Differential expression of GABAA receptor α-subunits in rat brain during development

AbstractUnique cytoplasmic loop regions of the α1, α2, α3 and α5 subunits of the GABAA receptor have been expressed in E. coli and used to generate polyclonal antisera specific for these subunits. The antibodies identify proteins by SDS-polyacrylamide gel electrophoresis and western blotting of molecular size 51 kDa, 53 kDa, 59 kDa and 55 kDa, respectively, which show differential patterns of expression during development. Whereas the α2 and α3 subunits are present at early stages, the expression of α1 and α5 subunits is low at birth and increases with age. This differential expression could be correlated with previous studies examining the developmental expression of BZ1 and BZ2 benzodiazepine binding sites

Menus for Feeding Black Holes

Black holes are the ultimate prisons of the Universe, regions of spacetime where the enormous gravity prohibits matter or even light to escape to infinity. Yet, matter falling toward the black holes may shine spectacularly, generating the strongest source of radiation. These sources provide us with astrophysical laboratories of extreme physical conditions that cannot be realized on Earth. This chapter offers a review of the basic menus for feeding matter onto black holes and discusses their observational implications.Comment: 27 pages. Accepted for publication in Space Science Reviews. Also to appear in hard cover in the Space Sciences Series of ISSI "The Physics of Accretion onto Black Holes" (Springer Publisher

Supermassive Black Hole Binaries: The Search Continues

Gravitationally bound supermassive black hole binaries (SBHBs) are thought to be a natural product of galactic mergers and growth of the large scale structure in the universe. They however remain observationally elusive, thus raising a question about characteristic observational signatures associated with these systems. In this conference proceeding I discuss current theoretical understanding and latest advances and prospects in observational searches for SBHBs.Comment: 17 pages, 4 figures. To appear in the Proceedings of 2014 Sant Cugat Forum on Astrophysics. Astrophysics and Space Science Proceedings, ed. C.Sopuerta (Berlin: Springer-Verlag

Photoaffinity labeling of the benzodiazepine binding site of alpha1beta3gamma2 gamma-aminobutyric acidA receptors with flunitrazepam identifies a subset of ligands that interact directly with His102 of the alpha subunit and predicts orientation of these within the benzodiazepine pharmacophore.

Photoincorporation of ligands into the benzodiazepine site of native gamma-aminobutyric acidA (GABAA) receptors provides useful information about the nature of the benzodiazepine (BZ) binding site. Photoincorporation of flunitrazepam into a single population of GABAA receptors, recombinant human alpha1beta3gamma2, was investigated to probe further the mechanism and orientation of flunitrazepam and other ligands in the BZ binding site. It was concluded that the receptor is primarily derivatized with the entire, unfragmented, flunitrazepam molecule, which undergoes a conformational change during photolysis and largely vacates the benzodiazepine binding site. Investigation of the BZ site after photoincorporation of [3H]flunitrazepam confirmed that binding of other radioligands was unaffected by incorporation of flunitrazepam. This did not correlate with their efficacy but depended on the presence of particular structural features in the molecule. It was observed that affected compounds have a pendant phenyl moiety, analogous to the 5-phenyl group of flunitrazepam, which are proposed to overlap and interact with the same residue or residues in the BZ binding site. Because the major site of flunitrazepam photoincorporation has been shown to be His102, we propose that this group of compounds interacts directly with His 102, whereas compounds of other structural types have no direct interaction with this amino acid. The orientation of ligands within the BZ binding site and their specific interaction with identified amino acids are not well understood. The data in the current study indicate that His102 interacts directly with the pendant phenyl group of diazepam, and further implications for the pharmacophore of the BZ binding site are discussed

Does amygdaloid corticotropin-releasing hormone (CRH) mediate anxiety-like behaviors? Dissociation of anxiogenic effects and CRH release

The brain corticotropin-releasing hormone (CRH) circuits are activated by stressful stimuli, contributing to behavioral and emotionalresponses. The present study assessed anxiety-like responses andin vivoneurochemical alterations at the central nucleus of theamygdala (CeA) evoked by exposure to an unfamiliar (anxiogenic) environment. Also, the impact of anxiolytic treatments and thosethat affect CRH were assessed in this paradigm. Novel environment (new cage) markedly suppressed ingestion of a palatable snack.This effect was dose-dependently antagonized by diazepam and was utilized as an index of anxiety in the rodent. Although exposureto a novel environment also stimulated thein vivorelease of CRH and glutamate at the CeA, various CRH antagonists (e.g.ah-CRH,Ca-MeCRH, CP-154,526, antisauvagine-30, preproTRH178-199) did not attenuate the stressor-elicited behavioral suppression,although Ca-MeCRH was found to attenuate the freezing response elicited by contextual stimuli that were associated with previouslyadministered footshock. Moreover, central infusion of CRH failed to suppress snack consumption in the home cage. Althoughdiazepam had potent anxiolytic effects in this paradigm, this treatment did not prevent the stressor-associated release of CRH andglutamate at the CeA. Thus, while neural circuits involving CRH and⁄or glutamatergic receptors at the CeA may be activated by anunfamiliar environment, the data challenge the view that activation of these receptors is necessary for the expression of anxiety-likebehavioral responses. Rather than provoking anxiety, these systems might serve to draw attention to events or cues of biologicalsignificance, including those posing a threat to survival