Hormonal hypothesis

On a larger taxonomic scale, the opposite pheromone-to-hormone hypothesis (Haldane, 1955) suggested that the interindividual pheromones of unicellular organisms such as protozoans enabled metazoan development and led to internal chemical communication in and between tissues by hormones in multicellular organisms. 

Ekins R. The free hormone hypothesis and measurement of free hormones. Clin Chem 1992 38 1289-93. 

W.M. Pardridge and E.M. Landow, Tracer kinetic model of blood brain barrier transport of plasma protein-bound ligands. Empiric testing of the free hormone hypothesis, J Clin Invest 7A 7A5-752 (198A). 

Considerable controversy currently centers on the free hormone hypothesis of thyroid and steroid hormone delivery. This postulates that hormonal effects are governed by free hormone concentrations as measured in vitro. Meanwhile the physiological role of the specific hormone binding proteins present in serum (such as thyroxine binding globulin [TBG]) remains unknown. 

By the time the paper was published, Lim was in China preparing to demonstrate that stimulation and inhibition of gastric secretion are mediated by blood-borne hormones, and Ivy alone must be held responsible for the fact that it was not until 13 years later that he realized that these experiments demonstrated hormonal stimulation of acid secretion. Instead, when he wrote the paper published in 1925, Ivy believed he had disproved the hormone hypothesis, and he felt driven to consider the vascular mechanism as the more profitable working hypothesis. Ivy feebly pulled together the evidence that all stimuli he and Lim had used increase blood flow through the mucosa, and he proposed that an increase in blood flow, in addition to some local nervous mechanism, stimulates secretion. Ivy wrote ... 

For a large number of dmgs, including neurotransmitters, peptide and protein hormones (qv), and thein analogues and antagonists, the ceU membrane is the principal locus of action. Concepts of ceU membrane stmcture are derived from the original Davson-DanieUi Hpid bilayer hypothesis. 

Rheumatoid arthritis (RA) is a chronic inflammatory disease of unknown aetiology with some autoimmune features. Current thinking favours the hypothesis that interplay between genetic factors, sex hormones, and possibly an infectious agent or another immune activating agent initiates an autoimmune pathogenic mechanism that culminates in a disease with inflammatory and destructive features. 

Nandi, S. Guzman, R. C. Yang, J. Hormones and mammary carcinogenesis in mice, rats, and humans a unifying hypothesis. Proc. Natl. Acad. Sci. USA 1995, 92, 3650-3657. 

SaOS-2 osteoblasts (Kim et al., 2003). Such an effect was shown to be dependent on the stage of cell differentiation. The mechanism of the differentiating activity of lycopene is still unclear. One of the most reliable hypothesis is that the carotenoid may activate the expression of nuclear hormone receptors, such as RAR and RXR (Sharoni et al., 2002). 

The hypothesis that hormones act through cell receptors is as old as the concept of the hormone. Nevertheless, and as usually occurs in science, hormone receptors were only discovered when the required technology became available. 

Pasqualini JR, Chetrite G, Nguyen BL, Maoloche C, Delalonde M, Talbi M, Feinstein MC, Blacker C, Botella J and Paris J (1995) Estrone sulfate-sulfatase and 17/3-hidroxis teroid dehydrogenase activities a hypothesis for their role in the evolution of human breast cancer from hormone-dependence to hormone-independence. J Steroid Biochem Mol Biol 53 407... 

Rodan GA, Martin TJ (1981) Role of osteoblast in hormonal control of bone resorption - a hypothesis. Calcif Tissue Int 33 349-351... 

Based on this concept of correlation between high replication rate/high persistent mutation risk, Pike et al. (1983) formulated the hypothesis of breast tissue age and developed a mathematical model to predict the effects of exposure to ovarian hormones. This model incorporates reproductive and endocrine items related to breast cancer and is able to predict the relative risk of individual situations with results that are very close to those observed in clinical trials. According to this hypothesis, both the years of exposure and the circulating serum levels of estrogens are associated to short-term breast cancer risk in postmenopausal women (Toniolo et al. 1995). 

We have tested the hypothesis that insulin inhibits the stimulatory effect of parathyroid hormone (PTH) on calcium reabsorption in the distal nephron. PTH is known to enhance calcium transport in renal cells, probably by stimulation of adenylate cyclase and subsequent increases in 3 5 cyclic AMP productoin. Since insulin had been observed to inhibit PTH-stimulated increases in kidney cyclic AMP levels in vitro (24) we investigated whether insulin-mediated hypercalciuria was dependent on the presence of PTH in vivo. 

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