Estrogen Reduces 11β‐Hydroxysteroid Dehydrogenase Type 1 in Liver and Visceral,but Not Subcutaneous,Adipose Tissue in Rats

Following menopause, body fat is redistributed from peripheral to central depots. This may be linked to the age related decrease in estrogen levels. We hypothesized that estrogen supplementation could counteract this fat redistribution through tissue‐specific modulation of glucocorticoid exposure. We measured fat depot masses and the expression and activity of the glucocorticoid‐activating enzyme 11β‐hydroxysteroid dehydrogenase type 1 (11βHSD1) in fat and liver of ovariectomized female rats treated with or without 17β‐estradiol. 11βHSD1 converts inert cortisone, or 11‐dehydrocorticosterone in rats into active cortisol and corticosterone. Estradiol‐treated rats gained less weight and had significantly lower visceral adipose tissue weight than nontreated rats (P < 0.01); subcutaneous adipose weight was unaltered. In addition, 11βHSD1 activity/expression was downregulated in liver and visceral, but not subcutaneous, fat of estradiol‐treated rats (P < 0.001 for both). This downregulation altered the balance of 11βHSD1 expression and activity between adipose tissue depots, with higher levels in subcutaneous than visceral adipose tissue of estradiol‐treated animals (P < 0.05 for both), opposite the pattern in ovariectomized rats not treated with estradiol (P < 0.001 for mRNA expression). Thus, estrogen modulates fat distribution, at least in part, through effects on tissue‐specific glucocorticoid metabolism, suggesting that estrogen replacement therapy could influence obesity related morbidity in postmenopausal women.     

11beta-hydroxysteroid dehydrogenase type 1 in adipose tissue and prospective changes in body weight and insulin resistance

Objective: Increased mRNA and activity levels of 11β‐hydroxysteroid dehydrogenase type 1 (11βHSD1) in human adipose tissue (AT) are associated with obesity and insulin resistance. The aim of our study was to investigate whether 11βHSD1 expression or activity in abdominal subcutaneous AT of non‐diabetic subjects are associated with subsequent changes in body weight and insulin resistance [homeostasis model assessment of insulin resistance (HOMA‐IR)]. Research Methods and Procedures: Prospective analyses were performed in 20 subjects (two whites and 18 Pima Indians) who had baseline measurements of 11βHSD1 mRNA and activity in whole AT (follow‐up, 0.3 to 4.9 years) and in 47 Pima Indians who had baseline assessments of 11βHSD1 mRNA in isolated adipocytes (follow‐up, 0.8 to 5.3 years). Results: In whole AT, although 11βHSD1 mRNA levels showed positive associations with changes in weight and HOMA‐IR, 11βHSD1 activity was associated with changes in HOMA‐IR but not in body weight. 11βHSD1 mRNA levels in isolated adipocytes were not associated with follow‐up changes in any of the anthropometric or metabolic variables. Discussion: Our results indicate that increased expression of 11βHSD1 in subcutaneous abdominal AT may contribute to risk of worsening obesity and insulin resistance. This prospective relationship does not seem to be mediated by increased 11βHSD1 expression in adipocytes.     

Insulin Action on Expression of Novel Adipose Genes in Healthy and Type 2 Diabetic Subjects

Objective: Adipose tissue secretes several molecules that may participate in metabolic cross‐talk to other insulin‐sensitive tissues. Thus, adipose tissue is a key endocrine organ that regulates insulin sensitivity in other peripheral insulin target tissues. We have studied the expression and acute insulin regulation of novel genes expressed in adipose tissue that are implicated in the control of whole body insulin sensitivity. Research Methods and Procedures: Expression of adiponectin, c‐Cbl—associated protein (CAP), 11‐β hydroxysteroid dehydrogenase type 1 (11β‐HSD‐1), and sterol regulatory element binding protein (SREBP)‐1c was determined in subcutaneous adipose tissue from type 2 diabetic and age‐ and BMI‐matched healthy men by real‐time polymerase chain reaction analysis. Results: Expression of adiponectin, CAP, 11β‐HSD‐1, and SREBP‐1c was similar between healthy and type 2 diabetic subjects. Insulin infusion for 3 hours did not affect expression of CAP, 11β‐HSD‐1, or adiponectin mRNA in either group. However, insulin infusion increased SREBP‐1c expression by 80% in healthy, but not in type 2 diabetic, subjects. Discussion: Our results provide evidence that insulin action on SREBP‐1c is dysregulated in adipose tissue from type 2 diabetic subjects. Impaired insulin regulation on gene expression of select targets in adipose tissue may contribute to the pathogenesis of type 2 diabetes.     

Obesity Is Accompanied by Disturbances in Peripheral Glucocorticoid Metabolism and Changes in FA Recycling

The glucocorticoid activating enzyme 11β‐hydroxysteroid dehydrogenase type 1 (11βHSD1) is of major interest in obesity‐related morbidity. Alterations in tissue‐specific cortisol levels may influence lipogenetic and gluco/glyceroneogenetic pathways in fat and liver. We analyzed the expression and activity of 11βHSD1 as well as the expression of phosphoenolpyruvate carboxykinase (PEPCK), sterol regulatory element binding protein (SREBP), and fatty acid synthase (FAS) in adipose and liver and investigated putative associations between 11βHSD1 and energy metabolism genes. A total of 33 obese women (mean BMI 44.6) undergoing gastric bypass surgery were enrolled. Subcutaneous adipose tissue (SAT), omental fat (omental adipose tissue (OmAT)), and liver biopsies were collected during the surgery. 11βHSD1 gene expression was higher in SAT vs. OmAT (P = 0.013), whereas the activity was higher in OmAT (P = 0.009). The SAT 11βHSD1 correlated with waist circumference (P = 0.045) and was an independent predictor for the OmAT area in a linear regression model. Energy metabolism genes had AT depot–specific expression; higher leptin and SREBP in SAT than OmAT, but higher PEPCK in OmAT than SAT. The expression of 11βHSD1 correlated with PEPCK in both AT depots (P = 0.05 for SAT and P = 0.0001 for OmAT). Hepatic 11βHSD1 activity correlated negatively with abdominal adipose area (P = 0.002) and expression positively with PEPCK (P = 0.003). In human obesity, glucocorticoid regeneration in the SAT is associated with central fat accumulation indicating that the importance of this specific fat depot is underestimated. Central fat accumulation is negatively associated with hepatic 11βHSD1 activity. A disturbance in peripheral glucocorticoid metabolism is associated with changes in genes involved in fatty acid (FA) recycling in adipose tissue (AT).     

Deep subcutaneous adipose tissue: a distinct abdominal adipose depot

Objective: Abdominal visceral (VAT) and subcutaneous adipose tissue (SAT) display significant metabolic differences, with VAT showing a functional association to metabolic/cardiovascular disorders. A third abdominal adipose layer, derived by the division of SAT and identified as deep subcutaneous adipose tissue (dSAT), may play a significant and independent metabolic role. The aim of this study was to evaluate depot‐specific differences in the expression of proteins key to adipocyte metabolism in a lean population to establish a potential physiologic role for dSAT. Research Methods and Procedures: Adipocytes and preadipocytes were isolated from whole biopsies taken from superficial SAT (sSAT), dSAT, and VAT samples obtained from 10 healthy normal weight patients (7 women and 3 men), with a mean age of 56.4 ± 4.04 years and a mean BMI of 23.1 ± 0.5 kg/m². Samples were evaluated for depot‐specific differences in insulin sensitivity using adiponectin, glucose transport protein 4 (GLUT4), and resistin mRNA and protein expression, glucocorticoid metabolism by 11β‐hydroxysteroid dehydrogenase type‐1 (11β‐HSD1) expression, and alterations in the adipokines leptin and tumor necrosis factor‐α (TNF‐α). Results: Although no regional differences in expression were observed for adiponectin or TNF‐α, dSAT whole biopsies and adipocytes, while intermediary to both sSAT and VAT, reflected more of the VAT expression profile of 11β‐HSD1, leptin, and resistin. Only in the case of the intracellular pool of GLUT4 proteins in whole biopsies was an independent pattern of expression observed for dSAT. In an evaluation of the homeostatic model, dSAT 11β‐HSD1 protein (r = 0.9573, p = 0.0002) and TNF‐α mRNA (r = 0.8210, p = 0.0236) correlated positively to the homeostatic model. Discussion: Overall, dSAT seems to be a distinct abdominal adipose depot supporting an independent metabolic function that may have a potential role in the development of obesity‐associated complications.     

Regulation of UCP1, UCP2, and UCP3 mRNA expression in brown adipose tissue, white adipose tissue, and skeletal muscle in rats by estrogen

The effects of ovariectomy (OVX) and estrogen substitution on body weight, body composition, food intake, weight gain, and expression of uncoupling proteins (UCPs) in brown adipose tissue (BAT), white adipose tissue (WAT), and skeletal muscle were studied in four groups of rats: (1) Sham-operated rats (N = 8), (2) ovariectomized rats (OVX - E) (N = 8), (3) estrogen-treated OVX rats (OVX + E) (N = 8), and (4) OVX rats on energy restriction (OVX - E + D) (N = 8). OVX was associated with an increase in food intake and body weight gain during a 5-week study period compared to sham-operated rats. The estrogen-substituted rats had a significantly lower food intake and weight gain during the 5 weeks compared to the sham-operated group. However, we also included a nontreated OVX group that was allowed to eat only enough chow to match the weight gain of the sham-operated group. To match the weight gain in the two groups, the OVX group had to consume 16% less chow than the sham-operated group. In BAT, the UCP1 expression was significantly lower in estrogen-deficient rats compared to either intact rats or estrogen-substituted rats, whereas UCP2 and UCP3 mRNA expression was similar in BAT from all four groups. In WAT, both estrogen-deficient groups had significantly lower UCP2 mRNA expression compared to the control rats and estrogen-treated rats; In contrast, the UCP3 mRNA expression in WAT was similar in all four groups. Finally, in skeletal muscle the OVX group on mild energy restriction had reduced UCP3 mRNA expression compared to control, OVX, and estrogen-treated rats. In contrast, the UCP2 mRNA expression in skeletal muscle was similar in all four groups. Thus, the findings that estrogen deficiency is followed by reduced UCP1 expression in BAT and reduced UCP2 expression in WAT in association with weight gain probably caused by a decrease in energy expenditure might indicate that UCPs play a role for the estrogen-mediated changes in body weight and energy expenditure.     

Omental 11beta-hydroxysteroid dehydrogenase 1 correlates with fat cell size independently of obesity

Objectives: In ideopathic obesity, there is evidence that enhanced cortisol regeneration within abdominal subcutaneous adipose tissue may contribute to adiposity and metabolic disease. Whether the cortisol regenerating enzyme, 11β‐hydroxysteroid dehydrogenase type 1 (11βHSD1), or glucocorticoid receptor (GRα) levels are altered in other adipose depots remains uncertain. Our objective was to determine the association between 11βHSD1 and GRα mRNA levels in four distinct adipose depots and measures of obesity and the metabolic syndrome. Research Methods and Procedures: Adipose tissue biopsies were collected from subcutaneous (abdominal, thigh, gluteal) and intra‐abdominal (omental) adipose depots from 21 women. 11βHSD1 and GRα mRNA levels were measured by real‐time polymerase chain reaction. Body composition, fat distribution, fat cell size, and blood lipid, glucose, and insulin levels were measured. Results: 11βHSD1 mRNA was highest in abdominal subcutaneous (p < 0.001) and omental (p < 0.001) depots and was positively correlated with BMI and visceral adiposity in all depots. Omental 11βHSD1 correlated with percent body fat (R = 0.462, p < 0.05), fat cell size (R = 0.72, p < 0.001), and plasma triglycerides (R = 0.46, p < 0.05). Conversely, GRα mRNA was highest in omental fat (p < 0.001). GRα mRNA was negatively correlated with BMI in the abdominal subcutaneous (R = ?0.589, p < 0.05) and omental depots (R = ?0.627, p < 0.05). Omental GRα mRNA was inversely associated with visceral adiposity (R = ?0.507, p < 0.05), fat cell size (R = ?0.52, p < 0.01), and triglycerides (R = ?0.50, p < 0.05). Discussion: Obesity was associated with elevated 11βHSD1 mRNA in all adipose compartments. GRα mRNA is reduced in the omental depot with obesity. The novel correlation of 11βHSD1 with omental fat cell size, independent of obesity, suggests that intracellular cortisol regeneration is a strong predictor of hypertrophy in the omentum.     

Mechanisms of 17beta-estradiol on the production of ET-1 in ovariectomized rats

In order to clarify the mechanism underlying the possible preventive effect of estrogen on atherogenesis, we investigated the role of 17beta-estradiol (E2) in the regulation of endothelin-1 (ET-1) production in ovariectomized rats, which may contribute to atherogenesis. Female Spragure-Dawly rats were randomly divided into three groups: sham-operated group (sham), ovariectomized group (OVX) and 17beta-estradiol replacement group (OVX + E2, 20 microg(-1).kg.d(-1),s.c.). 4 weeks after operation, the plasma concentration of ET-1, clearance of ET-1, functional ECE activity and preproET-1 mRNA expression in aorta were measured. Concentration of plasma ET-1 change from 107.8 +/- 18.3 pg/ml (sham) and 135.5 +/- 27.6 pg/ml (OVX + E2) to 190.7 +/- 25.5 pg/ml (OVX ) (n = 8, p < 0.05). There was no significant difference in the clearance of 125IET-1 among three groups (p > 0.05). Functional ECE activity was increased in OVX group in comparison to that in sham group (p < 0.05). The OVX increased the preproET-1 mRNA expression in sham, whereas treatment with estrogen reversed these changes (p < 0.05). The present study have shown that estrogen down-regulates plasma ET-1 levels by inhibiting the preproET-1 mRNA expression and functional ECE activity. Clearance of ET-1 was not affected. Inhibition of ET-1 production mediated by modulating ECE activity may be one of the novel mechanisms of the protective of estrogens on the cardiovascular system.     

17beta-estradiol deficiency reduces potassium excretion in an angiotensin type 1 receptor-dependent manner

This study examined the effects of ovariectomy (OVX) and 17beta-estradiol (E(2)) replacement (OVX + E(2)) on renal function in Sprague-Dawley rats. OVX caused a 40% decrease in the fractional excretion of potassium (FE(K(+))) that was prevented by E(2) replacement [Sham, 24.2 +/- 2.9%; OVX, 14.5 +/- 2.1% (P < 0.05 vs. OVX + E(2)); and OVX + E(2), 26.2 +/- 2.7%; n = 7-11] and that corresponded to significant increases in plasma potassium [(in mmol/l): Sham, 3.15 +/- 0.087; OVX, 3.42 +/- 0.048 (P < 0.05 vs. OVX + E(2)); and OVX + E(2), 3.19 +/- 0.11; n = 7-11]. No effects of OVX were detected on plasma levels of sodium and aldosterone. Angiotensin II type 1 receptor (AT(1)R) densities in ovariectomized rats were 1.4-fold and 1.3-fold higher in glomerular [maximum binding capacity (B(max); in fmol/mg protein): Sham, 482 +/- 21; OVX, 666 +/- 20 (P < 0.05 vs. OVX + E(2)); and OVX + E(2), 504 +/- 26; n = 7-11] and proximal tubular [B(max) (in fmol/mg protein): Sham, 721 +/- 16; OVX, 741 +/- 24 (P < 0.05 vs. OVX + E(2)); and OVX + E(2), 569 +/- 23; n = 7-11] membranes compared with E(2) replete animals, respectively. Both the angiotensin-converting enzyme inhibitor captopril and the AT(1)R antagonist losartan prevented the OVX-induced decrease in the FE(K(+)) and the increase in renal AT(1)R densities, suggesting that E(2) deficiency reduces potassium excretion in an ANG II/AT(1)R-dependent manner. These findings may have implications for renal function in postmenopausal women as well as contribute to the reasons underlying the age-induced increase in susceptibility to hypertension-associated disease in women.     

17β-Estradiol and Vitamin E Modulates Oxidative Stress-Induced Kidney Toxicity in Diabetic Ovariectomized Rat

The aim of this study was to investigate the effects of vitamin E (alpha-tocopherol) and 17β-estradiol (E(2)) supplementation on malondialdehyde (MDA), glutathione (GSH), vitamin A, beta carotene, selenium-dependent glutathione peroxidase (GSH-Px), zinc-dependent superoxide dismutase (SOD), and copper/zinc-dependent catalase (CAT) values in the kidney of ovariectomized (OVX) diabetic rats. Forty-two female rats were randomly divided into seven equal groups as follows: group I, control; group II, OVX; group III, OVX+E(2); group IV, OVX+E(2)+alpha-tocopherol; group V, OVX+diabetic; group VI, OVX+diabetic+E(2); and group VII, OVX+diabetic+E(2)+alpha-tocopherol. E(2) (40?μg?kg(-1)/day) and alpha-tocopherol (100?μg?kg(-1)/day) were given. Bilateral ovariectomy was performed in all groups except group I. After 4?weeks, antioxidant and MDA levels in the kidney for all groups were analyzed. GSH-Px, CAT, SOD, GSH levels, vitamin A, and beta carotene levels were decreased in OVX group compared to those in the control group but MDA level was elevated via ovariectomy. However, E(2) and E(2)+alpha-tocopherol supplementations in OVX group was associated with an increase in the GSH-Px, GSH, CAT and Zn-SOD values, vitamin A, and beta carotene levels but a decrease in MDA levels in kidney. The MDA levels in the kidney of diabetic OVX rats were found higher than those in the control and OVX groups. However, GSH, GSH-Px, CAT, SOD, vitamin A, and beta carotene levels in kidney were lower in OVX diabetic rats. On the other hand, E(2) and E(2)+alpha-tocopherol supplementations to OVX diabetic rats have caused an increase in GSH-Px, CAT and SOD, GSH, vitamin A, and beta carotene levels but a decrease in MDA levels. In conclusion, the E(2) and E(2)+alpha-tocopherol supplementations to diabetic OVX and OVX rats may strengthen the antioxidant defense system by reducing lipid peroxidation, and therefore they may play a role in preventing renal disorders.     

Selection and optimization of MCF‐7 cell line for screening selective inhibitors of 11β‐hydroxysteroid dehydrogenase 2

An 11β‐hydroxysteroid dehydrogenase type 1 (11β‐HSD1) produces glucocorticoid (GC) from 11‐keto metabolite, and its modulation has been suggested as a novel approach to treat metabolic diseases. In contrast, type 2 isozyme 11β‐HSD2 is involved in the inactivation of glucocorticoids (GCs), protecting the non‐selective mineralocorticoid receptor (MR) from GCs in kidney. Therefore, when 11β‐HSD1 inhibitors are pursued to treat the metabolic syndrome, preferential selectivity of inhibitors for type 1 over type 2 isozyme is rather important than inhibitory potency. Primarily, to search for cell lines with 11β‐HSD2 activity, we investigated the expression profiles of enzymes or receptors relevant to GC metabolism in breast, colon, and bone‐derived cell lines. We demonstrated that MCF‐7 cells had high expression for 11β‐HSD2, but not for 11β‐HSD1 with its cognate receptor. Next, for the determination of enzyme activity indirectly, we adopted homogeneous time resolved fluorescence (HTRF) cortisol assay. Obviously, the feasibility of HTRF to cellular 11β‐HSD2 was corroborated by constructing inhibitory response to an 11b‐HSD2 inhibitor glycyrrhetinic acid (GA). Taken together, MCF‐7 that overexpresses type 2 but not type 1 enzyme is chosen for cellular 11β‐HSD2 assay, and our results show that a nonradioactive HTRF assay is applicable for type 2 as well as type 1 isozyme. Copyright © 2010 John Wiley & Sons, Ltd.     

Molecular Screening of the 11β‐HSD1 Gene in Men Characterized by the Metabolic Syndrome

Adipose tissue type 1 11β‐hydroxysteroid dehydrogenase (11β‐HSD1), which generates hormonally active cortisol from inactive cortisone, has been shown to play a central role in adipocyte differentiation and abdominal obesity‐related metabolic complications. The objective was to investigate whether genetic variations in the human 11β‐HSD1 gene are associated with the metabolic syndrome among French‐Canadian men. We sequenced all exons, the exon‐intron splicing boundaries, and 5′ and 3′ regions of the human 11β‐HSD1 gene in 36 men with the metabolic syndrome, as defined by the National Cholesterol Education Program‐Adult Treatment Panel III, and two controls. Three intronic sequence variants were identified: two single‐nucleotide polymorphisms in intron 3 (g.4478T>G) and intron 4 (g.10733G>C) and one insertion in intron 3 (g.4437‐4438insA). The relative allele frequency was 19.6%, 22.1%, and 19.6% for the g.4478G, g.10733C, and g.4438insA alleles, respectively. One single‐nucleotide polymorphism was identified in exon 6 (c.744G>C or G248G). The frequency of the c.744C allele was only 0.46% in a sample of 217 men. Variants were not associated with components of the metabolic syndrome except for plasma apolipoprotein B levels. In conclusion, molecular screening of the 11β‐HSD1 gene did not reveal any sequence variations that can significantly contribute to the etiology of the metabolic syndrome among French‐Canadians.     

Cellular and genetic models of H6PDH and 11β‐HSD1 function in skeletal muscle

Glucocorticoids are important for skeletal muscle energy metabolism, regulating glucose utilization, insulin sensitivity, and muscle mass. Nicotinamide adenine dinucleotide phosphate‐dependent 11β‐hydroxysteroid dehydrogenase type 1 (11β‐HSD1)‐mediated glucocorticoid activation in the sarcoplasmic reticulum (SR) is integral to mediating the detrimental effects of glucocorticoid excess in muscle. 11β‐Hydroxysteroid dehydrogenase type 1 activity requires glucose‐6‐phosphate transporter (G6PT)‐mediated G6P transport into the SR for its metabolism by hexose‐6‐phosphate dehydrogenase (H6PDH) for NADPH generation. Here, we examine the G6PT/H6PDH/11β‐HSD1 triad in differentiating myotubes and explore the consequences of muscle‐specific knockout of 11β‐HSD1 and H6PDH. 11β‐Hydroxysteroid dehydrogenase type 1 expression and activity increase with myotube differentiation and in response to glucocorticoids. Hexose‐6‐phosphate dehydrogenase shows some elevation in expression with differentiation and in response to glucocorticoid, while G6PT appears largely unresponsive to these particular conditions. When examining 11β‐HSD1 muscle‐knockout mice, we were unable to detect significant decrements in activity, despite using a well‐validated muscle‐specific Cre transgene and confirming high‐level recombination of the floxed HSD11B1 allele. We propose that the level of recombination at the HSD11B1 locus may be insufficient to negate basal 11β‐HSD1 activity for a protein with a long half‐life. Hexose‐6‐phosphate dehydrogenase was undetectable in H6PDH muscle‐knockout mice, which display the myopathic phenotype seen in global KO mice, validating the importance of SR NADPH generation. We envisage these data and models finding utility when investigating the muscle‐specific functions of the 11β‐HSD1/G6PT/H6PDH triad.     

Cortisone induces insulin resistance in C2C12 myotubes through activation of 11beta‐hydroxysteroid dehydrogenase 1 and autocrinal regulation

The enzyme 11β‐hydroxysteroid dehydrogenase 1 (11β‐HSD1) is known to catalyse inactive glucocorticoids into active forms, and its dysregulation in adipose and muscle tissues has been implicated in the development of metabolic syndrome. To delineate the molecular mechanism by which active cortisol has an antagonizing effect against insulin, we optimized the metabolic production of cortisol and its biological functions in myotubes (C2C12). Myotubes supplemented with cortisone actively catalysed its conversion into cortisol, which in turn abolished phosphorylation of Akt in response to insulin treatment. This led to diminished uptake of insulin‐induced glucose. This was corroborated by the application of 11β‐HSD1 inhibitor glycyrrhetinic acid and a glucocorticoid receptor antagonist RU‐486, which reversed completely the antagonizing effects of cortisol on insulin action. Therefore, development of specific inhibitors targeting 11β‐HSD1 might be a promising way to improve impaired insulin‐stimulated glucose uptake. Copyright © 2013 John Wiley & Sons, Ltd.     

Regulation of components of the brain and cardiac renin-angiotensin systems by 17beta-estradiol after myocardial infarction in female rats

The present study tested the hypothesis that 17beta-estradiol (E2) inhibits increases in angiotensin-converting enzyme (ACE) and ANG II type 1 receptor (AT1R) in the brain and heart after myocardial infarction (MI) and, thereby, inhibits development of left ventricular (LV) dysfunction after MI. Age-matched female Wistar rats were treated as follows: 1) no surgery (ovary intact), 2) ovariectomy + subcutaneous vehicle treatment (OVX + Veh), or 3) OVX + subcutaneous administration of a high dose of E2 (OVX + high-E2). After 2 wk, rats were randomly assigned to coronary artery ligation (MI) and sham operation groups and studied after 3 wk. E2 status did not affect LV function in sham rats. At 2-3 wk after MI, impairment of LV function was similar across MI groups, as measured by echocardiography and direct LV catheterization. LV ACE mRNA abundance and activity were increased severalfold in all MI groups compared with respective sham animals and to similar levels across MI groups. In most brain nuclei, ACE and AT1R densities increased after MI. Unexpectedly, compared with the respective sham groups the relative increase was clearest (20-40%) in OVX + high-E2 MI rats, somewhat less (10-15%) in ovary-intact MI rats, and least (< 10-15%) in OVX + Veh MI rats. However, because in the sham group brain ACE and AT1R densities increased in the OVX + Veh rats and decreased in the OVX + high-E2 rats compared with the ovary-intact rats, actual ACE and AT1R densities in most brain nuclei were modestly higher (< 20%) in OVX + Veh MI rats than in the other two MI groups. Thus E2 does not inhibit upregulation of ACE in the LV after MI and amplifies the percent increases in ACE and AT1R densities in brain nuclei after MI, despite E2-induced downregulation in sham rats. Consistent with these minor variations in the tissue renin-angiotensin system, during the initial post-MI phase, E2 appears not to enhance or hinder the development of LV dysfunction.