Estradiol and the control of feeding behavior

This review lays out the evidence for the role of E2 in homeostatic and hedonic feeding across several species. While significant effort has been expended on homeostatic feeding research, more studies for hedonic feeding need to be conducted (i.e. are there increases in meal size and enhanced motivation to natural food rewards). By identifying the underlying neural circuitry involved, one can better delineate the mechanisms by which E2 influences feeding behavior. By utilizing more selective neural targeting techniques, such as optogenetics, significant progress can be made toward this goal. Together, behavioral and physiological techniques will help us to better understand neural deficits that can increase the risk for obesity in the absence of E2 (menopause) and aid in developing therapeutic strategies.

Contribution of S4 segments and S4-S5 linkers to the low-voltage activation properties of T-type CaV3.3 channels

Voltage-gated calcium channels contain four highly conserved transmembrane helices known as S4 segments that exhibit a positively charged residue every third position, and play the role of voltage sensing. Nonetheless, the activation range between high-voltage (HVA) and low-voltage (LVA) activated calcium channels is around 30–40 mV apart, despite the high level of amino acid similarity within their S4 segments. To investigate the contribution of S4 voltage sensors for the low-voltage activation characteristics of Ca_V3.3 channels we constructed chimeras by swapping S4 segments between this LVA channel and the HVA Ca_V1.2 channel. The substitution of S4 segment of Domain II in Ca_V3.3 by that of Ca_V1.2 (chimera IIS4C) induced a ~35 mV shift in the voltage-dependence of activation towards positive potentials, showing an I-V curve that almost overlaps with that of Ca_V1.2 channel. This HVA behavior induced by IIS4C chimera was accompanied by a 2-fold decrease in the voltage-dependence of channel gating. The IVS4 segment had also a strong effect in the voltage sensing of activation, while substitution of segments IS4 and IIIS4 moved the activation curve of Ca_V3.3 to more negative potentials. Swapping of IIS4 voltage sensor influenced additional properties of this channel such as steady-state inactivation, current decay, and deactivation. Notably, Domain I voltage sensor played a major role in preventing Ca_V3.3 channels to inactivate from closed states at extreme hyperpolarized potentials. Finally, site-directed mutagenesis in the Ca_V3.3 channel revealed a partial contribution of the S4-S5 linker of Domain II to LVA behavior, with synergic effects observed in double and triple mutations. These findings indicate that IIS4 and, to a lesser degree IVS4, voltage sensors are crucial in determining the LVA properties of Ca_V3.3 channels, although the accomplishment of this function involves the participation of other structural elements like S4-S5 linkers.

Ectopic ACTH secretion (EAS) associated to a well-differentiated peritoneal mesothelioma: case report

BACKGROUND

The association between mesotheliomas and ectopic ACTH secretion has been rarely reported; we present the first case of ectopic ACTH secretion (EAS) associated with a well-differentiated peritoneal mesothelioma in whom the high dose dexamethasone suppression test (HDDST) results and plasmatic ACTH levels were similar to those found in Cushing's disease (CD).

CASE PRESENTATION

A 43-year-old hispanic woman with a 20 year history of treatment resistant diabetes mellitus and arterial hypertension. She had a full moon face, a buffalo hump, increased volume in both supraclavicular regions, purple striae in her arms and abdomen, truncal obesity, polymenorrhea and umbilical hernia. A cortisol suppression test with low dose dexamethasone (LDDST) with a result of 16.6 μg/dL and ACTH plasma levels were measured at 32.6 pg/mL. The high dose dexamethasone test suppression percentage was 84.8% and magnetic resonance imaging (MRI) showed no evidence of pituitary alterations, computed tomography (CT) showed images suggestive of uterine fibroid and an intra-abdominal tumor that correlated with an umbilical hernia, which reinforcement after contrast. Surgery was performed, finding uterine fibroids and paracolic tumor implants as well as on the omentum, bladder, bowel, ovaries and appendix. Pathology reported a well-differentiated peritoneal mesothelioma with positive immunohistochemistry for ACTH.

CONCLUSIONS

Although most cases of ectopic secretion of ACTH derive from rapidly-developing lung tumors, with very high plasma ACTH levels and cortisol suppression percentages with high doses of dexamethasone under 60%, there is a small percentage of slow-developing, chronic tumors that are biochemically undistinguishable from Cushing's disease. Following the expert recommendations regarding imaging techniques it is possible to identify the associated tumor in most cases.

Ovarian steroids increase spinogenetic proteins in the macaque dorsal raphe

Dendritic spines are the basic structural units of neuronal plasticity. Intracellular signaling cascades that promote spinogenesis have centered on RhoGTPases. We found that ovarian steroids increase gene expression of RhoGTPases [Ras homolog gene family member A (RhoA), cell division control protein 42 homolog (Cdc42), and ras-related C3 botulinum toxin substrate (Rac)] in laser-captured serotonin neurons. We sought to confirm that the increases observed in gene expression translate to the protein level. In addition, a preliminary study was conducted to determine whether an increase in spines occurs via detection of the spine marker protein, postsynaptic density-95 (PSD-95). Adult ovariectomized (Ovx) monkeys were treated with estradiol (E), progesterone (P), or E+P for 1 month. Sections through the dorsal raphe nucleus were immunostained for RhoA and Cdc42 (n=3-4/group). The number and positive pixel area of RhoA-positive cells and the positive pixel area of Cdc42-positive fibers were determined. On combining E- and E+P-treated groups, there was a significant increase in the average and total cell number and positive pixel area of RhoA-positive cells. E, P, and E+P treatments, individually or combined, also increased the average and total positive pixel area of Cdc42-positive fibers. With remaining sections from two animals in each group, we conducted a preliminary examination of the regulation of PSD-95 protein expression. PSD-95, a postsynaptic scaffold protein, was examined with immunogold silver staining (n=2/group), and the total number of PSD-95-positive puncta was determined with stereology across four levels of the dorsal raphe. E, P, and E+P treatment significantly increased the total number of PSD-95-positive puncta. Together, these findings indicate that ovarian steroids act to increase gene and protein expression of two pivotal RhoGTPases involved in spinogenesis and preliminarily indicate that an increased number of spines and/or synapses result from this action. Increased spinogenesis on serotonin dendrites would facilitate excitatory glutamatergic input and in turn, increase serotonin neuronal activity throughout the brain.