Hormone receptors of the baboon cardiovascular system. Biochemical characterization of myocardial cytoplasmic androgen receptors.

Lin, Alan; McGill, Henry C.; Shain, Sydney A.

doi:10.1161/01.res.49.4.1010

Cited by 29 publications

(29 citation statements)

References 34 publications

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“…35 Specific binding data were evaluated by the method of Scatchard 38 and as double reciprocal plots. 37 Relative steroid specificity was determined by the single concentration inhibition assay previously used.…”

Section: Other Methodsmentioning

confidence: 99%

Estrogen-mediated cytoplasmic and nuclear distribution of rat cardiovascular estrogen receptors.

Lin

Shain

1985

Arteriosclerosis

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We used either the synthetic estrogen R2858 (moxestrol) or estradiol-17(3 to characterize estrogen receptors in cytoplasmic (R2858) and nuclear (estradiol-17B) preparations from rat aorta and myocardium. Relative steroid specificity studies showed that only estrogens were effective inhibitors of R2858 or estradiol-171) binding to aortic and myocardial estrogen receptors, whereas androgens, progestins, and cortisol were ineffective inhibitors. Low ionic strength sucrose density gradient analyses showed that myocardial estrogen receptors that localized in the cytoplasmic fraction migrated as macromolecules with sedimentation coefficients of 8S to 9S. In contrast, two binding components of sedimentation coefficients 8S to 9S and 10S to 11S were characteristic of the estrogen receptors localized in aortic cytoplasmic preparations. High ionic strength sucrose density gradient analysis showed that aortic and myocardial estrogen receptors localized in the nuclear fraction migrated as macromolecules with sedimentation coefficients of 4S to 6S. Saturation analyses showed that aortic and myocardial cytoplasmic preparations from intact young mature male rats contained 50.6 ± 12.9 (mean ± SD) and 51.0 ± 14.1 fmol receptor/mg DNA, respectively. The respective R2858 dissociation constants were 0.42 and 0.15 nM. Estrogen receptors could not be demonstrated in nuclear preparations from cardiovasculature of intact males. Estradiol-17(3 injection of intact young mature male rats caused "depletion" of aortic and myocardial cytoplasmic fraction estrogen receptors and resulted in the appearance of 51.9 ± 21.0 and 36.9 ± 9.5 fmol receptor/mg DNA in the corresponding nuclear fractions. The respective estradiol-17(3 dissociation constants were 1.56 and 0.71 nM. Increased estrogen receptor content of cardiovascular nuclear fractions of estradiol-17(3 injected male rats correlated well with the concomitant decreased cytoplasmic fraction receptor content. The ability of estradiol-17(3 to affect localization of cardiovascular estrogen receptors between cytoplasmic and nuclear fractions suggests these estrogen receptors are physiologically functional and indicates that estrogen may directly regulate cardiovascular cell function. (Arteriosclerosis 5:668-677, November/December 1985)T he higher incidence of coronary heart disease (CHD) in postmenopausal women as compared to premenopausal individuals 12 and in oral contraceptive users as compared to nonusers 23 and the decreased mortality of estrogen-only users as compared to nonusers 2 -"• 5 has suggested a possible Received December 17,1984; revision accepted July 10,1985. etiologic role for estrogens in CHD. This impression is supported by reports of higher plasma estrogen content in males who survived a myocardial infarction 6 " 11 or have documented coronary artery occlusion in the absence of an infarction. 8 ' 9 These clinical observations have led some investigators to conclude that hyperestrogenemia is an additional risk factor for CHD in males. 6810

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Section: Other Methodsmentioning

confidence: 99%

Estrogen-mediated cytoplasmic and nuclear distribution of rat cardiovascular estrogen receptors.

Lin

Shain

1985

Arteriosclerosis

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“…We have not yet further characterized this class of aortic R1881 binding sites; however, this binding component appears identical to the TA inhibitable R1881 binding sites that we have characterized in baboon myocardial cytosols. 28 Our current data for aortic cytosol are characteristic of R1881 binding to progesterone receptor-like components in extracts of tissues which contain both androgen receptors and progesterone receptor-like cytoplasmic binding components. (table 1 and figure 1), which shows that androgens are effective inhibitors, whereas progestins, estradiol-17/3, and cortisol are ineffective or only modestly effective inhibitors of R1881 binding; 2) sedimentation properties on linear sucrose density gradients (figure 3); 3) temperature instability; and 4) high-affinity limited-capacity binding.…”

Section: Discussionmentioning

confidence: 77%

“…28 Baboon aortic cytosols differed from baboon myocardial cytosols in that neither testosterone nor5a-dihydrotestosterone was metabolized during incubation at 2°C. These observations suggest that the differences in relative affinity of R1881, testosterone, and 5a-dihydrotestosterone for baboon aortic cytoplasmic androgen receptors probably reflect actual differences in binding properties.…”

Section: Discussionmentioning

confidence: 92%

“…The concentration of baboon aortic available cytoplasmic androgen receptors, 12.9 fmoles/mg protein, is comparable to that of rat myocardium'* 0 and striated muscle 41 " 44 and to that which we reported for baboon myocardium. 28 It should be noted that the number of sites quantitated may be a minimal estimate because neither the effects of oophorectomy nor the effect of freezing aortic tissue on detected androgen receptor content have been evaluated.…”

Section: Discussionmentioning

confidence: 99%

“…We employed isocratic chromatography on a C-18 reverse phase analytical column (ES Industries, Marlton, New Jersey) using methanol:water (55:45) as eluent to achieve separation of metabolites. 28 Radiolabeled testosterone or 5a-dihydrotestosterone (5a-DHT) was purified by chromatography using the chromatographic system employed for separation of metabolites.…”

Section: Purification Of Radlosterolds and Separation Of Steroid Metamentioning

confidence: 99%

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Hormone receptors of the baboon cardiovascular system. Biochemical characterization of aortic cytoplasmic androgen receptors.

Lin¹,

McGill²,

Shain³

1981

Arteriosclerosis

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Cytoplasmic androgen receptors were identified in the aorta of the baboon (Papio sp.)-Using the synthetic androgen R1881 (17/?-hydroxy-17a-methyl-estra-4,9,11-trien-3-one) as probe, androgen receptors were demonstrated only when the incubation mixtures contained 1.0 nM triamcinolone acetonide (TA). The relative binding affinity of selected steroids for the aortic androgen receptor was R1881, 100%; 5a-dihydrotestosterone, 46.1%; testosterone, 60.7%; progesterone, 9.1%; R5020, 3.1%; and estradlol-17/3, 7.5%. The androgen receptor migrated on low-ionic-strength linear sucrose density gradients as a macromolecule with a sedimentation coefficient of 8.0S. Saturation analysis performed at 2°C (available sites) showed that the androgen receptor content of baboon aortic cytoplasmic extracts was 12.9 ± 2.4 fmoles/mg protein and that the dissociation constant for R1881 was 1.47 ± 0.07 nM. The observation that TA was required in the cytoplasmic extracts in order to identify androgen receptor indicates the presence of progesterone receptor-like binding components. These aortic cytoplasmic androgen receptors are indicated to be physiologically functional by previous autoradiographic studies that showed localization of radioisotope in the nuclei of aortic smooth muscle cells following injection of baboons with 5a-dihydrotestosterone. (Arteriosclerosis 1981; 1:257-264) E strogens 1 " 5 and androgens 6 " 9 alter blood flow rates in accessory reproductive organs. Clinical observations and epidemiologic studies have repeatedly confirmed that women have lower rates of coronary heart disease (CHD) and less severe coronary atherosclerosis than do males of equivalent age. 10 These studies imply a possible role for sex steroid hormones as modulators of vascular tissue cell function.

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Heart contains receptors for dihydrotestosterone but not testosterone: Possible role in the sex differential in coronary heart disease

et al. 1989

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The sex differential in coronary heart disease is well documented but poorly understood. Previous studies have demonstrated receptors for dihydrotestosterone (DHT) in the myocardium and smooth muscle cells of arteries from a number of species. In this autoradiographic study, we further investigated and characterized the in vivo uptake and retention of the androgen binding in the male baboon. Adult castrated male baboons were injected with 1 micrograms/kg bw 3H-testosterone; 1 hr after the injection, the animals were rapidly exsanguinated while under anesthesia. The heart and arterial system were removed and processed for autoradiography. As a negative control, one animal received both 3H-testosterone and 100-fold unlabeled testosterone. For positive controls, the pituitary gland, prostate, seminal vesicles, and other tissues were also removed and processed for autoradiography. In contrast to our previous finding with 3H-DHT, no nuclear uptake and retention of 3H-steroid was found in any of the cells in either the heart or the arterial system. In the positive control tissues, pituitary gland, prostate, seminal vesicles, and others, a very distinct nuclear uptake and retention of 3H-steroid was observed, which was completely inhibited by the simultaneous injection of 100-fold unlabeled testosterone. In the binding study, Scatchard analysis of the cytosol prepared from a 17-year-old female baboon demonstrated levels of androgen receptor (as determined by the use of radiolabeled R1881) comparable to that found in young adults.(ABSTRACT TRUNCATED AT 250 WORDS)

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Hormone receptors of the baboon cardiovascular system. Biochemical characterization of myocardial cytoplasmic androgen receptors.

Cited by 29 publications

References 34 publications

Estrogen-mediated cytoplasmic and nuclear distribution of rat cardiovascular estrogen receptors.

Estrogen-mediated cytoplasmic and nuclear distribution of rat cardiovascular estrogen receptors.

Hormone receptors of the baboon cardiovascular system. Biochemical characterization of aortic cytoplasmic androgen receptors.

Heart contains receptors for dihydrotestosterone but not testosterone: Possible role in the sex differential in coronary heart disease

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