Glucose metabolism in isolated adipocytes from lean and obese Zucker rats following treatment with dehydroepiandrosterone

Role of the Steroid Sulfate Uptake Transporter Soat (Slc10a6) in Adipose Tissue and 3T3-L1 Adipocytes

In addition to the endocrine and paracrine systems, peripheral tissues such as gonads, skin, and adipose tissue are involved in the intracrine mechanisms responsible for the formation of sex steroids via the transformation of dehydroepiandrosterone and dehydroepiandrosterone sulfate (DHEA/DHEAS) into potent androgenic and estrogenic hormones. Numerous studies have examined the relationship between overweight, central obesity, and plasma levels of DHEA and DHEAS. The sodium-dependent organic anion transporter Soat (Slc10a6) is a plasma membrane uptake transporter for sulfated steroids. Significantly increased expression of Slc10a6 mRNA has been previously described in organs and tissues of lipopolysaccharide (LPS)-treated mice, including white adipose tissue. These findings suggest that Soat plays a role in the supply of steroids in peripheral target tissues. The present study aimed to investigate the expression of Soat in adipocytes and its role in adipogenesis. Soat expression was analyzed in mouse white intra-abdominal (WAT), subcutaneous (SAT), and brown (BAT) adipose tissue samples and in murine 3T3-L1 adipocytes. In addition, adipose tissue mass and size of the adipocytes were analyzed in wild-type and Slc10a6^−/− knockout mice. Soat expression was detected in mouse WAT, SAT, and BAT using immunofluorescence. The expression of Slc10a6 mRNA was significantly higher in 3T3-L1 adipocytes than that of preadipocytes and was significantly upregulated by exposure to lipopolysaccharide (LPS). Slc10a6 mRNA levels were also upregulated in the adipose tissue of LPS-treated mice. In Slc10a6^−/− knockout mice, adipocytes increased in size in the WAT and SAT of female mice and in the BAT of male mice, suggesting adipocyte hypertrophy. The serum levels of adiponectin, resistin, and leptin were comparable in wild-type and Slc10a6^−/− knockout mice. The treatment of 3T3-L1 adipocytes with DHEA significantly reduced lipid accumulation, while DHEAS did not have a significant effect. However, following LPS-induced Soat upregulation, DHEAS also significantly inhibited lipid accumulation in adipocytes. In conclusion, Soat-mediated import of DHEAS and other sulfated steroids could contribute to the complex pathways of sex steroid intracrinology in adipose tissues. Although in cell cultures the Soat-mediated uptake of DHEAS appears to reduce lipid accumulation, in Slc10a6^−/− knockout mice, the Soat deletion induced adipocyte hyperplasia through hitherto unknown mechanisms.

Sex differences, endogenous sex-hormone hormones, sex-hormone binding globulin, and exogenous disruptors in diabetes and related metabolic outcomes

In assessing clinical and pathophysiological development of type 2 diabetes (T2D), the critical role of the sex steroids axis is underappreciated, particularly concerning the sex-specific relationships with many relevant cardiometabolic outcomes. In this issue of the Journal of Diabetes, we provide a comprehensive overview of these significant associations of germline variants in the genes governing the sex steroid pathways, plasma levels of steroid hormones, and sex hormone-binding globulin (SHBG) with T2D risk that have been observed in many clinical and high-quality large prospective cohorts of men and women across ethnic populations. Together, this body of evidence indicates that sex steroids and SHBG should be routinely incorporated into clinical characterization of T2D patients, particularly in screening prediabetic patients, such as those with metabolic syndrome, using plasma levels of SHBG. Given that several germline mutations in the SHBG gene have also been directly related to both plasma concentrations of SHBG and clinical manifestation of T2D, targeting signals in the sex steroid axis, particularly SHBG, may have significant utility in the prediction and treatment of T2D. Further, many of the environmental endocrine disrupting chemicals may exert their potential adverse effects on cardiometabolic outcomes via either estrogenic or androgenic signaling pathways, highlighting the importance of using the sex steroids and SHBG as important biochemical markers in both clinical and population studies in studying sex-specific mechanisms in the pathogenesis of T2D and its complications, as well as the need to equitably allocate resources in studying both men and women.

Dehydroepiandrosterone up-regulates resistin gene expression in white adipose tissue

Dehydroepiandrosterone (DHEA), the most abundant steroid hormone in human blood, is considered to be one of fat-reducing hormones. However, the molecular mechanisms underlying DHEA mode of action in obesity has not been fully clarified. The pivotal role in the maintenance of cellular lipid and energy balance is played by peroxisome proliferator-activated receptor alpha (PPARalpha) which acts as transcriptional activator of numerous genes encoding enzymes involved in fatty acid catabolism. Lately published papers suggest that resistin, a low molecular-weight protein produced by adipose tissue, may act as an inhibitor of adipocyte differentiation and could regulate adipose tissue mass. Recent studies have established that the promoter region of the resistin gene contains several putative PPAR response elements. Since DHEA has been characterized as a peroxisome proliferator able to induce hepatic genes through PPARalpha, we hypothesised that DHEA might affect PPARalpha and, subsequently, resistin gene expression in adipose tissue. In order to test this hypothesis, an experiment was performed comparing PPARalpha and resistin gene expression in white adipose tissue (WAT) of male Wistar rats fed standard or DHEA-supplemented (0.6% (w/w)) diet for 2 weeks. DHEA administration to the rats induced PPARalpha and resistin gene expression in WAT (3- and 2.25-fold, respectively; as determined by real-time reverse transcription-polymerase chain reaction (RT-PCR)); reduced body weight, epididymal adipose tissue mass and decreased serum leptin levels. We propose that DHEA may impact on the transcription of resistin gene through a mechanism involving PPARalpha and that an elevated resistin level may lead to an inhibition of adipogenesis and a decrease in adipose tissue mass.

Dehydroepiandrosterone: is there a role for replacement?

Dehydroepiandrosterone (DHEA) and its sulfated ester are found in high concentrations in the plasma; however, their role in normal human physiology, other than as precursors for sex hormones, remains incompletely defined. Studies of rodent models have shown that these hormones have beneficial effects on a wide variety of conditions, such as diabetes, obesity, immune function, atherosclerosis, and many of the disorders associated with normal aging. However, rodents are not the best models to study the actions of these hormones because they have very little endogenous DHEA; thus, the doses given to these animals are usually suprapharmacological. Human studies have been performed to determine the potential beneficial effects of DHEA replacement in persons with low DHEA levels. Results have been conflicting. Human studies suggest a potential role for DHEA replacement in persons who have undergone adrenalectomy and possibly in the aging population. However, long-term studies assessing the benefits vs adverse effects must be done before DHEA replacement can be recommended.

Chronic effects of dehydroepiandrosterone on rat adipose tissue metabolism

The goal of the present study was to examine cellular mechanisms that regulate adipose cell metabolism in ovariectomized (OVX) and intact rats that were subjected to long-term (27 weeks) treatment with dehydroepiandrosterone (DHEA). Forty-eight 16-month-old female rats were divided into 4 groups of 9 to 11 animals (intact, intact-DHEA, OVX, OVX-DHEA). Adipose tissue lipoprotein lipase (LPL), hormone-sensitive lipase (HSL), and cyclic adenosine monophosphate (cAMP)-dependent phosphodiesterase (cAMP-PDE) activities were determined, and alpha2-, beta1/beta2-, and beta3-adrenoceptors (ARs) were quantified. DHEA did not affect body weight, fat, or muscle mass in intact rats. The similar retroperitoneal fat pad weight of intact-DHEA rats compared to intact animals was in agreement with the lack of difference in the enzyme activities and AR densities. The increased body weight of OVX rat was paralleled by a greater retroperitoneal adipose tissue mass (P <.01), which was in turn associated with a marked rise in LPL activity (P <.005) and a slight decrease in HSL activity (P <.05) compared to intact animals. OVX-DHEA rats, compared to untreated OVX animals, had a smaller retroperitoneal fat depot, which correlated with a decrease in LPL activity (P <.005) and moderate increase in both HSL activity and beta3-AR density (P <.05). DHEA-treatment lowered fasting insulin and triglyceride levels in both intact and OVX rats (P <.05). Plasma testosterone, androsterone, androstenedione, and androstenediol levels were also significantly increased in both intact-DHEA and OVX-DHEA rats compared to untreated animals (P <.0001). These findings suggest that the antiobesity action of DHEA may be related in part to changes in lipase activities and in beta3-AR density, and that it is dependent on the ovarian status of the animal.

Dehydroepiandrosterone down-regulates the expression of peroxisome proliferator-activated receptor gamma in adipocytes

Dehydroepiandrosterone (DHEA) is expected to have a weight-reducing effect. In this study, we evaluated the effect of DHEA on genetically obese Otsuka Long Evans Fatty rats (OLETF) compared with Long-Evans Tokushima rats (LETO) as control. Feeding with 0.4% DHEA-containing food for 2 wk reduced the weight of sc, epididymal, and perirenal adipose tissue in association with decreased plasma leptin levels in OLETF. Adipose tissue from OLETF showed increased expression of peroxisome proliferator-activated receptor gamma (PPARgamma) protein, which was prevented by DHEA treatment. Further, we examined the effect of DHEA on PPARgamma in primary cultured adipocytes and monolayer adipocytes differentiated from rat preadipocytes. PPARgamma protein level was decreased in a time- and concentration-dependent manner, and DHEA significantly reduced mRNA levels of PPARgamma, adipocyte lipid-binding protein, and sterol regulatory element-binding protein, but not CCAAT/enhancer binding protein alpha. DHEA-sulfate also reduced the PPARgamma protein, but dexamethasone, testosterone, or androstenedione did not alter its expression. In addition, treatment with DHEA for 5 d reduced the triglyceride content in monolayer adipocytes. These results suggest that DHEA down-regulates adiposity through the reduction of PPARgamma in adipocytes.

Physiological levels and action of dehydroepiandrosterone in Yucatan miniature swine

The biological role of dehydroepiandrosterone (DHEA) and its less active sulphated conjugate DHEAS was investigated in two experiments using Yucatan miniature swine. In experiment 1, plasma levels of both DHEA(S) among males were greater than female pigs that ranged in age from 0.3 to 84 mo old (P < 0.0001). In males, DHEA(S) were related inversely to serum triglycerides; DHEA was positively related to triglycerides in females (P < 0.01). In experiment 2, four 2-yr old male pigs, used as their own control, showed a 5% decrease in body weight, 11% increase in energy expenditure, 88% increase in lipid, and 100% decrease in glucose utilization (P < 0.0001) in response to DHEA vs. placebo treatments when adjusted for body weight. Plasma DHEA(S) were not different between treatment conditions. Glucose tolerance and plasma insulin levels were not different from controls. In vivo response to norepinephrine indicated beta-adrenergic sensitivity was altered by DHEA. Present findings suggest DHEA and/or its hormone products are important in modulating energy expenditure and lipid utilization for energy in male animals. The role of DHEA in energy metabolism and the difference between sexes warrant further investigation.

Long-term oral administration of dehydroepiandrosterone has different effects on energy intake of young lean and obese male Zucker rats when compared to controls of similar metabolic body size

AIM

The effects of dehydroepiandrosterone (DHEA) on appetite and weight in the Zucker rat have been examined by many investigators who have reported appetite suppression and metabolic effects. However, these studies compared the treated animals to controls of a similar age. Since animals of different sizes consume different amounts of food, perhaps the treated animals should be compared to controls of a similar size. We studied the effects of DHEA on energy intake and weight gain and analysed the effects by age and metabolic body size.

METHODS

Lean (n = 21) and obese (n = 16) male Zucker rats were fed plain chow or chow containing 6 g DHEA/kg chow (0.6% wt/wt) from age 4 wk to 20 wk. Daily energy intakes and body weights were determined at least once weekly.

RESULTS

As expected, the lean and obese rats given DHEA exhibited less daily energy intake (kJ/d) and less weight gain than their respective controls of the same age. The lean rats given DHEA did not exhibit any difference in daily energy intake when determined relative to body weight (b.w.) (kJ x d-1 x g b.w.-1) compared to lean controls of the same metabolic body size, while the obese rats given DHEA exhibited less daily energy intake relative to b.w. (kJ x d-1 x g b.w.-1) compared to obese control of the same metabolic body size.

CONCLUSIONS

Though DHEA reduced total energy intake among the lean and obese Zucker rats, only the obese rats exhibited less energy intake relative to b.w. compared to controls of the same metabolic body size. Thus, DHEA may exert different effects on energy intake relative to b.w. in lean and obese Zucker rats and perhaps the lean Zucker rat is a better model for evaluating the metabolic effects of DHEA since it does not exhibit any effect on energy intake relative to b.w. compared to rats of the same metabolic body size.

Dehydroepiandrosterone attenuates preadipocyte growth in primary cultures of stromal-vascular cells

The purpose of this study was to determine whether the antiobesity actions of dehydroepiandrosterone (DHEA) are due to an influence on preadipocyte proliferation and/or differentiation in primary cultures of pig and rat stromal-vascular (SV) cells. Pig SV cells were isolated from dorsal subcutaneous adipose tissue of 7-day-old pigs. For the proliferation assays, pig SV cells were grown for 4 days in plating medium containing DHEA at 0, 15, 50, or 150 microM. For the differentiation assays, pig SV cells were grown in plating medium for 3 days and then switched to a serum-free medium containing DHEA at 0, 15, 50, or 150 microM for the next 6 days. Rat SV cells were isolated from inguinal fat pads of 5-wk-old male rats. Rat SV cells were exposed to DHEA at 0, 5, 25, or 75 microM during proliferation. For the differentiation assays, rat SV cells were grown for 8 days in a serum-free medium containing DHEA at 0, 5, 25, or 75 microM. Preadipocyte differentiation [lipid staining, glycerol-3-phosphate dehydrogenase (GPDH) activity] and proliferation (preadipocyte-specific antigen staining) decreased with increasing levels of DHEA in cultures of pig SV cells. In cultures of rat SV cells, preadipocyte differentiation (lipid staining, GPDH activity) and proliferation ([3H]thymidine incorporation) were decreased in the 25 and 75 microM DHEA groups compared with the control and 5 microM DHEA groups. The level of expression of CCAAT enhancer binding protein-alpha, a master regulator of adipogenesis, in cultures of pig SV cells treated with 150 microM DHEA was 38% of control cultures. These data support the hypothesis that DHEA directly attenuates adipogenesis via attenuation of preadipocyte proliferation and differentiation.

Dehydroepiandrosterone reduces proliferation and differentiation of 3T3-L1 preadipocytes

The purpose of these studies was to determine whether the antiobesity actions of dehydroepiandrosterone (DHEA) and DHEA-sulfate (DHEAS) observed in vivo are due to an influence on proliferation and/or differentiation in monolayer cultures of 3T3-L1 preadipocytes. For the proliferation study (Exp. 1), cells were grown in plating medium containing DHEA at 0, 5, 25, 50, or 100 microM for 1-4 d. DHEAS was added at the 100 microM level only. For the differentiation study (Exp. 2), cultures were grown in plating medium containing DHEA at 0, 5, 30, 60, 120, or 240 microM for 2-6 d. DHEAS was added at the 240 microM level only. In Exp. 3, the effect of DHEA on mature adipocytes was determined by exposing adipocytes grown in plating medium to DHEA at 0, 75, 125, and 250 microM for 1-4 d. In Exp. 1, preadipocyte proliferation decreased as the level of DHEA increased in cultures of 3T3-L1 cells. DHEAS had no effect on preadipocyte proliferation. The antiproliferative effect of DHEA was partially reversed by the addition of 1 microM mevalonic acid to proliferating cultures containing 25 microM DHEA. In Exp. 2, preadipocyte differentiation decreased as the level of DHEA in the cultures increased. In contrast, neither DHEAS nor mevalonic acid treatment influenced preadipocyte differentiation decreased as the level and duration of DHEA treatment increased in cultures of mature adipocytes. These data support the hypothesis that DHEA, but not DHEAS, is the active form of the steroid that attenuates obesity via altering preadipocyte proliferation and differentiation. The addition of 1 microM mevalonic acid to cultures of 3T3-L1 preadipocytes partially reversed DHEA's antiproliferative effects.

The effect of dehydroepiandrosterone combined with a low-fat diet in spontaneously obese dogs: a clinical trial

Dehydroepiandrosterone (DHEA) has been shown to have antiobesity activity in rodents and spontaneously obese dogs. This study evaluated the effect of DHEA or placebo combined with a low-fat/high-fiber diet in spontaneously obese dogs in a clinical trial. Spontaneously obese, euthyroid dogs, referred to the University of Wisconsin School of Veterinary Medicine for treatment of their obesity, were evaluated for percent overweight, rate of weight loss, serum cholesterol, plasma lipoprotein and serum biochemistry profiles, complete blood count, and endocrine profiles (T4, T3, cortisol, insulin, and DHEA-sulfate). DHEA-treated dogs had a significantly increased rate of actual and percent excess weight loss compared with placebo-treated dogs. Serum cholesterol decreased in both treatment groups; however, DHEA-treated dogs had a significantly greater reduction than placebo-treated dogs. DHEA-treated dogs had a significant 32% reduction in total plasma cholesterol, which was due to a 27% reduction in the lipoprotein fraction containing the high-density lipoprotein (HDL) and a 50% reduction in the lipoprotein fraction containing the low-density lipoprotein (LDL). Placebo-treated dogs did not have a significant reduction in total plasma cholesterol or in the fraction containing LDL; however, they did have a significant 11% reduction in the fraction containing HDL. Significant decreases in serum T4 and T3 observed in dogs receiving DHEA were not noted in dogs receiving placebo. DHEA in combination with caloric restriction results in a faster rate of weight loss than does caloric restriction alone. In addition, DHEA has hypocholesterolemic activity, particularly affecting the lipoprotein fraction containing the LDL cholesterol.

DHEA protects against visceral obesity and muscle insulin resistance in rats fed a high-fat diet

Visceral obesity is frequently associated with muscle insulin resistance. Rats fed a high-fat diet rapidly develop obesity and insulin resistance. Dehydroepiandrosterone (DHEA) has been reported to protect against the development of obesity. This study tested the hypothesis that DHEA protects against the increase in visceral fat and the development of muscle insulin resistance induced by a high-fat diet in rats. Feeding rats a diet providing 50% of the energy as fat for 4 wk resulted in a twofold greater visceral fat mass and a 50% lower rate of maximally insulin-stimulated muscle 2-deoxyglucose (2-DG) uptake compared with controls. Rats fed the high-fat diet plus 0.3% DHEA were largely protected against the increase in visceral fat (+ 11.3 g in high fat vs. + 2.9 g in high fat plus DHEA, compared with controls) and against the decrease in insulin-stimulated muscle 2-DG uptake (0.94 +/- 0.15 mumol.ml-1.20 min-1, controls; 0.46 +/- 0.06 mumol.ml-1.20 min-1, high-fat diet; 0.78 +/- 0.07 mumol.ml-1.20 min-1, high fat + DHEA). DHEA did not affect food intake. These results show that DHEA has a protective effect against accumulation of visceral fat and development of muscle insulin resistance in rats fed a high-fat diet.

The antiobesity effect of dehydroepiandrosterone in castrated or noncastrated obese Zucker male rats

Although antiobesity effect of dehydroepiandrosterone (DHEA) has been reported in rats, it remains unclear whether the effect is brought about by itself or mediated by sex steroids converted from DHEA in gonads. In the present study, to clarify this point, the effect of DHEA on growth in obese Zucker male rats was reevaluated under two conditions: with or without castration. Castration did not affect the pattern of growth curve of obese Zucker male rats. Three-months treatment of castrated Zucker rats with 0.3% DHEA in the diet resulted in dramatic decrease of body weight gain in comparison to DHEA-untreated and castrated rats. The degree of antiobesity effect of DHEA in castrated rats was almost same as that observed in non-castrated rats. These results suggest that DHEA exerted its antiobesity effect by itself rather than through conversion to testosterone in testis.

Dehydroepiandrosterone and body fat

Dehydroepiandrosterone sulfate (DHEA-S) is the most abundant circulating adrenal steroid in man, yet its physiologic role and that of its parent compound DHEA are unknown. Age-related decreases in DHEA in association with increases in obesity, insulin resistance, and atherosclerosis are well known. Recent investigations in lower mammals (which do not secrete DHEA) have suggested that DHEA (or its metabolites) may function as an antiobesity agent in these models of obesity independent of food intake. Proposed mechanisms for the decrease in fat mass and lower weight gain when DHEA is given orally include increases in futile cycling and peroxisomal beta-oxidation and decreases in de novo lipogenesis. Alterations in the availability of reducing equivalents for lipid synthesis do not appear to explain this decrease. Changes in pancreatic insulin secretion or insulin sensitivity may also be responsible for some of these effects. Studies in humans have failed to demonstrate a beneficial effect of DHEA on body composition or energy expenditure at either pharmacologic or physiologic replacement doses for 1-3 months. Administration of DHEA to men or women has also not been shown to alter insulin sensitivity as measured by the minimal model or the euglycemic clamp technique. The effect of DHEA on peroxisomal beta-oxidation and de novo lipogenesis is not known. We conclude that a significant role for DHEA in the pharmacologic treatment of human obesity is unlikely.

Effect of dehydroepiandrosterone on glucose uptake in cultured human fibroblasts

Dehydroepiandrosterone (DHEA) and its sulfate derivative (DHEA-S) reportedly have antidiabetic and antiobesity effects. The effect of DHEA on glucose uptake in cultured human fibroblasts was examined. Incubation of cells with supraphysiologic concentrations of DHEA (10(-5) mol/L) for > or = 10 hours enhanced 2-deoxyglucose (2-DG) uptake significantly (P < .05). Supraphysiologic concentrations of insulin (10(-7) mol/L) increased the sensitivity of glucose uptake to DHEA. Conversely, the sensitivity of glucose uptake to insulin was increased by incubating cells with 10(-6) mol/L DHEA. Both the abundance of transcripts encoding glucose transporter-1 (Glut-1) and the maximal velocity (Vmax) of 2-DG transport were increased in cultured fibroblasts incubated with DHEA. Cultured fibroblasts expressed a specific binding factor with low affinity for [3H]DHEA (maximal number of binding sites, 18,496 sites per cell; Kd, 298 nmol/L). Other androgen hormones exerted a less-marked effect on glucose uptake; DHEA-S had no effect. These results suggested that DHEA increases Glut-1 mRNA through binding to a specific factor in cultured human fibroblasts and thereby stimulates glucose uptake in these cells.

Individual differences in the macronutrient preference profile of outbred rats: implications for nutritional, metabolic, and pharmacologic studies

While screening outbred male Holtzman Sprague-Dawley rats for their macronutrient (protein, carbohydrate, and fat) preferences, we noticed substantial group-to-group variation in the preference profile. This led us to analyze preference data on two hundred and seventy rats collected over a three-year period to determine whether preferences could be predicted. The results led us to conclude that observed variations in macronutrient preference profiles may be secondary to genetic heterogeneity in the outbred population. We have also shown that the outcome of the pharmacologic effects of two agents (insulin and enterostatin) on appetitive behavior will vary from animal to animal within a single group. Accordingly, researchers must be aware that the breeding history of the laboratory animal is a major factor in the outcome of the experiment and interpretation of the findings.

Diabetes and adrenal disease

Disorders of the adrenal cortex and medulla can result in glucose intolerance or overt diabetes mellitus. Cushing's syndrome, characterized by excessive secretion of glucocorticoids, impairs glucose tolerance primarily by causing insulin resistance at the post-receptor level. On the other hand, phaeochromocytoma and hyperaldosteronism, via the respective actions of catecholamines and hypokalaemia on the pancreatic beta-cell, impair glucose tolerance primarily by inhibiting insulin release. The glucose intolerance associated with these adrenal disorders is usually only mild to moderate in severity. Marked hyperglycaemia, glycosuria, and polyuria are uncommon and ketosis is rare. Moreover, the late complications of diabetes mellitus are distinctly uncommon in patients with these disorders, and the prognosis for morbidity and death is usually that of the underlying disease and not that of diabetes mellitus. The impaired glucose tolerance induced by all three of these adrenal disorders usually returns to normal once the underlying aetiology has been cured. These factors must guide the clinician in treatment of these secondary forms of diabetes, and suggest that tight (near normal) blood glucose control may not be an appropriate goal in patients with these disorders. The relationship between adrenal androgens and glucose tolerance is more uncertain. Several studies in humans have demonstrated an acute decline in serum concentrations of the adrenal steroids DHEA and DHEA-sulfate in response to experimentally-induced hyperinsulinaemia, but the regulatory role of insulin on adrenal androgen metabolism in normal physiology or disease remains speculative. In several animal models DHEA appears to exert potent anti-obesity and anti-diabetogenic actions, but such effects have yet to be demonstrated in humans. Human studies of DHEA are limited, and more research needs to be conducted to determine whether the observations made in animal models will prove applicable to man.

Effects of dietary dehydroepiandrosterone on food intake and body weight in rats with medial hypothalamic knife cuts

Dehydroepiandrosterone (DHEA) is a steroid which has been reported to have anti-obesity effects when added to the diets of rats and mice. In this report, rats made hyperphagic with medial hypothalamic knife cuts were placed on a diet containing 0.45% DHEA or a control diet. Knife cut rats on the control diet ate more food and gained more weight than sham-operated rats on the control diet. In contrast, knife cut rats fed the DHEA diet weighed the same as shams on the DHEA diet and were only observed to be hyperphagic on one of eight 24 hour measurements taken during a five week period. Dietary DHEA reduced food intake and body weight of both knife cut and sham-operated rats, though the effects were smaller in shams. As these effects of DHEA were reminiscent of the effects of dietary quinine adulteration on intake by knife cut rats, a second experiment measured the food intake of unoperated rats when given a choice between a control high-fat diet and one adulterated with various concentrations of DHEA. Even at a concentration of 0.05%, rats clearly identified and avoided the DHEA-adulterated diet. While these results do not rule out effects of DHEA on metabolic rate or lipogenesis, they do indicate that the unpalatability of DHEA-adulterated diets may be a contributing factor in the observed effects on food intake and body weight.