Differences in the dynamics of changes in the concentration of kynurenic acid in the blood serum of depressed patients treated with electroconvulsive therapy

BACKGROUND

Nowadays, depression is a serious clinical problem, as the prevalence of its various forms increases and there are growing numbers of patients with severe forms of depression and treatment-refractory depression. Depressed patients have been observed to have decreased levels of kynurenic acid (KYNA), which is the only endogenous antagonist of ionotropic N-methyl-D-aspartate (NMDA) receptors. The aim of this study was to identify subgroups of patients differing in the dynamics of changes in KYNA concentration during electroconvulsive therapy (ECT).

SUBJECTS AND METHODS

The study included 32 patients with an ICD-10 diagnosis of a major depressive episode receiving ECT treatment and 48 healthy volunteers. Blood serum KYNA concentrations were determined using HPLC-based methods, and clinical assessment was performed using the Montgomery-Åsberg Depression Rating Scale (MADRS) and the Clinical Global Impressions (CGI) Scale.

RESULTS

Three subgroups of patients with depression were identified which differed in baseline KYNA levels and in the dynamics of changes in blood serum KYNA concentrations during and after ECT.

CONCLUSIONS

The largest number of patients with clinical improvement (83%) was observed in the subgroup with significantly lower pre-treatment, treatment and post-treatment KYNA concentrations than those determined in the control group. This subgroup of patients also showed the lowest dynamics of changes in KYNA concentrations during ECT. Clinical improvement was observed in 75% of depressed patients who had insignificantly lower pre-treatment levels of KYNA and slightly higher levels of this acid after 6 and 12 ECT sessions than controls. The smallest number of patients with clinical improvement (50%) was observed in the subgroup of patients who had similar pre-treatment and treatment concentrations of KYNA to controls and whose post-treatment concentrations of KYNA were significantly lower than those of healthy individuals.

Blood serum concentrations of kynurenic acid in patients diagnosed with recurrent depressive disorder, depression in bipolar disorder, and schizoaffective disorder treated with electroconvulsive therapy

OBJECTIVES

The aim of the present study was to compare blood serum kynurenic acid (KYNA) concentrations measured before ECT and after 1, 6 and 12 electroconvulsive treatment (ECT) sessions in patients with diagnoses of recurrent depressive disorder (RDD), depression in bipolar disorder (DBD) and schizoaffective disorder (SAD).

METHODS

The study group comprised of 50 patients with ICD-10 diagnoses of RDD, DBD and SAD. Blood serum KYNA concentrations were determined and clinical assessment was performed using the MADRS and the GAF scale.

RESULTS

Significant differences were found in blood serum KYNA levels between RDD, DBD and SAD patients treated with electroconvulsive therapy and healthy controls: 1) KYNA concentrations in DBD patients measured before ECT and after 12 ECT sessions were significantly lower than in the control group; 2) KYNA concentrations in the serum of RDD patients measured before ECT and after one and 12 ECT sessions were significantly lower than in the control group, while those measured after 6 ECT session did not differ significantly from KYNA concentrations in healthy controls; 3) higher pre-treatment blood serum concentrations of KYNA in DBD patients correlated with a higher number of illness phases and poorer general functioning before treatment; 4) significant relationships were found between higher blood serum concentrations of KYNA in RDD patients after 1 ECT session and male gender, and between higher KYNA concentrations after 6 ECT sessions and increased depression and poorer functioning before treatment in those patients.

CONCLUSIONS

Results show that KYNA concentrations in all diagnostic groups were lower before ECT (not statistically significant for the SAD group) and that there were no significant changes in those concentrations (compared with the baseline) during ECT.

Formation of Avenacein Y by Fusarium avenaceum Fries Sacc. isolates from Germany and pathogenicity of the isolates to cereal seedlings

Twelve isolates ofFusarium avenaceum Fries Sacc. originating from diseased corn plants from Germany produced Avenacein Y in amounts ranging from 0.001 to 1.6 g/kg of wheat grain. The isolates proved most pathogenic to triticale seedlings, less pathogenic to rye seedlings and least to wheat. Pathogenicity of the isolates was not correlated with their ability to produce Avenacein Y.

beta-adrenergic enhancement of brain kynurenic acid production mediated via cAMP-related protein kinase A signaling

The central levels of endogenous tryptophan metabolite kynurenic acid (KYNA), an antagonist of N-methyl-d-aspartate (NMDA) and alpha7-nicotinic receptors, affect glutamatergic and dopaminergic neurotransmission. Here, we demonstrate that selective agonists of beta(1)-receptors (xamoterol and denopamine), beta(2)-receptors (formoterol and albuterol), alpha- and beta-receptors (epinephrine), 8pCPT-cAMP and 8-Br-cAMP (analogues of cAMP) increase the production of KYNA in rat brain cortical slices and in mixed glial cultures. Neither betaxolol, beta(1)-adrenergic antagonist, nor timolol, a non-selective beta(1,2)-adrenergic antagonist has influenced synthesis of KYNA in both paradigms. In contrast, KT5720, a selective inhibitor of protein kinase A (PKA), strongly reduced KYNA formation in cortical slices (2-10 microM) and in glial cultures (100 nM). beta-adrenergic antagonists and KT5720 prevented the beta-adrenoceptor agonists-induced increases of KYNA synthesis. In vivo, beta-adrenergic agonist clenbuterol (0.1-1.0 mg/kg) increased the cortical endogenous level of KYNA; the effect was blocked with propranolol (10 mg/kg). beta-adrenoceptors agonists, cAMP analogues and KT5720 did not affect directly the activity of KAT I or KAT II measured in partially purified cortical homogenate. In contrast, the exposure of intact cultured glial cells to pCPT-cAMP, 8-Br-cAMP and formoterol has lead to an enhanced action of KATs. These findings demonstrate that beta-adrenoceptor-mediated enhancement of KYNA production is a cAMP- and PKA-dependent event. PKA activity appears to be an essential signal affecting KYNA formation. Described here novel mechanism regulating KYNA availability may be of a potential importance, considering that various stimuli, among them clinically used drugs, activate cAMP/PKA pathway, and thus could counteract the central deficits of KYNA.

Clenbuterol enhances the production of kynurenic acid in brain cortical slices and glial cultures

The effect of a beta(2)-adrenergic agonist, clenbuterol on the production of a glutamate receptor antagonist, kynurenic acid was studied in vitro. Clenbuterol enhanced the production of kynurenic acid in brain cortical slices (0.1-1.0 mM) and in glial cultures (1-50 muM). Timolol, a non-selective beta-adrenergic antagonist prevented this effect. The presented data indicate a novel mechanism of action of beta(2)-adrenoceptor agonists and suggest that an increased formation of the endogenous glutamate receptor antagonist, kynurenic acid could partially contribute to their neuroprotective activity.

Antibiotic Y: biosynthesis by Fusarium avenaceum (Corda ex Fries) Sacc., isolation, and some physicochemical and biological properties

A compound very similar to the mycotoxin citrinin was observed on thin-layer chromatographic plates during the screening analysis of grain extracts. This compound was produced by 22 of the tested Fusarium avenaceum (Corda ex Fries) Sacc. strains isolated from wheat, triticale, barley, corn, and potatoes. A chemical test confirmed the presence of an unknown compound, which was given the preliminary name of antibiotic Y (indicating yellow fluorescence). The following properties of the new metabolite are described: spectroscopic (UV, infrared, proton nuclear magnetic resonance, fluorescence, and mass spectrometry), phytotoxic, antibiotic (inhibitory effect of bacterial growth), and toxic (toxicity to Artemia salina, chicken embryos, and mouse fibroblasts). Elemental analysis of the compound showed that it had the general formula C15H10O8, in agreement with the mass spectrometric finding that the molecular ion had a molecular weight of 318. The structure of the compound is presently under study.

Synthesis and analysis of 1-octen-3-ol, the main flavour component of mushrooms

The most abundant volatile occurring in mushrooms and responsible for the mushroom odour is 1-octen-3-ol. To meet the demand for a flavour compound yielding a mushroom odour a study was carried out on the possibility of obtaining 1-octen-3-ol synthetically. On the basis of literature data and experiments performed, the synthesis of this compound was carried out by two methods, i.e. by Grignard reaction between acrolein and amyl iodide and by selective reduction of 1-octen-3-on. The purity of the 1-octen-3-ol obtained was determined by GLC chromatography and by spectroscopic methods. The compound obtained by Grignard reaction had its IR, 13C NMR spectra and GLC chromatogram identical with those of the standard. The yield of 1-octen-3-ol by Grignard reaction was 65%, while the reduction of the ketone to the alcohol gave a yield of 90%.