Irena Baranowska-Bosiacka

Energy Metabolism of the Brain, Including the Cooperation between Astrocytes and Neurons, Especially in the Context of Glycogen Metabolism.

Glycogen metabolism has important implications for the functioning of the brain, especially the cooperation between astrocytes and neurons. According to various research data, in a glycogen deficiency (for example during hypoglycemia) glycogen supplies are used to generate lactate, which is then transported to neighboring neurons. Likewise, during periods of intense activity of the nervous system, when the energy demand exceeds supply, astrocyte glycogen is immediately converted to lactate, some of which is transported to the neurons. Thus, glycogen from astrocytes functions as a kind of protection against hypoglycemia, ensuring preservation of neuronal function. The neuroprotective effect of lactate during hypoglycemia or cerebral ischemia has been reported in literature. This review goes on to emphasize that while neurons and astrocytes differ in metabolic profile, they interact to form a common metabolic cooperation.

Perinatal exposure to lead induces morphological, ultrastructural and molecular alterations in the hippocampus.

The aim of this paper is to examine if pre- and neonatal exposure to lead (Pb) may intensify or inhibit apoptosis or necroptosis in the developing rat brain. Pregnant experimental females received 0.1% lead acetate (PbAc) in drinking water from the first day of gestation until weaning of the offspring; the control group received distilled water. During the feeding of pups, mothers from the experimental group were still receiving PbAc. Pups were weaned at postnatal day 21 and the young rats of both groups then received only distilled water until postnatal day 28. This treatment protocol resulted in a concentration of Pb in rat offspring whole blood (Pb-B) below the threshold of 10 μg/dL, considered safe for humans.We studied Casp-3 activity and expression, AIF nuclear translocation, DNA fragmentation, as well as Bax, Bcl-2 mRNA and protein expression as well as BDNF concentration in selected structures of the rat brain: forebrain cortex (FC), cerebellum (C) and hippocampus (H). The microscopic examinations showed alterations in hippocampal neurons.Our data shows that pre- and neonatal exposure of rats to Pb, leading to Pb-B below 10 μg/dL, can decrease the number of hippocampus neurons, occurring concomitantly with ultrastructural alterations in this region. We observed no morphological or molecular features of severe apoptosis or necrosis (no active Casp-3 and AIF translocation to nucleus) in young brains, despite the reduced levels of BDNF. The potential protective factor against apoptosis was probably the decreased Bax/Bcl-2 ratio, which requires further investigation. Our findings contribute to further understanding of the mechanisms underlying Pb neurotoxicity and cognition impairment in a Pb-exposed developing brain.

Conjugated linoleic acid increases intracellular ROS synthesis and oxygenation of arachidonic acid in macrophages

OBJECTIVE Conjugated linoleic acids (CLAs) have potential antiatherosclerotic properties: they may inhibit atherosclerotic processes by reducing the intensity of inflammatory processes. However, in vivo studies have shown that the application of trans-10, cis-12 CLA in obese men increased their oxidative stress. The objective of this study was to determine whether CLA can lead to an increase in oxidative stress and to isoprostane synthesis in macrophages. METHODS Monocytes from peripheral blood and human monocytic leukemia cells were used in this study. Monocytes were differentiated to macrophages, and were incubated with 30 microM cis-9, trans-11 CLA and trans-10, cis-12 CLA or linoleic acid for 2 days. In some experiments the inhibitors of peroxisome proliferator-activated receptor-alpha (PPAR-alpha) or respiratory chain were added. After incubation, synthesis of reactive oxygen species (ROS), total cellular concentration of adenosine triphosphate, concentration of 8-epi-prostaglandin F2 alpha, activity of cytoplasolic phospholipase A2 (cPLA2), activity of mitochondria, and expression of mRNA of PPAR-alpha were measured. RESULTS In cells cultured with CLAs intercellular ROS synthesis increased. In this condition the mitochondrial energy potential was high, and the inhibitors of the respiratory chain and PPAR-alpha reduced ROS concentration. At the same time, the cPLA2 activity was abolished. In contrast, 8-iPF2 alpha III synthesis increased in CLA cells. CONCLUSION Cultivation of cells with CLA leads to an increased ROS synthesis, partly by PPAR-alpha mechanism. An increase in ROS concentration and inhibition of cPLA2 activity can stimulate oxygenation of arachidonic acid and contribute to an increase in 8-epi-PF2 alpha III level and in the apoptosis process in macrophages.

P2X and P2Y receptors—role in the pathophysiology of the nervous system.

Purinergic signalling plays a crucial role in proper functioning of the nervous system. Mechanisms depending on extracellular nucleotides and their P2 receptors also underlie a number of nervous system dysfunctions. This review aims to present the role of purinergic signalling, with particular focus devoted to role of P2 family receptors, in epilepsy, depression, neuropathic pain, nervous system neoplasms, such as glioma and neuroblastoma, neurodegenerative diseases like Parkinson’s disease, Alzheimer’s disease and multiple sclerosis. The above-mentioned conditions are associated with changes in expression of extracellular ectonucleotidases, P2X and P2Y receptors in neurons and glial cells, as well as releasing considerable amounts of nucleotides from activated or damaged nervous tissue cells into the extracellular space, which contributes to disturbance in purinergic signalling. The numerous studies indicate a potential possibility of using synthetic agonists/antagonists of P2 receptors in treatment of selected nervous system diseases. This is of particular significance, since numerous available agents reveal a low effectiveness and often produce side effects.

Fluoride as a pro-inflammatory factor and inhibitor of ATP bioavailability in differentiated human THP1 monocytic cells.

Chronic exposure of humans to fluorine compounds in the air, water and food may be atherogenic via the activation of oxidative stress and increased ROS production. The most important factor that promotes the formation of ROS seems to be the oxidoreduction of electron carriers in the critical points of the respiratory chain, which depends, among other things, on the cellular demand for ATP. This paper examines the effect of fluorides in concentrations determined in human serum on the intracellular synthesis of ROS, the activity of the respiratory chain enzymes and the synthesis of ATP via oxidative and substrate-level phosphorylation. The incubation of macrophages in fluoride solutions significantly decreased the amount of synthesized cellular ATP and increased formation of ROS and apoptosis in a dose-dependent pattern. The addition of respiratory chain inhibitors resulted in a significant decrease in the synthesized ROS. Sodium fluoride probably promotes oxidative stress in macrophages, which is manifested by a strong increase in ROS synthesis and a decrease in ATP. We suppose that fluoride may destabilize the action of respiratory chain. Our results indicate that the respiratory chain is the main site of ROS synthesis. One cannot exclude the stimulating role of fluorine compounds on the formation of ROS that is independent of the respiratory chain.

Altered energy status of primary cerebellar granule neuronal cultures from rats exposed to lead in the pre- and neonatal period

This paper examines the effect of pre- and neonatal exposure of rats to lead (0.1% lead acetate in drinking water, resulting in rat offspring whole blood lead concentration (Pb-B) 4μg/dL) on the energy status of neuronal mitochondria by measuring changes in ATP, ADP, AMP, adenosine, TAN concentration, adenylate energy charge value (AEC) and mitochondrial membrane potential in primary cerebellar granule neurons (CGC) in dissociated cultures. Fluorescence studies were performed to imaging and evaluate mitochondria mass, mitochondrial membrane potential, intracellular and mitochondrial reactive oxygen species (ROS) production. The Na(+)/K(+) ATPase activity in intact CGC was measured spectrophotometrically. Our data shows that pre- and neonatal exposure of rats to Pb, even below the threshold of whole blood Pb value considered safe for people, affects the energy status of cultured primary cerebellar granule neurons through a decrease in ATP and TAN concentrations and AEC value, inhibition of Na(+)/K(+) ATPase, and increase in intracellular and mitochondrial ROS concentration. These observations suggest that even these low levels of Pb are likely to induce important alterations in neuronal function that could play a role in neurodegeneration.

Hymenolepis diminuta: Analysis of the expression of Toll-like receptor genes and protein (TLR3 and TLR9) in the small and large intestines of rats

Toll-like receptors (TLRs) play a fundamental role in the rapid activation of innate immune responses to a variety of pathogen-associated molecular patterns (PAMPs). In a previous study we observed an increase in the level of expression of TLR2 and TLR4 mRNA in the jejunum and colon during experimental hymenolepidosis in rats. In this study, we performed a quantitative real-time polymerase chain reaction (qRT-PCR), Western blot analysis and immunohistochemical staining of TLR3 and TLR9 receptors during experimental hymenolepidosis in rats. The levels of mRNA and protein expression of TLR3 and TLR9 in the jejunum had increased at 16 days post Hymenolepis diminuta infection (dpi) in the case of TLR3 and at 16 and 25 dpi in the case of TLR9. In the colon the expression of TLR3 and TLR9 had increased at 16, 25 and 40 dpi. The results of the immunohistochemical reactions showed that H. diminuta infected rats (16, 25, 40 and 60 dpi) exhibited changes in TLR3 and TLR9 localization and intensity in the epithelial cells of the jejunum and colon. The changes in the level of TLR3 and TLR9 expression may confirm involvement of the innate immune system in the pathomechanism of hymenolepidosis.

Haptoglobin 2-1 phenotype predicts rapid growth of abdominal aortic aneurysms

BACKGROUND Haptoglobin (Hp) polymorphism is associated with the prevalence and clinical evolution of many inflammatory diseases and atherosclerosis. Circulating neutrophils and neutrophil-associated proteases are an important initial component of experimental abdominal aortic aneurysm (AAA) formation. Elastase and C-reactive protein (CRP) levels are elevated in patients with AAAs. This study assessed the relationship between AAA expansion and Hp phenotypes, neutrophil count, elastase, and CRP levels. METHODS Eighty-three consecutive AAA patients underwent annual ultrasound scans. Three major Hp phenotypes (1-1, 2-1, and 2-2) were determined, and the neutrophil count, serum elastase, and high-sensitivity (hs) CRP levels were measured at the initial examination. After initial screening, patients were rescanned at 6- to 12-month intervals up to a period of 2 to 7 years. The mean yearly growth of the AAA largest transverse diameter was estimated for each group of Hp patients. The results are presented as median (interquartile range). RESULTS Hp 2-1 patients had a significantly higher growth rate (3.69 [2.40] mm/y) of AAA compared with patients with Hp 2-2 (1.24 [0.79], P < .00001) and Hp 1-1 (1.45 [0.68], P = .00004). This association remained significant in the multivariate analysis. Elevated elastase serum activity was also evident in AAA patients with Hp 2-1 (0.119 [0.084] arbitrary units) in contrast to Hp 2-2 (0.064 [0.041], P < .00001) and Hp 1-1 (0.071 [0.040], P = .0006) patients. CRP serum levels (mg/L) were significantly higher in patients with Hp 2-1 (7.2 [7.1]) than in Hp 2-2 (3.4 [3.1], P = .0058) and Hp 1-1 (2.8 [4.1], P = .044). The neutrophil count was not significantly different among Hp groups. CONCLUSIONS The Hp 2-1 phenotype showed a strong association with increased rates of the expansion of AAAs and may be a useful independent predictor of growth rate. Further large follow-up studies will be needed to investigate the pathomechanisms of association and the role of elastase and inflammation in the progression of AAA.

Multiple effects of copper on NMDA receptor currents

Copper (Cu) is an essential metal present in the human brain and released from synaptic vesicles following neuronal depolarization. Cu is known to reduce the NMDA receptor (NR) current with IC50≈20 µM. We have studied the effect of Cu on the NR current in cultured neonatal rat cerebellum granule cells (CGC) and in transiently transfected HEK293 cells (HEK), expressing either GluN1/GLUN2A or GluN1/GluN2B receptors. In CGCs, Cu causes a potentiation of the NR current at concentrations <30 µM (EC50=4.6 µM) and a block at higher concentrations (IC50=24 µM). In Fura2 loaded CGCs, Cu (≤30 µM) caused an increase of NMDA-driven calcium influx. This facilitating effect was prevented by pre-treatment with the reducing agent DTT. Cu also caused an increase of the NR current in GluN1/GluN2A receptors (EC50=2 µM) and a block at higher concentrations (IC50=26 µM). Both facilitation and inhibition were independent of voltage. The effect of Cu was quantitatively similar in GluN1/GluN2B receptors, which were potentiated by 10 µM and inhibited by 100 µM Cu. Potentiation was absent in mutants deleted of their entire amino terminal domain (ATD) of the protein, suggesting an involvement of this region in the interaction. These results indicate that Cu can facilitate the NR current at lower concentrations than those required for blocking it; this effect can have consequences on the activity of the metal at synaptic and extrasynaptic sites.

Hymenolepis diminuta: Effect of infection on ion transport in colon and blood picture of rats.

The aim of this study was to examine the effect of an infection with Hymenolepis diminuta on ion transport in an isolated colon and blood picture of rats. Fifty rats were orally infected with five cysticercoids of H. diminuta. The experimental groups of rats were assigned to four groups: group I - 8 days post-infection (dpi), group II - 16 dpi, group III - 40 dpi and group IV- 60 dpi. The control group comprised non-infected rats. The experiments consisted of measuring the transepithelial electrical potential difference (PD) and the transepithelial electrical resistance (R) of the rat colon under controlled conditions as well as during mechanical stimulation (MS) using a modified Ussing chamber. Ion transport was modified using inhibitors of the epithelial sodium channel (amiloride - AMI) and the epithelial chloride channel (bumetanide - BUME), and also using capsaicin (CAPSA), a substance which activates C-fibres. The experimental data presented in this study indicates that experimental hymenolepidosis inhibits sodium and chloride ion transport in the epithelium of the rat colon, with preserved tight junction continuity (except at 40 dpi) and a decreased mechanical sensitivity. The effect of capsaicin on ion transport in the rat colon was varied. In control rats it increased ionic current, and in H. diminuta-infected rats it did not cause any changes in PD. Blood picture in this study showed a statistically significantly lower red blood cells (RBC) count and haemoglobin (HGB) concentration in infected rats in comparison to non-infected. Red cell distribution width (RDW) values and platelet (PLT) count were negatively correlated with the duration of infection, whereas mean corpuscular volume (MCV) value was positively correlated. We did not observe leukocytosis during infection, and amongst the differential leukocyte counts eosinophils and basophils showed statistically significant lower values in infected rats in comparison to non-infected. Our results indicate that hymenolepidosis is associated with the activation of inflammatory mediators and stimulation of nervous fibres, which significantly affects the function of ion channels in the epithelium of the colon in the host. At the same time, a significant decrease in eosinophil count during infection suggests that such an infection did not trigger a strong immunological reaction in rats.