Hormone pathways

Table 1-9-2 is a summary of the major components of water-soluble hormone pathways reviewed in this section. There are several different G proteins (GTP-binding) involved. Tfimeric G pro- teins include G, Gj, G, and in the photoreceptor pathway reviewed in Chapter 10, G (trans- ducin). Receptors that engage these aU have the 7-helix membrane-spanning structure. Receptor stimulation causes the Ga subunit to bind GTP and become active. The Ga subunit subsequently hydrolyzes the GTP to GDP, terminating the signal. The p21 G protein is monomeric. 

All the stimulating primer effects in mammals analyzed so far share a common hormonal pathway the first measurable event is stimulation of LH-releasing hormone (LHRH) release. This, in turn, stimulates LH levels and leads to increases of estrogens in females and testosterone in males. In females, changes in size and function of uterus and ovaries follow, while males respond... 

The physiological hormone for the RARs is all-frans-retinoic acid RA 221 and that for the RXRs is its geometric isomer, 9-czs-retinoic acid (9-czs-RA 222) [320]. However, these polyolefinic hormones are of only limited use in elucidating the precise biological roles of each receptor family. Synthetic ligands that specifically activate only the RXR or RAR hormonal pathway and which cannot be converted into forms that activate the other pathway would be of much greater use in this regard. 

FIGURE 29-1 Pathways of adrenal steroid biosynthesis. Cholesterol is the precursor for the three steroid hormone pathways. Note the similarity between the structures of the primary mineralocorticoid (aldosterone), the primary glucocorticoid (cortisol), and the sex hormones (testosterone, estradiol). See text for further discussion. 

Hormonal Pathways Regulating Intermale and Interfemale Aggression Neal G. Simon, Qianxing Mo, Shan Hu,... 

Hormone defects at key point in the hormonal pathways may give rise to a variety of syndromes in which there are increased or decreased mineralocorticoid, glucocorticoid and/or androgen-estrogen function. 

C. Guillemette, N. Ishibe, D.J. Hunter et al. (2003). Polymorphisms in steroid hormone pathway genes and mammographic density. Breast Cancer Res. Treat. 77, 27-36. 

Note-. Many factors regulate customization of life histories, including genetics, epigenetics and hormonal pathways. 

Silverman, A. J., Antunes, J. L., Abrams, G. M., Nilaver, G., Thau, R., Robinson, J. A., Ferin, M., and Krey, L. C., 1982, The luteinizing hormone-releasing hormone pathways in rhesus, Macaca mulatta and pigtailed, Maccaca nemestrina monkeys, J. Comp. Neurol., 211 309. 

Pugh TW, DeFreese DC, Gramling BA, Shima- 2130. saki CD, Jupe ER (2007) Age-specific association of steroid hormone pathway gene polymorphisms with breast cancer risk. Cancer 109 1940-1948 Davies E, Holloway CD, Ingram MC, Inglis GC, 2131. Friel EC, Morrison C, Anderson NH, Fraser R,... 

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