CCK receptors in release of pancreatic polypeptide (PP) in dogs

Pancreatic polypeptide (PP) is released after ingestion of protein-fat meals and following administration of some gut hormones (CCK and bombesin), but the hormonal contribution to the physiological release of PP has not been elucidated. We used specific and potent CCK-receptor antagonist, L-364,718, administered intravenously in a dose of 0.5 mumol/kg or intraduodenally in a dose of 2 mumol/kg to assess the role of CCK in the release of PP. Exogenous CCK-8 infused intravenously in gradually increasing doses (12.5-400 pmol/kg/hr) caused a dose-dependent increase in plasma PP from basal 28 +/- 4 pM to 136 +/- 18 pM, and this PP increase was completely suppressed by both intravenous and intraduodenal administration of L-364,718. Meat feeding caused a dramatic increase in plasma PP from a basal level of 26 +/- 4 pM to a peak of about 190 +/- 32 pM, and the pretreatment with intravenous or intraduodenal L-364,718 reduced this PP increase by about 60%. Duodenal perfusion with oleate (0.12-4.0 mmol/hr) or L-Trp (0.12-4.0 mmol/hr) also increased plasma PP, reaching, respectively, 180 +/- 28 pM and 76 +/- 6 pM. Pretreatment with intravenous or intraduodenal L-364,718 completely abolished the plasma PP responses to oleate and L-Trp. Bombesin (100 pmol/kg/hr) raised plasma PP to the level similar to that achieved by meat feeding and L-364,718 given intravenously or intraduodenally blocked completely these plasma PP increments.(ABSTRACT TRUNCATED AT 250 WORDS)     

Lymphocyte function in patients with chronic glomerulonephritis

Lymphocyte suppressive activity after stimulation with Con A and lymphocyte function as the effectors in the ADCC test had been examined in 68 patients with chronic glomerulonephritis (GN) and in 20 healthy controls. Lymphocyte suppressive activity was lower in patients with chronic GN than in the healthy individuals. In regard to chronic proliferative GN and mesangial GN the difference was statistically significant. The lymphocyte efficiency in the ADCC test was generally adequate in patients with chronic GN and none of the morphological types showed significant deviation from the control group. In the general analysis of patients with chronic proliferative, mesangial, membrano-proliferative and membranous GN a decrease of lymphocyte suppressive activity below the lower standard limit has been detected (45% of cases). A similar defect in lymphocyte function in the ADCC test has been found in 18.6%. A statistically significant relationship between the lymphocyte function disorders and the high clinical dynamism of GN has been noticed, although in some cases there was a deviation from this tendency. It is supposed that circulating immune complexes, detected in some patients with chronic GN are not the only decisive factors responsible for defects in lymphocyte function.     

Homology modeling of the serotonin 5-HT1A receptor using automated docking of bioactive compounds with defined geometry

This paper describes a rhodopsin-based model of 5-HT(1A) serotonin receptor. The flexibility of the receptor was considered by using large number of models for ligand dockings. Rearrangements of the heptahelical bundle were introduced, which resulted in the improvement of correlation between computational results and experimental data. The model was validated by automated docking of conformationally restricted arylpiperazines. Specific interactions, responsible for the recognition of arylpiperazine derivatives, were identified. An ionic bond was formed between the protonated amine of ligands and Asp3.32. The aromatic moiety and its substituents specifically interacted with Phe6.52 and Ser5.42, respectively, while the carbonyl groups of imide part of ligands formed hydrogen bonds with Asn7.39 and Tyr7.43. The model reproduced the binding affinity of the test group of ligands (correlation r = 0.8 between pK(i) and docking score). It also gave the enrichment in virtual screening-like experiment (100 compounds), in which 34 high-affinity compounds were found among 50 top-scored ligands.     

Ca2+-mediated ascorbate release from coronary artery endothelial cells

1.--The addition of Ca(2+) ionophore A23187 or ATP to freshly isolated or cultured pig coronary artery endothelial cells (PCEC) potentiated the release of ascorbate (Asc). Cultured PCEC were used to characterize the Ca(2+)-mediated release. An increase in Ca(2+)-mediated Asc release was observed from PCEC preincubated with Asc, Asc-2-phosphate or dehydroascorbic acid (DHAA). 2.--The effects of various ATP analogs and inhibition by suramin were consistent with the ATP-induced release being mediated by P2Y2-like receptors. 3.--ATP-stimulated Asc release was Ca(2+)-mediated because (a) ATP analogs that increased Asc release also elevated cytosolic [Ca(2+)], (b) Ca(2+) ionophore A23187 and cyclopiazonic acid stimulated the Asc release, (c) removing extracellular Ca(2+) and chelating intracellular Ca(2+)inhibited the ATP-induced release, and (d) inositol-selective phospholipase C inhibitor U73122 also inhibited this release. 4.--Accumulation of Asc by PCEC was examined at Asc concentrations of 10 microM (Na(+)-Asc symporter not saturated) and 5 mM (Na(+)-Asc symporter saturated). At 10 microM Asc, A23187 and ATP caused an inhibition of Asc accumulation but at 5 mM Asc, both the agents caused a stimulation. Substituting gluconate for chloride did not affect the basal Asc uptake but it abolished the effects of A23187. 5.--PCEC but not pig coronary artery smooth muscle cells show a Ca(2+)- mediated Asc release pathway that may be activated by agents such as ATP.     

Effect of MPEP treatment on brain-derived neurotrophic factor gene expression

Treatment with most antidepressants induces expression of the gene coding for brain-derived neurotrophic factor (BDNF) in the hippocampus (and cerebral cortex). Recent data indicate antidepressant-like activity of group I mGlu receptor (mGluR1 and mGluR5) antagonists in animal tests/models. We now report that chronic treatment with 2-methyl-6-(phenylethynyl)-pyridine (MPEP), a selective mGlu5 receptor antagonist, increased hippocampal but reduced cortical BDNF mRNA level (Northern blot). Desipramine, a classic antidepressant, increased BDNF mRNA level in both examined brain regions. This is the first demonstration that an antagonist of mGlu5 receptors, like a majority of well-established antidepressants, induces hippocampal BDNF gene expression. A significance of MPEP ability to reduce cortical BDNF needs further study. Nevertheless, this observation further indicates a potential antidepressant activity of the group I mGlu receptor antagonists in human depression.     

Mast cells as a source of nitric oxide in the human placenta--morphometric analysis in preeclampsia complicated pregnancy

The aim of the study was to test hypothesis, that in placenta mast cells are significant source of iNOS. Material: Placentas were collected after term delivery from healthy (control, n=13) and preeclamptic (n=11) women. Mast cells and iNOS expression were detected in obtained samples with monoclonal anti-iNOS and anti-tryptase antibodies. Next, morphometric analysis were performed. There were no significant difference between iNOS expression and number of iNOS-positive cells in normal and preeclamptic placentas. There was a significant increase in mast cells number in preeclamptic placentas (8.32 +/- 1.3 SD vs 5.14 +/- 1.2 SD in control) and decrease in percentage of iNOS positive cells among them (68.1% vs 23.6%). We conclude, that in uncomplicated pregnancies, mast cells are the main source of iNOS in placenta while in preeclampsia they loss their potential to synthetase iNOS.     

Systemic management of autoimmune anterior uveitis

Autoimmune uveitis is an acute, recurrent, sight-threatening disease that can lead to severe visual loss and blindness. It requires systemic immunosuppressive therapy and continuous monitoring by ophthalmologist and rheumatologist. There are no universally accepted referral patterns for the treatment of endogenous uveitis. Most specialists indicate corticosteroids, methotrexate and cyclosporine A as the first use drugs. Anti-cytokine drugs are a new opportunity for the patients unresponsive to the conventional anti-inflammatory and immunosuppressive therapy.     

Zinc and depression. An update

Unsatisfactory clinical efficacy and a variety of adverse effects of current antidepressant drugs have incited search for better therapy. Zinc, an antagonist of the glutamate/N-methyl-D-aspartate (NMDA) receptor, exhibits antidepressant-like activity in rodent tests/models of depression. Similarly to antidepressants, zinc induces brain derived neurotrophic factor (BDNF) gene expression and increases level of synaptic pool of zinc in the hippocampus. Clinical observations demonstrated serum hypozincemia in depression, which was normalized by effective antidepressant treatment. Moreover, our preliminary clinical study demonstrated the benefit of zinc supplementation in antidepressant therapy. All the data indicate the important role of zinc homeostasis in psychopathology and therapy of depression and potential clinical antidepressant activity of this ion.