Somatopause, weaknesses of the therapeutic approaches and the cautious optimism based on experimental ageing studies with soy isoflavones

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Abstract

The pathological phenomenon of somatopause, noticeable in hypogonadal ageing subjects, is based on the growth hormone (GH) production and secretion decrease along with the fall in GH binding protein and insulin-like growth factor 1 (IGF-1) levels, causing different musculoskeletal, metabolic and mental issues. From the perspective of safety and efficacy, GH treatment is considered to be highly controversial, while some other therapeutic approaches (application of IGF-1, GH secretagogues, gonadal steroids, cholinesterase-inhibitors or various combinations) exhibit more or less pronounced weaknesses in this respect. Soy isoflavones, phytochemicals that have already demonstrated the health benefits in treated elderly, at least experimentally reveal their potential for the somatopausal symptoms remediation. Namely, genistein enhanced GHRH-stimulated cAMP accumulation and GH release in rat anterior pituitary cells; refreshed and stimulated the somatotropic system (hypothalamic nuclei and pituitary GH cells) function in a rat model of the mild andropause, and stimulated the GH output in ovariectomized ewes as well as the amplitude of GH pulses in the rams. Daidzein, on the other hand, increased body mass, trabecular bone mass and decreased bone turnover in the animal model of severe andropause, while both isoflavones demonstrated blood cholesterol-lowering effect in the same model. These data, which necessarily need to be preclinically and clinically filtered, hint some cautious optimism and call for further innovative designing of balanced soy isoflavone-based therapeutics.

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Most cited references 135

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Phyto-oestrogens and Western diseases.

H Adlercreutz, W Mazur (1997)

Incidences of breast, colorectal and prostate cancer are high in the Western world compared to countries in Asia. We have postulated that the Western diet compared to the semivegetarian diet in some Asian countries may alter hormone production, metabolism or action at the cellular level by some biochemical mechanisms. Our interest has been focused on two groups of hormone-like diphenolic phyto-oestrogens of dietary origin, the lignans and isoflavonoids abundant in plasma of subjects living in areas with low cancer incidence. The precursors of the biologically active compounds detected in man are found in soybean products, whole-grain cereal food, seeds, and berries. The plant lignan and isoflavonoid glycosides are converted by intestinal bacteria to hormone-like compounds. The weakly oestrogenic diphenols formed influence sex-hormone production, metabolism and biological activity, intracellular enzymes, protein synthesis, growth factor action, malignant cell proliferation, differentiation, cell adhesion and angiogenesis in such a way as to make them strong candidates for a role as natural cancer-protective compounds. Their effect on some of the most important steroid biosynthetic enzymes may result in beneficial modulation of hormone concentrations and action in the cells preventing development of cancer. Owing to their oestrogenic activity they reduce hot flushes and vaginal dryness in postmenopausal women and may to some degree inhibit osteoporosis, but alone they may be insufficient for complete protection. Soy intake prevents oxidation of the low-density lipoproteins in vitro when isolated from soy-treated individuals and affect favourably plasma lipid concentrations. Animal experiments provide evidence suggesting that both lignans and isoflavonoids may prevent the development of cancer as well as atherosclerosis. However, in some of these experiments it has not been possible to separate the phyto-oestrogen effect from the effect of other components in the food. The isoflavonoids and lignans may play a significant inhibitory role in cancer development particularly in the promotional phase of the disease, but recent evidence points also to a role in the initiation stage of carcinogenesis. At present, however, no definite recommendations can be made as to the dietary amounts needed for prevention of disease. This review deals with all the above-mentioned aspects of phyto-oestrogens.

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The insulin-like growth factor-binding protein (IGFBP) superfamily.

V Hwa, Y. Oh, R Rosenfeld (1999)

Over the last decade, the concept of an IGFBP family has been well accepted, based on structural similarities and on functional abilities to bind IGFs with high affinities. The existence of other potential IGFBPs was left open. The discovery of proteins with N-terminal domains bearing striking structural similarities to the N terminus of the IGFBPs, and with reduced, but demonstrable, affinity for IGFs, raised the question of whether these proteins were "new" IGFBPs (22, 23, 217). The N-terminal domain had been uniquely associated with the IGFBPs and has long been considered to be critical for IGF binding. No other function has been confirmed for this domain to date. Thus, the presence of this important IGFBP domain in the N terminus of other proteins must be considered significant. Although these other proteins appear capable of binding IGF, their relatively low affinity and the fact that their major biological actions are likely to not directly involve the IGF peptides suggest that they probably should not be classified within the IGFBP family as provisionally proposed (22, 23). The conservation of this single domain, so critical to high-affinity binding of IGF by the six IGFBPs, in all of the IGFBP-rPs, as well, speaks to its biological importance. Historically, and perhaps, functionally, this has led to the designation of an "IGFBP superfamily". The classification and nomenclature for the IGFBP superfamily, are, of course, arbitrary; what is ultimately relevant is the underlying biology, much of which still remains to be deciphered. The nomenclature for the IGFBP related proteins was derived from a consensus of researchers working in the IGFBP field (52). Obviously, a more general consensus on nomenclature, involving all groups working on each IGFBP-rP, has yet to be reached. Further understanding of the biological functions of each protein should help resolve the nomenclature dilemma. For the present, redesignating these proteins IGFBP-rPs simplifies the multiple names already associated with each IGFBP related protein, and reinforces the concept of a relationship with the IGFBPs. Beyond the N-terminal domain, there is a lack of structural similarity between the IGFBP-rPs and IGFBPs. The C-terminal domains do share similarities to other internal domains found in numerous other proteins. For example, the similarity of the IGFBP C terminus to the thyroglobulin type-I domain shows that the IGFBPs are also structurally related to numerous other proteins carrying the same domain (87). Interestingly, the functions of the different C-terminal domains in members of the IGFBP superfamily include interactions with the cell surface or ECM, suggesting that, even if they share little sequence similarities, the C-terminal domains may be functionally related. The evolutionary conservation of the N-terminal domain and functional studies support the notion that IGFBPs and IGFBP-rPs together form an IGFBP superfamily. A superfamily delineates between closely related (classified as a family) and distantly related proteins. The IGFBP superfamily is therefore composed of distantly related families. The modular nature of the constituents of the IGFBP superfamily, particularly their preservation of an highly conserved N-terminal domain, seems best explained by the process of exon shuffling of an ancestral gene encoding this domain. Over the course of evolution, some members evolved into high-affinity IGF binders and others into low-affinity IGF binders, thereby conferring on the IGFBP superfamily the ability to influence cell growth by both IGF-dependent and IGF-independent means (Fig. 10). A final word, from Stephen Jay Gould (218): "But classifications are not passive ordering devices in a world objectively divided into obvious categories. Taxonomies are human decisions imposed upon nature--theories about the causes of nature's order. The chronicle of historical changes in classification provides our finest insight into conceptual revolutions

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Estrogen and bone health in men and women.

Jane Cauley (2015)

Estrogen is the key regulator of bone metabolism in both men and women. Menopause and the accompanying loss of ovarian estrogens are associated with declines in bone mineral density (BMD): 10-year cumulative loss was 9.1% at the femoral neck and 10.6%, lumbar spine. Estradiol concentrations also predict fractures. Total estradiol levels, <5 pg/ml were associated with a 2.5-fold increase in hip and vertebral fractures in older women, an association that was independent of age and body weight. Similar associations were found in men. Despite the lower BMD and higher fracture risk in hypogonadal men, there is little association between circulating testosterone, fracture and bone loss. Nevertheless, the combination of any low sex steroid hormone and 25-hydroxyvitamin D was associated with an increased fracture risk. Menopausal hormone therapy has been shown to reduce hip and all fractures in the Women's Health Initiative with little difference between the estrogen-alone and the estrogen plus progestin trials. The risk reductions were attenuated in both trials post intervention; however, a significant hip fracture benefit persisted over 13 years for women assigned to the combination therapy. Clinical trials of testosterone replacement in older men give tantalizing but inconclusive results. The results suggest that testosterone treatment probably improves BMD, but the results are less conclusive in older versus younger men. The Testosterone Trial is designed to test the hypothesis that testosterone treatment of men with unequivocally low serum testosterone (<275 ng/dL) will increase volumetric BMD (vBMD) of the spine. Results of the Testosterone Trials are expected in 2015.

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Author and article information

Journal

Journal ID (nlm-ta): EXCLI J

Journal ID (iso-abbrev): EXCLI J

Journal ID (publisher-id): EXCLI J

Title: EXCLI Journal

Publisher: Leibniz Research Centre for Working Environment and Human Factors

ISSN (Electronic): 1611-2156

Publication date (Electronic): 21 March 2018

Publication date Collection: 2018

Volume: 17

Pages: 279-301

Affiliations

[1 ]Department of Cytology, Institute for Biological Research "Siniša Stankovic", University of Belgrade, Belgrade, Serbia

[2 ]Clinic for Endocrinology, Diabetes and Diseases of Metabolism, Clinical Center of Serbia, Faculty of Medicine, University of Belgrade, Belgrade, Serbia

Author notes

*To whom correspondence should be addressed: Svetlana Trifunovic, avlada@ 123456ibiss.bg.ac.rs

Article

Publisher ID: 2017-956 Publisher ID: Doc279

DOI: 10.17179/excli2017-956

PMC ID: 5938552

SO-VID: 041fb197-2b42-40d0-a5cd-831d66456278

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This is an Open Access article distributed under the terms of the Creative Commons Attribution Licence ( http://creativecommons.org/licenses/by/4.0/) You are free to copy, distribute and transmit the work, provided the original author and source are credited.

Somatopause, weaknesses of the therapeutic approaches and the cautious optimism based on experimental ageing studies with soy isoflavones

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Negative Pressure Wound Therapy

Most cited references 135

Phyto-oestrogens and Western diseases.

The insulin-like growth factor-binding protein (IGFBP) superfamily.

Estrogen and bone health in men and women.

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