Estrogen deficiency causes central leptin insensitivity and increased hypothalamic neuropeptide Y (original) (raw)
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The Journal of Nutritional Biochemistry, 2004
Estradiol is a potent hypophagic agent that reduces food intake and body weight without a concomitant fall in plasma leptin levels. We investigated whether the hypophagic effect of estradiol is mediated by stimulating POMC and/or inhibiting NPY neuronal pathways in the hypothalamus, which respectively inhibit and stimulate feeding. We examined hypothalamic gene expression of Ob-Rb, NPY, POMC, MC4-R, and AgRP in intact Wistar rats treated with estradiol for 48 hours. Food intake and body weight were reduced in estradiol-treated rats but fat mass was unchanged; plasma leptin and insulin levels were not significantly different from untreated, freely fed controls. In untreated rats that were pair-fed to match the estradiol-treated group, body weight was also reduced without changes in fat mass, although leptin and insulin levels decreased significantly. Ob-Rb expression was increased in both hypophagic groups despite serum leptin were only decreased in pair-fed animals, suggesting an estradiol-stimulating effect on Ob-Rb expression. No significant differences were found in POMC, AgRP, or MC4-R expression among any of the experimental groups. A significant but small decrease in NPY expression was also found in both hypophagic groups; this was explained by the combined effect of both surgery and reduced food intake. These results indicate that estradiol mediated hypophagia in intact rats could be brought about by an enhanced hypothalamic leptin sensitivity but is unlikely to be driven by changes in NPY or melanocortin system.
Endocrinology, 2014
Several studies have shown that estrogens mimic leptin's effects on energy balance regulation. However, the findings regarding the consequences of reduced sex hormone levels on leptin sensitivity are divergent. In the present study, we employed different experimental paradigms to elucidate the interaction between estrogens, leptin, and energy balance regulation. We confirmed previous reports showing that ovariectomy caused a reduction in locomotor activity and energy expenditure leading mice to obesity and glucose intolerance. However, the acute and chronic anorexigenic effects of leptin were preserved in ovariectomized (OVX) mice despite their increased serum leptin levels. We studied hypothalamic gene expression at different time points after ovariectomy and observed that changes in the expression of genes involved in leptin resistance (suppressors of cytokine signaling and protein-tyrosine phosphatases) did not precede the early onset of obesity in OVX mice. On the contrary, ...
Laboratory animal research, 2013
The integration of metabolism and reproduction involves complex interactions of hypothalamic neuropeptides with metabolic hormones, fuels, and sex steroids. Of these, estrogen influences food intake, body weight, and the accumulation and distribution of adipose tissue. In this study, the effects of estrogen on food intake, serum leptin levels, and leptin mRNA expression were evaluated in ovariectomized rats. Seven-week-old female Wistar-Imamichi rats were ovariectomized and divided into three treatment groups: group 1 (the control group) received sesame oil, group 2 was given 17β-estradiol benzoate, and group 3 received 17β-estradiol benzoate plus progesterone. The body weight and food consumption of each rat were determined daily. Serum leptin levels and leptin mRNA expression were measured by ELISA and quantitative RT-PCR, respectively. Food consumption in the control group was significantly higher (P<0.05) than that in groups 2 and 3, although body weight did not significantly...
European Journal of Endocrinology, 2001
Objectives: For adipostatic control, increases in food intake are followed by increased leptin levels that in turn reduce food intake. However, progesterone administration increases both food intake and body weight. The aim of this study was to analyze changes in the white adipose tissue±leptin system in rats with enhanced plasma levels of progesterone. Methods: Female Wistar rats received progesterone chronically by means of subcutaneous implants over 30 days. Results: They showed an increased food intake followed by increased body weight and heavier fat depots. An enhanced ob-mRNA level was detected in inguinal white adipose tissue depot on day 2 of treatment but the increase was transient, disappearing on day 6 of treatment. No changes in ob-mRNA levels were found in parametrial and retroperitoneal white adipose tissue depots. Plasma and cerebrospinal fluid leptin levels were unchanged either during the treatment or between corresponding treated and control rats. Leptin concentrations in cerebrospinal fluid were ten times lower than in plasma (0.2±0.3 ng/ml versus 2±3 ng/ml respectively). Conclusions: These results indicated that progesterone favours a positive energy balance not only by enhancing food intake but also by inhibiting the concurrent enhancement in plasma and cerebrospinal fluid leptin levels expected from the increased fat mass.
American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, 2001
Otsuka Long-Evans Tokushima Fatty (OLETF) rats lacking CCK-A receptors are hyperphagic, obese, and diabetic. We have previously demonstrated that these rats have a peripheral satiety deficit resulting in increased meal size. To examine the potential role of hypothalamic pathways in the hyperphagia and obesity of OLETF rats, we compared patterns of hypothalamic neuropeptide Y (NPY), proopiomelanocortin (POMC), and leptin receptor mRNA expression in ad libitum-fed Long-Evans Tokushima (LETO) and OLETF rats and food-restricted OLETF rats that were pair-fed to the intake of LETO controls. Pair feeding OLETF rats prevented their increased body weight and elevated levels of plasma insulin and leptin and normalized their elevated POMC and decreased NPY mRNA expression in the arcuate nucleus. In contrast, NPY expression was upregulated in the dorsomedial hypothalamus (DMH) in pair-fed OLETF rats. A similar DMH NPY overexpression was evident in 5-wk-old preobese OLETF rats. These findings su...
Diabetes, 1996
Correction of the obese state induced by genetic leptin deficiency reduces elevated levels of both blood glucose and hypothalamic neuropeptide Y (NPY) mRNA in ob/ob mice. To determine whether these responses are due to a specific action of leptin or to the reversal of the obese state, we investigated the specificity of the effect of systemic leptin administration to ob/ob mice (ji = 8) on levels of plasma glucose and insulin and on hypothalamic expression of NPY mRNA. Saline-treated controls were either fed ad libitum (n = 8) or pair-fed to the intake of the leptin-treated group (ji = 8) to control for changes of food intake induced by leptin. The specificity of the effect of leptin was further assessed by 1) measuring NPY gene expression in db/db mice (ji = 6) that are resistant to leptin, 2 ) measuring NPY gene expression in brain areas outside the hypothalamus, and 3 ) measuring the effect of leptin administration on hypothalamic expression of corticotropin-releasing hormone (CRH) mRNA. Five daily intraperitoneal injections of recombinant mouse leptin (150 |xg) in 06/06 mice lowered food intake by 56% (P < 0.05), body weight by 4.1% (P < 0.05), and levels of NPY mRNA in the hypothalamic arcuate nucleus by 42.3% (P < 0.05) as compared with saline-treated controls. Pairfeeding of 06/06 mice to the intake of leptin-treated animals produced equivalent weight loss, but did not alter expression of NPY mRNA in the arcuate nucleus. Leptin administration was also without effect on food intake, body weight, or NPY mRNA levels in the arcuate nucleus of db/db mice. In 06/06 mice, leptin did not alter NPY mRNA levels in cerebral cortex or hippocampus or the expression of CRH mRNA in the hypothalamic paraventricular nucleus (PVN). Leptin administration to 06/06 mice also markedly reduced serum glucose (8.3 ± 1.2 vs. 24.5 ± 3.8 mmol/L; P < 0.01) and insulin levels (7,263 ± 1,309 vs. 3,150 ± 780 pmol/1), but was ineffective in db/db Zymogenetics Corporation is a wholly owned subsidiary of Novo Nordisk A/S, a manufacturer of therapeutics for the treatment of diabetes.
Steroids, 2010
We evaluated the interplay among estrogen, leptin and thyroid function in the regulation of body mass in female rats. Adult female rats were divided into four groups: control (C, sham-operated), ovariectomized (OVX), ovariectomized treated with estradiol benzoate (Eb) 0.7 or 14 g/100 g bw per day, during 21 days. OVX led to an increase in body mass, food intake and food efficiency (change in body mass as function of the amount of food ingested) which were normalized by the lower Eb dose, and decreased significantly when the higher dose was given. Serum leptin levels were increased more than two-fold in all ovariectomized groups. Serum T4 levels of the Eb treated OVX were significantly lower than in the controls. Serum T3 and TSH were unaffected by OVX or by Eb treatment. Uterine type 2 iodothyronine deiodinase (D2) activity changed in parallel with serum estradiol: decreased after OVX, returned to control levels after the lower E2 treatment, and increased significantly after the high Eb dosage. The hypothalamic D2 activity was reduced around 30% in all castrated groups, treated or not with estrogen, whereas in the brown adipose tissue the enzyme was not changed. Interestingly, although estrogen-treated OVX rats had lower body weight, serum leptin was high, suggesting that estrogen increases leptin secretion. Our results show that estradiol is necessary for the hypothalamic action of leptin, since the increase in leptin levels observed in all ovariectomized rats was associated with a decrease in food intake and food efficiency only in the rats treated with estrogen.
Endocrine, 2003
Estradiol has been implicated in the regulation of food intake; however, its effect seems to be exerted in a bimodal fashion. We examined whether a single im injection of estradiol valerate (E2V), lastingly effective, could induce changes in parametrial fat function that further induce a new set point of leptin sensitivity in the female rat. E2V induced severe anorexia and loss of body weight between d 4 and 12 posttreatment. E2V rats recovered normal food intake and departing body weights on wk 2 and 3 posttreatment, respectively; however, they did not reach body weights of control rats. On d 61 posttreatment, we found that unfasting E2V, vs control, rats displayed increased E2 and leptin circulating levels; reduced plasma tumor necrosis factor-alpha(TNF-alpha) concentrations; similar circulating levels of glucose, insulin, and triglyceride; and lower parametrial fat mass containing a higher number of adipocytes that, although normal in size, in vitro released more leptin. Metaboli...