51
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McEwen BS, Cameron H, Chao HM, Gould E, Magarinos AM, Watanabe Y, Woolley CS. Adrenal steroids and plasticity of hippocampal neurons: toward an understanding of underlying cellular and molecular mechanisms. Cell Mol Neurobiol 1993; 13:457-82. [PMID: 8252613 DOI: 10.1007/bf00711583] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- B S McEwen
- Laboratory of Neuroendocrinology, Rockefeller University, New York, New York 10021
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52
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Pavlides C, Watanabe Y, McEwen BS. Effects of glucocorticoids on hippocampal long-term potentiation. Hippocampus 1993; 3:183-92. [PMID: 8353605 DOI: 10.1002/hipo.450030210] [Citation(s) in RCA: 247] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The effects of chronic and acute corticosterone (CORT) administration were investigated on hippocampal long-term potentiation (LTP) in the dentate gyrus granule cell layer of the rat. Electrophysiological experiments were performed in vivo under urethane anesthesia. Chronic CORT treatment (40 mg/kg/day) over 21 days decreased LTP compared to vehicle controls, even when LTP was measured 48 hours after cessation of CORT treatment, when serum CORT levels had returned to baseline. A single injection of CORT also decreased LTP compared to vehicle controls, but only when CORT levels were high, since at 48 hours after a single acute CORT injection LTP was not depressed. The decrements in LTP were seen both for the slope of the excitatory postsynaptic potential and for the population spike. Yet CORT had no effects on posttetanic potentiation or neuronal excitability. These findings are consistent with previous reports showing a reduction in LTP in the CA1 field of animals exposed to stress or acute CORT administration.
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Affiliation(s)
- C Pavlides
- Rockefeller University, New York, New York 10021
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53
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Oitzl MS, Josephy M, Spruijt BM. An ACTH/MSH(4-9) analog counteracts the behavioral effects of a mineralocorticoid receptor antagonist. Pharmacol Biochem Behav 1993; 44:447-50. [PMID: 8383343 DOI: 10.1016/0091-3057(93)90489-g] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The ACTH/MSH(4-9) analog Org2766 has been demonstrated to counteract age-related behavioral and morphological parameters especially those related to hippocampal functioning. Hippocampal mineralocorticoid receptors (MRs) are known to decline in the senescent rat. This decrease can be also counteracted by a chronic treatment with an ACTH(4-9) analog. The apparent effect of the peptide on hippocampal functioning prompted us to study a possible interaction between ACTH and MRs at a behavioral level. A chronic treatment with the ACTH(4-9) analog prevented the behavioral alteration induced by a specific MR antagonist (RU28318; 100 ng/microliters, ICV) in the Morris water maze and a step-through avoidance task. A possible role for neuronal excitation, involving MR activation, in peptide-facilitated behavioral recovery as seen in lesion studies and aging is discussed.
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Affiliation(s)
- M S Oitzl
- Center of Bio-Pharmaceutical Sciences, Division of Medical Pharmacology, University of Leiden, The Netherlands
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54
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Affiliation(s)
- E R de Kloet
- Division of Medical Pharmacology, University of Leiden, The Netherlands
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55
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Landfield PW, Thibault O, Mazzanti ML, Porter NM, Kerr DS. Mechanisms of neuronal death in brain aging and Alzheimer's disease: role of endocrine-mediated calcium dyshomeostasis. JOURNAL OF NEUROBIOLOGY 1992; 23:1247-60. [PMID: 1469387 DOI: 10.1002/neu.480230914] [Citation(s) in RCA: 95] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
This paper reviews evidence that brain aging and Alzheimer's disease (AD) are somehow closely related and that the hippocampus (CA1) is highly vulnerable to cell loss under both conditions. In addition, two current lines of evidence on the mechanisms of hippocampal cell loss with aging are considered, including studies of neuronal calcium dysregulation and studies of cumulative glucocorticoid (GC) neurotoxicity. Moreover, recent electrophysiological studies have shown that excess glucocorticoid activation of hippocampal neurons increases the influx of calcium through voltage-activated calcium channels. Second messenger systems may mediate the steroid modulation of calcium channels. Therefore, it is hypothesized that excess glucocorticoid activation and neuronal calcium dysregulation may be two phases of a single process that increases the susceptibility of neurons to neurodegeneration during aging and Alzheimer's disease.
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Affiliation(s)
- P W Landfield
- Department of Pharmacology, University of Kentucky, College of Medicine, Lexington 40536-0084
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56
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Watanabe Y, Gould E, Cameron HA, Daniels DC, McEwen BS. Phenytoin prevents stress- and corticosterone-induced atrophy of CA3 pyramidal neurons. Hippocampus 1992; 2:431-5. [PMID: 1308199 DOI: 10.1002/hipo.450020410] [Citation(s) in RCA: 254] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Repeated daily restraint stress and daily corticosterone administration to adult male Sprague-Dawley rats leads to decreases in the number of branch points and length of dendrites of CA3 pyramidal neurons of the hippocampal formation. This decrease is prevented by daily administration of the antiepileptic drug phenytoin (Dilantin), which is known to interfere with excitatory amino acid release and actions. Phenytoin had no obvious effect on behavior during and after stress and failed to prevent stress-induced reduction of body weight gain and stress-induced increases of adrenal weight relative to body weight; it also failed to attenuate glucocorticoid-induced diminution of the size of the thymus gland, indicating that it does not directly antagonize glucocorticoid actions. Stress- and corticosterone-induced effects on dendritic length and branch point number are more pronounced on the apical, as opposed to the basal, CA3 dendrites that receive the largest mossy fiber input from the dentate gyrus. Because phenytoin is also known to prevent ischemic damage, these results are consistent with a model in which stress- and corticosterone-induced CA3 dendritic atrophy is produced by excitatory amino acids released from the mossy fibers.
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Affiliation(s)
- Y Watanabe
- Laboratory of Neuroendocrinology, Rockefeller University, New York, New York 10021
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57
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Spruijt BM. Effects of the ACTH4-9 analog Org2766 on brain plasticity: modulation of excitatory neurotransmission? Psychoneuroendocrinology 1992; 17:315-25. [PMID: 1332099 DOI: 10.1016/0306-4530(92)90037-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
ACTH-like neuropeptides have been investigated in various paradigms such as cognition, neuronal damage and neuronal excitation. All their effects may be collectively described as modulation of neural plasticity. However, the mechanism of action accounting for these effects remains to be demonstrated. This report is an overview of the data and has incorporated some additional findings of the influence of the ACTH4-9 analog, Org2766, on neuronal excitation, especially in the hippocampus. An interaction with NMDA receptors may account for the various aspects of plasticity. Based on recent findings demonstrating that the ACTH4-9 analog counteracts both the NMDA antagonist, AP5, and NMDA-induced explosive running behavior, the hypothesis is put forward that glutamatergic neurotransmission is involved in behavioral changes induced by the ACTH4-9 analog.
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Affiliation(s)
- B M Spruijt
- Institute of Molecular Biology, University of Utrecht, The Netherlands
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58
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59
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McEwen BS, Angulo J, Cameron H, Chao HM, Daniels D, Gannon MN, Gould E, Mendelson S, Sakai R, Spencer R. Paradoxical effects of adrenal steroids on the brain: protection versus degeneration. Biol Psychiatry 1992; 31:177-99. [PMID: 1737079 DOI: 10.1016/0006-3223(92)90204-d] [Citation(s) in RCA: 135] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- B S McEwen
- Laboratory of Neuroendocrinology, Rockefeller University, New York, NY 10021
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60
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Abstract
Effect of chronic treatment of the ACTH4-9 analog, Org2766, on social attention was studied longitudinally in aging rats. A 6-week treatment temporarily enhanced specific combinations of behaviors of two interacting animals. During a 6-month treatment social attention of treated animals remained at the same level, whereas control animals showed a gradual decrease. Two months after the treatment was ceased this effect on social attention was still present; moreover, the peptide-treated animals performed better in a spatial water maze task three months after the last injection. In addition, the nerve conduction velocity of the major caudal nerves and the sciatic nerve were measured; aged, peptide-treated animals preserved their conduction velocity. The present study shows beneficial long-lasting effects of the ACTH4-9 analog in aging rats on complex behavioral indices and on a physiological measure.
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Affiliation(s)
- B M Spruijt
- Division of Molecular Neurobiology, University of Utrecht, The Netherlands
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61
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Landfield PW, Applegate MD, Schmitzer-Osborne SE, Naylor CE. Phosphate/calcium alterations in the first stages of Alzheimer's disease: implications for etiology and pathogenesis. J Neurol Sci 1991; 106:221-9. [PMID: 1802970 DOI: 10.1016/0022-510x(91)90261-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The present study tested aspects of a novel etiological/pathogenetic hypothesis of Alzheimer's disease (AD), which proposes that alterations in endocrine regulation of peripheral calcium/phosphate (Ca/PO4) homeostasis (e.g., by glucocorticoids, vitamin D, etc.) induce and/or reflect altered calcium homeostasis and neurotoxicity in brain neurons. Two key predictions of this hypothesis were tested, namely that: (1) alterations in serum Ca and/or PO4 regulation should be present before or near the onset of AD and (2) these alterations should be found consistently in subjects with unconfounded AD. Previous studies have sought evidence of changes in Ca regulation primarily late in the disease, and usually in severely demented, thin and immobile inpatients in whom Ca/PO4 measures are likely to be confounded. In the present study, only mobile, relatively healthy, adequately nourished outpatients with probable AD were selected. In comparison to age-matched controls or demented subjects with even mild indications of vascular contributions, the AD subjects were characterized by lower serum PO4 and, to a lesser degree, lower serum Ca as well as a higher chloride/PO4 ratio. On serum chemistry tests from the first stages of AD (within 1 or 3 years after the onset of cognitive symptoms), these changes in serum PO4/Ca were as pronounced as they were later in the disease. Moderately low values of either PO4, Ca, or both (below -1.0 S.D. from the control group mean) identified 74% of all AD subjects and 100% of early onset AD subjects, in comparison to only 46% of mixed/vascular dementia subjects and 31% of normal age-matched controls. Thus, the results were consistent with the predictions and may have significant etiological/pathogenetic implications. If larger tests confirm these frequencies, serum Ca/PO4 indices may also prove useful in differential diagnosis.
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Affiliation(s)
- P W Landfield
- Department of Pharmacology, University of Kentucky College of Medicine, Lexington 40536
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62
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Dilman VM. Pathogenetic approaches to prevention of age-associated increase of cancer incidence. Ann N Y Acad Sci 1991; 621:385-400. [PMID: 1859098 DOI: 10.1111/j.1749-6632.1991.tb16994.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- V M Dilman
- Laboratory of Endocrinology, N.N. Petrov Research Institute of Oncology, Leningrad, USSR
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63
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van Eekelen JA, Rots NY, Sutanto W, Oitzl MS, de Kloet ER. Brain corticosteroid receptor gene expression and neuroendocrine dynamics during aging. J Steroid Biochem Mol Biol 1991; 40:679-83. [PMID: 1659889 DOI: 10.1016/0960-0760(91)90290-l] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The present study examined the stress responsiveness of the hypothalamic-pituitary-adrenal axis in relation to the properties of corticosteroid receptors in the brain and pituitary in old (30 months) and young (3 months) male Brown Norway rats. The data demonstrate that circulating ACTH rather than the corticosteroid plasma level was elevated under basal conditions and following stress. Furthermore, a reduction of mineralocorticoid receptor (MR) number in the hippocampus and of glucocorticoid receptor (GR) number in the hypothalamus and the pituitary correspond to increased neuroendocrine responsiveness and negative feedback following stress. The changes in receptor binding do not parallel the changes in the amount of MR and GR mRNA measured with in situ hybridization. This suggests that the processing rather than the receptor gene expression is affected in senescence.
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Affiliation(s)
- J A van Eekelen
- Division of Medical Pharmacology, University of Leiden, The Netherlands
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64
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Pitsikas N, Spruijt BM, Algeri S, Gispen WH. The ACTH/MSH (4-9) analog Org2766 improves retrieval of information after a fimbria fornix transection. Peptides 1990; 11:911-4. [PMID: 2178248 DOI: 10.1016/0196-9781(90)90008-s] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The fimbria fornix of male Wistar rats was transected unilaterally after they had been successfully trained in the Morris maze and the passive avoidance task. Sham-operated and lesioned animals were treated either with Org2766 or saline for two weeks. Subsequently, the performance of all groups was tested again starting two days after the last treatment. The lesioned animals showed a deficit in performance in both tasks, indicating interference of the lesion with retrieval of information. Org2766 improved the poor performance of the lesioned animals in the Morris maze, but not in the passive avoidance task.
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Affiliation(s)
- N Pitsikas
- Division of Molecular Neurobiology, Rudolf Magnus Institute, University of Utrecht, The Netherlands
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65
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Nichols NR, Masters JN, Finch CE. Changes in gene expression in hippocampus in response to glucocorticoids and stress. Brain Res Bull 1990; 24:659-62. [PMID: 2357595 DOI: 10.1016/0361-9230(90)90004-j] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Glucocorticoid hormones, acting through two types of intracellular receptors to modulate gene activity, have diverse behavioral, neurochemical and neurodegenerative effects in hippocampus. We have previously cloned hippocampal mRNAs that respond to the endogenous glucocorticoid, corticosterone (CORT): glycerol phosphate dehydrogenase (EC 1.1.1.8; GPDH), an oligodendrocyte marker; CR16, whose sequence is not yet identified; and glial fibrillary acidic protein (GFAP), a marker of astroglial reactivity. In these studies, we have subjected rats to 2 hr vibratory stress as a treatment that raises circulating CORT levels, and analyzed changes in GPDH, CR16 and GFAP mRNAs in rat hippocampus. Only GPDH mRNA responded to stress in intact rats; GPDH mRNA did not respond to the same treatment in rats where the adrenal source of CORT had been removed surgically. The lack of stress responsiveness of CR16 and GFAP mRNAs, despite elevated corticosterone levels, is consistent with their slower (greater than 2 hr but less than 8 hr) response to administered CORT. These studies indicate that temporal aspects of CORT regulation may account in part for differential responses to vibratory stress of CORT-dependent mRNA responses in hippocampus. An increase in GPDH gene activity represents a CORT-dependent stress response that can be used to characterize changes in neuroendocrine status and stress responsiveness of target cells.
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Affiliation(s)
- N R Nichols
- Department of Biological Sciences, University of Southern California, Los Angeles 90089-0191
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66
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Odio MR, Brodish A. Glucoregulatory responses of adult and aged rats after exposure to chronic stress. Exp Gerontol 1990; 25:159-72. [PMID: 2196183 DOI: 10.1016/0531-5565(90)90047-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Stress has been implicated as an environmental factor that may accelerate the process of biological aging. However, this proposal has remained largely anecdotal due to relatively few studies that directly tested this hypothesis. In the present experiments groups of 6-month-old and 20-month-old male F-344 rats were chronically stressed for a six-month period. After the last stress session, when the animals were 12 months of age (adult) and 26 months of age (old), control and chronically stressed rats were tested for their ability to: (a) elicit glucose and insulin responses to an acute, novel stressor; (b) remove a circulatory glucose load elicited either by acute stress exposure or by injection of d-glucose; and (c) raise insulin levels after a glucose challenge. In control rats, we observed a deficit in each of these parameters in old compared to adult rats. Exposure to chronic stress did not exacerbate deterioration of these response mechanisms in either adult or old rats. In fact, the data showed a modest improvement in glucose tolerance in chronically stressed compared to age-matched control rats. We conclude that chronic stress did not exacerbate age-dependent decline of glucoregulatory capacity. From these results and from our earlier work, we speculate that the decline during aging of the functional integrity of systems involved in the response to stress may be sustained by periodic challenges from the organism's external environment.
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Affiliation(s)
- M R Odio
- Department of Physiology/Pharmacology, Bowman Gray School of Medicine, Wake Forest University, Winston-Salem, North Carolina 27103
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67
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Kerr DS, Campbell LW, Hao SY, Landfield PW. Corticosteroid modulation of hippocampal potentials: increased effect with aging. Science 1989; 245:1505-9. [PMID: 2781293 DOI: 10.1126/science.2781293] [Citation(s) in RCA: 230] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Adrenal steroids bind specifically to hippocampal neurons under normal conditions and may contribute to hippocampal cell loss during aging, but little is known about the neurophysiological mechanisms by which they may change hippocampal cell functions. In the present studies, adrenal steroids have been shown to modulate a well-defined membrane conductance in hippocampal pyramidal cells. The calcium-dependent slow afterhyperpolarization is reduced in hippocampal slices from adrenalectomized rats, and it is increased after in vivo or in vitro administration of the adrenal steroid, corticosterone. Calcium action potentials are also reduced in adrenalectomized animals, indicating that the primary effect of corticosteroids may be on calcium conductance. The afterhyperpolarization component reduced by adrenalectomy is greater in aged rats than in young rats, suggesting that, with aging, there is an increased effect of corticosteroids on some calcium-mediated brain processes. Because elevated concentrations of intracellular calcium can be cytotoxic, these observations may increase the understanding of glucocorticoid involvement in brain aging as well as of the normal functions of these steroids in the brain.
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Affiliation(s)
- D S Kerr
- Department of Physiology and Pharmacology, Bowman Gray School of Medicine, Winston-Salem, NC 27103
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68
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Affiliation(s)
- D G Hazzard
- Office of Resource Development, National Institute on Aging, Bethesda, Maryland 20892
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69
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De Kloet ER, Ratka A, Reul JM, Sutanto W, Van Eekelen JA. Corticosteroid receptor types in brain: regulation and putative function. Ann N Y Acad Sci 1987; 512:351-61. [PMID: 3327424 DOI: 10.1111/j.1749-6632.1987.tb24973.x] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- E R De Kloet
- Rudolf Magnus Institute of Pharmacology, Medical Faculty, University of Utrecht, The Netherlands
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