Plasma oestrone-fatty acid ester levels are correlated with body fat mass in humans

Estrogens and the regulation of glucose metabolism

The main estrogens: estradiol, estrone, and their acyl-esters have been studied essentially related to their classical estrogenic and pharmacologic functions. However, their main effect in the body is probably the sustained control of core energy metabolism. Estrogen nuclear and membrane receptors show an extraordinary flexibility in the modulation of metabolic responses, and largely explain gender and age differences in energy metabolism: part of these mechanisms is already sufficiently known to justify both. With regard to energy, the estrogen molecular species act essentially through four key functions: (1) Facilitation of insulin secretion and control of glucose availability; (2) Modulation of energy partition, favoring the use of lipid as the main energy substrate when more available than carbohydrates; (3) Functional protection through antioxidant mechanisms; and (4) Central effects (largely through neural modulation) on whole body energy management. Analyzing the different actions of estrone, estradiol and their acyl esters, a tentative classification based on structure/effects has been postulated. Either separately or as a group, estrogens provide a comprehensive explanation that not all their quite diverse actions are related solely to specific molecules. As a group, they constitute a powerful synergic action complex. In consequence, estrogens may be considered wardens of energy homeostasis.

Prenatal stress-immune programming of sex differences in comorbidity of depression and obesity/metabolic syndrome

Major depressive disorder (MDD) is the number one cause of disability worldwide and is comorbid with many chronic diseases, including obesity/metabolic syndrome (MetS). Women have twice as much risk for MDD and comorbidity with obesity/MetS as men, although pathways for understanding this association remain unclear. On the basis of clinical and preclinical studies, we argue that prenatal maternal stress (ie, excess glucocorticoid expression and associated immune responses) that occurs during the sexual differentiation of the fetal brain has sex-dependent effects on brain development within highly sexually dimorphic regions that regulate mood, stress, metabolic function, the autonomic nervous system, and the vasculature. Furthermore, these effects have lifelong consequences for shared sex-dependent risk of MDD and obesity/MetS. Thus, we propose that there are shared biologic substrates at the anatomical, molecular, and/or genetic levels that produce the comorbid risk for MDD-MetS through sex-dependent fetal origins.

Gut-Brain Endocrine Axes in Weight Regulation and Obesity Pharmacotherapy

In recent years, the obesity epidemic has developed into a major health crisis both in the United States as well as throughout the developed world. With current treatments limited to expensive, high-risk surgery and minimally efficacious pharmacotherapy, new therapeutic options are urgently needed to combat this alarming trend. This review focuses on the endogenous gut-brain signaling axes that regulate appetite under physiological conditions, and discusses their clinical relevance by summarizing the clinical and preclinical studies that have investigated manipulation of these pathways to treat obesity.

Regulation of appetite to treat obesity

Obesity has escalated into a pandemic over the past few decades. In turn, research efforts have sought to elucidate the molecular mechanisms underlying the regulation of energy balance. A host of endogenous mediators regulate appetite and metabolism, and thereby control both short- and long-term energy balance. These mediators, which include gut, pancreatic and adipose neuropeptides, have been targeted in the development of anti-obesity pharmacotherapy, with the goal of amplifying anorexigenic and lipolytic signaling or blocking orexigenic and lipogenic signaling. This article presents the efficacy and safety of these anti-obesity drugs.

Are there endogenous estrone fatty acyl esters in human plasma or ovarian follicular fluid?

BACKGROUND

Estrone and its sulfated esters are the most abundant estrogens in blood in men and in women after the menopause. However, previous studies on the esterification of estrone with fatty acids have yielded conflicting results, some studies reporting high nanomolar concentrations of estrone fatty acyl esters in plasma.

METHODS

We developed an estrone radioimmunoassay (RIA) method to determine endogenous concentrations of estrone and after saponification, applied it to male and female plasma. In addition, the concentration of estrone fatty acyl esters in ovarian follicular fluid was analyzed by gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-tandem mass spectrometry (LC-MS/MS).

RESULTS

By estrone RIA, we did not find measurable amounts of estrone fatty acyl esters in male or female plasma, except for one premenopausal woman who had the highest plasma concentration of nonesterified estrone. The concentration of hydrolyzed estrone fatty acyl esters determined by LC-MS/MS in follicular fluid obtained from women undergoing ovarian stimulation was below the limit of quantification of <10 pmol/l (<2.7 ng/l).

CONCLUSIONS

In contrast to previous data by others, our study suggests that estrone fatty acyl esters are in most cases not detectable in plasma of healthy men or healthy nonpregnant women.

Oleoyl-estrone is a precursor of an estrone-derived ponderostat signal

Oleoyl-estrone (OE) is a powerful anti-obesity compound that decreases food intake, decreases insulin resistance and circulating cholesterol. OE stimulates a severe loss of body fat by decreasing adipose tissue lipid synthesis and maintaining lipolysis. Therefore, the body economy loses lipid energy because energy expenditure is maintained. This study analyses the discrepancy between OE effects and the distribution of labelled OE in plasma. Estrone radioimmunoassay of organic solvent plasma extracts of rats treated with OE showed the massive presence of acyl-estrone, but saponification did not release estrone, but containing similar unknown compound. Analysis of label distribution in plasma after oral gavages of (3)H-OE showed the presence of a more hydrophilic compound than OE or any estrogen as well as (3)H(2)O, formed from (3)H-OE in the acidic stomach medium. OE was not attached to a specific transporter in plasma. Through serum HPLC analysis we found W, a labelled derivative more hydrophilic than OE or estrone. The results were confirmed using (14)C-OE. HPLC-MS/MS studies showed that plasma OE levels were one order of magnitude lower than those of W. When liver cell cytosols from rats laden with (3)H-OE were incubated with nuclei from untreated rats, the OE-derived label (i.e., Ws) was found attached to nuclear DNA. Neither estradiol nor estrone interfered with its binding. W is a fairly hydrophilic compound of low molecular weight containing the estrone nucleus, but it is not an ester because saponification or esterases do not yield estrone as OE does. It is concluded that OE acts through its conversion to W, its active form; which binds to a nuclear receptor different from that of estrogen. The estimated W serum levels are proportional to the pharmacological OE effects in vivo. We postulate W as a new type of hormone that exerts the full range of in vivo effects thus far attributed to OE. The full identification of W is anticipated to open the way for the development of new OE-like anti-obesity drugs.

Fatty acid esters of steroids: synthesis and metabolism in lipoproteins and adipose tissue

At the end of the last century ideas concerning the physiological role of the steroid fatty acid ester family were emerging. Estrogens, fatty acylated at C-17 hydroxyl group and incorporated in lipoproteins were proposed to provide antioxidative protection to these particles. A large number of studies involving non-estrogenic adrenal steroids, and their fatty acylated forms, demonstrated their lipoprotein-mediated transport into cells and subsequent intracellular activation, suggesting a novel transport mechanism for lipophilic steroid derivatives. After these important advances the main focus of interest has shifted away from C-19 and C-21 steroids to fatty acylated estrogens. However, interest in their lipoprotein-mediated transport has decreased because only minute amounts of these derivatives were detected in circulating lipoproteins, and their antioxidative activity remained unconfirmed under physiological circumstances. It now appears that the overwhelming majority of estradiol in postmenopausal women resides in adipose tissue, most of it in esterified form. This is poorly reflected in plasma levels which are very low. Recent data suggest that estrogen fatty acid esters probably represent a storage form. The future focus of investigation is likely to be on firstly, the enzymatic mechanisms regulating the esterification and de-esterification of estradiol and other steroids residing in adipose tissue and secondly, on the role of insulin and other hormones in the regulation of these enzymatic mechanisms. Thirdly, as a large proportion of fatty acid esterified C-19 and C-21 non-estrogenic steroids is transported in lipoproteins and as they are important precursors of androgens and estrogens, this field should be investigated further.

Oleoyl-estrone

Oleoyl-estrone (OE) is a powerful slimming agent that is also present in plasma and adipose tissue, where it is synthesized. It acts through the formation of a derivative W. OE effects (and W levels) are proportional to the dose. OE reduces food intake but maintains energy expenditure (thermogenesis). The energy gap is fulfilled with adipose tissue fat, sparing body protein and maintaining glycemia (and glycogen) with lower insulin and leptin levels. OE (in fact W) acts through specific receptors, different from those of estrogen. OE increases cholesterol catabolism, reducing hypercholesterolemia in obese rats. The main metabolic effect on adipose tissue is lowering of lipid synthesis, maintaining unchanged the intracellular lipolytic processes; the imbalance favors the progressive loss of fat, which is largely used by the muscle. OE administration induces additive effects with other antiobesity agents, such as β(3)-adrenergic agonists, forcing a massive loss of lipid. Corticosteroids markedly limit OE action by altering the liver control of lipogenesis. OE also inhibits the action of 17β-hydroxysteroid dehydrogenase, decreasing the synthesis of β-estradiol and testosterone. Discontinuous treatment allows for maximal efficacy both in rats and humans. OE has the advantage that the loss of fat is maintained and does not require additional dietary limitations.

Action profile of the antiobesity drug candidate oleoyl-estrone in rats

Oleoyl-estrone (OE) has been presented as a potential antiobesity therapeutic, but the published series of studies from one laboratory has not yet been independently confirmed, and the exact mechanism of action is unknown. Based on the hypothesis that OE has potential for the treatment of obesity, male and female rats were chronically treated with several doses of OE to evaluate the impact of this compound on energy metabolism. Body weight, body composition, energy balance parameters and the expression of hypothalamic neuropeptides regulating food intake as well as key markers of the reproductive system were examined. OE impressively reduced food consumption and body weight gain in both sexes. Although a major part of the loss in body weight could be explained by decreased fat mass, a substantial loss of lean mass also occurred after OE administration. The loss of weight can be sufficiently explained by the suppression of food consumption, as there were no major changes in energy expenditure, locomotor activity or respiratory quotient. In situ hybridization data showed no significant change in the expression of key neuropeptides and hormone receptors regulating feeding behavior after OE treatment. Cocaine-amphetamine-regulated transcript (CART) mRNA levels were decreased in the arcuate nucleus of OE-treated rats. Hypogonadism and low plasma testosterone levels were found in OE-treated males, whereas females showed substantially increased liver size. The present data suggest that OE decreases food intake and body weight but also appears to cause a significant impact on the hypothalamus-pituitary-reproductive axis.

Current trends in targeting the hormonal regulation of appetite and energy balance to treat obesity

With the eruption of the obesity pandemic over the past few decades, much research has been devoted to understanding the molecular mechanisms by which the human body regulates energy balance. These studies have revealed several mediators, including gut/pancreatic/adipose hormones and neuropeptides that control both short- and long-term energy balance by regulating appetite and/or metabolism. These endogenous mediators of energy balance have been the focus of many anti-obesity drug-development programs aimed at either amplifying endogenous anorexigenic/lipolytic signaling or blocking endogenous orexigenic/lipogenic signaling. Here, we discuss the efficacy and safety of targeting these pathways for the pharmacologic treatment of obesity.

Treatment of pregnant rats with oleoyl-estrone slows down pup fat deposition after weaning

BACKGROUND

In rats, oral oleoyl-estrone (OE) decreases food intake and body lipid content. The aim of this study was to determine whether OE treatment affects the energy metabolism of pregnant rats and eventually, of their pups; i.e. changes in normal growth patterns and the onset of obesity after weaning.

METHODS

Pregnant Wistar rats were treated with daily intragastric gavages of OE in 0.2 ml sunflower oil from days 11 to 21 of pregnancy (i.e. 10 nmol oleoyl-estrone/g/day). Control animals received only the vehicle. Plasma and hormone metabolites were determined together with variations in cellularity of adipose tissue.

RESULTS

Treatment decreased food intake and lowered weight gain during late pregnancy, mainly because of reduced adipose tissue accumulation in different sites. OE-treated pregnant rats' metabolic pattern after delivery was similar to that of controls. Neonates from OE-treated rats weighed the same as those from controls. They also maintained the same growth rate up to weaning, but pups from OE-treated rats slowed their growth rate afterwards, despite only limited differences in metabolite concentrations.

CONCLUSION

The OE influences on pup growth can be partially buffered by maternal lipid mobilization during the second half of pregnancy. This maternal metabolic "imprinting" may condition the eventual accumulation of adipose tissue after weaning, and its effects can affect the regulation of body weight up to adulthood.

Short-term oleoyl-estrone treatment affects capacity to manage lipids in rat adipose tissue

BACKGROUND

Short-term OE (oleoyl-estrone) treatment causes significant decreases in rat weight mainly due to adipose tissue loss. The aim of this work was to determine if OE treatment affects the expression of genes that regulate lipid metabolism in white adipose tissue.

RESULTS

Gene expression in adipose tissue from female treated rats (48 hours) was analysed by hybridization to cDNA arrays and levels of specific mRNAs were determined by real-time PCR. Treatment with OE decreased the expression of 232 genes and up-regulated 75 other genes in mesenteric white adipose tissue. The use of real-time PCR validate that, in mesenteric white adipose tissue, mRNA levels for Lipoprotein Lipase (LPL) were decreased by 52%, those of Fatty Acid Synthase (FAS) by 95%, those of Hormone Sensible Lipase (HSL) by 32%, those of Acetyl CoA Carboxylase (ACC) by 92%, those of Carnitine Palmitoyltransferase 1b (CPT1b) by 45%, and those of Fatty Acid Transport Protein 1 (FATP1) and Adipocyte Fatty Acid Binding Protein (FABP4) by 52% and 49%, respectively. Conversely, Tumour Necrosis Factor (TNFalpha) values showed overexpression (198%).

CONCLUSION

Short-term treatment with OE affects adipose tissue capacity to extract fatty acids from lipoproteins and to deal with fatty acid transport and metabolism.

Oleoyl-Estrone Treatment to Late Pregnant and Mid-Lactating Rats Affects the Expression of Lipid Metabolism Genes

The purpose of this study was to determine whether OE treatment affects the expression of genes related to lipid metabolism under two physiological conditions: late pregnancy and mid-lactation, both characterized by lipid mobilization. Samples of periovarian and retroperitoneal adipose tissue from 21-day pregnant or 15-day lactating dams were used. The expression of LPL, FATP1, FABP4, HSL, ACC1, FAS, PEPCK, GLUT4, PDK4, SREBP1c, adiponutrin and leptin, were compared with their expression in virgin rats. In pregnant rats, FABP4, HSL, PEPCK and PDK4 were over expressed in the periovarian site compared to virgin rats, whereas adiponutrin, FAS, GLUT4 and SREBP1c were underexpressed; the retroperitoneal fat depot showed a similar pattern but ACC1 and leptin were also underexpressed. OE treatment caused a generalized decrease in gene expression in both adipose depots. In lactating dams, the gene expression profile at the periovarian depot was similar to that observed in pregnant rats. OE treatment mimicked the trend observed in pregnant rats, although the intensity of the gene expression changes was lower. After OE treatment, the retroperitoneal adipose depot showed a completely different pattern since the values were close to those of virgin rats. These results corroborate that OE effects in adipose tissue, lowering lipids and depressing their metabolism, already described under other physiological situations, can be also found in late pregnancy and lactation.

Oleoyl-estrone treatment activates apoptotic mechanisms in white adipose tissue

To determine whether lipid mobilization in white adipose tissue caused by oleoyl-estrone (OE) treatment leads to activation of apoptosis, female Wistar rats were given a daily oral gavage of 10 micromol/kg of OE in 0.2 ml of sunflower oil and DNA fragmentation in different adipose tissues was assessed by ligation-mediated PCR after 6, 24, 48, or 240 h. Expression of selected apoptotic target genes was analysed by RT-PCR in adipose tissue from animals treated for 2 days. The response of adipose tissue to OE treatment was not the same in all locations. In mesenteric adipose tissue, a significant increase in the expression of Bid, Bax, caspase 3 and caspase 8 was detected, whereas in periovaric adipose tissue, only Bax and caspase 3 expression showed significant increases. No effect was detected in subcutaneous or retroperitoneal adipose tissue. The increased expression of apoptotic factors suggests that this pathway could be activated by OE treatment.

Rats treated with oleoyl-oestrone maintain glucidic homeostasis: comparisons with a pair-fed model

To determine whether or not the weight (and fat) loss induced by oleoyl-oestrone treatment results only as a consequence of decreased food intake, we compared treated animals with a pair-fed model. To this end, Wistar female rats received daily oral gavages of 10 mumol/kg per d oleoyl-oestrone in sunflower oil, or vehicle alone for 10 or 20 d. A second group of rats received the gavage of sunflower oil and the same amount of food ingested as the oleoyl-oestrone-treated animals (pair-fed group). Rats treated with oleoyl-oestrone maintained glucidic metabolism homeostasis despite a marked decrease in adipose tissue weight (P<0.001). Pair-fed rats exhibited a different pattern, comparable to short-term starvation, with greatly decreased glycogen stores (P<0.0001). The most significant effects were detected in the 10 d period groups. Oleoyl-oestrone affected the activity of the ponderostat system not only by decreasing appetite but also by modifying energy partition: treated animals maintained their glucose and energy homeostasis despite decreased food intake and the massive depletion of lipid stores.

Hormone replacement therapy, body mass index and asthma in perimenopausal women: a cross sectional survey

BACKGROUND

Hormone replacement therapy (HRT) and obesity both appear to increase the risk of asthma. A study was undertaken to investigate the association of HRT with asthma and hay fever in a population of perimenopausal women, focusing on a possible interaction with body mass index (BMI).

METHODS

A postal questionnaire was sent to population based samples in Denmark, Estonia, Iceland, Norway, and Sweden in 1999-2001, and 8588 women aged 25-54 years responded (77%). Pregnant women, women using oral contraceptives, and women <46 years were excluded. Analyses included 2206 women aged 46-54 years of which 884 were menopausal and 540 used HRT. Stratified analyses by BMI in tertiles were performed.

RESULTS

HRT was associated with an increased risk for asthma (OR 1.57 (95% CI 1.07 to 2.30)), wheeze (OR 1.60 (95% CI 1.22 to 2.10)), and hay fever (OR 1.48 (95% CI 1.15 to 1.90)). The associations with asthma and wheeze were significantly stronger among women with BMI in the lower tertile (asthma OR 2.41 (95% CI 1.21 to 4.77); wheeze OR 2.04 (95% CI 1.23 to 3.36)) than in heavier women (asthma: p(interaction) = 0.030; wheeze: p(interaction) = 0.042). Increasing BMI was associated with more asthma (OR 1.08 (95% CI 1.05 to 1.12) per kg/m2). This effect was only found in women not taking HRT (OR 1.10 (95% CI 1.05 to 1.14) per kg/m2); no such association was detected in HRT users (OR 1.00 (95% CI 0.92 to 1.08) per kg/m2) (p(interaction) = 0.046). Menopause was not significantly associated with asthma, wheeze, or hay fever.

CONCLUSIONS

In perimenopausal women there is an interaction between HRT and BMI in the effects on asthma. Lean women who were HRT users had as high a risk for asthma as overweight women not taking HRT. It is suggested that HRT and overweight increase the risk of asthma through partly common pathways.

Zucker obese rats store less acyl-estrone than lean controls

OBJECTIVE

To measure acyl-estrone levels in the plasma of Zucker obese rats. If these are lower than expected on the basis of their body-fat content, as observed in morbidly obese humans, this might provide a possible link relating obesity and low body estrone levels. We also examined the effect of pharmacological treatment with oral oleoyl-estrone on the accumulation of estrone.

DESIGN

Undisturbed Wistar, Goto-Kakizaki and Zucker (lean Fa/?and obese fa/fa) rats were used to determine the relation between circulating acyl-estrone and body lipids, as well as the total body estrone/lipid ratios. One group of Wistar rats was used to measure the effect of oral gavages of oleoyl-estrone (from 0 to 20 micromol/kg/day) for 10 days on the body content of estrone.

MEASUREMENTS

Body weight change and food intake. Total estrone intake, estrone accrual and excretion (by difference) in rats receiving oleoyl-estrone. Total body lipid and estrone. Circulating acyl-estrone levels.

RESULTS

In lean rats (Wistar, Zucker and Goto-Kakizaki) there was a direct relation between body lipid content and circulating acyl-estrone; this relation was not found in Zucker obese rats. The estrone/lipid mass ratio was in a similar range in lean rats, but obese animals showed much lower values. Wistar rats receiving pharmacological doses of oleoyl-estrone did not accumulate significant amounts of estrone, but excreted almost all the estrone ingested.

CONCLUSIONS

The pharmacological administration of acyl-estrone to rats does not result in the accrual of estrone within a wide range of doses, which confirms the safety of this compound. In rats there is a similar relation between the percentage of body lipids and circulating acyl-estrone to that found in humans. Likewise, obese rats showed lower levels of acyl-estrone than expected. The total content of estrone in the bodies of obese rats was also lower than expected from their high lipid content, which suggests that obese rats are deficient in acyl-estrone.

Effect of oral oleoyl-estrone on adipose tissue composition in male rats

OBJECTIVE

To determine whether the oral administration of oleoyl-estrone has similar mass-decreasing effects on the main different sites of white adipose tissue (WAT).

DESIGN

Adult male Zucker lean rats were given a daily oral gavage of oleoyl-estrone (OE, 10 micromol/kg) in 0.2 ml of sunflower oil for 10 days, and were compared with controls receiving only the oil. The mass of the main WAT sites: subcutaneous, epididymal, mesenteric, retroperitoneal, gluteal, perirenal and interscapular, as well as perirenal and interscapular brown adipose tissue (BAT), were dissected and studied.

MEASUREMENTS

The tissue weight, DNA, protein, lipid and total cholesterol content, together with the levels of leptin and acyl-estrone in the larger WAT and BAT masses, were measured.

RESULTS

The weights of WAT depots were correlated with body weight but those of BAT were not. Cell size was maximal for epididymal and mesenteric and minimal for subcutaneous and retroperitoneal WAT and BAT. Differences were detected in DNA, and in protein and lipid content between distinct WAT sites. OE treatment tended to decrease cell number and cell size in WAT; only small differences in composition were found between WAT locations inside the visceral cavity and those outside. Decreases in lipid content were maximal in mesenteric fat. Leptin and acyl-estrone content were fairly uniform at the different WAT sites, except for high concentrations in gluteal WAT. OE induced a greater decrease in leptin and acyl-estrone than in DNA and lipids; changes in these hormones were fairly parallel in all sites.

CONCLUSIONS

In general, the differences in composition between visceral and peripheral subcutaneous WAT and their responses to OE were less marked than the individual differences observed between specific sites, regardless of location. WAT sites are fairly diverse in composition, but their response to OE treatment was uniform. OE decreased the weight of WAT through reduction of both cell numbers and size; but did not change the mass or composition of BAT significantly. The effects of OE are more marked in the hormonal signals (leptin and acyl-estrone) from the tissue than in its composition and mass.

Effect of oral oleoyl-estrone treatment on plasma lipoproteins and tissue lipase activities of Zucker lean and obese female rats

OBJECTIVE

To study the effect of oral oleoyl-estrone on the plasma lipoprotein profile and tissue lipase activities in order to determine the handling of circulating lipids by adipose tissue, liver and muscle of obese female rats.

DESIGN

Lean (Fa/?) and obese (fa/fa) female Zucker rats treated for 10 days with a daily gavage of 0.2 ml sunflower oil containing 0 (controls) or 10 micromol/kg of oleoyl-estrone. After sacrifice, samples of tissues and plasma were taken.

MEASUREMENTS

Plasma lipoprotein classes and composition; lipoprotein lipase and hepatic lipase activities in plasma, liver, skeletal muscle and periovaric and mesenteric white adipose tissue (WAT).

RESULTS

Oleoyl-estrone decreased plasma cholesterol (mainly in HDLs: 76%) of lean rats, but dramatically decreased all lipid classes in obese rats, in which chylomicra and VLDL lost most of their triacylglycerols (95 and 81%, respectively). Hepatic lipase activity decreased markedly with oleoyl-estrone in all groups, both in plasma (79% lean, 100% obese) and liver (62% in both groups). Lipoprotein lipase activity was largely unchanged by oleoyl-estrone in lean rats, but in the obese it decreased in WAT (82% in periovaric, and 49% in mesenteric), and increased in plasma (x4) and in skeletal muscle (x5); liver levels showed no change.

CONCLUSIONS

The shift observed in obese rats from a decrease in liver and WAT lipoprotein lipase and hepatic lipase activities to an increase in muscle lipoprotein lipase is coincident with the hypolipemic effect of oleoyl-estrone, especially in obese rats, and indicates that muscle is a key site for the disposal of endogenous fat mobilized due to oleoyl-estrone treatment.

[Hormonal alterations on young morbid obese women]

BACKGROUND

Human obesity is a widespread disease with considerable variability as to its severity, metabolic and endocrine manifestations and etiology. In the present study we have determined whether the alterations of uncomplicated severe obesity in adult young women affect with different intensity the circulating levels of hormones that have been postulated to intervene in the development and maintenance of obesity.

SUBJECTS AND METHOD

Age-matched 20 morbidly obese (BMI 52.6 [8.3 SD] kg/m2) and 10 normal-weight control women (BMI 19.9 [2.1 SD] kg/m2)were studied and determined the basal circulating levels of hormones and proteins related with the control of body weight.

RESULTS

Obese women showed higher concentrations of insulin and leptin, and lower of cortisol and cortisol-binding globulin (CBG). No significant differences were appreciated for free thyroxine, TSH, free and acylestrone and dehydroepiandrosterone-sulphate.

CONCLUSIONS

The results suggest that morbid obesity implies the alteration of the main hormonal systems controlling the availability of energy and the response to external challenges, with the noteworthy exception of the thyroid. There were clear alterations of insulin and leptin,but cortisol changes could be more related to factors other than obesity. The lower than expected levels of acylestrone point to a possible deficit of this ponderostat signal in obese women. The relatively young age of the women in the study may account for the relative shallowness of the hormonal changes observed.

Daily oral oleoyl-estrone gavage induces a dose-dependent loss of fat in Wistar rats

OBJECTIVE

To establish whether single daily oral doses of oleoyl-estrone result in dose-dependent slimming effects on normal weight rats, and to determine the changes in energy parameters induced by this treatment.

RESEARCH METHODS AND PROCEDURES

The effects of a daily oral gavage of oleoyl-estrone (0, 0.2, 0.5, 1, 2, 5, 10, and 20 micromol/kg per day) in 0.2 ml of sunflower oil given over a 10-day period were studied in groups, each of which contained six adult female Wistar rats initially weighing 190 to 230 g. A group of intact control rats receiving no gavage was included for comparison. Body weight and food intake were measured daily. Rats were killed on day 10 of treatment, and body composition (protein nitrogen, lipids, and water), liver lipids, and plasma parameters (glucose, triacylglycerols, total cholesterol, free fatty acids, 3-hydroxybutyrate, urea, aspartate, alanine transaminases, insulin, leptin, and free and acyl-estrone) were measured.

RESULTS

The administration of oleoyl-estrone resulted in a dose-dependent loss of body fat, because of a partly maintained energy expenditure combined with decreased food intake. The differences in the energy budget were met by internal fat pools. The changes recorded did not affect the levels of the main plasma energy homeostasis indicators: unaltered glucose, triacylglycerols, free fatty acids, 3hydroxybutyrate, and urea. Protein was accrued even under conditions of severe lipid store drainage. There were no changes in transaminases. No lipid accumulation was recorded in the liver. Plasma insulin and leptin levels decreased with increased oleoyl-estrone doses, whereas the levels of free and esterified estrone increased with treatment, although not in proportion to the dose received.

DISCUSSION

Oral treatment with oleoyl-estrone resulted in the specific dose-related loss of fat reserves with little change to other metabolic parameters. These results agree with the postulated role of oleoyl-estrone as a ponderostat signal.

Oral oleoyl-estrone induces the rapid loss of body fat in Zucker lean rats fed a hyperlipidic diet

OBJECTIVE

To test whether oleoyl-estrone affects body weight when given orally, which may help curtail the secondary growth-boosting effects of derived estrone.

DESIGN

The rats were fed for 15 days with a powdered hyperlipidic diet (16.97 MJ/kg metabolizable energy) in which 46.6% was lipid-derived and 16.1% protein-derived energy (HL group), containing 1.23+/-0.39micromol/kg of fatty-acyl esters of estrone. This diet was supplemented with additional oleoyl-estrone to produce diets with 2.5 micromol/kg (diet OE2.5), 4.4 micromol/kg (diet OE4.4), and 33.3 micromol/kg content in fatty-acyl estrone (diet OE33).

SUBJECTS

Twelve-week old female Zucker lean (Fa/?) rats initially weighing 200-235g.

MEASUREMENTS

Food intake and body weight changes; urine and droppings production and nitrogen content. Body composition (water, lipid, protein) and total energy. Energy and nitrogen balances. Plasma chemistry including free amino acids.

RESULTS

Oral administration of oleoyl-estrone in a hyperlipidic diet resulted in significant losses of fat, energy and, ultimately, weight, which were dependent on the dose of oleoyl-estrone ingested. Treatment induced the maintenance of energy expenditure combined with lower food intake, creating an energy gap that was filled with internal fat stores whilst preserving body protein. The decrease in food intake was not a consequence of food aversion but of diminished appetite. Energy expenditure was practically constant for all groups except for the OE33, which showed values about 25% lower than the controls. In most of the groups studied, there was a net protein deposition in spite of severe lipid and energy drainage. Amino acid levels agreed with this N-sparing shift. In spite of lowered energy intake, the N balance was positive or near zero in all groups, with a sizeable N-gap in controls and in lower-dose groups that disappeared in the OE33 group.

CONCLUSION

Treatment of rats with a hyperlipidic diet containing added oleoyl-estrone resulted in the dose-related loss of fat reserves with scant modification of other metabolic parameters and preservation of body protein. The results agree with the postulated role of oleoyl-estrone as a ponderostat signal and open the way for its development as anti-obesity drug.

Oleoyl-estrone induces the massive loss of body weight in Zucker fa/fa rats fed a high-energy hyperlipidic diet

To test whether oleoyl-estrone plus a hyperlipidic diet affects body weight in Zucker fa/fa rats, 13-week-old male Zucker obese (fa/fa) rats initially weighing 440-470 g were used. They were fed for 15 days with a powdered hyperlipidic diet (16.97 MJ/kg metabolizable energy) in which 46.6% was lipid-derived and 16.1% was protein-derived energy and containing 1.23 +/- 0.39 µmol/kg of fatty-acyl esters of estrone. This diet was supplemented with added oleoyl-estrone to produce a diet with 33.3 µmol/kg of fatty-acyl estrone. Oral administration of oleoyl-estrone in a hyperlipidic diet (at a mean dose of 0.5 µmol. kg(-1).d(-1)) resulted in significant losses of fat, energy and, ultimately, weight. Treatment induced the maintenance of energy expenditure combined with lower food intake, creating an energy gap that was filled with internal fat stores while preserving body protein, in contrast with the marked growth of controls fed the hyperlipidic diet. Treatment of genetically obese rats with a hyperlipidic diet containing additional oleoyl-estrone resulted in the loss of fat reserves with scant modification of other metabolic parameters, except for lower plasma glucose and insulin levels. The results agree with the postulated role of oleoyl-estrone as a ponderostat signal.

Gonadal steroids and energy homeostasis in the leptin era

Gonadal steroids influence food intake and body weight. Although the specific mechanisms underlying these effects are not clear, a consideration of their effects in the context of current models of energy homeostasis may ultimately lead to the identification of these mechanisms. When compared with leptin, the prototypical humoral signal of energy balance, sex steroids share many common properties related to food intake and body weight. Specifically, gonadal steroids circulate in proportion to fat mass and current energy balance, and administration of these compounds influences food intake, energy expenditure, body weight, and body composition. Moreover, both estrogens and androgens modulate central nervous system effectors of energy homeostasis that are targets for the action of leptin, including pathways that contain neuropeptide Y, pro-opiomelanocortin, or melanin-concentrating hormone. Sex steroids and leptin also regulate one another's production. Although gonadal steroids, unlike leptin, are clearly not critical to the maintenance of normal energy homeostasis, they do appear to function as physiologic modulators of this process. Identifying the specific central mediators of their effects will contribute to our understanding of their role in energy homeostasis.

Plasma acyl-estrone levels are altered in obese women

A group of obese women (BMI>27 kg/m2; N=73) was studied together with lean controls (BMI <27 kg/m2; N=25). Three groups were defined by the compliance with: BMI lower than 27 kg/m2, glycaemia lower than 5.5 mM and insulinaemia lower than 0.2 nM (controls, group 1, N=19). The subjects with BMI>27 kg/m2, glucose >5.5 mM and insulin >0.2 nM constituted group 3 (N=41), and those with BMI>27 with glycaemia and/or insulinaemia lower than the limits set constituted group 2 (N=32). The women in group 3 had higher fat content, BMI and fat-free mass than those in group 2 and the controls. There were no changes in most plasma parameters, such as free estrone and beta-estradiol. Leptin levels were higher in groups 2 and 3 than in controls. In controls, leptin and acyl-estrone levels were well correlated with BMI and fat content; this correlation was not found in groups 2 and 3 for acyl-estrone, although it was found for leptin. Acyl-estrone levels were lower than expected in most obese women when compared to those of controls, suggesting an altered availability or function of this hormone. In obese women, acyl-estrone levels -and probably function- are lower than expected, contrasting with maintained leptin-BMI correlations. The role of insulin in the control of body weight, perhaps through acyl estrone-mediated effects, should be re-evaluated.

Effect of food deprivation on rat plasma estrone fatty acid esters

The present study was devised to determine whether the circulating levels of estrone fatty esters are modified by 6-48 h starvation in the rat, in parallel to changes in fat reserves, as a test to check the plausibility of its function as a ponderostat signal in the mammal. Food deprivation resulted in a decrease in glucose and triacylglycerols, rapid disappearance of liver glycogen and increases in fatty acids and, especially, 3-hydroxybutyrate. Insulin and leptin decreased, corticosterone and free estrone increased from 6 h onwards and total estrone levels were maintained. Starvation reduced the lipid content of the rat by 25.6%. Plasma esterified estrone levels decreased more slowly, by 13% in 48 h, but its circulating mass decreased in the same proportion as the total lipid content of the rat. The small change in circulating estrone fatty esters is consistent with the postulated role of oleoyl-estrone as a medium-term ponderostat signal.