Hormones, effect

Hormonal effects on the aging process have been areas of current interest. The intricacies of the interaction of the various hormones are undoubtedly involved in the aging process and hence these hormones could be called antiaging agents. Both androgens and estrogens have been studied. Low level estrogen replacement therapy (ERT) has been used to treat postmenopausal women. 

In a 1996 review, the Committee of Toxicity of Chemicals in Food, Consumer Products and the Environment (COT) estimated the intake of isoflavones from soya-milk to be approximately 4 mg/kg/day over the first 4 months of life. This is greater than that associated with hormonal effects in premenopausal women, but the COT nonetheless supported the existing Department of Health s advice that... 

Figure 43-11. The hormone response transcription unit. The hormone response transcription unit is an assembly of DNA elements and bound proteins that interact, through protein-protein interactions, with a number of coactivator or corepressor molecules. An essential component is the hormone response element which binds the ligand (A)-bound receptor (R). Also Important are the accessory factor elements (AFEs) with bound transcription factors. More than two dozen of these accessory factors (AFs), which are often members of the nuclear receptor superfamily, have been linked to hormone effects on transcription. The AFs can interact with each other, with the liganded nuclear receptors, or with coregulators. These components communicate with the basal transcription complex through a coregulator complex that can consist of one or more members of the pi 60, corepressor, mediator-related, or CBP/p300 families (see Table 43-6).

The health effects of phytoestrogens fertility, development and hormonal effects... 

There is much interest in the possible hormonal effects of phytoestrogens in both men and women. The majority of studies conducted in women have examined the ability of phytoestrogens to alleviate menopausal symptoms. Whilst hormone replacement therapy is recommended for women experiencing menopausal symptoms, there remains some uncertainty as to whether HRT can increase the risk of breast cancer. As a result of these concerns, investigations into natural alternatives such as phytoestrogens have received considerable attention. 

DUNCAN A M, MERZ B E, XU X, NAGEL T C, PHIPPS W R, KURZER M S (1999a) Soy isoflaVOneS exert modest hormonal effects in premenopausal women. J Clin Endocrinol Metab. 84 192-7. 

Fig. 5.8(b) VN-x and releasing hormone effects on female receptive behaviour facilitation by LHRH and latency to tactile induction of lordosis in hamster (latency duration, sec.). LHRH restores responsiveness over saline control (from Mackay-Sim and Rose, 1986). 

JA Williamson, JR Monack. (1989). Hormone effects on cellular Ca2+ fluxes. Annu Rev Physiol 51 107-124. 

Sokol RZ. 1987. Hormonal effects of lead acetate in the male rat Mechanism of action. Biol Reprod 37 1135-1138. 

The acute CNS effects of MDMA administration are mediated by the release of monoamine transmitters, with the subsequent activation of presynaptic and postsynaptic receptor sites.40 As specific examples in rats, MDMA suppresses 5-HT cell firing, evokes neuroendocrine secretion, and stimulates locomotor activity. MDMA-induced suppression of 5-HT cell firing in the dorsal and median raphe involves activation of presynaptic 5-HT1A autoreceptors by endogenous 5-HT.4142 Neuroendocrine effects of MDMA include secretion of prolactin from the anterior pituitary and corticosterone from the adrenal glands 43 Evidence supports the notion that these MDMA-induced hormonal effects are mediated via postsynaptic 5-HT2 receptors in the hypothalamus, which are activated by released 5-HT. MDMA elicits a unique profile of locomotor effects characterized by forward locomotion and elements of the 5-HT behavioral syndrome such as flattened body posture, Straub tail, and forepaw treading.44 6 The complex motor effects of MDMA are dependent on monoamine release followed by activation of multiple postsynaptic 5-HT and DA receptor subtypes in the brain,47 but the precise role of specific receptor subtypes is still under investigation. 

Several criteria determine whether a steroid-hormone-binding site is a putative receptor. First, the steroid-hormone-binding site must be present in hormone-responsive tissues or brain regions, and absent from nonresponsive ones. Second, it should bind steroids that are either active agonists or effective antagonists of the hormone effect, and should not bind steroids that are inactive in either sense. 

In some situations, one might also envisage analyses of other combinations of specific tumors, such as tumors at related sites (e.g., endocrine organs if the compound had a hormonal effect) or of similar histological type. 

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