Divergent effect of dehydroepiandrosterone on energy intakes of Zucker rats

Dehydroepiandrosterone sulfate levels predict weight gain in women with anorexia nervosa

OBJECTIVE

Anorexia nervosa (AN) is a serious condition characterized by undernutrition, complicated by endocrine dysregulation, and with few predictors of recovery. Urinary free cortisol (UFC) is a predictor of weight gain, but 24-h urine samples are challenging to collect. We hypothesized that serum dehydroepiandrosterone sulfate (DHEAS), which like cortisol is regulated by adrenocorticotropic hormone (ACTH), would predict weight gain and increases in fat mass in women with AN.

METHODS

We prospectively studied 34 women with AN and atypical AN, mean age 27.4 ± 7.7 years (mean ± SD), who received placebo in a 6-month randomized trial. Baseline DHEAS and 24-h UFC were measured by liquid chromatography with tandem mass spectrometry. Body composition was assessed at baseline and 6 months by DXA and cross-sectional abdominal CT at L4.

RESULTS

Mean baseline DHEAS level was 173 ± 70 μg/dl (0.7 ± 0.3 times the mean normal range for age) and mean baseline UFC (n = 15) was 20 ± 18 μg/24 h (normal: 0-50 μg/24 h). Higher DHEAS levels predicted weight gain over 6 months (r = 0.61, p < .001). DHEAS levels also predicted increases in fat mass (r = 0.40, p = .03), appendicular lean mass (r = 0.38, p = .04), and abdominal adipose tissue (r = 0.60, p < .001). All associations remained significant after controlling for age, baseline BMI, OCP use, duration of AN, and SSRI/SNRI use. DHEAS levels correlated with UFC (r = 0.61, p = .02).

DISCUSSION

In women with AN, higher serum DHEAS predicts weight gain and increases in fat and muscle mass. Additional studies are needed to confirm these findings and further elucidate the association between DHEAS and weight gain.

PUBLIC SIGNIFICANCE

Anorexia nervosa is a severe psychiatric condition, and predictors of weight recovery are needed to improve prognostication and guide therapeutic decision making. While urinary cortisol is a predictor of weight gain, 24-h urine collections are challenging to obtain. Like cortisol, dehydroepiandrosterone sulfate (DHEAS) is a hormone produced by the adrenal glands. As a readily available blood test, DHEAS holds promise as more practical biomarker of weight gain in anorexia nervosa.

Dehydroepiandrosterone on metabolism and the cardiovascular system in the postmenopausal period

Dehydroepiandrosterone (DHEA), mostly present as its sulfated ester (DHEA-S), is an anabolic hormone that naturally declines with age. Furthermore, it is the most abundant androgen and estrogen precursor in humans. Low plasma levels of DHEA have been strongly associated with obesity, insulin resistance, dyslipidemia, and high blood pressure, increasing the risk of cardiovascular disease. In this respect, DHEA could be regarded as a promising agent against metabolic syndrome (MetS) in postmenopausal women, since several age-related metabolic diseases are reported during aging. There are plenty of experimental evidences showing beneficial effects after DHEA therapy on carbohydrate and lipid metabolism, as well as cardiovascular health. However, its potential as a therapeutic agent appears to attract controversy, due to the lack of effects on some symptoms related to MetS. In this review, we examine the available literature regarding the impact of DHEA therapy on adiposity, glucose metabolism, and the cardiovascular system in the postmenopausal period. Both clinical studies and in vitro and in vivo experimental models were selected, and where possible, the main cellular mechanisms involved in DHEA therapy were discussed. Schematic representation showing some of the general effects observed after administration DHEA therapy on target tissues of energy metabolism and the cardiovascular system. ↑ represents an increase, ↓ represents a decrease, - represents a worsening and ↔ represents no change after DHEA therapy.

Appetite and endocrine regulators of energy balance after 2 days of energy restriction: insulin, leptin, ghrelin, and DHEA-S

Using a double-blind, placebo-controlled crossover design, the effects of 48 h near complete energy restriction on endocrine regulators of appetite and satiety were assessed. Twelve men and one woman participated in this controlled, 2-day diet intervention study. One experimental trial was completed in a calorie deprived state (CAL-DEP; <10% of estimated energy requirements) and others in a fed condition (carbohydrate only and carbohydrate and fat; data were pooled and compared to CAL-DEP). Test meals containing prescribed energy intake and indistinguishable in sensory characteristics were provided during each trial. Glucose, insulin, leptin, ghrelin, cortisol, dehydroepiandrosterone-sulfate (DHEA-S), and satiety were repeatedly assessed. Mean glucose, insulin, and leptin concentrations were lower (P < 0.0001) for CAL-DEP compared to the fully fed (FED) state. Ghrelin and DHEA-S were higher (P < 0.0001) for CAL-DEP relative to FED. Cortisol levels declined each day regardless of diet (P < 0.0001) but were 32% higher (P < 0.01) at the conclusion of the session for CAL-DEP compared to FED. Satiety was 25% lower (P < 0.0001) for CAL-DEP relative to FED and decreased (P < 0.0001) over time regardless of diet. In the FED state, insulin (r = 0.55), glucose (r = 0.76), cortisol (r = -0.59), and DHEA-S (r = -0.62) were associated (P < 0.05) with satiety, but not during CAL-DEP. These findings show that 2 days of severe energy restriction alter several endocrine regulators of appetite independent of perception of increased hunger suggesting a physiological mechanism to explain overeating following acute periods of severe energy restriction.

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.

Synergistic anorectic effect of dehydroepiandrosterone and d-Fenfluramine on the obese Zucker rat

Fasted obese, female Zucker rats accustomed to eating a single high fat meal within 1 h a day were treated with intraperitoneal injections of dehydroepiandrosterone (DHEA) and dextrofenfluramine (d-fen), either individually or in combination. Caloric intake was measured over a 1-h period 2 h after drug administration, and results compared to that of vehicle-treated controls. At 50 mg/kg body weight, DHEA did not affect food intake. At doses of < or = 2 mg/kg d-fen did not affect food intake. Together, however, DHEA 50 mg/kg and d-fen < or = 2 mg/kg significantly decreased food intake. At doses of > or = 3 mg/kg d-fen diminished caloric intake by itself, and the addition of DHEA significantly augmented this effect. Neurotransmitter levels in select regions of the hypothalamus of animals treated using a similar drug protocol showed several changes in the levels of serotonin and its metabolite 5 hydroxyindole acetic acid (5-HIAA). It is hypothesized that DHEA augments the production of serotonin while d-fenfluramine enhances its release, and together these two actions may account for the synergistic action of DHEA and d-fenfluramine.

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.

DHEA and DHEA-S: a review

Dehydroepiandrosterone (DHEA) and its sulfated metabolite DHEA-S are endogenous hormones secreted by the adrenal cortex in response to adrenocorticotrophin (ACTH). Much has been published regarding potential effects on various systems. Despite the identification of DHEA and DHEA-S more than 50 years ago, there is still considerable controversy as to their biological significance. This article reviews the metabolism and physiology of DHEA and DHEA-S, the influence of age and gender on concentrations, and changes in endogenous concentrations associated with disease states and other factors, including diet and exercise. This article is unique in that it also summarizes the influence of drugs on DHEA and DHEA-S concentrations, as well as concentrations of DHEA and DHEA-S observed after the administration of DHEA by various routes. Sections of the article specifically address DHEA and DHEA-S concentrations as they relate to stress, central nervous system function and psychiatric disorders, insulin sensitivity, immunological function, and cardiovascular disorders.

Dietary and hypothalamic changes in delta 4-androstenedione-treated Zucker rats

Dehydroepiandrosterone (DHEA) has been shown to alter hypothalamic monoamines and reduce energy intake (EI) in Zucker rats (ZRs). We hypothesized that a metabolite of DHEA, delta 4-Androstenedione (delta 4), may mediate these effects. Male lean and obese ZRs (LZR, OZR) were fed control chow (CC) for 7 days, during which basal EI was recorded, various concentrations of delta 4 for 7 days, during which 0.6 and 0.3% delta 4 reduced EI significantly, and CC for 7 days, which resulted in a return of EI to basal levels. After delta 4 administration, neurotransmitter contents of various hypothalamic areas were determined. Serotonin (5-HT) has been shown to be correlated with feeding inhibition, and we have shown DHEA to increase lateral hypothalamic 5-HT synthesis; however, after 1 day and 7 days of delta 4, the OZR exhibited an increased metabolism, not synthesis, of 5-HT in the lateral and paraventricular hypothalamus, respectively, delta 4 was compared to DHEA in a macronutrient self-selection study with female OZRs. One group was injected intraperitoneally (IP) with sesame oil (control), another with DHEA (100 mg/kg), and another with delta 4 (100 mg/kg). Previous studies have shown that DHEA decreases both EI and % calories from fat. In this study, delta 4 decreased % calories from fat, but did not decrease total EI. Contrary to DHEA's effect of reducing serum insulin through 28 days of treatment, delta 4 in chow reduced insulin only acutely (1 day). We conclude, based on these differences, that DHEA has unique effects not mediated by its metabolite, delta 4-Androstenedione.

A paradoxical elevation of brain cyclo(His-Pro) levels in hyperphagic obese Zucker rats

Several studies suggest a role for endogenous cyclo(His-Pro) or CHP in appetite regulation. In the present study, we have examined the regional brain distribution of CHP in hyperphagic obese Zucker rats and their lean littermates. The data show a significant elevation in the levels of CHP in many brain regions, including hypothalamus of the obese rat. Within the hypothalamus, the lateral hypothalamic (LH) nucleus of obese rats had significantly higher levels of CHP when compared to that of the lean littermates. Administration of dehydroepiandrosterone, a steroid hormone known to decrease food intake and body weight gain, to obese rats led to decrease in the levels of CHP in the LH. These data further suggest a role for the endogenous CHP in attenuating food intake.

Does taste aversion play a role in the effect of dehydroepiandrosterone in Zucker rats?

Dehydroepiandrosterone (DHEA) reduces food intake in obese Zucker rats. To study the role of taste aversion on this process, we used two approaches. First, we presented increasing concentrations of DHEA in chow to lean and obese Zucker rats, either in competition with unadulterated chow, or alone. Second, we examined energy intake following parenteral DHEA administration. Both lean and obese rats always preferred nonadulterated chow to DHEA-supplemented chow. However, lean rats required a higher DHEA concentration (0.06%) than obese rats (0.015%) to achieve the same degree of aversion. When DHEA-supplemented chow was presented alone, only high concentrations (0.3 and 0.6% DHEA) decreased food intake. Rats given DHEA by IP injection (200 mg/kg/day) also decreased their energy intakes. The results demonstrate that although DHEA can cause taste aversion at low concentrations in Zucker rats, it does not alter energy intake until high concentrations are given. In addition, nonoral DHEA also decreases energy intake in these animals. These results suggest that DHEA's antiobesity effect is not mediated by taste aversion.

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.