Synergism hormones

Crofton KM, Craft ES, Hedge JM, Gennings C, Simmons JE, Carchman RA, Carter WH Jr, DeVito MJ (2005) Thyroid-hormone-disrupting chemicals evidence for dose-dependent additivity or synergism. Environ Health Perspect 113 1549-1554... 

FIGURE 2.22 Rate of bicarbonate production with different hormonal stimulations. The numbers designate control subjects infused with saline (1) and experimental subjects infused with CCK only (2), secretin only (3), and both CCK and secretin (4). The results reveal that bicarbonate output was maximal with infusion of both hormones (4). The rate of bicarbonate release with both hormones (4) was greater than the sum of the rates released with each of the two hormones alone (2,3). This effect is called synergism, the cooperative effect of two or more stimuli. (Redrawn with permission from You et al, 1983.)... 

Sequential Interaction. Synergism between two hormones is sometimes more clearly observed in sequential treatments of the two hormones. Thus, GA pretreatment always results in synergistic enhancement of IAA-induced elongation of hypocotyl sections (37). Sequential interaction between BR and IAA is very similar to that between GA and IAA (3). Sections pretreated with BR for 2 h respond to IAA synergistically. The reverse order treatment is rather inhibitory as is the case for GA. Therefore, both BR and GA seem to sensitize hypocotyl sections to a later response by IAA. These facts suggest that cells which have already been initiated to elongation by IAA are not the target cells of BR/GA. 

Phosphofructokinase at any constant level of fructose-6-phosphate is inhibited by elevated ATP, which is further exacerbated by the presence of elevated citrate (Fig. 11.4). Citrate in the presence of noninhibitory levels of ATP will not in itself cause inhibition. The action in this case is one of synergism. Activators of PFK include 50 AMP and fructose-2,6-bisphosphate (which is under hormonal control see Chapter 13). 

BikDE (2002) Selenium-iodine synergism and thyroid hormone metabolism in sheep. Mengen- und Spurenelemente 21 444-448. 

VIII, 186, 187 effect on uterus, VIII, 227 synergism with estrogen, VIII, 186 hormones of, see also under names of individual hormones action of, VIII, 246-248... 

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