Differential interaction of estrogen receptor and thyroid hormone receptor isoforms on the rat oxytocin receptor promoter leads to differences in transcriptional regulation

Both the estrogen receptor (ER) and thyroid hormone receptor (TR) are members of the nuclear receptor superfamily. Two isoforms of the ER, alpha and beta, exist. The TRalpha and beta isoforms are products of two distinct genes that are further differentially spliced to give TRalpha1 and alpha2, TRbeta1 and beta2. The TRs have been shown to interfere with ER-mediated transcription from both the consensus estrogen response element (ERE) and the rat preproenkephalin (PPE) promoter, possibly by competing with ER binding to the ERE or by squelching coactivators essential for ER-mediated transcription. The rat oxytocin receptor (OTR) gene is thought to be involved in several facets of reproductive and affiliative behaviors. 17beta-Estradiol-bound ERs upregulate the OTR gene in the ventromedial hypothalamus, a region critical for the induction of lordosis behavior in several species. We investigated the effects of the ligand-binding TR isoforms on the ER-mediated transcription from a physiological promoter of a behaviorally relevant gene such as the OTR. Only ERalpha could induce the OTR gene in two cell lines tested, the CV-1 and the SK-N-BE2C neuroblastoma cell lines. ERbeta was incapable of inducing the gene in either cell line. ERalpha is therefore not equivalent to ERbeta on this physiological promoter. Indeed, in the neural cell line, ERbeta can inhibit ERalpha-mediated induction from the OTR promoter. While the TRalpha1 isoform inhibited ERalpha-mediated induction in the neural cell line, the TRbeta1 isoform stimulated induction, thus demonstrating isoform specificity in the interaction. The use of a DNA-binding mutant, the TR P box mutant, showed that inhibition of ERalpha-mediated induction of the rat OTR gene promoter by the TRalpha1 isoform does not require DNA-binding ability. SRC-1 overexpression relieved TRalpha1-mediated inhibition in both cell lines, suggesting that squelching for coactivators is an important molecular mechanism in TRalpha-mediated inhibition. Such interactions between TR and ER isoforms on the rat OTR promoter provide a mechanism to achieve neuroendocrine integration.

Serum oxytocin concentrations in elective caesarean delivery: a randomized comparison of three infusion regimens

Background: The aim of this study was to determine serum oxytocin concentrations following different regimens of prophylactic oxytocin administration in women undergoing elective caesarean delivery. Methods: Thirty healthy pregnant patients were randomized, after clamping of the umbilical cord, to receive intravenous oxytocin in one of the following groups: G1 (n = 9), 10 IU of oxytocin infused over 30 min (0.33 IU/min); G2 (n = 11), 10 IU of oxytocin infused over 3 min and 45 s (2.67 IU/min); and G3 (n = 10), 80 IU of oxytocin infused over 30 min (2.67 IU/min). Both patient and surgeon were blinded to allocation. Uterine tone was assessed by surgical palpation. Serum oxytocin concentration was determined by enzyme immunoassay before anaesthesia (T0) and at 5 (T5), 30 (T30) and 60 (T60) min after the start of oxytocin infusion. Results: Serum oxytocin concentrations (mean standard error, ng/mL) were not significantly different in the groups at T0 (0.06 +/- 0.02, 0.04 +/- 0.02 and 0.07 +/- 0.04, respectively, P = 0.76), and T60 (0.65 +/- 0.26, 0.36 +/- 0.26 and 0.69 +/- 0.26, respectively, P = 0.58). G3 showed higher concentrations than G1 at 15 (3.65 +/- 0.74 versus 0.71 +/- 0.27, P = 0.01) and at T30 (6.19 +/- 1.19 versus 1.17 +/- 0.37, P < 0.01), and were higher than G2 at T30 (6.19 +/- 1.19 versus 0.41 +/- 0.2, P < 0.01). Haemodynamic data and uterine tone were considered satisfactory and similar in all groups. No additional uterotonic agents were needed. Conclusion: Serum oxytocin measurements made using enzyme immunoassay in healthy pregnant women undergoing elective caesarean delivery showed that administration of 80 IU oxytocin over 30 min resulted in higher serum oxytocin levels after 5 and 30 min than the two other regimens. The concentrations did not differ between groups at 60 min. (C) 2011 Elsevier Ltd. All rights reserved.

Bradykinin B(1) receptor antagonist R954 inhibits eosinophil activation/proliferation/migration and increases TGF-beta and VEGF in a murine model of asthma

In the present study the effects of bradykinin receptor antagonists were investigated in a murine model of asthma using BALB/c mice immunized with ovalbumin/alum and challenged twice with aerosolized ovalbumin. Twenty four hours later eosinophil proliferation in the bone marrow, activation (lipid bodies formation), migration to lung parenchyma and airways and the contents of the pro-angiogenic and pro-fibrotic cytokines TGF-beta and VEGF were determined. The antagonists of the constitutive B(2) (HOE 140) and inducible B(1) (R954) receptors were administered intraperitoneally 30 min before each challenge. In sensitized mice, the antigen challenge induced eosinophil proliferation in the bone marrow, their migration into the lungs and increased the number of lipid bodies in these cells. These events were reduced by treatment of the mice with the B(1) receptor antagonist. The B(2) antagonist increased the number of eosinophils and lipid bodies in the airways without affecting eosinophil counts in the other compartments. After challenge the airway levels of VEGF and TGF-beta significantly increased and the B(1) receptor antagonist caused a further increase. By immunohistochemistry techniques TGF-beta was found to be expressed in the muscular layer of small blood vessels and VEGF in bronchial epithelial cells. The B(1) receptors were expressed in the endothelial cells. These results showed that in a murine model of asthma the B(1) receptor antagonist has an inhibitory effect on eosinophils in selected compartments and increases the production of cytokines involved in tissue repair. It remains to be determined whether this effects of the B(1) antagonist would modify the progression of the allergic inflammation towards resolution or rather towards fibrosis. (C) 2009 Elsevier Ltd. All rights reserved.

Endothelin A receptor antagonist modulates lymphocyte and eosinophil infiltration, hyperreactivity and mucus in murine asthma

Levels of endothelins are particularly high in the lung, and there is evidence that these peptides are involved in asthma. Asthma is a chronic inflammatory disease associated with lymphocyte infiltration. In the present study, we used a murine model of asthma to investigate the role of endothelins in lymphocyte and eosinophil infiltration into the airway hyperreactivity and mucus secretion. Sensitized C57B1/6 mice were treated with endothelin ET(A) receptor antagonist (BQ123) or endothelin ET(B) receptor antagonist (BQ788) 30 min before an antigen aerosol challenge. After 24 h, dose response curves to methacholine were performed in isolated lungs, FACS analysis of lymphocytes and eosinophil counts were performed in bronchoalveolar lavage fluid and mucus index was determined by histopathology. In sensitized and antigen-challenged mice there is a marked increase in the T CD(4)(+), T CD(8)(+), B220(+), T gamma delta(+) and NK1.1(+) lymphocyte subsets. Treatment with BQ123 further increased these cell populations. The number of eosinophils, airway hyperreactivity and mucus were all reduced by BQ123 treatment. The BQ788 had no significant effect on the parameters analyzed. Treatment with BQ123 reduced the endothelin concentration in lung homogenates, suggesting that endothelins exert a positive feedback on their synthesis. We show here that in murine asthma the ET(A) receptor antagonist up-regulates lymphocyte infiltration and reduces eosinophils, hyperreactivity and mucus. (C) 2008 Elsevier B.V. All rights reserved.

Brainstem oxytocinergic modulation of heart rate control in rats: effects of hypertension and exercise training

Oxytocinergic brainstem projections participate in the autonomic control of the circulation. We investigated the effects of hypertension and training on cardiovascular parameters after oxytocin (OT) receptor blockade within the nucleus tractus solitarii (NTS) and NTS OT and OT receptor expression. Male spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats were trained (55% of maximal exercise capacity) or kept sedentary for 3 months and chronically instrumented (NTS and arterial cannulae). Mean arterial blood pressure (MAP) and heart rate (HR) were measured at rest and during an acute bout of exercise after NTS pretreatment with vehicle or OT antagonist (20 pmol of OT antagonist (200 nl of vehicle)-1). Oxytocin and OT receptor were quantified (35S-oligonucleotide probes, in situ hybridization) in other groups of rats. The SHR exhibited high MAP and HR (P < 0.05). Exercise training improved treadmill performance and reduced basal HR (on average -11%) in both groups, but did not change basal MAP. Blockade of NTS OT receptor increased exercise tachycardia only in trained groups, with a larger effect on trained WKY rats (+31 +/- 9 versus +12 +/- 3 beats min-1 in the trained SHR). Hypertension specifically reduced NTS OT receptor mRNA density (-46% versus sedentary WKY rats, P < 0.05); training did not change OT receptor density, but significantly increased OT mRNA expression (+2.5-fold in trained WKY rats and +15% in trained SHR). Concurrent hypertension- and training-induced plastic (peptide/receptor changes) and functional adjustments (HR changes) of oxytocinergic control support both the elevated basal HR in the SHR group and the slowing of the heart rate (rest and exercise) observed in trained WKY rats and SHR.

Analysis of Agonist and Antagonist Effects on Thyroid Hormone Receptor Conformation by Hydrogen/Deuterium Exchange

Thyroid hormone receptors (TRs) are ligand-gated transcription factors with critical roles in development and metabolism. Although x-ray structures of TR ligand-binding domains (LBDs) with agonists are available, comparable structures without ligand (apo-TR) or with antagonists are not. It remains important to understand apo-LBD conformation and the way that it rearranges with ligands to develop better TR pharmaceuticals. In this study, we conducted hydrogen/deuterium exchange on TR LBDs with or without agonist (T(3)) or antagonist (NH(3)). Both ligands reduce deuterium incorporation into LBD amide hydrogens, implying tighter overall folding of the domain. As predicted, mass spectroscopic analysis of individual proteolytic peptides after hydrogen/deuterium exchange reveals that ligand increases the degree of solvent protection of regions close to the buried ligand-binding pocket. However, there is also extensive ligand protection of other regions, including the dimer surface at H10-H11, providing evidence for allosteric communication between the ligand-binding pocket and distant interaction surfaces. Surprisingly, C-terminal activation helix H12, which is known to alter position with ligand, remains relatively protected from solvent in all conditions suggesting that it is packed against the LBD irrespective of the presence or type of ligand. T(3), but not NH(3), increases accessibility of the upper part of H3-H5 to solvent, and we propose that TR H12 interacts with this region in apo-TR and that this interaction is blocked by T(3) but not NH(3.) We present data from site-directed mutagenesis experiments and molecular dynamics simulations that lend support to this structural model of apo-TR and its ligand-dependent conformational changes. (Molecular Endocrinology 25: 15-31, 2011)

Aspergillus species, cyclic dimeric dipeptide derivative substance P antagonist biosynthetic products thereof, and process for preparation thereof

A novel Aspergillus species, cyclic dimeric dipeptide derivatives which are biosynthetic products thereof and are useful as Substance P antagonists and therefore as analgesic and/or antiinflammatory agents, and a process for preparation of the biosynthetic products are disclosed.

The role of oxytocin in mother-infant relations : a systematic review of human studies

Background: Oxytocin is associated with the establishment and quality of maternal behavior in animal models. Parallel investigations in humans are now under way. This article reviews the current research examining the role of oxytocin in mother-infant relations, attachment, and bonding in humans. Methods: A systematic search was made of three electronic databases and other bibliographic sources for published research studies that examined oxytocin and mother-infant relations in humans, including attachment, maternal behavior, parenting, and mother-infant relations. Results: Eight studies were identified, all of which were unique in their methodologies, populations studied, and measures used. Seven studies found significant and strong associations between levels or patterns of oxytocin and aspects of mother-infant relations or attachment. Conclusions: Oxytocin appears to be of crucial importance for understanding mother-infant relationships. The findings of this review suggest that the pioneering, but preliminary, research undertaken to date is promising and that replication with larger samples is needed. Research that draws on more robust measures of attachment and bonding, as well as improved measures of oxytocin that include both central and peripheral levels, will elucidate the role of oxytocin in human mother-infant relationships. As the production of oxytocin is by no means restricted to mothers, the extension of the oxytocin studies to fathering, as well as to alloparental caregiving, would be an intriguing next step.

Antagonist CHILL OUT LOOP

A relaxed chill out loop.

Catecholamine and oxytocin cells respond to hypovolaemia as well as hypotension

Medullary catecholamine and hypothalamic neurosecretory oxytocin cells are activated by hypotension, but previous studies have provided uncertain outcomes concerning their ability to respond to a purely hypovolaemic stimulus. In the present study, injections of PEG/water and pentolinium were used to elicit non-hypotensive, isosmotic hypovolaemia and isovolaemic, isosmotic hypotension, respectively, in conscious rats. Animals were sacrificed 2 h after treatment. Immunolabelling for Fos, tyrosine hydroxylase and oxytocin established that these two stimuli activate almost identical populations of catecholamine neurons in the ventrolateral and dorsomedial medulla, and very similar populations of oxytocin cells in the supraoptic and paraventricular nuclei of the hypothalamus.

Association between the oxytocin receptor gene and amygdalar volume in healthy adults

Background: Recent studies have suggested that oxytocin affects social cognition and behavior mediated by the oxytocin receptor (OXTR) in amygdala in humans as well as in experimental animals. Genetic studies have revealed a link between the OXTR gene and the susceptibility to autism spectrum disorders (ASD), especially in the social dysfunctional feature of ASD.

Methods: We examined the relationship between amygdala volume measured with manual tracing methodology and seven single nucleotide polymorphisms and one haplotype-block in OXTR, which were previously reported to be associated with ASD, in 208 socially intact Japanese adults with no neuropsychiatric history or current diagnosis.

Results: The rs2254298A allele of OXTR was significantly associated with larger bilateral amygdala volume. The rs2254298A allele effect on amygdala volume varied in proportion to the dose of this allele. The larger the number of rs2254298A alleles an individual had, the larger their amygdala volume. Such an association was not observed with hippocampal volume or with global brain volumes, including whole gray, white matter, and cerebrospinal-fluid space. Furthermore, two three–single nucleotide polymorphism haplotypes, including rs2254298G allele, showed significant associations with the smaller bilateral amygdala volume.

Conclusions: The present results suggest that OXTR might be associated with the susceptibility to ASD, especially in its aspects of social interaction and communication mediated by a modulation of amygdala development, one of the most distributed brain regions with high density of OXTR. Furthermore, amygdala volume measured with magnetic resonance imaging could be a useful intermediate phenotype to uncover the complex link between OXTR and social dysfunction in ASD.

Reversal of vascular macrophage accumulation and hypertension by a CCR2 antagonist in deoxycorticosterone/salt-treated mice

Infiltration of macrophages into the artery wall plays detrimental roles during hypertension by promoting vascular inflammation and endothelial dysfunction, and it occurs via a chemo-attractant action of chemokines on macrophage cytokine receptors. We sought to identify the key chemokine receptors associated with macrophage infiltration into the vascular wall during deoxycorticosterone acetate (DOCA)/salt-induced hypertension in mice and to evaluate the impact of pharmacological inhibition of these receptors on blood pressure and leukocyte accumulation. Mice treated with DOCA/salt for 21 days displayed markedly elevated systolic blood pressure (158±2 versus 114±5 mm Hg in sham group; P<0.0001). Polymerase chain reaction screening via a gene array of 20 chemokine receptors indicated an increased expression of CCR2 in aortas of DOCA/salt-treated mice. Real-time polymerase chain reaction confirmed mRNA upregulation of CCR2 in aortas from DOCA/salt-treated animals and of the CCR2 ligands CCL2, CCL7, CCL8, and CCL12 (all >2-fold versus sham; P<0.05). Flow cytometry revealed 2.9-fold higher macrophage numbers (ie, CD45+ CD11b+ F4/80+ cells) in the aortic wall of DOCA/salt versus sham-treated mice. Intervention with a CCR2 antagonist, INCB3344 (30 mg/kg per day, IP), 10 days after the induction of hypertension with DOCA/salt treatment, reduced the aortic expression of CCR2 mRNA and completely reversed the DOCA/salt-induced influx of macrophages. Importantly, INCB3344 substantially reduced the elevated blood pressure in DOCA/salt-treated mice. Hence, our findings highlight CCR2 as a promising therapeutic target to reduce both macrophage accumulation in the vascular wall and blood pressure in hypertension.

The M4 muscarinic antagonist MT-3 inhibits myopia in chick: evidence for site of action

It is well established that the broad-band muscarinic antagonist, atropine is effective at inhibiting the progression of myopia and does so by preventing the elongation of the vitreous chamber of the eye. However, uncertainty remains as to whether this effect occurs through a receptoral mechanism and, if so, which muscarinic receptor subtype mediates this effect. Previous work, in avian and mammalian models of myopia, implicates the M1 and M4 receptors as potential targets. The current study used physiologically relevant concentrations of highly selective muscarinic antagonists (MT-3 and MT-7) to further characterise the role of the M4 receptor in the control of myopia in the chick model of refractive development.