheon
TC
Kim
Yong-Sun
YS
Won
Moo Ho
MH
D000818:Animals; D001253:Astrocytes / Q000378:metabolism*; D016923:Cell Death; D005849:Gerbillinae; D006624:Hippocampus / Q000378:metabolism*; D007150:Immunohistochemistry; D002546:Ischemic Attack, Transient / Q000378:metabolism* / Q000473:pathology; D008297:Male; D017628:Microglia / Q000378:metabolism*; D009474:Neurons / Q000473:pathology; D011965:Receptors, Glucocorticoid / Q000096:biosynthesis*; D018161:Receptors, Mineralocorticoid / Q000096:biosynthesis*
D011965:Receptors, Glucocorticoid; D018161:Receptors, Mineralocorticoid