In naive mice the selective D2 agonist LY171555 dose-dependently (0.5-5 mg/kg) induces defensive responses toward non-aggressive conspecifics. In order to investigate possible anxiogenic properties of the D2 agonist, its behavioural effects were compared with those produced by the benzodiazepine receptor inverse agonist methyl-beta-carboline-3-carboxylate(beta-CCM) in the elevated plus maze and in social interactions with non-aggressive opponents. When tested in the elevated plus maze, mice injected with LY 171555 (0.005-1 mg/kg) showed no decrease either of the number of entries or of the time spent in the open arms. At 5 mg/kg an actual increase of these two measures was observed. By contrast, beta-CCM (1-3 mg/kg) dose-dependently decreased both the number of entries and the time spent in the open arms without altering locomotion. The effects of beta-CCM were antagonized by the benzodiazepine receptor antagonist RO 15-1788 (3 mg/kg) showing a selective involvement of benzodiazepine receptors in their modulation. On the other hand, beta-CCM, (1-3 mg/kg) did not produce significant effects on defensive behaviour of mice interacting with non-aggressive opponents and the defensive responses of mice treated with 1 mg/kg LY 171555 were not prevented by 5 mg/kg chlordiazepoxide. These results show that DA D2-mediated hyperdefensiveness and anxiety modulated by benzodiazepine receptors are unrelated phenomena and suggest that this behavioural response may represent a model of those forms of fear-related reaction that do not respond to benzodiazepine treatment.

This article presents the design and characteristics of new wideband iris polarizer based on a square waveguide with diaphragms. Matching and polarization characteristics of the iris polarizer have been simulated and optimized. Frequency dependences of the simulated characteristics are presented. Developed iris polarizer can be applied in modern satellite antennas.

This article presents the design and characteristics of new wideband polarization transformer based on a square waveguide with diaphragms. Matching and polarization characteristics of the polarization transformer have been simulated and optimized. Frequency dependences of the simulated characteristics are presented. Developed polarization transformer can be applied in modern satellite antennas.

This article presents the design and characteristics of new wideband polarizer based on a square waveguide with diaphragms. Matching and polarization characteristics of the new polarizer have been simulated and optimized. Frequency dependences of the simulated characteristics are presented. Developed new polarizer can be applied in modern satellite antennas.

This article presents the design and characteristics of new wideband polarization transformer based on a square waveguide with diaphragms. Matching and polarization characteristics of the polarization transformer have been simulated and optimized. Frequency dependences of the simulated characteristics are presented. Developed polarization transformer can be applied in modern satellite antennas.