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Bacterial Outer Membrane Proteins↗
Biomedical subjects
L Rägo
Publications and source records attributed to L Rägo.
Variation in behavioral response to baclofen: correlation with benzodiazepine binding sites in mouse forebrain.
Mice treated with (+/-)baclofen (2 mg/kg i.p.) displayed profound differences to the motor depressant action of this drug. Mice were divided into three groups termed as responders (20%), moderate responders (65%) and nonresponders (15%). No differences were detected in the spontaneous motor activity between the selected groups. When the animal population in the home cages was kept unchanged the different responses to baclofen were reproducible three weeks after selection. A borderline dose of diazepam (1.5 mg/kg) decreased highly significantly motor activity in baclofen responders but failed to do this in nonresponders group. Ex vivo studies with 3H-flunitrazepam (labelling in vivo and binding carried out in vitro) demonstrated that 3H-flunitrazepam binding in mouse forebrain was significantly smaller in baclofen responders than in nonresponders. Further, the apparent number of 3H-flunitrazepam binding sites in vitro was significantly decreased in the forebrain of baclofen responders. It is concluded that some actions of baclofen depend on the functional state of benzodiazepine recognition sites.
Animals↗
Behavioural effects of pinoline in the rat forced swimming, open field and elevated plus-maze tests.
Pinoline (6-methoxy-1,2,3,4-tetrahydro-beta-carboline) is a naturally occurring compound in the mammalian body which inhibits serotonin (5-hydroxytryptamine) uptake and monoamine oxidase-A activity. The present study was designed to assess potential antidepressant- or anxiolytic-like behavioural effects of pinoline in rat forced swimming, open field and elevated plus-maze tests. In the forced swimming test pinoline dose-dependently reduced the immobility time, starting from a dose of 8 mg kg-1. In the open field test pinoline reduced the total open field activity. This effect was significant at 20 mg kg-1, whereas the dose of 15 mg kg-1 only significantly reduced the number of rearings. In the plus-maze test pinoline decreased the total number of arm entries, the number of line crossings and time spent in the open part of the apparatus, but increased the number of approaches to the open part of the maze. The effects of pinoline were dose-dependent in all three behavioural tests used. Since antidepressant drugs reduce the immobility time in the forced swimming test but typically inhibit activity in open field and elevated plus-maze tests, the behavioural effects of pinoline resemble those of drugs with an antidepressant profile.
Animals↗
Changes in GABA-benzodiazepine receptor complex and in peripheral benzodiazepine receptors in male mice after copulation.
We studied the effect of copulation on GABA and benzodiazepine (BZD) receptors in the male mouse. After copulation, there was an 18% increase in the in vitro number of [3H]muscimol binding sites in frontal cortex. No changes were observed in central BZD binding sites labelled either in vivo by [3H]flunitrazepam or in vitro (in olfactory bulbs and in frontal cortex) by [3H]flumazenil, but further in vitro studies demonstrated that the GABA-stimulated [3H]flunitrazepam binding was reduced in both frontal cortex and olfactory bulbs. Copulation increased the number of peripheral BZD binding sites labelled by 3H-Ro 5-4864 in olfactory bulbs by 22% and in heart by 36%, but not in frontal cortex or in testes. The changes of GABA/BZD and peripheral BZD receptors in mouse suggest that the GABAergic system may be affected by copulation.
Animals↗
3H-atipamezole binding sites in mouse cerebral cortex: possible involvement of alpha 2-adrenoceptors in sexual behavior.
Atipamezole is a new specific alpha 2-adrenoceptor antagonist. In this study, first, the presence of specific 3H-atipamezole binding sites in the sagittal and coronal sections of mouse brain was established using autoradiography. In vitro experiments with mouse cerebral cortex membranes indicated that d-medetomidine, a new alpha 2-adrenoceptor agonist structurally related to atipamezole, displaces labelled atipamezole more potently than noradrenaline. The saturation isotherm with d-medetomidine demonstrated high affinity binding with the apparent number of binding sites KD 1.36 nM and 760 fmol/mg, respectively. In the next series of experiments male mice were sacrificed immediately after copulation and cerebral cortex 3H-atipamezole and 3H-flumazenil binding was studied. Oxymetazoline and prazosin are known to label preferably alpha 2A and alpha 2B subtypes of alpha 2-adrenoceptors. Therefore, parallelly with noradrenaline both these compounds were used to determine non-specific binding of 3H-atipamezole. When noradrenaline or oxymetazoline were used as displacing agents copulation caused a significant increase of 3H-atipamezole binding sites. No significant changes were observed when prazosin was used. 3H-Flumazenil binding remained unchanged by copulation. The up-regulation of 3H-atipamezole binding sites indicates that not only alpha 2-adrenoceptors in the periphery but also in the CNS may participate in the regulation of sexual behavior. Moreover, in regulation of sexual behavior central alpha 2-adrenoceptors may be more important than benzodiazepine receptors.
Adrenergic alpha-Antagonists↗
Autoradiographic localization of [3H]-pinoline binding sites in mouse tissues.
Pinoline (6-methoxy-1,2,3,4-tetrahydro-beta-carboline) has been found in similar concentrations to those of melatonin in various mammalian tissues. The present study investigates the subcellular distribution of in vivo administered [3H]-pinoline in mouse tissues using light and electron microscopic autoradiography. The antioxidative capacity of pinoline was determined in vitro and compared with that of the structurally similar pineal hormone melatonin. Autoradiograms revealed that [3H]-pinoline was present in all tissues studied 30 min after administration, but in most tissues binding was nonspecific. Adrenal glands showed the highest specific binding for [3H]-pinoline 0.5-1 h after administration of the labelled compound. In all tissues a large amount (approximately 40%) of radioactivity was located in nuclei of cells. Specific nuclear binding was the highest in adrenal glands and cerebral cortex. Both pinoline and melatonin potently inhibited lipid peroxidation. Therefore, we suggest that pinoline may act in cells and nuclei as an antioxidant. Direct genomic effects of pinoline cannot be excluded.
Adrenal Cortex↗