Estrogen receptor–α in medial amygdala neurons regulates body weight

Estrogen receptor–α (ERα) activity in the brain prevents obesity in both males and females. However, the ERα-expressing neural populations that regulate body weight remain to be fully elucidated. Here we showed that single-minded–1 (SIM1) neurons in the medial amygdala (MeA) express abundant levels of ERα. Specific deletion of the gene encoding ERα (Esr1) from SIM1 neurons, which are mostly within the MeA, caused hypoactivity and obesity in both male and female mice fed with regular chow, increased susceptibility to diet-induced obesity (DIO) in males but not in females, and blunted the body weight–lowering effects of a glucagon-like peptide-1–estrogen (GLP-1–estrogen) conjugate. Furthermore, selective adeno-associated virus-mediated deletion of Esr1 in the MeA of adult male mice produced a rapid body weight gain that was associated with remarkable reductions in physical activity but did not alter food intake. Conversely, overexpression of ERα in the MeA markedly reduced the severity of DIO in male mice. Finally, an ERα agonist depolarized MeA SIM1 neurons and increased their firing rate, and designer receptors exclusively activated by designer drug–mediated (DREADD-mediated) activation of these neurons increased physical activity in mice. Collectively, our results support a model where ERα signals activate MeA neurons to stimulate physical activity, which in turn prevents body weight gain

PI3K in the ventromedial hypothalamic nucleus mediates estrogenic actions on energy expenditure in female mice

Estrogens act in the ventromedial hypothalamic nucleus (VMH) to regulate body weight homeostasis. However, the molecular mechanisms underlying these estrogenic effects are unknown. We show that activation of estrogen receptor-α (ERα) stimulates neural firing of VMH neurons expressing ERα, and these effects are blocked with intracellular application of a pharmacological inhibitor of the phosphatidyl inositol 3-kinase (PI3K). Further, we demonstrated that mice with genetic inhibition of PI3K activity in VMH neurons showed a sexual dimorphic obese phenotype, with only female mutants being affected. In addition, inhibition of VMH PI3K activity blocked effects of 17β-estradiol to stimulate energy expenditure, but did not affect estrogen-induced anorexia. Collectively, our results indicate that PI3K activity in VMH neurons plays a physiologically relevant role in mediating estrogenic actions on energy expenditure in females

SRC-1 Regulates Blood Pressure and Aortic Stiffness in Female Mice

<div><p>Framingham Heart Study suggests that dysfunction of steroid receptor coactivator-1 may be involved in the development of hypertension. However, there is no functional evidence linking steroid receptor coactivator-1 to the regulation of blood pressure. We used immunohistochemistry to map the expression of steroid receptor coactivator-1 protein in mouse brain, especially in regions implicated in the regulation of blood pressure. Steroid receptor coactivator-1 protein was found in central amygdala, medial amygdala, supraoptic nucleus, arcuate nucleus, ventromedial, dorsomedial, paraventricular hypothalamus, and nucleus of the solitary tract. To determine the effects of steroid receptor coactivator-1 protein on cardiovascular system we measured blood pressures, blood flow velocities, echocardiographic parameters, and aortic input impedance in female steroid receptor coactivator-1 knockout mice and their wild type littermates. Steroid receptor coactivator-1 knockout mice had higher blood pressures and increased aortic stiffness when compared to female wild type littermates. Additionally, the hearts of steroid receptor coactivator-1 knockout mice seem to consume higher energy as evidenced by increased impedance and higher heart rate pressure product when compared to female wild type littermates. Our results demonstrate that steroid receptor coactivator-1 may be functionally involved in the regulation of blood pressure and aortic stiffness through the regulation of sympathetic activation in various neuronal populations.</p></div

Cardiac flow velocity indices.

<p>Peak aortic outflow velocity (<b>A</b>), peak mitral-E flow velocity (<b>B</b>), peak mitral-A flow velocity (<b>C</b>) and mitral E/A ratio (<b>D</b>) obtained from cardiac Doppler flow velocity signals in female WT and SRC-1-KO mice. Data are presented as mean±SEM (n = 4-6/group); <b>*</b>—p<i><</i> 0.05. The information supporting this figure is in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0168644#pone.0168644.s004" target="_blank">S4 Dataset</a>.</p

Validation of SRC-1-KO mice.

<p>3,3′-diaminobenzidine immunohistochemistry staining for SRC-1 in the medial amygdala of female WT (<b>A</b>) or SRC-1-KO (<b>B</b>) mice. OPT, optic tract; MeA, medial amygdala. Scale bar = 100 μm.</p

Loss of SRC-1 in female mice results in aortic stiffness.

<p>Parameters of aortic impedance in female WT and SRC-1-KO mice. Total peripheral resistance, Z_P (<b>A</b>), impedance at first harmonic, Z₁ (<b>B</b>), characteristic impedance, Z_C (<b>C</b>), and impedance based pulse wave velocity, PWV_Z (<b>D</b>). Data are presented as mean±SEM (n = 4-6/group); <b>* =</b> p<i><</i> 0.05. The information supporting this figure is in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0168644#pone.0168644.s005" target="_blank">S5 Dataset</a>.</p

Expression of SRC-1 in the brain.

<p>Immunofluorescence staining of SRC-1 in various brain regions of WT female mice. 3V, third ventricle; ARC, arcuate nucleus of the hypothalamus; CeA, central amygdala; DMH, dorsal medial nucleus of the hypothalamus; MeA, medial amygdala; NTS, the nucleus of the solitary tract; OPT, optic tract; PVN, paraventricular nucleus of the hypothalamus; Sch, suprachiasmatic nucleus; SON, supraoptic nucleus; VMH, ventromedial nucleus of the hypothalamus (VMH). Scale bars = 100 μm.</p

Echocardiographic parameters of female WT and SRC-1 KO mice.

<p>Echocardiographic parameters of female WT and SRC-1 KO mice.</p

Aortic blood pressure and rate pressure product.

<p>Aortic blood pressure parameters of female WT and SRC-1-KO mice. (<b>A</b>) Systolic blood pressure (SBP), (<b>B</b>) Diastolic blood pressure (DBP), (<b>C</b>) Mean blood pressure (MBP), (<b>D</b>) Pulse pressure, (<b>E</b>) Heart rate, and (<b>F</b>) Rate pressure product (RPP). Data are presented as mean±SEM (n = 5-7/group); <b>*</b>—p<i><</i> 0.05. The information supporting this figure is in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0168644#pone.0168644.s001" target="_blank">S1 Dataset</a>.</p

Diameter of the aortic arch.

<p>Representative B-mode images of aortic arch in female WT (<b>A</b>) and SRC-1-KO (<b>B</b>) mice. Quantification (<b>C</b>) revealed a decrease in diameter of the aortic arch in SRC-1-KO mice. Data are presented as mean±SEM (n = 4-5/group); <b>*</b>—p<i><</i> 0.05. The information supporting this figure is in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0168644#pone.0168644.s003" target="_blank">S3 Dataset</a>.</p