Ambien online research references
Brain Res Dev Brain Res. 1991 Feb 22;58(2):283-7.
Differential ontogenesis of type I and II benzodiazepine receptors in mouse cerebellum.
Bacon E, de Barry J, Gombos G.
Centre de Neurochimie du CNRS et U44 INSERM, Strasbourg, France.
The ontogeny of type I and type II benzodiazepine binding sites was studied in mouse cerebellum by displacement of [3H]flunitrazepam binding by zolpidem, a ligand specific for the type I sites. Type I binding sites predominate throughout development and in the adult while type II sites account for 25% of total cerebellar benzodiazepine binding sites at birth and, during development, decrease to 10% or less in the adult. On a per cerebellum basis type II sites increase during the first postnatal week and then remain at a steady level while type I sites increase until adulthood. These results may indicate a specific localization of the type II sites (and of the corresponding alpha-protein subunits in the GABA/benzodiazepine receptor complex) in structures already present at birth and developing during a short early postnatal period. The affinity of zolpidem for its high affinity (type I) binding sites increases during cerebellar ontogeny, this increase possibly indicates an epigenetic (post-translational) 'maturation' process of the corresponding receptor molecule. Hill numbers indicate the existence of an additional binding site heterogeneity greater during development but still present in the adult; probably this is to be related to the simultaneous presence of different 'maturation' stages during development and with a certain variety of the final products.
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Psychopharmacology (Berl). 1990;102(4):479-84.
Relative efficacies of benzodiazepine receptor agonists in affecting red nucleus electrical activity in rabbits.
Massotti M, De Medici D, De Luca C.
Laboratorio di Farmacologia, Istituto Superiore di Sanita, Roma, Italy.
The effects of benzodiazepine receptor agonists on the electrical activity of red nucleus (RN) and neocortex were studied in rabbits. Under basal conditions, 30-40 microV, 40-50 Hz waves were recorded in RN. An increase of the amplitude (Emax, 75-90 microV) was found after IV injection of flunitrazepam (ED50, 0.14 mg/kg), diazepam (ED50, 0.28 mg/kg), alpidem (ED50, 1.57 mg/kg) and zolpidem (ED50, 0.73 mg/kg). Clonazepam (ED50, 0.12 mg/kg) and Cl 218,872 (ED50, 0.63 mg/kg) were less effective. In contrast, 2-10-fold higher doses were required to induce a slight decrease of the frequency. At the level of the cortex all benzodiazepine agonists induced synchronization and spindles. The effects of diazepam (5 mg/kg IV) in both areas were antagonized by flumazenil (0.04 mg/kg IV) and bicuculline (0.2 mg/kg IV). Pentamethylentetrazole (10-30 mg/kg IV) selectively abated the effect at the level of the cortex, whereas both clonazepam (2 mg/kg IV) and beta-CCM (0.6 mg/kg IV) selectively suppressed only the effects on the RN. These results suggest that activation of benzodiazepine receptor mainly influences the RN waves amplitude. The efficacy in increasing the amplitude appears related to the reported relative efficacy of the compound in potentiating GABA responses. The possibility exists that these effects are dependent upon the partial or full agonist action of the drugs or upon their binding at distinct benzodiazepine receptor types.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1965749&dopt=Abstract
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Eur J Pharmacol. 1990 Apr 25;179(3):339-45.
Reduction of reticulata neuronal activity by zolpidem and alpidem, two imidazopyridines with high affinity for type I benzodiazepine receptors.
Mereu G, Carcangiu G, Concas A, Passino N, Biggio G.
Department of Experimental Biology, University of Cagliari, Italy.
Zolpidem and alpidem, two imidazopyridines with high affinity for the type I benzodiazepine recognition site, have recently been proposed as preferential hypnotic (zolpidem) and anxiolytic (alpidem) drugs notable for the minor incidence of side-effects. To further characterize the molecular mechanism involved in the action of these drugs, we studied their effects in comparison with those of diazepam on the spontaneous electrical activity of substantia nigra pars reticulata (SNR) neurons. These cells have been shown to be extremely sensitive to various positive and negative modulators of GABAergic transmission. All three drugs consistently produced a dose-dependent (0.03-8.0 mg/kg i.v.) inhibition of the firing of SNR cells when administered as a single bolus. However, zolpidem was more potent and efficacious than diazepam or alpidem. The ID50s were 0.076, 0.492 and 0.821 mg/kg, respectively. When the drugs were injected in exponentially (ratio 2) increasing doses up to 8.0 mg/kg, the rank order for tachyphylaxis was zolpidem much greater than diazepam greater than alpidem. Since the effects of the drugs were abolished and prevented by a small dose (0.5 mg/kg i.v.) of flumazenil (Ro 15-1788), it is likely that the effects were mediated through activation of benzodiazepine receptors. The results indicate that the hypnotic, zolpidem, has a more potent inhibitory action on SNR cell activity than the anxiolytics, alpidem and diazepam.
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Eur J Pharmacol. 1990 Oct 23;187(3):487-94.
Differences in pharmacological profiles of a new generation of benzodiazepine and non-benzodiazepine hypnotics.
Perrault G, Morel E, Sanger DJ, Zivkovic B.
Synthelabo Recherche (L.E.R.S.), Bagneux, France.
The hypnotics, quazepam (a benzodiazepine), brotizolam (a thienotriazolodiazepine), zopiclone (a cyclopyrrolone) and zolpidem (an imidazopyridine) have a common ability to bind to the benzodiazepine recognition site (omega receptor) within the GABAA receptor. For this reason we compared their pharmacological profiles in mice. All compounds shared anticonvulsant and central depressant effects. However, the sedative activity of zolpidem appeared at much lower doses than did the anticonvulsant and myorelaxant effects but the opposite was observed with the other hypnotics. In contrast to brotizolam, quazepam and zopiclone, zolpidem did not increase food intake in mice placed in a novel environment, indicating that this drug lacks disinhibitory activity. Moreover the efficacy of zolpidem at the GABAA receptor, as indicated by its activity against convulsions induced by the GABA synthesis inhibitor, isoniazid, was much greater than that of other hypnotics. These results suggest that the hypnoselective properties observed with zolpidem might be related to a high selectivity for the omega 1 recognition site of the GABAA receptor coupled with a very high intrinsic activity.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1981555&dopt=Abstract
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J Pharm Pharmacol. 1990 Aug;42(8):562-5.
Preferential decrease in dopamine utilization in prefrontal cortex by zopiclone, diazepam and zolpidem in unstressed rats.
Boireau A, Dubedat P, Laduron PM, Doble A, Blanchard JC.
Rhone-Poulenc Sante, Centre de recherche de Vitry-Alfortville, Vitry-sur-Seine, France.
This study has compared the effects of a cyclopyrrolone, zopiclone, a benzodiazepine, diazepam, and an imidazopyridine, zolpidem, on dopamine (DA) and DOPAC levels, and DA utilization (DOPAC/DA ratio) in rat striatum and prefrontal cortex. The endogenous levels of DA were significantly increased by both zopiclone (2.5, 10 and 40 mg kg-1 p.o.) and diazepam (10 and 40 mg kg-1 p.o.) in the prefrontal cortex, whereas striatal DA content was significantly increased only with the highest dose of diazepam (40 mg kg-1 p.o.). Diazepam (10 and 40 mg kg-1 p.o.) decreased cortical level of DOPAC more markedly than striatal levels, whereas zopiclone (40 mg kg-1 p.o.) only slightly decreased striatal DOPAC levels. Zopiclone and diazepam dose-dependently decreased DA utilization, an effect which was more marked in prefrontal cortex than in striatum. This result was confirmed with zolpidem, another benzodiazepine ligand. Zopiclone was most potent at decreasing DA utilization at the cortical level. The diazepam-induced decreases in DA metabolism and utilization were antagonized by Ro 15-1788, suggesting that the effects seen were mediated by specific benzodiazepine receptors. Thus, our results clearly show that ligands acting on the benzodiazepine receptor GABA receptor chloride ionophore complex can decrease the utilization of dopamine in unstressed rats. The preferential decrease in cortical DA utilization induced by benzodiazepine ligands may be compared to the well-known activation by stress of the mesocortical DAergic system.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1981584&dopt=Abstract
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