Context The role of diet composition in response to overeating and energy dissipation in humans is unclear. Objective To evaluate the effects of overconsumption of low, normal, and high protein diets on weight gain, energy expenditure, and body composition. Design, Setting, and Participants A single-blind, randomized controlled trial of 25 US healthy, weight-stable male and female volunteers, aged 18 to 35 years with a body mass index between 19 and 30. The first participant was admitted to the inpatient metabolic unit in June 2005 and the last in October 2007. Intervention After consuming a weight-stabilizing diet for 13 to 25 days, participants were randomized to diets containing 5% of energy from protein (low protein), 15% (normal protein), or 25% (high protein), which they were overfed during the last 8 weeks of their 10- to 12-week stay in the inpatient metabolic unit. Compared with energy intake during the weight stabilization period, the protein diets provided approximately 40% more energy intake, which corresponds to 954 kcal/d (95% CI, 884–1022 kcal/d). Main Outcome Measures Body composition was measured by dual-energy x-ray absorptiometry biweekly, resting energy expenditure was measured weekly by ventilated hood, and total energy expenditure by doubly labeled water prior to the overeating and weight stabilization periods and at weeks 7 to 8. Results Overeating produced significantly less weight gain in the low protein diet group (3.16 kg; 95% CI, 1.88–4.44 kg) compared with the normal protein diet group (6.05 kg; 95% CI, 4.84–7.26 kg) or the high protein diet group (6.51 kg; 95% CI, 5.23–7.79 kg) (P=.002). Body fat increased similarly in all 3 protein diet groups and represented 50% to more than 90% of the excess stored calories. Resting energy expenditure, total energy expenditure, and body protein did not increase during overfeeding with the low protein diet. In contrast, resting energy expenditure (normal protein diet: 160 kcal/d [95% CI, 102–218 kcal/d]; high protein diet: 227 kcal/d [95% CI, 165–289 kcal/d]) and body protein (lean body mass) (normal protein diet: 2.87 kg [95% CI, 2.11–3.62 kg]; high protein diet: 3.18 kg [95% CI, 2.37–3.98 kg]) increased significantly with the normal and high protein diets. Conclusions Among persons living in a controlled setting, calories alone account for the increase in fat; protein affected energy expenditure and storage of lean body mass, but not body fat storage.

This review is intended to assess the state of current knowledge on the role of estrogen receptors (ERs) in the neuroprotective effects of estrogens in models for acute neuronal injury and death. We evaluate the overall evidence that estrogens are neuroprotective in acute injury and critically assess the role of ERα, ERβ, GPR 30, and nonreceptor-mediated mechanisms in these robust neuroprotective effects of this ovarian steroid hormone. We conclude that all three receptors, as well as nonreceptor-mediated mechanisms can be involved in neuroprotection, depending on the model used, the level of estrogen administrated, and the mode of administration of the steroid. Also, the signaling pathways used by both ER-dependent and ER-independent mechanisms to exert neuroprotection are considered. Finally, further studies that are needed to parse out the relative contribution of receptor versus nonreceptor-mediated signaling are discussed.

Background: Energy expenditure (EE) increases with overfeeding, but it is unclear how rapidly this is related to changes in body composition, increased body weight, or diet. Objective: The objective was to quantify the effects of excess energy from fat or protein on energy expenditure of men and women living in a metabolic chamber. Design: We conducted a randomized controlled trial in 25 participants who ate w40% excess energy for 56 d from 5%, 15%, or 25% protein diets. Twenty-four-hour EE (24EE) and sleeping EE (SleepEE) were measured on days 1, 14, and 56 of overfeeding and on day 57 while consuming the baseline diet (usually day 57). Metabolic and molecular markers of muscle metabolism were measured in skeletal muscle biopsy specimens. Results: In the low-protein diet group whose excess energy was fat, the 24EE and SleepEE did not increase during the first day of overfeeding. When extra energy contained protein, both 24EE and SleepEE increased in relation to protein intake (r = 0.50, P = 0.02). The 24EE over 8 wk in all 3 groups was correlated with protein intake (r = 0.60, P = 0.004) but not energy intake (r = 0.16; P = 0.70). SleepEE was unchanged by overfeeding in the low-protein diet group, and baseline surface area predicted increased 24EE in this group. Protein and fat oxidation were reciprocally related during overfeeding. Observed 24EE was higher than predicted on days 1 (P # 0.05), 14 (P = 0.0001), and 56 (P = 0.0007). There was no relation between change in fat mass and change in EE. Conclusions: Excess energy, as fat, does not acutely increase 24EE, which rises slowly as body weight increases. Excess energy as protein acutely stimulates 24EE and SleepEE. The strongest relation with change in 24EE was the change in energy expenditure in tissue other than muscle or fat-free mass. This trial was registered at clinicaltrials.gov as NCT00565149.Am J Clin Nutr 2015; 101:496-505.

Arginine vasopressin (AVP) and oxytocin (OXY) are released by magnocellular neurosecretory cells that project to the posterior pituitary. While AVP and OXY currently receive more attention for their contributions to affiliative behavior, this mini-review discusses their roles in cardiovascular function broadly defined to include indirect effects that influence cardiovascular function. The traditional view is that neither AVP nor OXY contributes to basal cardiovascular function, although some recent studies suggest that this position might be re-evaluated. More evidence indicates that adaptations and neuroplasticity of AVP and OXY neurons contribute to cardiovascular pathophysiology.

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Hyponatremia is the most frequently occurring electrolyte disorder encountered and is an independent risk factor for increased mortality in liver failure patients. Dilutional hyponatremia seen in liver failure is due to inappropriate arginine vasopressin (AVP) release and can be studied using animal model of bile duct ligation (BDL). Our previous studies to address the knowledge gap of sex differences in this model showed that unlike male BDL rats, female and ovariectomized (OVX) BDL rats did not develop hyponatremia, supraoptic AVP neuron activation, or increased copeptin (CPP), a surrogate to measure AVP, secretion compared to sham ligated females. Interestingly, we also found an increased adrenal estradiol (E2) concentration that could explain the increased plasma E2 observed in OVX BDL rats. An intracerebroventricular infusion of estrogen receptor (ER) antagonist, ICI 182,780 (ICI) in female BDL rats increased CPP concentration compared to BDL‐vehicle and sham groups. These data suggest ER involvement in the prevention of BDL‐induced hyponatremia in female rats. However, ICI is also a G protein‐coupled estrogen receptor 1 (GPER) agonist at high concentrations. We tested GPER expression within the hypothalamo‐neurohypophyseal system of female rats to further elucidate the role of ER in this model. Adult female Sprague‐Dawley rats (n=6) were anesthetized with inactin (100 mg/kg ip) and transcardially perfused with 4% paraformaldehyde and brains harvested. Double‐immunostaining was performed on three separate sets of coronal sections (40μm thick) of forebrain containing PVN and SON. All sets were processed for GPER using polyclonal rabbit anti‐GPER (1:1000, Abcam) and Cy3 donkey anti‐rabbit (1:500, Jackson ImmunoResearch). First set: GPER and AVP, using polyclonal guinea pig anti‐AVP (1:10000, Peninsula Laboratories) and Cy2 donkey anti‐guinea pig (1:500, Jackson ImmunoResearch). Second set: GPER and oxytocin (OXY), using monoclonal mouse anti‐oxytocin (1:5000, Millipore) and Cy2 donkey anti‐mouse (1:500, Jackson ImmunoResearch). Third set: GPER and glial fibrillary acidic protein (GFAP), using monoclonal mouse anti‐GFAP (1:1000, Millipore) and Cy2 donkey anti‐mouse (1:500, Jackson ImmunoResearch). Images of the sections were captured using an Olympus BX41 fluorescence microscope. Co‐localization of GPER+AVP and GPER+OXY was observed in a subpopulation of neurons in the PVN and SON of all rats. Unilateral SON counts for co‐localization: GPER+AVP, 64.8% and GPER+OXY, 64.0%. GPER+GFAP co‐localization was not observed in either region of interest. To conclude, GPER is expressed on a subset of AVP and OXY neurons and not astrocytes in the hypothalamo‐neurohypophyseal system of female rats. Future studies combining GPER antagonist and ICI in this model of hyponatremia will provide further insight toward mechanisms underlying sex differences in hyponatremia related to liver failure. Support or Funding Information NHLBI R01 HL142341, NIH 2 T32 AG020494‐16A1

Arginine Vasopressin (AVP) and oxytocin (OXY) contribute to body fluid balance homeostasis. Salt loading (2% NaCl for 7 days) increases both AVP and OXY release in rats. The chronic increase in AVP release is associated with a change in the sensitivity of AVP neurons in the supraoptic nucleus (SON) to GABA so that GABAA receptor activation becomes excitatory. It is not clear if a similar mechanism is associated with chronic OXY release in this model. Our hypothesis is that changes in chloride homeostasis associated with salt loading occur in OXY neurons. To test this hypothesis, we used a chloride imaging approach with a ratiometric chloride sensitive dye, ClopHensorN (Addgene #50758) combined with an AAV with an oxytocin specific promoter (pFBOT563, Addgene # 40864). Adult, intact, Sprague Dawley rats of both sexes were anesthetized with isoflurane (2‐3%) and were bilaterally injected with the AAV2‐pFBOT‐‐ClophensorN virus directly into the SON. After a two‐week recovery period, the animals were sacrificed and the brains were rapidly removed. The SON was dissected away from the brain and the cells were dissociated, plated on cover slips, and incubated for two hours. After incubation, recordings were taken using ratiometric live cell imaging on an inverted microscope. Selected neurons were sequentially excited at 445nm and 556nm and then emission data was collected between 500‐550nm and 580‐653nm respectively. After 40 cycles of 3‐second recordings, muscimol (100nM), a GABAA receptor agonist was transiently applied to the cells and then allowed to wash off. Background fluorescence was subtracted. In cells from males, muscimol resulted in chloride influx in 50% of the OXY cells tested while chloride influx was observed in all OXY cells tested from females. The results suggest that salt loading may influence GABA responses of OXY neurons in males but not females.