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      Combined Therapy with Estrogen and Testosterone Eliminates the Aggravating Effect of Estrogen Replacement Therapy on Glomerular Injury in Hypercholesterolemic Female Imai Rats

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          Hypercholesterolemic Imai rats spontaneously develop proteinuria and glomerulosclerosis, especially male animals. Ovariectomy aggravates glomerular injury in femal Imai rats. However, estrogen replacement therapy did not abolish this aggravating effect of ovariectomy and rather aggravated glomerular injury with an increase in serum levels of lipids and growth hormone (GH). Whereas we have already reported that treatment with testosterone in addition to estrogen reduces GH levels and attenuates glomerular injury as compared with estrogen alone in male Imai rats, in the present study, to investigate whether increased GH levels may contribute to an enhancing effect of estrogen on glomerular injury, we treated ovariectomized female Imai rats with estrogen puls testosterone. Group 1 was sham operated and group 2 was ovariectomized at 6 weeks of age. Groups 3, 4, and 5 were ovariectomized and received estrogen, testosterone, or estrogen plus testosterone, respectively. Body weight, urinary protein, and serum constituents were investigated every 4 weeks from 12 to 24 weeks of age. At 24 weeks of age, the rats were studied morphologically. Each treatment with estrogen or testosterone equally aggravated glomerular injury with an increase in both proteinuria and serum lipids with increased serum GH levels in estrogen–treated rats but without influencing GH levels in testosterone–treated rats; combined treatment with estrogen plus testosterone resulted in a reduction of both proteinuria and serum lipids to levels of the controls and attenuated glomerular injury to levels close to those of controls with a reduction of the elevated serum GH levels. These results suggest that increased GH levels may contribute to an enhancing effect of estrogen replacement therapy on glomerular injury and that testosterone, when administered to the estrogen–treated rats, seems to exert an attenuating effect on glomerular injury by suppressing GH levels.

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          Contrasting effects of testosterone and stanozolol on serum lipoprotein levels.

          Oral anabolic steroids produce striking reductions in serum concentrations of high-density lipoprotein (HDL) cholesterol. We hypothesized that this effect related to their route of administration and was unrelated to their androgenic potency. We administered oral stanozolol (6 mg/d) or supraphysiological doses of intramuscular testosterone enanthate (200 mg/wk) to 11 male weight lifters for six weeks in a crossover design. Stanozolol reduced HDL-cholesterol and the HDL2 subfraction by 33% and 71%, respectively. In contrast, testosterone decreased HDL-cholesterol concentration by only 9% and the decrease was in the HDL3 subfraction. Apolipoprotein A-I level decreased 40% during stanozolol but only 8% during testosterone treatment. The low-density lipoprotein cholesterol concentration increased 29% with stanozolol and decreased 16% with testosterone treatment. Stanozolol, moreover, increased postheparin hepatic triglyceride lipase activity by 123%, whereas the maximum change during testosterone therapy (+25%) was not significant. Weight gain was similar with both drugs, but testosterone was more effective in suppressing gonadotropic hormones. We conclude that the undesirable lipoprotein effects of 17-alpha-alkylated steroids given orally are different from those of parenteral testosterone and that the latter may be preferable in many clinical situations.
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            Estrogen accelerates the development of renal disease in female obese Zucker rats.

            Renal failure is the primary cause of death in obese Zucker rats (OZR). We previously found that renal injury occurred earlier and with greater severity in female OZR; also, prevention of hyperphagia decreased renal damage in females more than males. To examine the relationship between estrogen (E), hyperphagia, hyperlipidemia, and renal injury in female OZR, we studied four groups from 5 to 10 or 21 weeks of age: Sham-operated (Sham), ovariectomized (Ovx), Ovx with estrogen treatment (Ovx + E), and since Ovx increases food intake, Ovx pair-fed to sham (Ovx-PF). By only six weeks of age, albumin excretion (UAE) increased significantly in Ovx + E (9.9 +/- 4.1 mg/day). Ovx + E also ate least and gained the least weight, but had the highest plasma lipid levels. In contrast, UAE in Ovx did not increase by 10 weeks of age, despite a significantly greater food consumption. The hyperlipidemia of Ovx + E was due primarily to triglycerides. Both plasma triglycerides and renal injury, judged from either histology or UAE, were greatest in the Ovx + E group Fasting plasma glucose was lower and insulin was higher in Ovx + E compared to Ovx rats at 15 weeks of age. Estrogen may promote renal injury in female OZR by increasing the plasma concentration of triglyceride-rich lipoproteins.
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              Estrogen Replacement Therapy with Its Physiological Dose Does Not Eliminate the Aggravating Effect of Ovariectomy on Glomerular Injury in Hypercholesterolemic Female Imai Rats

              Hypercholesterolemic Imai rats spontaneously develop proteinuria and glomerulosclerosis, especially in males. Estrogen administration attenuated glomerular injury in male Imai rats, and the aggravating effect of ovariectomy in female rats is found. To clarify whether this aggravating effect of ovariectomy is due to a lack of estrogen, we administered estrogen to ovariectomized female Imai rats. At 6 weeks of age, group 1 (control) was sham-operated and group 2 was ovariectomized. Groups 3 and 4 were ovariectomized and received estrogen replacement therapy (0.1 mg in group 3 and 0.2 mg in group 4 once a month subcutaneously). Body weight, urinary protein and serum constituents were investigated every month from 3 to 6 months of age. At 6 months of age, rats were studied morphologically. Estrogen replacement therapy increased serum estrogen to levels close to those of controls when 0.1 mg was used, or higher when 0.2 mg was used. Estrogen replacement therapy with 0.1 mg did not eliminate the aggravating effect of ovariectomy on glomerular injury and rather aggravated it, but conversely therapy with 0.2 mg attenuated glomerular injury and abolished the aggravating effect of ovariectomy. Estrogen replacement therapy markedly elevated serum GH levels dose-dependently. These results suggested that other hormones as well as estrogen may play a protective role of the ovary for the development of glomerular injury, and that estrogen seems to exert a dual effect on glomerular injury.

                Author and article information

                Kidney Blood Press Res
                Kidney and Blood Pressure Research
                S. Karger AG
                15 October 1999
                : 23
                : 1
                : 27-34
                Department of Internal Medicine, Saga Medical School, Saga, Japan
                25951 Kidney Blood Press Res 2000;23:27–34
                © 1999 S. Karger AG, Basel

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                Page count
                Figures: 6, Tables: 2, References: 30, Pages: 8
                Self URI (application/pdf): https://www.karger.com/Article/Pdf/25951
                Original Paper


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