Mineralocorticoid receptor blockade during a rat's first violent encounter inhibits its subsequent propensity for violence.

In individuals naive to serious conflict in an unfamiliar environment, violence has long-lasting effects on subsequent aggressive behavior. This effect of the stressful experience of a first violent conflict occurs in victims as well as offenders. The authors study in the male rat as offender the role of a rapid corticosterone signal mediated by brain mineralocorticoid receptors (MR) in adjusting the threshold of aggressive responses. For this purpose, the authors have applied electrical stimulation of the brain's aggression circuit via the hypothalamic attack area or HAA. Using this paradigm, they found that in inexperienced rats, retesting of the animals on subsequent days facilitated aggression. Hypothalamic attack thresholds decreased to about 50% of their initial level. However, blocking the MR once with the mineralocorticoid antagonist spironolactone, during the very first evoked attacks, permanently prevented attack facilitation in subsequent conflicts in that same environment. The MR-mediated effect blocked by the antagonist occurred within an hour following the start of the first aggression tests only. A later MR blockade was not effective. These findings suggest that the corticosterone stress response during a very first serious conflict initializes an enhanced propensity for violent aggression through the brain MR

N-d scattering above the deuteron breakup threshold

The complex Kohn variational principle and the (correlated) Hyperspherical Harmonics technique are applied to study the N--d scattering above the deuteron breakup threshold. The configuration with three outgoing nucleons is explicitly taken into account by solving a set of differential equations with outgoing boundary conditions. A convenient procedure is used to obtain the correct boundary conditions at values of the hyperradius $\approx 100$ fm. The inclusion of the Coulomb potential is straightforward and does not give additional difficulties. Numerical results have been obtained for a simple s-wave central potential. They are in nice agreement with the benchmarks produced by different groups using the Faddeev technique. Comparisons are also done with experimental elastic N--d cross section at several energies.Comment: LaTeX, 13 pages, 3 figure

Coping with the Forced Swim Stressor: Towards Understanding an Adaptive Mechanism

In the forced swim test (FST) rodents progressively show increased episodes of immobility if immersed in a beaker with water from where escape is not possible. In this test, a compound qualifies as a potential antidepressant if it prevents or delays the transition to this passive (energy conserving) behavioural style. In the past decade however the switch from active to passive "coping" was used increasingly to describe the phenotype of an animal that has been exposed to a stressful history and/or genetic modification. A PubMed analysis revealed that in a rapidly increasing number of papers (currently more than 2,000) stress-related immobility in the FST is labeled as a depression-like phenotype. In this contribution we will examine the different phases of information processing during coping with the forced swim stressor. For this purpose we focus on the action of corticosterone that is mediated by the closely related mineralocorticoid receptors (MR) and glucocorticoid receptors (GR) in the limbic brain. The evidence available suggests a model in which we propose that the limbic MR-mediated response selection operates in complementary fashion with dopaminergic accumbens/prefrontal executive functions to regulate the transition between active and passive coping styles. Upon rescue from the beaker the preferred, mostly passive, coping style is stored in the memory via a GR-dependent action in the hippocampal dentate gyrus. It is concluded that the rodent's behavioural response to a forced swim stressor does not reflect depression. Rather the forced swim experience provides a unique paradigm to investigate the mechanistic underpinning of stress coping and adaptation

Vector meson photoproduction studied in its radiative decay channel

We provide an analysis of vector meson photoproduction in the channel of the vector meson decaying into a pseudoscalar meson plus a photon, i.e. $V\to P\gamma$. It is shown that non-trivial kinematic correlations arise from the measurement of the $P\gamma$ angular distributions in the overall c.m. system in comparison with those in the vector-meson-rest frame. In terms of the vector meson density matrix elements, the implication of such kinematic correlations in the measurement of polarization observables is discussed. For the $\omega$ meson production, due to its relatively large branching ratios for $\omega\to\pi^0\gamma$, additional events from this channel may enrich the information about the reaction mechanism and improve the statistics of the recent measurement of polarized beam asymmetries by the GRAAL Collaboration. For $\phi\to \eta\gamma$, $\rho\to \pi\gamma$, and $K^*\to K\gamma$, we expect that additional information about the spin structure of the vector meson production vertex can be derived.Comment: Revtex, 14 pages, 2 eps figures; Version accepted by PR

The role of corticosterone in human hypothalamic– pituitary–adrenal axis feedback

Objective  In humans, the glucocorticoid corticosterone circulates in blood at 10–20-fold lower levels than cortisol, but is found in higher relative amounts in postmortem brain samples. Access of cortisol and corticosterone to the central nervous system may not be equal. Additionally, the relative affinities for the glucocorticoid and mineralocorticoid receptors differ, such that corticosterone may play a significant role in human brain function. Design  We measured cortisol and corticosterone levels in paired plasma and cerebrospinal fluid (CSF) samples. To test the relative potency of cortisol vs. corticosterone on hypothalamic–pituitary–adrenal (HPA) feedback, subjects underwent a three-phase, single-blind, randomized study assessing the postmetyrapone ACTH response over 3 h to an intravenous bolus of vehicle, cortisol or corticosterone (0·15 mg/kg and 0·04 mg/kg). Participants  Outpatients undergoing diagnostic lumbar puncture who were subsequently deemed to be free of disease. Feedback was tested in healthy male volunteers. Measurements  Plasma and CSF corticosterone to cortisol ratio was calculated and the ACTH response over time after the bolus glucocorticoid measured. Results  Plasma corticosterone : cortisol was 0·069 ± 0·007; CSF corticosterone : cortisol was 0·387 ± 0·050 ( P <  0·001). Cortisol and corticosterone (0·15 mg/kg) suppressed ACTH vs. vehicle ( P =  0·002); there was no difference between corticosterone and cortisol. The 0·04 mg/kg dose had no effect on ACTH despite supraphysiological plasma corticosterone levels. Conclusions  Corticosterone contributes almost 40% of total active glucocorticoids (cortisol and corticosterone) in the CSF. Significant effects on HPA axis suppression were only seen with supraphysiological levels of corticosterone, suggesting that corticosterone is not important in this model of nonstress-induced ACTH hypersecretion, in which the effect of cortisol predominates.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72329/1/j.1365-2265.2006.02540.x.pd

Partial-Wave Amplitudes and Resonances in pbar + p -> pi + pi

Partial wave amplitudes have been extracted from accurate data on pbar + p -> pi + pi by a method which incorporates the theoretical constraints of analyticity and crossing symmetry. The resulting solution gives a good fit to the annihilation data and is also consistent with the wealth of information in the crossed channel pi + N -> pi + N. The partial wave amplitudes show evidence for resonances in all partial waves with J < 6, at least one of which, a J = 0+ state, (and possibly another with J = 1-) is unlikely to have a simple quark-antiquark structure.Comment: 17 pages, Revtex, 21 postscript figure

Spin observables of the reactions NN -> DeltaN and pd -> Delta (pp)(1S0) in collinear kinematics

A general formalism for double and triple spin-correlations of the reaction NN -> DeltaN is developed for the case of collinear kinematics. A complete polarization experiment allowing to reconstruct all of the four amplitudes describing this process is suggested. Furthermore, the spin observables of the inelastic charge-exchange reaction pd -> Delta^0(pp)(1S0) are analyzed in collinear kinematics within the single pN scattering mechanism involving the subprocess pn -> Delta^0p. The full set of spin observables related to the polarization of one or two initial particles and one final particle is obtained in terms of three invariant amplitudes of the reaction pd -> Delta (pp)(1S0) and the transition form factor d->(pp)(1S0). A complete polarization experiment for the reaction pd -> Delta^0(pp)(1S0) is suggested which allows one to determine three independent combinations of the four amplitudes of the elementary subprocess NN -> DeltaN.Comment: 12 pages, 1 figur

A common and functional mineralocorticoid receptor haplotype enhances optimism and protects against depression in females

Mineralocorticoid (MR) and glucocorticoid receptors (GR) are abundantly expressed in the limbic brain and mediate cortisol effects on the stress-response and behavioral adaptation. Dysregulation of the stress response impairs adaptation and is a risk factor for depression, which is twice as abundant in women than in men. Because of the importance of MR for appraisal processes underlying the initial phase of the stress response we investigated whether specific MR haplotypes were associated with personality traits that predict the risk of depression. We discovered a common gene variant (haplotype 2, frequency ∼0.38) resulting in enhanced MR activity. Haplotype 2 was associated with heightened dispositional optimism in study 1 and with less hopelessness and rumination in study 2. Using data from a large genome-wide association study we then established that haplotype 2 was associated with a lower risk of depression. Interestingly, all effects were restricted to women. We propose that common functional MR haplotypes are important determinants of inter-individual variability in resilience to depression in women by differentially mediating cortisol effects on the stress system

Proton-proton scattering above 3 GeV/c

A large set of data on proton-proton differential cross sections, analyzing powers and the double polarization parameter A_NN is analyzed employing the Regge formalism. We find that the data available at proton beam momenta from 3 GeV/c to 50 GeV/c exhibit features that are very well in line with the general characteristics of Regge phenomenology and can be described with a model that includes the rho, omega, f_2, and a_2 trajectories and single Pomeron exchange. Additional data, specifically for spin-dependent observables at forward angles, would be very helpful for testing and refining our Regge model.Comment: 16 pages, 19 figures; revised version accepted for publication in EPJ

\pi\pi, K\pi and \pi N potential scattering and a prediction of a narrow \sigma meson resonance

Low energy scattering and bound state properties of the \pi N, \pi\pi and K\pi systems are studied as coupled channel problems using inversion potentials of phase shift data. In a first step we apply the potential model to explain recent measurements of pionic hydrogen shift and width. Secondly, predictions of the model for pionium lifetime and shift confirm a well known and widely used effective range expression. Thirdly, as extension of this confirmation, we predict an unexpected medium effect of the pionium lifetime which shortens by several orders of magnitude. The \sigma meson shows a narrow resonance structure as a function of the medium modified mass with the implication of being essentially energy independent. Similarly, we see this medium resonance effect realized for the K\pi system. To support our findings we present also results for the \rho meson and the \Delta(1232) resonance.Comment: 42 pages, 17 PS figures, REFTeX, epsfig.sty needed, submitted to Phys. Re