Lesions of putative glutamatergic pathways potentiate the increase of inositol phospholipid hydrolysis elicited by excitatory amino acids.

The stimulation of inositol phospholipid (PI) hydrolysis by excitatory amino acids was measured in the rat hippocampus or striatum after 3 different chemical or surgical lesions of putative glutamatergic pathways. Intrahippocampal infusions of kainate preferentially destroyed neurons in the CA3-4 areas, denervating the CA1 area of the ipsilateral and contralateral hippocampus. Infusions of colchicine selectively destroyed granule cells of fascia dentata, denervating the CA3 area of the ipsilateral hippocampus.

Beta-adrenergic receptor regulation of NGF-mRNA content in rat C6-2B glioma cells.

In C6-2B astrocytoma cells the Beta NGF content and secretion rate are increased by isoproterenol activation of beta-adrenergic receptors (Schwartz and Costa, 1977). Utilizing poly (A+) RNA hybridization analysis with a cRNA probe for mouse Beta NGF it was found that isoproterenol activation of C6-2B cells produces also a 4 fold increase of the content of messenger RNA encoding Beta NGF. This increase is specifically antagonized by 1-propanolol, but not by phentolamine.

Ganglioside inhibition of glutamate-mediated protein kinase C translocation in primary cultures of cerebellar neurons.

In primary cultures of cerebellar granule cells, protein kinase C (PKC) translocation and activation can be triggered by the stimulation of excitatory amino acid neurotransmitter receptors. Glutamate evokes a dose-related translocation of 4-beta-[3H]phorbol 12,13-dibutyrate ([3H]-P(BtO)2) binding sites from the cytosol to the neuronal membrane and stimulates the incorporation of 32P into a number of membrane proteins, particularly protein bands in the range of 80, 50, and 40 kDa. The glutamate-evoked PKC translocation is Mg2+ sensitive, is prevented by 2-amino-5-phosphonovalerate and phencyclidine, is not inhibited by nitrendipine (a voltage-dependent Ca2+-channel blocker) but is abolished by the removal of Ca2+ from the incubation medium, suggesting that glutamate-mediated Ca2+ influx is operative in the redistribution of PKC.

Activation of specific glutamate receptor subtypes increases C-fos proto-oncogene expression in primary cultures of neonatal rat cerebellar granule cells.

In primary cultures of rat cerebellar granule cells the activation of excitatory amino acid receptors by 1-glutamate enhances the steady state level of c-fos proto-oncogene messenger RNA. This effect is blocked by magnesium (1mM) as well as by the glutamate receptor antagonist 2-amino-5-phosphono-valerate (APV). Among the other excitatory amino acid agonists N-methyl-D-Aspartate (NMDA) and quisqualate also increased c-fos mRNA content, the latter however to a significantly lesser extent, while kainate failed to modify the basal level of c-fos expression.

Actions of benzodiazepine and beta-carboline derivatives on gamma-aminobutyric acid-activated Cl- channels recorded from membrane patches of neonatal rat cortical neurons in culture.

Using the patch-clamp, single-channel recording technique, the authors determined conductance and kinetics of gamma-aminobutyric acid-activated Cl- channels recorded from membrane patches excised from neonatal rat cortical neurons in primary culture. The anxiolytic benzodiazepine flunitrazepam increased the channel opening frequency, but it did not change conductance or channel opening burst duration. The anxiogenic compound methyl-6,7-dimethoxy-4-ethyl-beta-carboline-3-carboxylate decreased gamma-aminobutyric acid-activated Cl- channel opening frequency without changing conductance or opening duration.

Expression of rat mRNA coding for hormone-stimulated adenylate cyclase in Xenopus oocytes.

Beta-Adrenergic agonist-stimulated hyperpolarization, whole-cell cAMP accumulation, and activity of isoproterenol-stimulated membrane-bound adenylate cyclase (EC 4.6.1.

Effect of a protracted antidepressant treatment on signal transduction and [3H](-)-baclofen binding at GABAB receptors.

In membranes prepared from frontal cortex of rats receiving desmethylimipramine (10 mg/kg i.p. twice daily) or imipramine (7.

In rat hippocampus, somatostatin 14 and muscarinic receptor ligands modulate an adenylate cyclase belonging to a common domain of the receptor.

In hippocampal slices, somatostatin 14 and its stable analog L363 [cyclo(Phe-Pro-Phe-D-Trp-Lys-Thr)] fail to modify muscarinic signal transduction mediated by stimulation of phosphoinositide breakdown, whereas somatostatin 14 mimics oxotremorine in inhibiting adenylate cyclase activity of hippocampal membranes. The simultaneous addition of somatostatin 14 and oxotremorine elicits a nonadditive convergent inhibition of adenylate cyclase activity. Both L363 and oxotremorine nonadditively stimulate a high-affinity guanosine 5'-triphosphatase activity of hippocampal membranes.

In vivo studies of the regulation of neuropeptide stores in structures of the rat brain.

In order to evaluate the regulation of neuropeptide stores in structures of the rat brain, the content of the specific messenger ribonucleic acid for the peptide precursor, of the precursor and of its biologically active peptide fragment, resulting from the precursor processing was measured. Enkephalin stores of the striatum, but not that of other structures, were upregulated by repeated daily doses of dopaminergic receptor antagonists of the D-1 type. Morphine tolerance failed to change stores of enkephalin in brain but produced a down-regulation of the synthesis of pro-opiomelanocortin in the hypothalamus.

Co-localization and co-release of GABA and putative allosteric modulators of GABA receptor.

Diazepam binding inhibitor (DBI) belongs to a family of newly discovered neuropeptides that, when acting on the benzodiazepine/beta-carboline recognition site, provide an allosteric modulation of the function of GABAA receptor. The molecular size of DBI (10K Da) and its amino acid sequence characteristics are compatible with the view that this polypeptide can function as a precursor of smaller biologically active neuropeptides. In neurons of the cerebral cortex of the neonatal rat, in primary culture, DBI coexists with at least 4 different processing products.

Studies of a brain polypeptide functioning as a putative endogenous ligand to benzodiazepine recognition sites in rats selectively bred for alcohol related behavior.

The brain content of Diazepam Binding Inhibitor (DBI), its cell location and that of its specific mRNA were studied immunohistochemically and by in situ hybridization. Various strains of rats were genetically selected for their alcohol tolerance and the above mentioned brain parameters were studied before and after chronic ethanol consumption. The DBI like immunoreactivity (DBI-LI) was found to be located in selected neuronal population and in non-neuronal cells.