Search

In this review we described the interactions between ghrelin and the growth hormone (GH)-insulin-like growth factor 1 (IGF-1) axis in children and adults with growth hormone deficiency (GHD). A possible involvement of these interactions in the pathogenesis of unexplained cases of GHD was suggested. Current research provides more and more details to the knowledge on the circadian rhythm of ghrelin. We gathered reports on the decreasing effect of Helicobacter pylori -related chronic gastritis on the number of ghrelin immunopositive cells and the consequent decrease in ghrelin serum concentration. The gastrointestinal tract microflora modification of the ghrelin action, by the mechanism of molecular mimicry, was also stressed. Moreover, the mutual relationships between ghrelin and the TSH-FT4/FT3 axis in growth and metabolic processes are described. It is to be recalled that FT4 and FT3 exert a permissive impact on IGF-1 action and, in turn, GH, in reaction mediated by IGF-1, enhances the monodeiodination of FT4 to FT3. Finally, we discussed the latest attempts to use the GH secretagogue receptor (GHS-R) analogues for possible diagnostic and therapeutic purposes.

Objectives: Growth hormone (GH) and its tissue mediator, insulin-like growth factor-I (IGF-I), are involved in oxidative processes, lipid peroxidation (LPO) included. Bivalent iron (Fe2+) is frequently used to experimentally induce oxidative damage to macromolecules (Fe2++H2O2+H+→Fe3++•OH+H2O). The aim of the study was to evaluate the effect of GH and/or IGF-I on the iron-induced LPO in the rat liver and porcine thyroid homogenates., Methods: Rat liver and porcine thyroid homogenates were incubated in presence of GH (100; 10; 1.0; 0.1; 0.01; 0.001; 0.0001 µg/ml) or IGF-I (1000; 100; 10; 1.0; 0.1; 0.01; 0.001; 0.0001 µg/ml) or GH (100 µg/ml)+IGF-I, or FeSO4+H2O2 plus GH and/or IGF-I. The level of LPO was expressed as concentrations of malondialdehyde+4-hydroxyalkenals (MDA+4-HDA) per mg of protein., Results: GH and/or IGF-I did not change the basal level of oxidative damage to lipids. In the rat liver homogenates, GH did not affect the iron-induced LPO, whereas IGF-I--in the lowest two concentrations--enhanced the process. In porcine thyroid homogenates, GH--in its two lowest concentrations--prevented, whereas in other concentrations, it enhanced the iron-induced LPO. IGF-I, in all used concentrations, enhanced the iron-induced LPO., Conclusion: GH and/or IGF-I may reveal prooxidative effects. This fact does not support their application in the treatment of disorders associated with increased oxidative damage.

Under physiological conditions, there is a balance between the production and detoxification of reactive oxygen species (ROS). In the course of several diseases, an overproduction of ROS and their increased reaction with biological macromolecules, lead to disruption of this balance and to enhanced oxidative stress. Alterations in growth hormone (GH)/insulin-like growth factor I (IGF-I) pathway (e.g., in condition of GH overproduction or deficiency) are tightly linked with enhanced oxidative stress. The results of experimental and clinical studies, in which effects of GH and IGF-I on oxidative processes were revealed, are presented in the survey.

Iron overload may enhance oxidative damage. Growth hormone (GH) and insulin-like growth factor-I (IGF-I) are involved in oxidative processes, lipid peroxidation (LPO) included. The aim of the study was to evaluate the in vivo effects of GH, IGF-I and/or iron on LPO in rat tissues. Male Wistar rats were administered iron (Fe2+; 3mg/100g b.w., i.p., on the 8th day) and/or GH (0.2IU/100g b.w.), and/or IGF-I (2microg/100g b.w.) once daily for 8 days. LPO products (malondialdehyde+4-hydroxyalkenals) were measured in rat brain, lung, small intestine, liver, kidney, testis, spleen and serum. Iron injection increased LPO only in the small intestine and that effect was completely prevented by either GH or IGF-I. In the brain, GH decreased, whereas IGF-I increased, the basal LPO. GH and IGF-I possess some ability to prevent iron-induced oxidative damage in iron sensitive tissues, but contribute to oxidative imbalance in other tissues.