Learning-induced plasticity in the barrel cortex is disrupted by inhibition of layer 4 somatostatin-containing interneurons.

Gaba-ergic neurons are a diverse cell class with extensive influence over cortical processing, but their role in experience-dependent plasticity is not completely understood. Here we addressed the role of cortical somatostatin- (SOM-INs) and vasoactive intestinal polypeptide- (VIP-INs) containing interneurons in a Pavlovian conditioning where stimulation of the vibrissae is used as a conditioned stimulus and tail shock as unconditioned one. This procedure induces a plastic change observed as an enlargement of the cortical functional representation of vibrissae activated during conditioning. Using layer-targeted, cell-selective DREADD transductions, we examined the involvement of SOM-INs and VIP-INs activity in learning-related plastic changes. Under optical recordings, we injected DREADD-expressing vectors into layer IV (L4) barrels or layer II/III (L2/3) areas corresponding to the activated vibrissae. The activity of the interneurons was modulated during all conditioning sessions, and functional 2-deoxyglucose (2DG) maps were obtained 24 h after the last session. In mice with L4 but not L2/3 SOM-INs suppressed during conditioning, the plastic change of whisker representation was absent. The behavioral effect of conditioning was disturbed. Both L4 SOM-INs excitation and L2/3 VIP-INs inhibition during conditioning did not affect the plasticity or the conditioned response. We found the activity of L4 SOM-INs is indispensable in the formation of learning-induced plastic change. We propose that L4 SOM-INs may provide disinhibition by blocking L4 parvalbumin interneurons, allowing a flow of information into upper cortical layers during learning.

Betaine supplementation to rats alleviates disturbances induced by high-fat diet: pleiotropic effects in model of type 2 diabetes.

Betaine is a biologically active compound exerting beneficial effects in the organism, however, the exact mechanisms underlying its action are not fully elucidated. The present study aimed to explore, whether betaine alleviates disorders induced by feeding rats a high-fat diet (HFD). Rats were divided into 3 groups: control, fed an HFD and fed an HFD and receiving betaine (2% water solution for 8 weeks). Betaine improved glucose tolerance, decreased blood levels of non-esterified fatty acids and prevented lipid accumulation in the skeletal muscle of rats on an HFD. Betaine reduced activities of blood alanine aminotransferase, blood levels of bilirubin and hepatic lipid content. Expression of fatty acid synthase in the liver and the skeletal muscle was decreased in response to feeding an HFD, and this effect was deepened by betaine in the muscle tissue. Hepatic and muscular expression of genes related to insulin signaling were unchanged in HFD-fed rats. Lipolysis stimulated by epinephrine (an adrenergic receptor agonist), forskolin (an activator of adenylate cyclase), dibutyryl-cAMP (an activator of protein kinase A) and DPCPX (an adenosine A1 receptor antagonist) was diminished in the adipocytes of rats fed an HFD, however, this effect was alleviated by betaine. Moreover, blood leptin levels in HFD-fed rats were elevated, whereas leptinemia have normalized by betaine supplementation. Betaine prevented the increase in expression of N-methyl D-aspartate receptors in the hippocampus and in the cerebral cortex. These results indicate that betaine positively affects the insulin-sensitive tissues: liver (hepatoprotective effects), skeletal muscle (reduced lipid accumulation) and adipose tissue (a rise in lipolysis), which is associated with improved insulin sensitivity. Betaine-induced prevention of hyperleptinemia indicates restoration of leptin action, and changes in the brain reveal neuroprotective properties. Our results show that betaine induces positive changes in HFD-fed rats, its action is pleiotropic and involves different tissues.

Role of integrons in the proliferation of multiple drug resistance in selected bacteria occurring in poultry production.

1. The increase in microbial resistance, and in particular multiple drug resistance (MDR), is an increasing threat to public health. The uncontrolled use of antibiotics and antibacterial chemotherapeutics in the poultry industry, especially in concentrations too low to cause inhibition, and the occurrence of residues in feed and in the environment play a significant role in the development of resistance among zoonotic food-borne microorganisms.2. Determining the presence and transmission methods of resistance in bacteria is crucial for tracking and preventing antibiotic resistance. Horizontal transfer of genetic elements responsible for drug resistance is considered to be the main mechanism for the spread of antibiotic resistance.3. Of the many well-known genetic elements responsible for horizontal gene transfer, integrons are among the most important factors contributing to multiple drug resistance. The mechanism of bacterial drug resistance acquisition through integrons is one of the essential elements of MDR prevention in animal production.

Modulatory effect of inulin with soya isoflavones on plasma lipid profile and liver SCD-18 index in rats with induced type-2 diabetes mellitus.

Obesity and type-2 diabetes are often associated with nonalcoholic fatty liver disease (NAFLD). Soya isoflavones act as antidiabetic agents and protect against NAFLD. There are data suggesting that inulin may increase the plasma concentration and effect of soya isoflavones. The aim of the present study was to compare the effect of soya isoflavones, as opposed to the effect of soya isoflavones with inulin, on plasma lipid profile, liver morphology, and liver fatty acids in rats with induced type-2 diabetes mellitus. Data were collected on thirty-six male Sprague-Dawley rats divided into control and diabetic groups. Animals in the diabetic (DM) group were on a high-fat diet and were injected with low doses of streptozotocin. Animals in the control groups were fed a regular diet and were injected with a buffer. After the injections, the animals were divided into three groups of nondiabetic rats (nDM)-controls (c-nDM), rats treated with isoflavones (IS-nDM), and rats treated with isoflavones plus inulin (IS+IN-nDM)-and three parallel diabetic (DM) subgroups: controls (c-DM), rats treated with isoflavone (IS-DM), and rats treated with isoflavones plus inulin (IS+IN-DM). Hepatic steatosis and fibrosis were examined using hematoxylin-eosin staining and Mallory's trichrome methods respectively. Liver fatty acids were extracted and analyzed by gas chromatography. A lipid blood test was performed. The study showed significant changes in liver fatty acids, liver morphology, and plasma lipid profile. The estimated SCD-18 index significantly decreased in both the control and DM groups after isoflavone supplementation. The level of liver steatosis and fibrosis also decreased after isoflavone supplementation in the DM groups. The plasma lipid profile showed increased levels of HDL-C after isoflavone supplementation in the DM groups. These results support the protective use of isoflavones in liver steatosis and as beneficial to plasma lipid profile in individuals with diabetes. A novelty of this work is its comparison of supplementation using soya isoflavones with supplementation using both soya isoflavones and inulin. Surprisingly, additional supplementation with inulin modulates the positive effect of isoflavones.

Pre-and postnatal exposition to fluorides induce changes in rats liver morphology by impairment of antioxidant defense mechanisms and COX induction.

INTRODUCTION: Fluorides are common in the environment and are absorbed mostly in the stomach and gut, it can easily move through cell membranes and its accumulation can cause harmful effects in skeletal and soft tissues. One of the most important F- accumulation sites is the liver. The aim of this study was to determine whether F- can cause inflammation in rat liver by affecting the activity of antioxidant enzymes and changes in the synthesis of prostaglandin E2 (PGE2) and thromboxane B2 (TXB2). MATERIALS AND METHODS: An in vivo model of prenatal and postnatal exposure to sodium fluoride (NaF) was used to carry out the experiment. Animals from control group received tap water to drink, while animals exposed to F- received drinking water containing NaF, 50 mg/L. In serum and liver we analyzed F- concentration, in liver - antioxidant enzymes activity, PGE2 and TXB2 concentration and immunolocalization of COX1 and COX2 proteins were measured. RESULTS: We observed significant changes in F- concentration only in liver. The results of this study showed that F- affects antioxidant enzymes activity, COX2 protein expression and PGE2 synthesis in liver. Also, in some regions of the liver of rats exposed to F-, the hepatocytes were diffusely altered, with changes resembling microvesicular steatosis. CONCLUSION: Chronic exposure to F- during development causes an accumulation of this element in the liver and changes in antioxidant enzymes activity and cyclooxygenase expression. Long term exposure to this element is toxic to the liver and can cause disturbances in its homeostasis.

The short chain fatty acids and lipopolysaccharides status in Sprague-Dawley rats fed with high-fat and high-cholesterol diet.

Short chain fatty acids (SCFA) are produced by the gut microbiota during the fermentation of non-digestible polysaccharides. Diet is a major factor driving the composition and metabolism of the colonic microbiota. The aim of our study was to examine how a fat-rich and cholesterol-rich diet that, which leads to many metabolic disorders, affects the SCFA profile and lipopolysaccharide (LPS) concentration. The experiment was carried out on 72 male, 8-weeks-old Sprague-Dawley rats. The study group (n = 30 rats) received high-fat and high cholesterol diet (HFHCh). The control group (n = 30) received standard food for laboratory rats. The rats from study and control groups were sacrificed after 4, 8, 12, 16 and 20 weeks after start of dietary exposure. The analysis of SFA in feces was performed using gas chromatography (Agilent Technologies 1260 A GC). The exposure to high-fat and high-cholesterol diet was associated with significant changes in SCFA levels. Relative to the control, each of HFHCh subgroup revealed a statistically significant decrease in butyrate (12.5% ± 5.7% versus 32.8% ± 9.1%) and an increase in propionate level (45.4% ± 6.2% versus 19.14% ± 7.1%). The ratio of acetate: propionate: butyrate was also changed (from 1.1: 0.6: 1 for control groups to 3 : 3,6 : 1 for HFHCh groups). The main SCFA in the HFHCh group was propionate instead of acetate. The dietary exposure resulted in significant differences in LPS concentration. After 12 weeks of HFD exposure, LPS concentration was significantly higher compared to control groups (P < 0.05). Our study showed that HFHCh diet affected butyrate and propionate production associated with an increase in LPS secretion. The hypothesis that observed changes could result in intestinal imbalance secondary to gut barrier dysfunction requires further studies.

The effect of low levels of lead (Pb) in the blood on levels of sphingosine-1-phosphate (S1P) and expression of S1P receptor 1 in the brain of the rat in the perinatal period.

Sphingolipids are the main components of the lipid membrane. They also perform structural functions and participate in many signal transmission processes. One of the bioactive sphingolipids is sphingosine-1-phosphate (S1P), a ligand for five G protein-coupled receptors (S1PRs1-5), which can also act as an intracellular second messenger. S1P is responsible for the stimulation of progenitor cells in the brain, but it can also induce apoptosis of mature neurons. This study is aimed at assessing the effect of pre- and neonatal exposure to permissible Pb concentrations on S1P levels and S1PR1 (EDG1) expression in the prefrontal cortex, cerebellum, and hippocampus of rats. The concentrations of S1P were determined by RP-HPLC, S1PR1 expression was determined by RT PCR and Western Blot, and receptor immunolocalization was determined by immunohistochemistry method. Our results showed that even low blood Pb concentrations, i.e. within the acceptable limit of 10 µg/dL caused changes in the concentration of S1P in the cerebellum, prefrontal cortex, and hippocampus. Our data also showed a significant decrease in the level of S1PR1 in all studied part of brain, without significant changes in S1PR1 gene expression. Pre- and neonatal exposure to Pb also resulted in a decrease in the expression of S1PR1 in glial cells in all regions of the Cornu Ammonis (CA1-CA4) and Dentate Gyrus in the hippocampus, as well as in all layers of the cerebellum and prefrontal cortex, compared to the unexposed control group.

The Influence of Fluorine on the Disturbances of Homeostasis in the Central Nervous System.

Fluorides occur naturally in the environment, the daily exposure of human organism to fluorine mainly depends on the intake of this element with drinking water and it is connected with the geographical region. In some countries, we can observe the endemic fluorosis-the damage of hard and soft tissues caused by the excessive intake of fluorine. Recent studies showed that fluorine is toxic to the central nervous system (CNS). There are several known mechanisms which lead to structural brain damage caused by the excessive intake of fluorine. This element is able to cross the blood-brain barrier, and it accumulates in neurons affecting cytological changes, cell activity and ion transport (e.g. chlorine transport). Additionally, fluorine changes the concentration of non-enzymatic advanced glycation end products (AGEs), the metabolism of neurotransmitters (influencing mainly glutamatergic neurotransmission) and the energy metabolism of neurons by the impaired glucose transporter-GLUT1. It can also change activity and lead to dysfunction of important proteins which are part of the respiratory chain. Fluorine also affects oxidative stress, glial activation and inflammation in the CNS which leads to neurodegeneration. All of those changes lead to abnormal cell differentiation and the activation of apoptosis through the changes in the expression of neural cell adhesion molecules (NCAM), glial fibrillary acidic protein (GFAP), brain-derived neurotrophic factor (BDNF) and MAP kinases. Excessive exposure to this element can cause harmful effects such as permanent damage of all brain structures, impaired learning ability, memory dysfunction and behavioural problems. This paper provides an overview of the fluoride neurotoxicity in juveniles and adults.

Fluoride as a factor initiating and potentiating inflammation in THP1 differentiated monocytes/macrophages.

It is well known that exposure to fluorides lead to an increased ROS production and enhances the inflammatory reactions. Therefore we decided to examine whether cyclooxygenases (particular COX-2) activity and expression may be changed by fluoride in THP1 macrophages and in this way may change the prostanoids biosynthesis. In the present work we demonstrate that fluoride increased concentration of PGE2 and TXA2 in THP1 macrophages. Following exposure to 1-10 µM NaF, COX-2 protein and COX-2 transcript increased markedly. COX-2 protein up-regulation probably is mediated by ROS, produced during fluoride-induced inflammatory reactions. Additional fluoride activates the transcription factor, nuclear factor (NF)-kappaB, which is involved in the up-regulation of COX-2 gene expression. This study indicated that even in small concentrations fluoride changes the amounts and activity of COX-1 and COX-2 enzymes taking part in the initiating and development of inflammatory process.

The Fluoride Content of Yerba Mate Depending on the Country of Origin and the Conditions of the Infusion.

There are many reports of the positive effect of yerba mate on the human body. Elemental composition analysis of yerba mate revealed the presence of many microelements and macroelements, but there is no literature data referencing the content and the effect of the method of preparing the yerba mate infusion on the amount of released fluoride and thus the amount of this element supplied to the human body. Therefore, in the traditional way (cold and hot), we prepared infusions of yerba mate from different countries and determined in samples content of fluoride using potentiometric method. Hot infusions resulted in statistically significant (p = 0.03) increases in the amount of fluoride released from the dried material to the water, compared to brewing with water at room temperature. The successive refills of hot water also resulted in a release of the same amount of fluoride, although smaller than the infusion with water at room temperature (at the third refill, it was statistically significantly smaller at p = 0.003). With an increase in the number of hot water refills, the amount of fluoride released from the sample portion significantly decreased. Similar results were recorded when analyzing samples depending on the country of origin. The amount of fluoride released into the water differed statistically significantly depending on the country of origin. The most fluoride was determined in the infusions of yerba mate from Argentina and the least in infusions from Paraguay.