Effects of Testosterone on Renal Function in Salt-Loaded Rats

Cross-sex testosterone therapy modifies the renal morphology and function in female rats and might underlie increased systolic pressure

Testosterone esters are hormones commonly used for affirming gender identity in transmen. The present study evaluates the effect of testosterone on renal morphology and function in an animal model submitted to cross-sex hormone therapy used for transmen. Two-month-old Wistar rats were divided into three groups: male control (MC), female control (FC), and female on testosterone therapy (FTT). The FTT group received testosterone cypionate (3.0 mg/kg, i.m.), and the MC and MF groups received vehicle oil every 10 days for 4 months. Renal function and indirect systolic blood pressure (SBP) measurements were evaluated at 6 months of age. Plasma and urine concentrations of urea, creatinine, sodium, potassium, osmolality, and glomerular filtration rate (GFR) were measured. The kidneys were weighed, paraffin-embedded, and histological sections were prepared to evaluate the glomerular area. We verified that the FTT group, in comparison to FC, had increased kidney weight [MC, 3.2 ± 0.05; FC, 1.8 ± 0.04; FTT, 2.2 ± 0.06; g], decreased urine osmolarity [MC, 486.9 ± 18.3; FC, 1012.0 ± 5.4; FTT, 768.2 ± 40.3 mOsm/L/g kw], reduced GFR [MC, 0.77 ± 0.04; FC, 0.78 ± 0.02; FTT, 0.67 ± 0.03; mL/min/g kw], larger glomerular area [MC, 9334 ± 120.8; FC, 7884 ± 112.8; FTT, 9078 ± 133.4 µm² ], and higher SBP [MC, 126 ± 3.4; FC, 119 ± 1.0; FTT, 131 ± 1.4; mmHg]. Sodium excretion was higher in FC and FTT in comparison to MC [MC, 0.34 ± 0.05; FC, 0.56 ± 0.06; FTT, 0.54 ± 0.04; mEq/24 h/g kw]. Cross-sex hormone therapy with testosterone in female rats induces renal morphofunctional changes and may underlie increased systolic pressure, suggesting an adaptation similar to what is observed in transmen on long-term testosterone therapy.

Hyperandrogenemia and insulin resistance: The chief culprit of polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is one of the most common systemic reproductive endocrine diseases, which has a variety of effects on a woman's health. Because of the involvement of multiple pathways and the lack of common clues, PCOS demonstrates multifactorial properties and heterogeneity of symptoms. Recent studies have demonstrated that the core etiology and primary endocrine characteristics of PCOS are hyperandrogenemia (HA) and insulin resistance (IR). HA and IR are the main causes of PCOS and they can interplay each other in the occurrence and development of PCOS. Just because of this, the study about the effects of HA and IR on pathophysiology of various related symptoms of PCOS is very important to understand the pathogenesis of PCOS. This paper reviews the main symptoms of PCOS, including neuroendocrine disorders, reproductive processes, dyslipidemia, obesity, hypertension, nonalcoholic fatty liver disease (NAFLD), and sleep disordered breathing, which seriously affect the physical and mental health of PCOS women. The increasing knowledge of the development pattern of HA and IR in PCOS suggests that changes in diet and lifestyle, and the discovery of potential therapeutic agents may improve PCOS. However, further studies are needed to clarify the mutual influence and relation of HA and IR in development of PCOS. This review provides an overview of the current knowledge about the effects of HA and IR on PCOS.

Changes in plasma aldosterone and electrolytes levels, kidney epithelial sodium channel (ENaC) and blood pressure in normotensive WKY and hypertensive SHR rats following gonadectomy and chronic testosterone treatment

We hypothesized that testosterone-induced increase in blood pressure involve changes in aldosterone levels and expression of epithelial sodium channel (ENaC) in the kidneys.

METHODS

Ovariectomized female normotensive Wistar Kyoto (WKY) and Spontaneous hypertensive (SHR) rats were given six weeks treatment with testosterone via subcutaneous silastic implant. The rats were anesthetized and mean arterial pressure (MAP) was measured via direct cannulation of the carotid artery. Animals were sacrificed and kidneys were removed and subjected for α, β and γ-ENaC protein and mRNA expression analyses by Western blotting and Real-time polymerase chain reaction (qPCR), respectively. Distributions of α, β and γ-ENaC proteins in kidneys were observed by immunofluorescence. Plasma testosterone, aldosterone, electrolytes, osmolality, urea and creatinine levels were determined by biochemical assays. Analysis were also performed in non-testosterone treated orchidectomized and sham-operated male WKY and SHR rats.

RESULTS

Treatment of ovariectomized female WKY and SHR rats with testosterone causes increased in MAP but decreased in plasma aldosterone, sodium (Na⁺), osmolality and expression and distribution of α, β and γ-ENaC subunits in the kidneys. Orchidectomy decreased the MAP but increased plasma aldosterone, Na⁺, osmolality and α, β and γ-ENaC expression and distribution in the kidneys of male WKY and SHR rats.

CONCLUSIONS

Decreased in plasma aldosterone, Na⁺ and ENaC levels in kidneys under testosterone influence indicated that testosterone-induced increased in MAP were not due to increased plasma aldosterone and ENaC levels in kidneys, and thus the testosterone effect on MAP likely involve other mechanisms.

Selection of suitable endogenous reference genes for qPCR in kidney and hypothalamus of rats under testosterone influence

Real-time quantitative PCR (qPCR) is the most reliable and accurate technique for analyses of gene expression. Endogenous reference genes are being used to normalize qPCR data even though their expression may vary under different conditions and in different tissues. Nonetheless, verification of expression of reference genes in selected studied tissue is essential in order to accurately assess the level of expression of target genes of interest. Therefore, in this study, we attempted to examine six commonly used reference genes in order to identify the gene being expressed most constantly under the influence of testosterone in the kidneys and hypothalamus. The reference genes include glyceraldehyde-3-phosphate dehydrogenase (GAPDH), actin beta (ACTB), beta-2 microglobulin (B2m), hypoxanthine phosphoribosyltransferase 1 (HPRT), peptidylprolylisomerase A (Ppia) and hydroxymethylbilane synthase (Hmbs). The cycle threshold (Ct) value for each gene was determined and data obtained were analyzed using the software programs NormFinder, geNorm, BestKeeper, and rank aggregation. Results showed that Hmbs and Ppia genes were the most stably expressed in the hypothalamus. Meanwhile, in kidneys, Hmbs and GAPDH appeared to be the most constant genes. In conclusion, variations in expression levels of reference genes occur in kidneys and hypothalamus under similar conditions; thus, it is important to verify reference gene levels in these tissues prior to commencing any studies.

Myocardial infarction worsens glomerular injury and microalbuminuria in rats with pre-existing renal impairment accompanied by the activation of ER stress and inflammation

Deterioration of renal function occurs after chronic heart failure in approximately one-third of patients, particularly in those with pre-existing renal impairment such as diabetic nephropathy. Impaired renal function in these patients is always associated with a worse prognosis. However, the mechanisms underlying such deterioration of renal function are still largely unknown. In three separate protocols, we compared 1) sham operation (Ctr, n = 10) with surgically induced myocardial infarction (MI, n = 10); 2) unilateral nephrectomy (UNX, n = 10) with UNX + MI (n = 10); and 3) STZ-induced type 1 diabetes (DB, n = 10) with DB + MI (n = 10). The differences between combined injury models (UNX + MI, DB + MI) and simple MI were also examined. Renal remodeling, function, ER stress (CHOP and GRP78) and inflammation (infiltration of inflammatory cells, NF-κB p65) were evaluated 12 weeks after MI. In common SD rats, MI activated less glomerular ER stress and inflammation, resulting in a minor change of glomerular remodeling and microalbuminuria. However, MI significantly increased the glomerular expression of GRP78 and CHOP in UNX and DB rats. In addition, it also promoted the infiltration of CD4+ T cells, particularly inflammatory cytokine (IFN-γ, IL-17, IL-4)-producing CD4+ T cells, and the expression of NF-κB p65 in the glomeruli. By contrast, significant glomerular fibrosis, glomerulosclerosis, podocyte injury and microalbuminuria were found in rats with UNX + MI and DB + MI. MI significantly increased chronic glomerular injury and microalbuminuria at 12 weeks in rats with pre-existing renal impairment, i.e., UNX and DB, but not common SD rats. These changes were accompanied by increased glomerular ER stress and immune-associated inflammation.

Effects of nesiritide and predictors of urine output in acute decompensated heart failure: results from ASCEND-HF (acute study of clinical effectiveness of nesiritide and decompensated heart failure)

OBJECTIVES

This study sought to determine if nesiritide increases diuresis in congestive heart failure patients.

BACKGROUND

In the ASCEND-HF (Acute Study of Clinical Effectiveness of Nesiritide and Decompensated Heart Failure), 7,141 patients hospitalized with acute decompensated heart failure (ADHF) were randomized to receive nesiritide or placebo for 24 to 168 h, in addition to standard care. There were minimal effects of nesiritide on survival, future hospitalizations, and symptoms. However, whether or not nesiritide increases diuresis in ADHF patients is unknown.

METHODS

Urine output was measured in 5,864 subjects; of these, 5,320 received loop diuretics and had dose data recorded. Loop diuretics other than furosemide were converted to furosemide equivalent doses. A total of 4,881 patients had complete data. We used logistic regression models to identify the impact of nesiritide on urine output and the factors associated with high urine output.

RESULTS

Median (25th, 75th percentiles) 24-h urine output was 2,280 (1,550, 3,280) ml with nesiritide and 2,200 (1,550, 3,200) ml with placebo (p = NS). Loop diuretic dose (furosemide equivalent) was 80 (40, 140) mg with both nesiritide and placebo. Diuretic dose was a strong predictor of urine output. Other independent predictors included: male sex, greater body mass index, higher diastolic blood pressure, elevated jugular venous pressure, recent weight gain, and lower blood urea nitrogen. The addition of nesiritide did not change urine output. None of the interaction terms between nesiritide and predictors affected the urine output prediction.

CONCLUSIONS

Nesiritide did not increase urine output in patients with ADHF. Higher diuretic dose was a strong predictor of higher urine output, but neurohormonal activation (as evidenced by blood urea nitrogen concentration) and lower blood pressure limited diuresis.

Early life stress induces renal dysfunction in adult male rats but not female rats

Maternal separation (MatSep) is a model of behavioral stress during early life. We reported that MatSep exacerbates ANG II-induced hypertension in adult male rats. The aims of this study were to determine whether exposure to MatSep in female rats sensitizes blood pressure to ANG II infusion similar to male MatSep rats and to elucidate renal mechanisms involved in the response in MatSep rats. Wistar Kyoto (WKY) pups were exposed to MatSep 3 h/day from days 2 to 14, while control rats remained with their mothers. ANG II-induced mean arterial pressure (MAP; telemetry) was enhanced in female MatSep rats compared with control female rats but delayed compared with male MatSep rats. Creatinine clearance (Ccr) was reduced in male MatSep rats compared with control rats at baseline and after ANG II infusion. ANG II infusion significantly increased T cells in the renal cortex and greater histological damage in the interstitial arteries of male MatSep rats compared with control male rats. Plasma testosterone was greater and estradiol was lower in male MatSep rats compared with control rats with ANG II infusion. ANG II infusion failed to increase blood pressure in orchidectomized male MatSep and control rats. Female MatSep and control rats had similar Ccr, histological renal analysis, and sex hormones at baseline and after ANG II infusion. These data indicate that during ANG II-induced hypertension, MatSep sensitizes the renal phenotype in male but not female rats.