Angiotensin II Induces Vascular Endocannabinoid Release, Which Attenuates Its Vasoconstrictor Effect via CB1 Cannabinoid Receptors

In the vascular system angiotensin II (Ang II) causes vasoconstriction via the activation of type 1 angiotensin receptors. Earlier reports have shown that in cellular expression systems diacylglycerol produced during type 1 angiotensin receptor signaling can be converted to 2-arachidonoylglycerol, an important endocannabinoid. Because activation of CB(1) cannabinoid receptors (CB(1)R) induces vasodilation and reduces blood pressure, we have tested the hypothesis that Ang II-induced 2-arachidonoylglycerol release can modulate its vasoconstrictor action in vascular tissue. Rat and mouse skeletal muscle arterioles and mouse saphenous arteries were isolated, pressurized, and subjected to microangiometry. Vascular expression of CB(1)R was demonstrated using Western blot and RT-PCR. In accordance with the functional relevance of these receptors WIN55212, a CB(1)R agonist, caused vasodilation, which was absent in CB(1)R knock-out mice. Inhibition of CB(1)Rs using O2050, a neutral antagonist, enhanced the vasoconstrictor effect of Ang II in wild type but not in CB(1)R knock-out mice. Inverse agonists of CB(1)R (SR141716 and AM251) and inhibition of diacylglycerol lipase using tetrahydrolipstatin also augmented the Ang II-induced vasoconstriction, suggesting that endocannabinoid release modulates this process via CB(1)R activation. This effect was independent of nitric-oxide synthase activity and endothelial function. These data demonstrate that Ang II stimulates vascular endocannabinoid formation, which attenuates its vasoconstrictor effect, suggesting that endocannabinoid release from the vascular wall and CB(1)R activation reduces the vasoconstrictor and hypertensive effects of Ang II.     

Beta-amyloid peptides enhance the proliferative response of activated CD4CD28 lymphocytes from Alzheimer disease patients and from healthy elderly

Alzheimer's disease (AD) is the most frequent form of dementia among elderly. Despite the vast amount of literature on non-specific immune mechanisms in AD there is still little information about the potential antigen-specific immune response in this pathology. It is known that early stages of AD include β-amyloid (Aβ)- reactive antibodies production and inflammatory response. Despite some evidence gathered proving cellular immune response background in AD pathology, the specific reactions of CD4(+) and CD8(+) cells remain unknown as the previous investigations yielded conflicting results. Here we investigated the CD4(+)CD28(+) population of human peripheral blood T cells and showed that soluble β-amyloids alone were unable to stimulate these cells to proliferate significantly, resulting only in minor, probably antigen-specific, proliferative response. On the other hand, the exposure of in vitro pre-stimulated lymphocytes to soluble Aβ peptides significantly enhanced the proliferative response of these cells which had also lead to increased levels of TNF, IL-10 and IL-6. We also proved that Aβ peptide-enhanced proliferative response of CD4(+)CD28(+) cells is autonomous and independent from disease status while being associated with the initial, ex vivo activation status of the CD4(+) cells. In conclusion, we suggest that the effect of Aβ peptides on the immune system of AD patients does not depend on the specific reactivity to Aβ epitope(s), but is rather a consequence of an unspecific modulation of the cell cycle dynamics and cytokine production by T cells, occurring simultaneously in a huge proportion of Aβ peptide-exposed T lymphocytes and affecting the immune system performance.     

UCP2 induced by natural birth regulates neuronal differentiation of the hippocampus and related adult behavior

Mitochondrial uncoupling protein 2 (UCP2) is induced by cellular stress and is involved in regulation of fuel utilization, mitochondrial bioenergetics, cell proliferation, neuroprotection and synaptogenesis in the adult brain. Here we show that natural birth in mice triggers UCP2 expression in hippocampal neurons. Chemical inhibition or genetic ablation of UCP2 lead to diminished neuronal number and size, dendritic growth and synaptogenezis in vitro and impaired complex behaviors in the adult. These data reveal a critical role for Ucp2 expression in the development of hippocampal neurons and circuits and hippocampus-related adult behaviors.     

Everybody wins! Poland hosts thrilling competitions of viruses,RNAi and football teams

The ESF–EMBO conference on ‘Antiviral RNAi: From Molecular Biology towards Applications’ took place in June 2012 in Pultusk, Poland. It brought together scientists working at the interface of RNAi and virus infections in different organisms, covering the complete range from basic mechanisms of RNA silencing to RNAi‐based antiviral therapy.     

Characterization of mammalian sedoheptulokinase and mechanism of formation of erythritol in sedoheptulokinase deficiency

Our aim was to identify the product formed by sedoheptulokinase and to understand the mechanism of formation of erythritol in patients with sedoheptulokinase deficiency. Mouse recombinant sedoheptulokinase was found to be virtually specific for sedoheptulose and its reaction product was identified as sedoheptulose 7-phosphate. Assays of sedoheptulose in plant extracts disclosed that this sugar is present in carrots ( approximately 7mumol/g) and in several fruits. Sedoheptulose 1-phosphate is shown to be a substrate for aldolase B, which cleaves it to dihydroxyacetone-phosphate and erythrose. This suggests that, in patients deficient in sedoheptulose-7-kinase, sedoheptulose is phosphorylated by fructokinase to sedoheptulose 1-phosphate. Cleavage of the latter by aldolase B would lead to the formation of erythrose, which would then be reduced to erythritol.     

High-fat diet-induced obesity leads to increased NO sensitivity of rat coronary arterioles: role of soluble guanylate cyclase activation

The impact of obesity on nitric oxide (NO)-mediated coronary microvascular responses is poorly understood. Thus NO-mediated vasomotor responses were investigated in pressurized coronary arterioles ( approximately 100 microm) isolated from lean (on normal diet) and obese (fed with 60% of saturated fat) rats. We found that dilations to acetylcholine (ACh) were not significantly different in obese and lean rats (lean, 83 +/- 4%; and obese, 85 +/- 3% at 1 microM), yet the inhibition of NO synthesis with N(omega)-nitro-l-arginine methyl ester reduced ACh-induced dilations only in vessels of lean controls. The presence of the soluble guanylate cyclase (sGC) inhibitor oxadiazolo-quinoxaline (ODQ) elicited a similar reduction in ACh-induced dilations in the two groups of vessels (lean, 60 +/- 11%; and obese, 57 +/- 3%). Dilations to NO donors, sodium nitroprusside (SNP), and diethylenetriamine (DETA)-NONOate were enhanced in coronary arterioles of obese compared with lean control rats (lean, 63 +/- 6% and 51 +/- 5%; and obese, 78 +/- 5% and 70 +/- 5%, respectively, at 1 microM), whereas dilations to 8-bromo-cGMP were not different in the two groups. In the presence of ODQ, both SNP and DETA-NONOate-induced dilations were reduced to a similar level in lean and obese rats. Moreover, SNP-stimulated cGMP immunoreactivity in coronary arterioles and also cGMP levels in carotid arteries were enhanced in obese rats, whereas the protein expression of endothelial NOS and the sGC beta1-subunit were not different in the two groups. Collectively, these findings suggest that in coronary arterioles of obese rats, the increased activity of sGC leads to an enhanced sensitivity to NO, which may contribute to the maintenance of NO-mediated dilations and coronary perfusion in obesity.     

Galanin Alters GABAergic Neurotransmission in the Dorsal Raphe Nucleus

The neuropeptide galanin and its three receptor subtypes (Gal R1-3) are highly expressed in the dorsal raphe nucleus (DRN), a region of the brain that contains a large population of serotonergic neurons. Galanin is co-expressed with serotonin in approximately 40% of the DRN neurons, and galanin and GALR2 expression are elevated by antidepressants like the SSRI fluoxetine, suggesting an interaction between serotonin and galanin. The present study examines the effect of galanin (Gal 1–29), a pan ligand for GalR (1–3) and the GalR2/GalR3-selective ligand, Gal 2–11, on the electrophysiological properties of DRN serotonergic neurons in a slice preparation. We recorded from cells in the DRN with electrophysiological characteristics consistent with those of serotonergic neurons that exhibit high input resistance, large after-hyperpolarizations and long spike duration as defined by Aghajanian and Vandermaelen. Both Gal 1–29 and Gal 2–11 decreased the amplitudes pharmacologically-isolated GABAergic inhibitory postsynaptic potentials (IPSPs) in these putative serotonergic neurons. Furthermore, based on paired pulse facilitation studies, we show that Gal 1–29 likely decreases GABA release through a presynaptic mechanism, whereas Gal 2–11 may act postsynaptically. These findings may enhance understanding of the cellular mechanisms underlying the effects of antidepressant treatments on galanin and galanin receptors in DRN. Special issue article in honor of Dr. Frode Fonnum.     

N-alkyl-4-piperidinyl-2,3-diarylpyrrole derivatives with heterocyclic substitutions as potent and broad spectrum anticoccidial agents

Diaryl-(4-piperidinyl)-pyrrole derivatives bearing cyclic amine substituents have been synthesized and evaluated as anticoccidial agents. Improvements in potency of Et-PKG inhibition, such as azetidine derivative 3a, and broad spectrum anticoccidial activities in feed, such as morpholine derivative 8c, have been achieved.     

Involvement of auxin and cytokinins in initiation of growth of isolated pea buds

Axillary buds from the second primary scale excised from 21-day-old pea(Pisum sativum L. cv. Vladan) plants were used as a modelsystem for studying the release of buds from apical dominance. The isolatedbudswere transferred onto basal medium with or without a supplement of growthregulators and cultivated up to 24 h in short-term and up to 4weeks in long-term experiments. In both sets of experiments endogenous IAA,cytokinins and the uptake of labelled zeatin were analysed. The development ofbuds was monitored by image analysis, estimation of their weight, and byanatomical studies. Generative meristems were found in isolated axillary budsalready in 21-day-old plants at the beginning of the experimental period. Theonset of bud growth was recorded as soon as 2 h after the budexcision by image analysis. The bud growth was accompanied by a rapid transientincrease of the endogenous IAA level within the first 2 h,followedby an increase of iPA within 24 h. The uptake of the exogenouscytokinin ([³H]Z) reached its peak between the 6 and 8hafter the release from apical dominance. The cytokinin analyses of bothshort-term and long-term bud cultures revealed the increase of free cytokininsand their glucosides, indicating de novo synthesis ofcytokinins in the buds themselves.     

Nonacosane-5,8-diol: A new component of plant waxes

A new fraction has been isolated by chromatographic methods from the wax of the Bulgarian oil-bearing rose. According to its IR, NMR and MS it was characterized as an homologous series of γ-diols, from C¹⁷ to C³³ with the major homologues those containing an odd number of carbon atoms. Nonacosane-5,8-diol is the major constituent.