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

Acylation stimulating protein/C3adesArg in the metabolic states: role of adipocyte dysfunction in obesity complications

Adipose tissue, as an endocrine organ, secretes several adipocyte-derived hormones named 'adipokines' that are implicated in regulating energy haemostasis. Substantial evidence shows that white adipose tissue-derived adipokines mediate the link between obesity-related exogenous factors (like diet and lifestyle) and various biological events (such as pre- and postmenopausal status) that have obesity consequences (cardiometabolic disorders). One of the critical aetiological factors for obesity-related diseases is the dysfunction of adipokine pathways. Acylation-stimulating protein (ASP) is an adipokine that stimulates triglyceride synthesis and storage in adipose tissue by enhancing glucose and fatty acid uptake. ASP acts via its receptor C5L2. The primary objective of this review is to address the existing gap in the literature regarding ASP by investigating its diverse responses and receptor interactions across multiple determinants of obesity. These determinants include diet composition, metabolic disorders, organ involvement, sex and sex hormone levels. Furthermore, this article explores the broader paradigm shift from solely focusing on adipose tissue mass, which contributes to obesity, to considering the broader implications of adipose tissue function. Additionally, we raise a critical question concerning the clinical relevance of the insights gained from this review, both in terms of potential therapeutic interventions targeting ASP and in the context of preventing obesity-related conditions, highlighting the potential of the ASP-C5L2 interaction as a pharmacological target. In conclusion, these findings validate that obesity is a low-grade inflammatory status with multiorgan involvement and sex differences, demonstrating dynamic interactions between immune and metabolic response determinants.

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.

Dual therapy of rosiglitazone/pioglitazone with glimepiride on diabetic nephropathy in experimentally induced type 2 diabetes rats

Diabetic nephropathy is a major cause of end-stage renal disease (ESRD) in the general population. It is estimated that diabetic nephropathy will eventually develop in about 40% of all patients with diabetes; therefore, prevention is critical for delaying the development and progression of diabetic kidney disease. Despite extensive efforts, medical advances are still not successful enough to prevent the progression of the disease. In the present study, we focused on the comparison of combination therapies and whether they offered additional renoprotection. Type 2 diabetes mellitus was induced by intraperitoneally administering streptozotocin (90 mg/kg) in neonatal rats and then these rats were treated with rosiglitazone (1.0 mg/kg) in combination with glimepiride (0.5 mg/kg) or with pioglitazone (2.5 mg/kg) in combination with glimepiride (0.5 mg/kg). Diabetic nephropathy markers were evaluated by biochemical and ELISA kits and renal structural changes were examined by light microscopy and transmission electron microscopy. Results show that the combination of pioglitazone with glimepiride is more effective in amelioration of diabetic nephropathy than rosiglitazone with glimepiride drug therapy due to glycemic control, suppressing albumin excretion rate, total protein excretion rate and augmented TNF-a signaling during the development of streptozotocin induced type 2 diabetic nephropathy.

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.

Dual therapy versus monotherapy of trandolapril and telmisartan on diabetic nephropathy in experimentally induced type 2 diabetes mellitus rats

Objective: To investigate the combination of telmisartan with trandolapril therapy versus monotherapy of trandolapril and telmisartan on diabetic nephropathy in type 2 diabetes mellitus rats.

Material and methods: Neonatal rats (2 days old) were used for inducing type 2 diabetes mellitus. Streptozotocin at a dose of 90 mg/kg, in freshly prepared citrate buffer (0.1M, pH 4.5), was injected intraperitoneally. There were five groups: (1) normal control, (2) diabetic control, (3) diabetic treated with telmisartan, (4) diabetic treated with trandolapril and (5) diabetic treated with telmisartan and trandolapril. Albumin excretion rate, total protein excretion rate, plasma fibronectin, transforming growth factor beta 1(TGF-β1), tumour necrosis factor-α (TNF-α) concentration and renal structural changes were measured.

Results: Albumin excretion rate, total protein excretion rate, plasma fibronectin, TGF-β1, TNF-α concentration and renal structural changes increased significantly in untreated diabetic rats compared with normal control rats. Administration of telmisartan, trandolapril, or both decreased these changes.

Conclusions: Addition of the telmisartan to trandolapril was more effective in reducing renal structural changes and improvement of renal function than monotherapy with either drug, possibly due to dual inhibitory effect on the renin— angiotensin system, and thus suppression of TGF-β1, TNF-α.

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.

Oleoyl-estrone increases adrenal corticosteroid synthesis gene expression in overweight male rats

Oleoyl-estrone (OE) induces a marked loss of body fat in rats by maintaining energy expenditure, body protein and blood glucose despite decreasing food intake. OE increases glucocorticoids, but they arrest OE lipid-mobilization. We studied here whether OE induces a direct effect on adrenal glands function as part of this feedback regulation. Dietary overweight male rats were given oral 10nmol/g OE gavages for ten days. A group (PF) of pair-fed to OE rats, and controls received vehicle-only gavages. OE rats lost slightly more body than PF, but had larger adrenal glands. Tissue corticosterone levels, and gene expressions for glucocorticoid-synthesizing enzymes were increased in OE versus controls and PF; thus, we assumed that adrenal growth affected essentially its cortex since OE also lowered the expression of the medullar catecholamine synthesis enzyme genes. Serum corticosterone was higher in PF than in OE and controls, but liver expression of corticosteroid-disposing steroid 5alpha-reductase was 3x larger in OE than PF and controls. Circulating glucocorticoids changed little under OE, in spite of higher adrenal gland and liver content, hinting at modulation of glucocorticoid turnover as instrumental in their purported increased activity. In conclusion, we have observed that OE considerable enhanced the expression of the genes controlling the synthesis of glucocorticoids from cholesterol in the rat and increasing the adrenal glands' corticosterone, size and cellularity, but also the liver disposal of corticosteroids, suggesting that OE increases corticosterone synthesis and degradation (i.e. serum turnover), a process not driven by limited energy availability but directly related to the administration of OE.

Gene expression modulation of liver energy metabolism by oleoyl-oestrone in overweight rats

We intended to determine how the liver copes with the massive handling of lipids induced by OE (oleoyl-oestrone), as well as to characterize and differentiate the actual OE effects from those that may be only the consequence of decreased food intake. Thus we used male rats treated with oral OE (10 nmol/g per day) compared with a vehicle only PF (pair-fed) group and controls fed ad libitum (vehicle only). Plasma parameters, and total liver lipids, glycogen, DNA and total mRNA were measured. RNA was extracted and used for real-time PCR analysis of the gene expression of enzymes and regulatory factors of liver energy metabolism. Most hepatic proteins showed similar gene expressions in OE and controls, but the differences widened between OE and PF rats, showing that OE effects could not be merely attributed to a lower energy intake. The liver of OE-treated rats largely maintained its ability to mobilize glucose for the synthesis of fats; this was achieved in part by a peculiar combination of regulative modifications that facilitate both fatty acid disposal and restrained glucose utilization under conditions of limited food supply but ample availability of internal energy stores. In conclusion, the results presented suggest that the effect of OE on liver metabolism may be (at least in part) mediated through an insulin-sensitivity-dependent modulation of the expression of SREBP-1c (sterol-regulatory-element-binding protein-1c), resulting in the unique combined effect of mildly increased (or maintained) glucose disposal but also limited enhancement of lipogenesis.

Oleoyl-estrone affects lipid metabolism in adrenalectomized rats treated with corticosterone through modulation of SREBP1c expression

Oleoyl-estrone (OE) elicits a decrease in body fat, which is blocked by glucocorticoids. In order to analyze this counterregulatory effect, we studied the effects of oral OE on adrenalectomized female rats simultaneously receiving corticosterone (subcutaneous pellets). Circulating corticosteroids, liver glycogen, lipids and the expressions in whole liver, soleus muscle, interscapular brown adipose tissue (BAT), and the inguinal and periovaric white adipose tissue (WAT) of genes controlling lipid metabolism were analyzed. Corticosterone reversed OE lipid mobilization, storing fat in liver and subcutaneous WAT. This was not simply the predominance of corticosteroid enhancement of lipogenesis against OE inhibition, but a synergy to enhance lipogenesis. Periovaric WAT showed a different effect, with corticosterone inhibiting OE arrest of lipogenic gene expressions. The data presented suggests that interaction of OE and glucocorticoids (and the metabolic response) depends on the organ or WAT site; there was a direct relationship on the direction and extent of change of SREBP1c expression with those of important energy and lipid handling genes. Our results confirm that corticosterone blocks - and even reverses - OE effects on body lipids in a dose-dependent way, a process mediated, at least in part, by modulation of SREBP1c expression.

Triple verses glimepiride plus metformin therapy on cardiovascular risk biomarkers and diabetic cardiomyopathy in insulin resistance type 2 diabetes mellitus rats

IRtype2DM patients are often treated with a combination of antidiabetic agents. Drugs with different complementary mechanisms of action frequently used in daily clinical practice but glycemic control with monotherapeutic attempts fail in the long run. To date, biomarkers for cardiovascular risk and insulin sensitivity with combination of triple oral hypoglycemic therapies are not fully revelled in view of additional cardiovascular risk reduction. In the present study, IRtype2DM induced by administering streptozotocin (90 mg/kg, i.p.) in neonatal rat model. IRtype2DM rats were selected by determining FPI [>60 pmol/l]; HOMA-IR & Hyperinsulinemic euglycemic clamp technique at 6 weeks and then treated for 8 weeks with (i) Metformin (120 mg/kg, o.d.)+Glimepiride (1mg/kg, o.d.), (ii) Metformin (265 mg/kg, o.d.)+Rosiglitazone (1mg/kg, o.d.)+Glimepiride (0.7 mg/kg, o.d.). At the end cardiovascular risk parameters evaluated by ELISA kits and insulin sensitivity were determined by HOMA-IR. In conclusion, triple oral hypoglycemic therapy improves glycemic control, insulin sensitivity, retards diabetic cardiomyopathy and does not increased body weight; decrease more detrimental inflammatory markers, increase interleukin-10 and adiponectin in neonatal streptozotocin-induced IRtype2DM Wistar Albino Rats. Triple therapy showed a synergistic effect and was promising in insulin resistance, better in additional cardiovascular risk reduction and those nonresponders to metformin add on glimepiride therapy.

Lipoprotein lipase but not hormone-sensitive lipase activities achieve normality after surgically induced weight loss in morbidly obese patients

BACKGROUND

Although bariatric surgery is currently the most common practice for inducing weight loss in morbidly obese patients (BMI>40 kg/m2), its effect on the lipid content of adipose tissue and its lipases (lipoprotein lipase [LPL] and hormone-sensitive lipase [HSL]) are controversial.

METHODS

We analyzed LPL and HSL activities and lipid content from plasma as well as subcutaneous (SAT) and visceral (VAT) adipose tissue of 34 morbidly obese patients (MO) before and after (6 and 12 months) Roux-en-Y gastric bypass surgery and compare the values with those of normal weight (control) patients.

RESULTS

LPL activity was significantly higher in MO (SAT=32.9+/-1.0 vs VAT=36.4+/-3.3 mU/g tissue; p<0.001) than in control subjects (SAT=8.2+/-1.4 vs VAT=6.8+/-1.0 mU/g tissue) in both adipose depots. HSL activity had similar values in both types of tissue (SAT=32.8+/-1.6 and VAT=32.9+/-1.6 mU/g) of MO. In the control group, we found similar results but with lower values (SAT=11.9+/-1.4 vs VAT=12.1+/-1.4 mU/g tissue). Twelve months after surgery, SAT LPL activity diminished (9.8+/-1.4 mU/g tissue, p<0.001 vs morbidly obese), while HSL (46.6+/-3.7 mU/g tissue) remained high. All lipids in tissue and plasma diminished after bariatric surgery except plasma nonesterified fatty acids, which maintained higher levels than controls (16+/-3 vs 9+/-0 mg/dL; p<0.001, respectively).

CONCLUSIONS

When obese patients lose weight, they lose not only part of the lipid content of the cells but also the capacity to store triacylglycerides in SAT depots.

Oleoyl-oestrone inhibits lipogenic, but maintains thermogenic, gene expression of brown adipose tissue in overweight rats

In the present study we intended to determine how BAT (brown adipose tissue) maintained thermogenesis under treatment with OE (oleoyl-oestrone), a powerful slimming hormone that sheds off body lipid but maintains the metabolic rate. Overweight male rats were subjected to daily gavages of 10 nmol/g of OE or vehicle (control) for 10 days. A PF (pair-fed) vehicle-receiving group was used to discount the effects attributable to energy availability limitation. Interscapular BAT mass, lipid, DNA, mRNA and the RT-PCR (real-time PCR) expression of lipid and energy metabolism genes for enzymes and regulatory proteins were measured. BAT mass and lipid were decreased in OE and PF, with the latter showing a marked reduction in tissue mRNA. Maintenance of perilipin gene expression in PF and OE rats despite the loss of lipid suggests the preservation of the vacuolar interactive surface, a critical factor for thermogenic responsiveness. OE and, to a lesser extent, PF maintained the expression of genes controlling lipolysis and fatty acid oxidation, but markedly decreased the expression of those genes involved in lipogenic and acyl-glycerol synthesis. OE did not affect UCP1 (uncoupling protein 1) (decreased in PF), β3 adrenergic receptors or hormone-sensitive lipase gene mRNAs, which may translate in maintaining a full thermogenic system potential. OE rats were able to maintain a less energetically stressed BAT (probably through glucose utilization) than PF rats. These changes were not paralleled in PF rats, in which lower thermogenesis and glucose preservation resulted in a heavier toll on internal fat stores. Thus the mechanism of action of OE is more complex and tissue-specific than previously assumed.

Site-related white adipose tissue lipid-handling response to oleoyl-estrone treatment in overweight male rats

BACKGROUND

Oleoyl-estrone (OE) decreases energy intake while maintaining glucose homeostasis, and energy expenditure at the expense of body fat. White adipose tissue (WAT) depots behave differently under starvation, postprandial state and pharmacologically induced lipolysis.

AIM OF THE STUDY

To understand the mechanism of massive lipid loss from WAT elicited by OE treatment.

METHODS

We used overweight male rats. Rats receiving OE (10 nmol/g) gavages were compared with controls and a pair-fed group. Whole fat pads from the mesenteric, retroperitoneal, epididymal and inguinal subcutaneous sites were excised and analyzed for lipid, DNA, mRNA and the expression of lipogenic, fatty acid transporters and lipase genes.

RESULTS

In OE and pair-fed rats, WAT weights decreased, with the limited loss of cells. Patterns of gene expression in most WAT sites were similar for OE and PF, suggesting a shared mechanism of fat mobilization, but in mesenteric WAT, PF increased lipogenic and fatty acid transporter gene expressions. However, OE inhibited lipogenic expressions more deeply than PF.

CONCLUSIONS

White adipose tissue sites showed different expression patterns, hinting at relatively specialized functions in fat storage; thus, single site analyses cannot be extrapolated to whole WAT. Differences between mesenteric and the other sites suggest that 'visceral fat' should be reserved for this site only, and not applied to other abdominal fat depots (epididymal, retroperitoneal).

Corticosterone inhibits the lipid-mobilizing effects of oleoyl-estrone in adrenalectomized rats

Oleoyl-estrone (OE) is an adipose-derived signal that decreases energy intake and body lipid, maintaining energy expenditure and glycemic homeostasis. Glucocorticoids protect body lipid and the metabolic status quo. We studied the combined effects of OE and corticosterone in adrenalectomized female rats: daily OE gavages (0 or 10 nmol/g) and slow-release corticosterone pellets at four doses (0, 0.5, 1.7, and 4.8 mg/d). Intact and sham-operated controls were also included. After 8 d, body composition and plasma metabolites and hormones were measured. OE induced a massive lipid mobilization (in parallel with decreased food intake and maintained energy expenditure). Corticosterone increased fat deposition and inhibited the OE-elicited mobilization of body energy, even at the lowest dose. OE enhanced the corticosterone-induced rise in plasma triacylglycerols, and corticosterone blocked the OE-induced decrease in leptin. High corticosterone and OE increased insulin resistance beyond the effects of corticosterone alone. The presence of corticosterone dramatically affected OE effects, reversing its decrease of body energy (lipid) content, with little or no change on food intake or energy expenditure. The maintenance of glycemia and increasing insulin in parallel to the dose of corticosterone indicate a decrease in insulin sensitivity, which is enhanced by OE. The reversal of OE effects on lipid handling, insulin resistance, can be the consequence of a corticosterone-induced OE resistance. Nevertheless, OE effects on cholesterol were largely unaffected. In conclusion, corticosterone administration effectively blocked OE effects on body lipid and energy balance as well as insulin sensitivity and glycemia.

The conjugated linoleic acid ester of estrone induces the mobilisation of fat in male Wistar rats

We investigated whether the substitution of the fatty acid moiety in oleoyl-estrone (OE) by conjugated linoleic acid, i.e. conjugated linoleoyl-estrone (cLE) may help improve the antiobesity effects of OE. Overweight (17% fat) male rats were treated for 10 days with oral OE or cLE (10 nmol/g per day) and compared with controls receiving only the oily vehicle. Rat weight and food intake were measured daily. After killing by decapitation, body composition and main plasma parameters were analysed. cLE induced marked decreases in body weight, energy intake, carcass energy and body lipid, whilst sparing protein; the effects were not significantly different from those obtained with OE. Energy expenditure was unchanged, but energy intake decreased to 46% (OE) or 55% (cLE) of controls; whole body energy decreased by 29% (OE) or 24% (cLE) in the 10-day period studied. Plasma composition showed almost identical decreases in glucose and cholesterol elicited by OE and cLE, with a more marked decrease in triacylglycerols by OE and no effect of either on NEFA. OE decreased leptin and insulin levels, but the effects of cLE were more marked on both, with similar decreases in adiponectin. It can be concluded that cLE is a new drug of the OE family; its overall effects on energy were akin to those of OE, albeit fractionally less effective at the single dose tested. However, this lower potency on lipid mobilisation does not affect other effects, such as powerful hypercholesterolemic effects or the modulation of adiponectin. And last, but not least, cLE seems to produce a more marked decrease in leptin and insulin than OE, which may reflect a coordinate action of the conjugated linoleic acid moiety and the "OE effect" on target tissues. If that were the case, cLE may constitute an improvement over OE in its action on insulin resistance.

Effects of Combined Oleoyl-Estrone and Rimonabant on Overweight Rats

Oleoyl-estrone (OE) decreases appetite, maintains energy expediture, induces lipolysis (sparing protein), and decreases cholesterolemia and insulin resistance. Rimonabant (SR141716) is a cannabinoid-receptor inhibitor that decreases appetite and mobilizes fat. We studied whether their combination improves their slimming effects. Male overweight rats received daily gavages of 5.3 mg/kg OE, 10 mg/kg rimonabant, or both drugs during 10 days. Body weight and composition, energy balance, adipose tissue weight, and serum hormones and metabolites were measured. OE halved food intake and maintained energy expenditure at the expense of body fat. Rimonabant effects on appetite and energy balance were less marked, resulting in lower lipid mobilization. OE and rimonabant followed the OE pattern, with no additive or synergic effects. Glycemia was maintained, but OE decreased insulin, GLP-1, and cholesterol, whilst rimonabant increased cholecystokinin and cholesterol, and decreased NEFA. Both drugs decreased leptin and triacylglycerols; ghrelin was unchanged. The results hint at different mechanisms of action of both drugs: we can assume that OE effects do not involve the cannabinoid pathway. OE does not seem to act, either, after 10 days, through the secretion of ghrelin or the intestinal appetite-controlling peptides tested.

Lowering effect of an isoflavone-rich fermented soybean extract on the serum cholesterol concentrations in female rats, with or without ovariectomy, but not in male rats

We examined the effect of administering an isoflavone-rich fermented soybean extract (FSBE) on the serum cholesterol concentrations in male rats and in intact and ovariectomized (OVX) female rats. Dietary FSBE decreased the serum cholesterol concentrations in intact female and OVX rats, but did not affect the concentrations in male rats. Dietary FSBE increased the hepatic total and esterified cholesterol contents in the intact female rats, but decreased them in the OVX rats. This hypocholesterolemic effect was not a simple estrogenic effect because it has appeared in some reports that estrogen administration decreased serum cholesterol both male and female rats. Dietary FSBE increased the hepatic low-density lipoprotein receptor (LDLR) gene expression in the intact female rats as has previously been reported from many studies, but did not affect that of the OVX rats. Further investigation is needed into the hypocholesterolemic mechanism of FSBE.

Combined effects of oral oleoyl-estrone and limited food intake on body composition of young overweight male rats

OBJECTIVE

The combined effects of limited food intake and OE treatment have been analysed in order to determine whether hypocaloric diets enhance the slimming effects of OE on mature overweight male rats. Two levels of dietary limitation at 50 and 25% of a standard intake were established, roughly corresponding to the human LCDs and VLCDs.

DESIGN

Wistar male rats (6 weeks old) were made overweight by a cafeteria diet. After transition to standard diet, they were subjected to food restriction: down to 50 or 25% with respect to the transition period. Half the animals were given daily oral gavages of 10 nmol/g oleoyl-estrone (OE), and the rest received only the vehicle during 10 days.

MEASUREMENTS

Changes in weight and body composition: water, lipid, protein or gross energy were determined by comparing the final pool size with that of day 0, calculated from the initial body weight and the composition of untreated rats. Energy and nitrogen balances were estimated. Plasma levels of metabolites and hormones were also measured.

RESULTS

OE induced changes in body composition similar to those elicited by a 50% reduction in food, with massive loss of lipid and energy. OE-treated rats ate less than the controls, but additional effects on body composition on reduced diet were minimal. OE improved metabolic homoeostasis: better maintained glycaemia, lower cholesterol and shallower hormonal changes, but at the expense of slightly increased protein mobilisation.

CONCLUSIONS

The data presented suggest that no advantages are accomplished by combining OE treatment and hypocaloric diets compared with OE alone, at least under the experimental conditions tested, since the effects were not additive. Despite OE affecting food intake, mechanisms other than that are deemed responsible for the mobilisation of body fat, since intake alone cannot explain the effects on body weight, nor the metabolic and hormonal changes in OE-treated rats. It is concluded that the combination of food restriction and OE may result in unwanted increased protein mobilisation with no synergy between both slimming treatments.

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.

Combined effects of oleoyl-estrone and a beta3-adrenergic agonist (CL316,243) on lipid stores of diet-induced overweight male Wistar rats

Oleoyl-estrone (OE) decreases appetite, induces adipose tissue wasting and resets the ponderostat setting, sparing glucose and protein. The beta3-adrenergic agonists increase energy expenditure and lipolysis. We studied the combination of both treatments to enhance fat mobilization. Overweight male rats received oral OE for 10 days; they were compared with controls and rats receiving a beta3-adrenergic agonist, CL316,243 (B3A); another group received both OE and B3A. Serum 3-hydroxybutyrate, NEFA, triacylglycerols and glucose showed only slight changes in all groups vs. controls; OE-treated rats showed lower cholesterol. OE decreased food intake and B3A increased energy expenditure. OE rats lost about 15%, B3A 24%, and those receiving both compounds lost 39% of their initial total body energy. In all cases, most of this energy imbalance was accounted for by the loss of body lipid. The combined treatment of OE and B3A reduced food intake, nevertheless maintaining a high energy expenditure. The combination of a beta3-adrenergic agonist with OE may help compensate the short-lived effects of the agonist and enhance the lipid mobilization action of OE. The eventual combination of both compounds should be explored as a way to obtain faster and more effective ways to treat obesity.

Short-term oral oleoyl-estrone treatment increases plasma cholesterol turnover in the rat

OBJECTIVE

Oral treatment with oleoyl-estrone induces the loss of body fat and improvement of insulin resistance. Since cholesterol levels are deeply affected by oleoyl-estrone, we investigated here whether short-term treatment affected cholesterol turnover and overall metabolite changes.

DESIGN

Wistar female rats received a single oral dose of 10 mumol/kg oleoyl-estrone in 0.2 ml of sunflower oil. Groups of animals were killed at timed intervals and blood samples were taken. In a second experiment series, rats had implanted carotid and jugular cannulas and were given a single gavage of oleoyl-estrone. These rats were used for the measurement of the cholesterol turnover rate.

MEASUREMENTS

Body weight change and food intake: Glucose, total and HDL-cholesterol, triacylglycerols, 3-hydroxybutyrate, nonesterified fatty acids, insulin, HOMA score in the rats of the first series. Cholesterol: Cholesterol pool changes and cholesterol turnover rates in the rats of the second series.

RESULTS

OE induced early effects, decreasing food intake, cholesterol and HDL-cholesterol levels, and increasing insulin sensitivity (HOMA score). OE also increased cholesteryl-ester turnover, and decreased circulating total cholesterol, especially esterified cholesterol pools.

CONCLUSIONS

The role of early changes in insulin sensitivity induced by oral OE cannot explain per se the deep changes in cholesterol handling, essentially a consequence of accelerated lipoprotein turnover. However, the increase in cholesteryl-ester turnover observed with OE treatment may be, at least in part, a consequence of the decrease in insulin resistance. The compounded effect of increased insulin sensitivity and accelerated lipoprotein turnover may help explain the early and marked hypocholesterolaemic effects of OE.

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.