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Hormonal Regulation of Type II Glucocorticoid Receptor Messenger Ribonucleic Acid in Rat Brain

Hormonal Regulation of Type II Glucocorticoid Receptor Messenger Ribonucleic Acid in Rat Brain Differences in the regulation of type II glucocorticoid receptor (GR) mRNA levels in female rat brain regions involved in the control of the hypo thalamic-pituitary-ad renal axis were studied by Northern blot analysis after chronic administration of corticosterone or dexamethasone to adrenalectomized (ADX), ovariectomized (OVX), and ADX/OVX animals. The effect of chronic estradiol or progesterone treatment of intact animals was also studied. Our results show that type II GR mRNA levels of ADX animals were significantly increased above control values in amygdala (140%) and hippocampus (196%), but not in hypothalamus. These increased transcript levels were down-regulated by corticosterone or dexamethasone, with the exception of those in the amygdala, where corticosterone had no effect. Ovariectomy significantly increased hypothalamic GR mRNA content (174%) over control values, and this increase was sensitive to dexamethasone. The combined effect of adrenalectomy/ovariectomy on GR mRNA levels was greater than that of adrenalectomy only in amygdala. Corticosterone increased amygdala transcript levels in OVX and ADX/OVX animals. Estradiol administration to intact animals raised the GR mRNA content of amygdala, while progesterone treatment had no effect on any of the brain regions studied. We conclude that there exists heterogeneity with respect to type II GR mRNA regulation by corticosterone and dexamethasone in brain regions of ADX female rats, and that certain limbic structures show greater sensitivity to these hormonal manipulations, suggesting a more prominent role in the regulation of the hypothalamic-pituitary-adrenal axis. Our results also suggest that circulating estrogens can influence the sensitivity of brain structures (i.e. hypothalamus and amygdala) to glucocorticoids by altering GR mRNA levels. These regions may represent integration sites at which gonadal steroids are able to alter stress hormone secretion. (Endocrinology129: 2166–2174, 1991) This content is only available as a PDF. Author notes * This work was supported by a grant from the Medical Research Council of Canada (to N.B.). Copyright © 1991 by The Endocrine Society http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Endocrinology Oxford University Press

Hormonal Regulation of Type II Glucocorticoid Receptor Messenger Ribonucleic Acid in Rat Brain

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References (49)

Publisher
Oxford University Press
Copyright
Copyright © 1991 by The Endocrine Society
ISSN
0013-7227
eISSN
1945-7170
DOI
10.1210/endo-129-4-2166
Publisher site
See Article on Publisher Site

Abstract

Differences in the regulation of type II glucocorticoid receptor (GR) mRNA levels in female rat brain regions involved in the control of the hypo thalamic-pituitary-ad renal axis were studied by Northern blot analysis after chronic administration of corticosterone or dexamethasone to adrenalectomized (ADX), ovariectomized (OVX), and ADX/OVX animals. The effect of chronic estradiol or progesterone treatment of intact animals was also studied. Our results show that type II GR mRNA levels of ADX animals were significantly increased above control values in amygdala (140%) and hippocampus (196%), but not in hypothalamus. These increased transcript levels were down-regulated by corticosterone or dexamethasone, with the exception of those in the amygdala, where corticosterone had no effect. Ovariectomy significantly increased hypothalamic GR mRNA content (174%) over control values, and this increase was sensitive to dexamethasone. The combined effect of adrenalectomy/ovariectomy on GR mRNA levels was greater than that of adrenalectomy only in amygdala. Corticosterone increased amygdala transcript levels in OVX and ADX/OVX animals. Estradiol administration to intact animals raised the GR mRNA content of amygdala, while progesterone treatment had no effect on any of the brain regions studied. We conclude that there exists heterogeneity with respect to type II GR mRNA regulation by corticosterone and dexamethasone in brain regions of ADX female rats, and that certain limbic structures show greater sensitivity to these hormonal manipulations, suggesting a more prominent role in the regulation of the hypothalamic-pituitary-adrenal axis. Our results also suggest that circulating estrogens can influence the sensitivity of brain structures (i.e. hypothalamus and amygdala) to glucocorticoids by altering GR mRNA levels. These regions may represent integration sites at which gonadal steroids are able to alter stress hormone secretion. (Endocrinology129: 2166–2174, 1991) This content is only available as a PDF. Author notes * This work was supported by a grant from the Medical Research Council of Canada (to N.B.). Copyright © 1991 by The Endocrine Society

Journal

Endocrinology – Oxford University Press

Published: Oct 1, 1991

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