Mirko Tomić

Neuropharmacological evaluation of diethylether extract and xanthones of Gentiana kochiana

Diethylether extract of aerial parts of Gentiana kochiana mostly consists of two tetraoxygenated xanthones: gentiacaulein (1,7-dihidroxy-3,8-dimethoxyxanthone; 76.1%) and gentiakochianin (1,7,8-trihidroxy-3-methoxyxanthone; 14.2%). The extract and these xanthones were evaluated for the CNS pharmacological activity in rodents. In vitro assays on rat brain preparations revealed insignificant interaction of the compounds with the specific dopamine and serotonin receptors or synaptosomal uptake of serotonin. However, the extract and gentiacaulein strongly inhibited rat microsomal MAO A (IC50=0.22 microg/ml and 0.49 microM, respectively). Their effects on MAO B and a gentiakochianin blocking potential on both MAO enzymes were moderate. Behavioral examinations on mice showed that 10 day s.c. administration of the extract (20 mg/kg) significantly decreased immobility score in a forced swimming test and strongly inhibited ambulation and stereotypy in an open-field test. These effects resembled those induced by 10 mg/kg imipramine. The ex vivo MAO A activity in crude brain mitochondrial fraction of mice treated with 20 mg/kg of the extract was significantly elevated, whilst that outside brain nerve terminals was declined. This study suggests some antidepressant therapeutic potential of G. kochiana, particularly of gentiacaulein, with an ambiguity whether pharmacological mechanism could be related only to the central inhibition of MAO A.

The mechanisms responsible for neuroprotective capacity of arylpiperazine dopaminergic ligands against cell death induced by sodium nitroprusside

A group of sixteen arylpiperazines had been previously synthesized and evaluated for atypical antipsychotic activity. Here we examined these compounds for their neuroprotective capacity. The affinity and agonist/antagonist action of the arylpiperazines at dopamine hD(2S) receptors were determined in vitro on membranes from stably transfected CHO-hD(2S) cell line. The assays for cell viability and antioxidative capacity (total glutathione and total superoxide dismutase activity), amount of nitric oxide and superoxide radicals, as well as influence on prosurvival pathways (Akt and ERK), were performed on the human neuroblastoma cell line SH-SY5Y. Cell death was induced by oxidative or nitrosative stress, or by growing cells in the medium deprived of serum. Only four of the arylpiperazines exhibited notable neuroprotection against cell death induced by sodium nitroprusside. Two of these arylpiperazines induced elevations of pAkt, while two other compounds reduced the levels of pErk, whereas these actions are considered to support the cell survival. The benzimidazole heteroaryl-group, that mimics catechol moiety of the dopamine molecule, might be the prerequisite structure for the neuroprotective action of these ligands. It is postulated that neuroprotection was acquired also by elevation of endogenous glutathione or total superoxide dismutase activity.

Effect of soman intoxication on the organization of rat brain ribosomes and the translational activity of mRNA in a cell-free system

The effect of soman on rat brain ribosomes organization and translational activity of mRNA in cellfree system was studied in rats exposed to 1.3 LD50 soman (120 μg/kg body weight) and in rats repeatedly injected with 0.4 LD50 soman (35 μg/kg). Fifteen minutes after the injection of 1.3 LD50 soman the heavy polyribosomal fraction from rat brain was found to be enriched and translational activity of mRNA was enhanced. In rats administered five injections of 0.4 LD50 soman at 24-h intervals, the low density ribosomes appeared as the predominant fraction whereas the activity of mRNA in all cell-free system was significantly impaired. It is concluded that soman intoxication expresses a stimulatory or inhibitory effect on the processes of protein synthesis in the rat brain, depending on the dose schedule of soman administration.

Evaluation of angiogenic and neuroprotective potential of different extracts from three Veronica species

Methanol and 70% acetone extracts from Veronica jacquinii, Veronica urticifolia and Veronica teucrium were evaluated regarding their neuroprotective/antioxidant effects on the human neuroblastoma SH-SY5Y cell line. All extracts exhibited modest protective activity by increasing cell survival in cells stressed with sodium nitroprusside (9–12%) and hydrogen peroxide (16–21%) compared to non-treated cells. These activities were accompanied by reductions in the amount of superoxide radicals and index of lipid peroxidation. Extracts were further analysed for the content of total phenolics, phenylpropanoid glycosides and iridoids, and the major compounds acteoside and aucubin. The highest amount of total phenolics was observed in V. jacquinii, while V. teucrium was richest in total iridoids, acteoside and aucubin. Angiogenic properties on EA.hy926 human endothelial cells were also examined. At the highest non-toxic concentration (25 µg/ml), the tested extracts inhibited spontaneous tube formation of endothelial cells on the extracellular matrix, implying their possible antiangiogenic activity. The most potent inhibitory effects were shown by methanol extract of V. jacquinii and aqueous acetone extract of V. teucrium. The extracts did not significantly change the adhesive or migratory capacity of EA.hy926 cells. Considering the traditional use of Veronica species, these results suggest a need for further assessment of their supposed wound-healing properties.

Pharmacological Evaluation of Halogenated and Non-halogenated Arylpiperazin-1-yl-ethyl-benzimidazoles as D2 and 5-HT2A Receptor Ligands

Five groups of previously synthesized and initially screened non‐substituted and 4‐halogenated arylpiperazin‐1‐yl‐ethyl‐benzimidazoles were estimated for their in‐vitro binding affinities at the rat D2, 5‐HT2A, and α1‐adrenergic receptors. Among all these compounds, 2‐methoxyphenyl and 2‐chlorophenyl piperazines demonstrate the highest affinities for the tested receptors. The effects of 4‐halogenation of benzimidazoles reveal that substitution with bromine may greatly increase the affinity of the compounds for the studied receptors, while the effect of substitution with chlorine is less remarkable. Most of the tested components show 5‐HT2A/D2 pKi binding ratios slightly above or less than 1, while only 4‐chloro‐6‐(2‐{4‐[3‐(trifluoromethyl)phenyl]piperazin‐1‐yl}ethyl)‐1H‐benzimidazole expresses an appropriate higher binding ratio (1.14), which was indicated for atypical neuroleptics. This compound exhibits a non‐cataleptic action in rats and prevents d‐amphetamine‐induced hyperlocomotion in mice, which suggest its atypical antipsychotic potency.

Sedative and anxiolytic-like activities of the moss Rhodobryum ontariense water extract in rodents: a preliminary study

Abstract This is the first study designed to explore behavioral effects of the water extract of the moss Rhodobryum ontariense (ROE). Experimental adult animals received intraperitoneal injections of ROE (50–400 mg/kg; vs. saline) 45 min before behavioural evaluation. Motor effects of ROE were estimated in male mice using the open field test (OFT), whereas the elevated plus maze (EPM) model of anxiety was applied on male rats. Single ROE treatments significantly decreased motor activity of mice in OFT (p<0.001) by reducing both the percentage of activity time and the distance travelled in 15 min. Also, ROE in rats significantly increased (p<0.05) the percentage of time spent in open arms and the number of open-arm-entries during 5 min, which was similar to the actions of diazepam in rats (1 mg/kg). These results demonstrated that ROE produced motor sedation and anxiolytic-like effects in rodents.

Disturbances of systemic and hippocampal insulin sensitivity in macrophage migration inhibitory factor (MIF) knockout male mice lead to behavioral changes associated with decreased PSA-NCAM levels

ABSTRACT Macrophage migration inhibitory factor (MIF) is a multifunctional cytokine well known for its role in inflammation enhancement. However, a growing body of evidence is emerging on its role in energy metabolism in insulin sensitive tissues such as hippocampus, a brain region implicated in cognition, learning and memory. We hypothesized that genetic deletion of MIF may result in the specific behavioral changes, which may be linked to impairments in brain or systemic insulin sensitivity by possible changes of the hippocampal synaptic plasticity. To assess memory, exploratory behavior and anxiety, three behavioral tests were applied on Mif gene‐deficient (MIF−/−) and “wild type” C57BL/6J mice (WT). The parameters of systemic and hippocampal insulin sensitivity were also determined. The impact of MIF deficiency on hippocampal plasticity was evaluated by analyzing the level of synaptosomal polysialylated‐neural cell adhesion molecule (PSA‐NCAM) plasticity marker and mRNA levels of different neurotrophic factors. The results showed that MIF−/− mice exhibit emphasized anxiety‐like behaviors, as well as impaired recognition memory, which may be hippocampus‐dependent. This behavioral phenotype was associated with impaired systemic insulin sensitivity and attenuated hippocampal insulin sensitivity, characterized by increased inhibitory Ser307 phosphorylation of insulin receptor substrate 1 (IRS1). Finally, MIF−/− mice displayed a decreased hippocampal PSA‐NCAM level and unchanged Bdnf, NT‐3, NT‐4 and Igf‐1 mRNA levels. The results suggest that the lack of MIF leads to disturbances of systemic and hippocampal insulin sensitivity, which are possibly responsible for memory deficits and anxiety, most likely through decreased PSA‐NCAM‐mediated neuroplasticity rather than through neurotrophic factors. HIGHLIGHTSMacrophage migration inhibitory factor (MIF)−/− mice show anxiety‐like behaviorMIF−/− mice exhibit impaired recognition memoryMIF loss was associated with impaired systemic and hippocampal insulin sensitivityBehavioral changes are related to decreased synaptic plasticity

Effects of Aronia melanocarpa juice on plasma and liver phospholipid fatty acid composition in Wistar rats

Abstract A nutritional placebo-controlled study was performed in Wistar rats in order to investigate the effects of 5-weeks aronia juice consumption towards fatty acid (FA) composition of phospholipids in the plasma and liver, as well as plasma glucose (Glu) and cholesterol levels. The animals were divided into 3 groups of 8 animals each, and randomized to receive either the full polyphenol dose of Aronia melanocarpa juice (AMJ), 4 times less polyphenol dose (¼-AMJ) or polyphenol-lacking placebo beverage (PLB). Each group of 8 male adult Wistar rats received the liquid ad libitum. AMJ decreased the levels of low-density lipoprotein (LDL) (P < 0.05) vs. PLB. AMJ increased dihomo-γ-linoleic acid (DGLA, 20:3n-6) (P < 0.05) and decreased arachidonic acid content (AA, 20:4n-6) (P < 0.05) vs. PLB in liver phospholipids. AMJ significantly increased monounsaturated fatty acids (MUFA) levels both in the liver (P < 0.05) and plasma (P < 0.05). Both aronia juice doses elevated the levels of beneficial n-3 polyunsaturated fatty acids (PUFA) in the plasma and liver. There was a dose-dependent, significant increase (P < 0.001) in cis-vaccenic acid (VA, 18:1n-7) in phospholipids in the plasma and liver. Our results indicate favorable effects of aronia juice intake on lipid parameters in Wistar rats. These findings suggest the potential of aronia dietary intake in cardiometabolic diseases primary prevention strategies in the human population.