Adrenocortical Hyporesponsiveness and Glucocorticoid Feedback Resistance in Old Male Brown Norway Rats

Eekelen, Anke van; Oitzl, Melly S.; Kloet, E. R. de

doi:10.1093/gerona/50a.2.b83

Cited by 38 publications

(21 citation statements)

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“…Likewise, corticosterone responses to novelty stress over a 4-hour period were comparable between young and old rats.  In a follow-up work, van Eekelen et al, [431] demonstrated that stress-induced peak circulating corticosterone levels were not different between two age groups, but in vivo sensitivity of adrenal glands to in vivo ACTH 1-24 challenge was reduced in aged (29-30-mo) compared to young (6-mo) adrenal glands. However, neither the magnitude of response to ACTH nor total capacity of the adrenal cortex to synthesize and secrete corticosterone in response to ACTH 1-24 stimulation was impacted by aging.…”

Section: Aging and Adrenal Androgen Secretions Humansmentioning

confidence: 96%

Impact of Aging on Steroid Hormone Biosynthesis and Secretion

Zaidi¹

2013

TOLSJ

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Steroid hormones are lipophilic, low-molecular weight organic compounds all of which are derived from cholesterol. They are primarily synthesized by steroidogenic glands such as gonads (ovary and testis), the adrenal gland and, during pregnancy, by the placental trophoblasts. Limited steroid synthesis also takes place in the brain. Steroid hormones are crucial for the proper functioning of the body. They mediate a wide variety of vital physiological functions, ranging from maintaining normal reproductive function and secondary sexual characteristics, to regulating virtually every metabolic process in the body. Like many age-related endocrine disorders, aging also progressively impacts the tissue-specific synthesis and secretion of steroid hormones. The goal of this review is to summarize the effects of aging on steroid hormone synthesis and secretion by the adrenal gland and gonads of both human and experimental animal models, to describe the potential involvement of excessive oxidative stress in mediating age-related alterations in steroidogenesis, and to discuss the possible underlying mechanisms involved.

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Section: Aging and Adrenal Androgen Secretions Humansmentioning

confidence: 96%

Impact of Aging on Steroid Hormone Biosynthesis and Secretion

Zaidi¹

2013

TOLSJ

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“…Exposure to synthetic glucocorticoids also increases hippocampal MR (Reul et al 1987(Reul et al , 1989 as do tricyclic antidepressants (Seckl & Fink 1992), whereas aged, chronically stressed and/or depressed individuals have a suppressed brain MR expression (van Eekelen et al 1995, Klok et al 2011b. Adult rodents that have experienced extensive maternal care as pups have higher expression of hippocampal MR than their littermates that have received poor care (Champagne et al 2008).…”

Section: Selected Linesmentioning

confidence: 99%

30 YEARS OF THE MINERALOCORTICOID RECEPTOR: The brain mineralocorticoid receptor: a saga in three episodes

Joëls

Kloet

2017

Journal of Endocrinology

118

109

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In 1968, Bruce McEwen discovered that 3 H-corticosterone administered to adrenalectomised rats is retained in neurons of hippocampus rather than those of hypothalamus. This discovery signalled the expansion of endocrinology into the science of higher brain regions. With this in mind, our contribution highlights the saga of the brain mineralocorticoid receptor (MR) in three episodes. First, the precloning era dominated by the conundrum of two types of corticosterone-binding receptors in the brain, which led to the identification of the high-affinity corticosterone receptor as the 'promiscuous' MR cloned in 1987 by Jeff Arriza and Ron Evans in addition to the classical glucocorticoid receptor (GR). Then, the post-cloning period aimed to disentangle the function of the brain MR from that of the closely related GR on different levels of biological complexity. Finally, the synthesis section that highlights the two faces of brain MR: Salt and Stress. 'Salt' refers to the regulation of salt appetite, and reciprocal arousal, motivation and reward, by a network of aldosterone-selective MR-expressing neurons projecting from nucleus tractus solitarii (NTS) and circumventricular organs. 'Stress' is about the limbic-forebrain nuclear and membrane MRs, which act as a switch in the selection of the best response to cope with a stressor. For this purpose, activation of the limbic MR promotes selective attention, memory retrieval and the appraisal process, while driving emotional expressions of fear and aggression. Subsequently, rising glucocorticoid concentrations activate GRs in limbic-forebrain circuitry underlying executive functions and memory storage, which contribute in balance with MR-mediated actions to homeostasis, excitability and behavioural adaptation.

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“…The higher basal plasma concentrations of ACTH and cortisol in the young dogs may indicate that the stress of handling caused a stronger activation of the pituitary-adrenocortical axis in these young dogs than in the old dogs. In some species, ageing is associated with a decrease in stress-induced activation of adrenocortical function (Van Eekelen et al, 1995).…”

Section: Ghrp-6mentioning

confidence: 99%

Effects of growth hormone secretagogues on the release of adenohypophyseal hormones in young and old healthy dogs

Bhatti

Duchateau

Ham

et al. 2006

The Veterinary Journal

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The effects of three growth hormone secretagogues (GHSs), ghrelin, growth hormone-releasing peptide-6 (GHRP-6), and growth hormone-releasing hormone (GHRH), on the release of adenohypophyseal hormones, growth hormone (GH), adrenocorticotropic hormone (ACTH), thyroid-stimulating hormone (TSH), luteinising hormone (LH), prolactin (PRL) and on cortisol were investigated in young and old healthy Beagle dogs.Ghrelin proved to be the most potent GHS in young dogs, whereas in old dogs GHRH administration was associated with the highest plasma GH concentrations. The mean plasma GH response after administration of ghrelin was significantly lower in the old dogs compared with the young dogs. The mean plasma GH concentration after GHRH and GHRP-6 administration was lower in the old dogs compared with the young dogs, but this difference did not reach statistical significance. In both age groups, the GHSs were specific for GH release as they did not cause significant elevations in the plasma concentrations of ACTH, cortisol, TSH, LH, and PRL. It is concluded that in young dogs, ghrelin is a more powerful stimulator of GH release than either GHRH or GHRP-6. Ageing is associated with a decrease in GH-releasing capacity of ghrelin, whereas this decline is considerably lower for GHRH or GHRP-6.

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Adrenocortical Hyporesponsiveness and Glucocorticoid Feedback Resistance in Old Male Brown Norway Rats

Cited by 38 publications

References 0 publications

Impact of Aging on Steroid Hormone Biosynthesis and Secretion

Impact of Aging on Steroid Hormone Biosynthesis and Secretion

30 YEARS OF THE MINERALOCORTICOID RECEPTOR: The brain mineralocorticoid receptor: a saga in three episodes

Effects of growth hormone secretagogues on the release of adenohypophyseal hormones in young and old healthy dogs

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