Enriched environment treatment restores impaired hippocampal synaptic plasticity and cognitive deficits induced by prenatal chronic stress

Prenatal stress can cause long-term effects on cognitive functions in offspring. Hippocampal synaptic plasticity, believed to be the mechanism underlying certain types of learning and memory, and known to be sensitive to behavioral stress, can be changed

Chronic Morphine Treatment Impaired Hippocampal Long-Term Potentiation and Spatial Memory via Accumulation of Extracellular Adenosine Acting on Adenosine A(1) Receptors

Chronic exposure to opiates impairs hippocampal long-term potentiation (LTP) and spatial memory, but the underlying mechanisms remain to be elucidated. Given the well known effects of adenosine, an important neuromodulator, on hippocampal neuronal excitability and synaptic plasticity, we investigated the potential effect of changes in adenosine concentrations on chronic morphine treatment-induced impairment of hippocampal CA1 LTP and spatial memory. We found that chronic treatment in mice with either increasing doses (20-100 mg/kg) of morphine for 7 d or equal daily dose (20 mg/kg) of morphine for 12 d led to a significant increase of hippocampal extracellular adenosine concentrations. Importantly, we found that accumulated adenosine contributed to the inhibition of the hippocampal CA1 LTP and impairment of spatial memory retrieval measured in the Morris water maze. Adenosine A(1) receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine significantly reversed chronic morphine-induced impairment of hippocampal CA1 LTP and spatial memory. Likewise, adenosine deaminase, which converts adenosine into the inactive metabolite inosine, restored impaired hippocampal CA1 LTP. We further found that adenosine accumulation was attributable to the alteration of adenosine uptake but not adenosine metabolisms. Bidirectional nucleoside transporters (ENT2) appeared to play a key role in the reduction of adenosine uptake. Changes in PKC-alpha/beta activity were correlated with the attenuation of the ENT2 function in the short-term (2 h) but not in the long-term (7 d) period after the termination of morphine treatment. This study reveals a potential mechanism by which chronic exposure to morphine leads to impairment of both hippocampal LTP and spatial memory.

POSTSYNAPTIC ALPHA-2 RECEPTOR STIMULATION IMPROVES MEMORY IN AGED MONKEYS - INDIRECT EFFECTS OF YOHIMBINE VERSUS DIRECT EFFECTS OF CLONIDINE

Very low doses (0.00001 mg/kg) of the alpha-2 adrenergic antagonist, yohimbine, improved working memory performance in a subset of aged monkeys. Improvement appeared to result from increased norepinephrine (NE) release onto postsynaptic alpha-2 adrenoceptors, as the response was blocked by the ''postsynaptic'' alpha-2 antagonist, SKF104078. Cognitive-enhancing effects of low dose yohimbine treatment may depend on aged animals retaining an intact, endogenous NE system. In contrast to yohimbine, the alpha-2 agonist, clonidine, has improved working memory in air aged animals examined. In the present study, clonidine's beneficial effects were also blocked by the postsynaptic antagonists SKF104078 and SKF104856, suggesting that clonidine acts by directly stimulating postsynaptic alpha-2 adrenoceptors. Beneficial doses of clonidine (0.01 mg/kg) and yohimbine (0.00001 mg/kg) were combined to see if they would produce additive effects on memory enhancement. This strategy was successful in young monkeys with intact NE systems but was not effective in the aged monkeys. These findings demonstrate that drugs that indirectly stimulate postsynaptic alpha-2 receptors by increasing NE release are not as reliable in aged monkeys as directly acting agonists that can replace NE at postsynaptic alpha-2 receptors.

Dose-dependent effects of the dopamine D1 receptor agonists A77636 or SKF81297 on spatial working memory in aged monkeys

With advancing age, monkeys develop deficits in spatial working memory resembling those induced by lesions of the prefrontal cortex (PFC). Aged monkeys also exhibit marked loss of dopamine from the PFC, a transmitter known to be important for proper PFC cognitive function. Previous results suggest that D1 agonist treatment can improve spatial working memory abilities in aged monkeys. However, this research was limited by the use of drugs with either partial agonist actions or significant D2 receptor actions. In our study, the selective dopamine D1 receptor full agonists A77636 and SKF81297 were examined in aged monkeys for effects on the working memory functions of the PFC. Both compounds produced a significant, dose-related effect on delayed response performance without evidence of side effects: low doses improved performance although higher doses impaired or had no effect on performance. Both the improvement and impairment in performance were reversed by pretreatment with the D1 receptor antagonist, SCH23390. These findings are consistent with previous results demonstrating that there is a narrow range of D1 receptor stimulation for optimal PFC cognitive function, and suggest that very low doses of D1 receptor agonists may have cognitive-enhancing actions in the elderly.

Polishing Treatment of Molasses Wastewater with Iron Salts: the Role of Counter-ions

The effect of counter-ions on the coagulation of biologically treated molasses wastewater using iron-based coagulants was investigated. Parameters such as removals of chemical oxygen demand (COD) and color, and residual turbidity, were measured to evaluate coagulation performance. Experimental results showed that ferric chloride and ferric nitrate were more effective than ferric sulfate at optimal dosages, achieving 89 to 90% and 98 to 99% of COD and color removals, respectively, with residual turbidity of less than 5 NTU. High-performance size exclusion chromatography (HPSEC) results revealed differences in the removal of the molecular weight fraction of organic compounds using iron salts. Scanning electron microscopy (SEM) showed randomly formed coagulated flocs characterized with irregular, sheet-like shapes. Nitrate and chloride counter-ions had similar effects on coagulation performance compared to sulfate. Both FeCl3 and Fe(NO3)(3) yielded better results than Fe(SO4)(2) under underdosed and optimum dosage conditions. Coagulation efficiency was less adversely affected in the overdosed regions, however, if sulfate rather than chloride or nitrate was present. Water Environ. Res., 81, 2293 (2009).

Effects of Organic-Rich Sediment and Below-Ground Sulfide Exposure on Submerged Macrophyte, Hydrilla verticillata

The effects of organic-rich sediment and sulfide exposure on Hydrilla verticillata were investigated. The organic richness of sediment was simulated by adding sucrose into sediments, and sulfide exposure was conducted by adding sodium sulfide to plant roots. The length, biomass and density of shoot reduced in the sucrose-amended sediments, and the largest reduction occurred in the highest 1.0% addition treatment by 84.2%, 56.7% and 92.4%, respectively. However, the 0.1% addition treatment stimulated the growth of root. The effects of below-ground sulfide exposure on the physiological activities of H. verticillata were determined by adding sulfide to the below-ground tissue. Significantly inhibitory effects of sulfide were observed on plant photosynthesis, root carbohydrate and nitrogen synthetic reserves. The net photosynthetic rates, soluble carbohydrate and soluble protein contents in root were reduced by 104%, 71.8% and 49.8%, respectively, in the 0.6 mM sulfide treatment.

Effects of adrenergic agents on the expression of zebrafish (Danio rerio) vitellogenin Ao1

Teleost vitellogenins (VTGs) are large multidomain apolipoproteins, traditionally considered to be estrogen-responsive precursors of the major egg yolk proteins, expressed and synthesized mainly in hepatic tissue. The inducibility of VTGs has made them one of the most frequently used in vivo and in vitro biomarkers of exposure to estrogen-active substances. A significant level of zebrafish vtgAo1, a major estrogen responsive form, has been unexpectedly found in heart tissue in our present studies. Our studies on zebrafish cardiomyopathy, caused by adrenergic agonist treatment, suggest a similar protective function of the cardiac expressed vtgAo1. We hypothesize that its function is to unload surplus intracellular lipids in cardiomyocytes for "reverse triglyceride transportation" similar to that found in lipid transport proteins in mammals. Our results also demonstrated that zebrafish vtgAo1 mRNA expression in heart can be suppressed by both (x-adrenergic agonist, phenylephrine (PE) and beta-adrenergic agonist, isoproterenol (ISO). Furthermore, the strong stimulation of zebrafish vtgAo1 expression in plasma induced by the beta-adrenergic antagonist, MOXIsylyl, was detected by Enzyme-Linked ImmunoSorbent Assay (ELISA). Such stimulation cannot be suppressed by taMOXIfen, an antagonist to estrogen receptors. Thus, Our present data indicate that the production of teleost VTG in vivo can be regulated not only by estrogenic agents, but by adrenergic signals as well. (c) 2009 Elsevier Inc. All rights reserved.

Effects of sediment anoxia and light on turion germination and early growth of Potamogeton crispus

Potamogeton crispus is a cosmopolitan aquatic species and is widely used as a pioneer species for vegetation restoration of eutrophic lakes. However, many restoration projects applying P. crispus turions have not been successful. Earlier studies focused on effects of light and temperature on turion germination. The purpose of this study was to determine whether sediment anoxia and light interactively affected the turion germination and early growth of P. crispus. Anoxic conditions in the experiment were produced by adding sucrose to the sediment. The germination rate of the turions was 68-73% lower in the highly anoxic condition treatment than in the control. Medium light intensity (10% of natural light at the water surface) was more favorable for germination under slightly anoxic conditions than either low or high light intensity. The growth of newly-formed sprouts was also significantly inhibited by sediment anoxia. Photosynthesis and shoot biomass were reduced under sediment anoxia, whereas total chlorophyll content, root biomass, and soluble protein content were highest in the low anoxic condition treatment. Medium light improved net photosynthesis and biomass production of the sprouts. We conclude that turion germination and sprout growth can be significantly inhibited by sediment anoxia. Medium light intensity may alleviate this inhibition by anoxia, but light has little effect when sediment anoxia is severe. For the purposes of vegetation restoration, more attention should be paid to the role of sediment anoxia, and it is necessary to improve sediment and light conditions for turion germination and early growth of P. crispus in eutrophic lakes. These results will contribute to a more complete understanding of turion germination dynamics of P. crispus and will be useful for future restoration programs.

Effects of arsenate on the growth and microcystin production of Microcystis aeruginosa isolated from Taiwan as influenced by extracellular phosphate

Arsenic pollution and eutrophication are both prominent issues in the aquaculture ponds of Taiwan. It is important to study the effects of arsenic on algal growth and toxin production in order to assess the ecological risk of arsenic pollution, or at least to understand naturally occurring ponds. The sensitivity of algae to arsenate has often been linked to the structural similarities between arsenate and phosphate. Thus, in this study we examined the effects of arsenate (10(-8) to 10(-4) M) on Microcystis aeruginosa TY-1 isolated from Taiwan, under two phosphate regimes. The present study showed that M. aeruginosa TY-1 was arsenate tolerant up to 10(-4) M, and that this tolerance was not affected by extracellular phosphate. However, it seems that extracellular phosphate contributed to microcystin production and leakage by M. aeruginosa in response to arsenate. Under normal phosphate conditions, total toxin yields after arsenate treatment followed a typical inverted U-shape hormesis, with a peak value of 2.25 +/- 0.06 mg L-1 in the presence of 10(-7) M arsenate, whereas 10(-8) to 10(-6) M arsenate increased leakage of similar to 75% microcystin. Under phosphate starvation, total toxin yields were not affected by arsenate, while 10(-6) and 10(-5) M arsenate stimulated microcystin leakage. It is suggested that arsenate may play a role in the process of microcystin biosynthesis and excretion. Given the arsenic concentrations in aquaculture ponds in Taiwan, arsenate favors survival of toxic M. aeruginosa in such ponds, and arsenate-stimulated microcystin production and leakage may have an impact on the food chain.

EFFECTS OF IRON ON PHYSIOLOGICAL AND BIOCHEMICAL CHARACTERISTICS OF Microcystis wesenbergii (Kom.) Kom. (Cyanobacterium)

Iron is an essential trace element for biological requirements of phytoplankton. Effects of iron on physiological and biochemical characteristics of Microcystis wesenbergii were conducted in this study. Results showed that 0.01 mu M [Fe3+] seriously inhibited growth and chlorophyll synthesis of M. wesenbergii, and induced temporary increase of ATPase activities, however, NR. ACP and ALP activities were restrained by iron limitation. Interestingly, iron addition on day 8 resulted in the gradual restoration of structures and functions of above enzymes and resisted a variety of stresses from iron limitation. M. wesenbergii in 10 mu M [Fe3+] treatment group grew normally. enzymes maintained normal levels, and residual phosphate contents in cultures first sharply decreased, then smoothly as M. wesenbergii has a characteristic of luxury consumption of phosphorus. Above parameters in 100 mu M [Fe3+] treatment group were almost same with those in 10 mu M [Fe3+] treatment group except for NR, ACP and ALP activities. In 100 mu M [Fe3+] treatment group, activities of ACP and ALP had temporary increase because phosphate and ferric iron could form insoluble compound - ferric phosphate (Fe3PO4) through adsorption effect. resulting in lack of bioavailable phosphate in culture media. The experiment suggested that too low or too high iron can affect obviously physiological and biochemical characteristics of M. wesenbergii.

Effects of gibberellin A(3) on growth and microcystin production in Microcystis aeruginosa (cyanophyta)

Environmental. factors that affect the growth and microcystin production of microcystis have received worldwide attention because of the hazards microcystin poses to environmental safety and public health. Nevertheless, the effects of organic anthropogenic pollution on microcystis are rarely discussed. Gibberellin A(3) (GA(3)) is a vegetable hormone widely used in agriculture and horticulture that can contaminate water as an anthropogenic pollutant. Because of its common occurrence, we studied the effects of GA3 on growth and microcystin production of Microcystis aeruginosa (M. aeruginosa) PCC7806 with different concentrations (0.001-25mg/L) in batch culture. The control was obtained without gibberellin under the same culture conditions. Growth, estimated by dry weight and cell number, increased after the GA3 treatment. GA3 increased the amounts of chlorophyll a, phycocyanin and cellular-soluble protein in the cells of M. aeruginosa PCC7806, but decreased the accumulation of water-soluble carbohydrates. In addition, GA3 was observed to affect nitrogen absorption of the test algae, but to have no effect on the absorption of phosphorus. The amount of microcystin measured by enzyme-Linked immunosorbent assay (ELISA) increased in GA3 treatment groups, but the stimulatory effects were different in different culture phases. It is suggested that GA3 increases M. aeruginosa growth by stimulating its absorbance of nitrogen and increasing its ability to use carbohydrates, accordingly increasing cellular pigments and thus finally inducing accumulation of protein and microcystin. (C) 2007 Elsevier GmbH. All rights reserved.

Effects of dietary ascorbic acid supplementation on the growth performance, immune and stress response in juvenile Leiocassis longirostris Gunther exposed to ammonia

This experiment was designed to investigate the effect of dietary supplemental ascorbic acid (AA) on the feed intake, growth, serum lysozyme, hepatic superoxide dismutase (SOD) and handling stress response in Chinese longsnout catfish (Leiocassis longirostris Gunther) exposed to three levels of unionized ammonia nitrogen (UIA-N). Juvenile Chinese longsnout catfish were reared in 54 fibreglass tanks with a 3 x 3 factorial design treatment consisting of three supplemental AA levels in ascorbyl 2-monophosphate (38, 364 and 630 mg AA equivalent kg(-1) diet) and three UIA-N concentrations [0.004 (the control), 0.037 and 0.292 mg L-1]. The fish were sampled on the 11th, 32nd and 60th day. On the 62nd day, the remaining fish were subjected to an acute stress by being held in a dipnet out of water for 60 s, and sampled at 30 min post handling. The results showed that the specific growth rate (SGR) in 32 days significantly decreased with increased water UIA-N (P=0.0476) but was not affected by dietary supplemental AA (P > 0.05). After 60 days, SGR, feeding rate (FR) and feed conversion efficiency (FCE) significantly increased with increased dietary supplemental AA (P < 0.001) while remaining unaffected by water UIA-N (P > 0.05). There was no significant interaction between dietary AA and UIA-N for growth responses (P > 0.05). The serum lysozyme activity on the 11th day and the hepatic SOD activity on the 32nd day were significantly affected at high (0.292 mg L-1) water UIA-N. On the 62nd day, the increase in cortisol resulting from acute stress significantly decreased by higher UIA-N (P=0.038). It is suggested that Chinese longsnout catfish displayed an adaptive response after long-term UIA-N exposure, and AA had beneficial effects on the growth and feed intake of catfish and alleviated the negative effects of chronic ammonia stress. A chronically higher ammonia level shows a tendency to inhibit the cortisol response to another acute stressor.

Effects of Cd2+ and Pb2+ on the substrate biofilms in the integrated vertical-flow constructed wetland

The effects of single Cd2+ and Pb2+, and combined Cd2+ and Pb2+ on dehydrogenase activity and polysaccharide content of the substrate biofilms in the integrated vertical-flow constructed wetland (IVCW) were studied. Dehydrogenase activities decreased linearly with the increasing concentrations of Cd2+ and Pb2+ at different times (6, 24, 72, and 120 h). The activities at both 6 and 24 h were significantly higher than that at 72 and 120 h in the case of single and combined treatments. The single Cd2+ and Pb2+ treatments significantly inhibited dehydrogenase activities at concentrations in excess of 20 mu mol/L Cd2+ and 80 mu mol/L Pb2+, respectively. The inhibitory effect of Cd2+ was much greater than that of Pb2+. At the same time, the combined treatment of Cd2+ and Pb2+ Significantly inhibited dehydrogenase activities at all five concentrations studied and the lowest combined concentration was 1.25 mu mol/L Cd2+ and 5 mu mol/L Pb2+. A synergistic effect of Cd2+ and Pb2+ was observed. On the other hand, polysaccharide contents varied unpredictably with the increasing concentrations of Cd2+ and Pb2+ and extended experimental time. There were no significant statistical differences within the range of concentration and time studied, whether singly or in combination. These results implied that the effects of heavy metals on biofilms should be a concern for the operation and maintenance of constructed wetlands.

Combined effects of ultraviolet radiation and temperature on morphology, photosynthesis, and DNA of Arthrospira (Spirulina) platensis (Cyanophyta)

Natural levels of solar UVR were shown to break and alter the spiral structure of Arthrospira (Spirulina) platensis (Nordst.) Gomont during winter. However, this phenomenon was not observed during summer at temperatures of similar to 30 degrees C. Since little has been documented on the interactive effects of solar UV radiation (UVR; 280-400 nm) and temperature on cyanobacteria, the morphology, photosynthesis, and DNA damage of A. platensis were examined using two radiation treatments (PAR [400-700 nm] and PAB [PAR + UV-A + UV-B: 280-700]), three temperatures (15, 22, and 30 degrees C), and three biomass concentrations (100, 160, and 240 mg dwt [dry weight] . L-1). UVR caused a breakage of the spiral structure at 15 degrees C and 22 degrees C, but not at 30 degrees C. High PAR levels also induced a significant breakage at 15 degrees C and 22 degrees C, but only at low biomass densities, and to lesser extent when compared with the PAB treatment. A. platensis was able to alter its spiral structure by increasing helix tightness at the highest temperature tested. The photochemical efficiency was depressed to undetectable levels at 15 degrees C but was relatively high at 30 degrees C even under the treatment with UVR in 8 h. At 30 degrees C, UVR led to 93%-97% less DNA damage when compared with 15 degrees C after 8 h of exposure. UV-absorbing compounds were determined as negligible at all light and temperature combinations. The possible mechanisms for the temperature-dependent effects of UVR on this organism are discussed in this paper.

Allelopathic effects on Scenedesmus obliquus by two submerged macrophytes Najas minor and Potamogeton malaianus

The allelopathic effects of two submerged macrophytes, Najas minor and Potamogeton malaianus, on growth, photosynthesis and antioxidant systems of Scenedesmus obliquus were assessed in coexistence experiments. The growth of S. obliquus was significantly suppressed by the two macrophytes. Moreover, P. malaianus showed the stronger growth inhibition effect on S. obliquus than N. minor. P. malaianus obviously inhibited the photosynthetic rate of S. obliquus, while N. minor had no inhibitory effect. Lipid peroxidation and three antioxidant enzymes activities (superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD)) of S. obliquus were investigated at the end of the co-cultures. The two macrophytes significantly enhanced the malondialdehyde (MDA) content, a product of lipid peroxidation, in S. obliquus. Activities of the three antioxidant enzymes of S. obliquus were simultaneously stimulated in P. malaianus treatment, while no significant variation of POD activity was observed in N. minor treatment. The results indicated that the two macrophytes N. minor and P. malaianus had significant allelopathic effects on S. obliquus. However, the two macrophytes influenced S. obliquus in different ways.