Project description:Beneficial effects of a soy diet on bone quality have been assumed to be due to the putative estrogenic actions of isoflavones. We studied the effects of soy protein isolate (SPI) on bone quality and compared these effects to 17Î²-estradiol (E2) in pre-pubertal rats. Female rats were weaned to a control diet with or without E2 (0.1, 1, 10 Âµg/kg/d), or SPI-containing diet with or without E2 (10 Âµg/kg/d) for 14 days beginning on postnatal day 20. In long bones from SPI-fed rats, only cancellous bone mineral density (BMD) was increased (p<0.05), while cortical BMD was decreased accompanied by lower bone strength compared to control casein-fed rats (p<0.05). In sharp contrast, 10 Âµg/kg/d E2 not only increased trabecular BMD, but also cortical BMD compared to controls. Rats treated with the combination of SPI and E2 had an intermediate bone effect. SPI increased while E2 decreased bone turnover, and increased trabecular BMD by both E2 and SPI was associated with decreased serum sclerostin levels. Microarray analysis revealed 652 genes regulated by SPI diet, 491 genes regulated by E2, and 266 genes regulated in common by both SPI diet and E2 compared to rats fed casein. The expression of caveolin-1, a protein localized in cell membrane, was down-regulated (p<0.05) in rats fed SPI, but not by E2 compared to rats fed casein. Down-regulated caveolin-1 by SPI was associated with increased BMP2, Smad and Runx2 expression in bone and osteoblasts (p<0.05). These results suggest SPI consumption results in significant non-classical estrogenic stimulation of cancellous bone formation prior to puberty, but may have adverse effects on overall bone quality and strength at this developmental stage as a result of reduced cortical bone formation. The study was designed to compare expression of bone development associated genes between soy protein isolate fed and estrogen treated pre pubertal female rats. Therefore, total RNA was isolated from bone from rats fed with control casein diet, SPI diet, 17 beta estrodial treated and SPI diet plus 17 beta estrodial.

Project description:A series of two color gene expression profiles obtained using Agilent 44K expression microarrays was used to examine sex-dependent and growth hormone-dependent differences in gene expression in rat liver. This series is comprised of pools of RNA prepared from untreated male and female rat liver, hypophysectomized (‘Hypox’) male and female rat liver, and from livers of Hypox male rats treated with either a single injection of growth hormone and then killed 30, 60, or 90 min later, or from livers of Hypox male rats treated with two growth hormone injections spaced 3 or 4 hr apart and killed 30 min after the second injection. The pools were paired to generate the following 6 direct microarray comparisons: 1) untreated male liver vs. untreated female liver; 2) Hypox male liver vs. untreated male liver; 3) Hypox female liver vs. untreated female liver; 4) Hypox male liver vs. Hypox female liver; 5) Hypox male liver + 1 growth hormone injection vs. Hypox male liver; and 6) Hypox male liver + 2 growth hormone injections vs. Hypox male liver. A comparison of untreated male liver and untreated female liver liver gene expression profiles showed that of the genes that showed significant expression differences in at least one of the 6 data sets, 25% were sex-specific. Moreover, sex specificity was lost for 88% of the male-specific genes and 94% of the female-specific genes following hypophysectomy. 25-31% of the sex-specific genes whose expression is altered by hypophysectomy responded to short-term growth hormone treatment in hypox male liver. 18-19% of the sex-specific genes whose expression decreased following hypophysectomy were up-regulated after either one or two growth hormone injections. Finally, growth hormone suppressed 24-36% of the sex-specific genes whose expression was up-regulated following hypophysectomy, indicating that growth hormone acts via both positive and negative regulatory mechanisms to establish and maintain the sex specificity of liver gene expression. For full details, see V. Wauthier and D.J. Waxman, Molecular Endocrinology (2008)

Project description:A series of two color gene expression profiles obtained using Agilent 44K expression microarrays was used to examine sex-dependent and growth hormone-dependent differences in gene expression in rat liver. This series is comprised of pools of RNA prepared from untreated male and female rat liver, hypophysectomized (‘Hypox’) male and female rat liver, and from livers of Hypox male rats treated with either a single injection of growth hormone and then killed 30, 60, or 90 min later, or from livers of Hypox male rats treated with two growth hormone injections spaced 3 or 4 hr apart and killed 30 min after the second injection. The pools were paired to generate the following 6 direct microarray comparisons: 1) untreated male liver vs. untreated female liver; 2) Hypox male liver vs. untreated male liver; 3) Hypox female liver vs. untreated female liver; 4) Hypox male liver vs. Hypox female liver; 5) Hypox male liver + 1 growth hormone injection vs. Hypox male liver; and 6) Hypox male liver + 2 growth hormone injections vs. Hypox male liver. A comparison of untreated male liver and untreated female liver liver gene expression profiles showed that of the genes that showed significant expression differences in at least one of the 6 data sets, 25% were sex-specific. Moreover, sex specificity was lost for 88% of the male-specific genes and 94% of the female-specific genes following hypophysectomy. 25-31% of the sex-specific genes whose expression is altered by hypophysectomy responded to short-term growth hormone treatment in hypox male liver. 18-19% of the sex-specific genes whose expression decreased following hypophysectomy were up-regulated after either one or two growth hormone injections. Finally, growth hormone suppressed 24-36% of the sex-specific genes whose expression was up-regulated following hypophysectomy, indicating that growth hormone acts via both positive and negative regulatory mechanisms to establish and maintain the sex specificity of liver gene expression. For full details, see V. Wauthier and D.J. Waxman, Molecular Endocrinology (2008) This series is comprised of pools of liver RNA prepared from untreated male, hypophysectomized (‘Hypox’) male, untreated female and Hypox female rats (3-4 livers/pool), as well as liver RNA prepared from Hypox male rats treated with a single growth hormone injection and killed either 30, 60, or 90 minutes later (pool of n = 4 livers) or from Hypox male rats treated with two growth hormone injections spaced 3 or 4 hr apart (pool of n = 5 livers). The pools were paired to generate the following 6 direct microarray comparisons: 1) untreated male liver vs. untreated female liver; 2) Hypox male liver vs. untreated male liver; 3) Hypox female liver vs. untreated female liver; 4) Hypox male liver vs. Hypox female liver; 5) Hypox male liver + 1 growth hormone injection vs. Hypox male liver; and 6) Hypox male liver + 2 growth hormone injections vs. Hypox male liver. Dye swapping experiments were carried out for each of the six hybridization experiments, as follows. The Alexa 555-labeled cDNA from one of the two untreated male pools was mixed with the Alexa 647-labeled cDNA from one of the two untreated female pools. Similarly, Alexa 647-labeled cDNA from the second untreated male pool was mixed with the Alexa 555-labeled cDNA from the second untreated female pool. Together, these two mixed cDNA samples comprise a fluorescent reverse pair (dye swap). Dye swaps were similarly carried out for each of the five other competitive hybridization experiments, except that for experiments 5 and 6, a single pool of M-Hypox + GH liver cDNA, or a single pool of M-Hypox + 2GH liver cDNA, was used in each half of the fluorescent reverse pair. Two microarrays, one for each mixed cDNA sample, were hybridized for each of the six fluorescent reverse pairs, giving a total of 12 microarrays.

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Rattus norvegicus

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