Assessment of sediment contamination by persistent organic pollutants in Gyeonggi Bay, Korea

Persistent organic pollutants were determined in 33 surface sediments from Gyeonggi Bay, Korea. The concentrations (ng/g dry weight-range, mean in brackets) of PCBs, DDTs and HCHs in sediments were 0.16–41.9 (2.22), 0.03–5.17 (0.67) and 0.03–0.88 (0.29), respectively. Sum of 24 PAHs ranged from 6.37 to 648 ng/g (111 ng/g). Tributyltin (TBT), dibutyltin (DBT) and monobutyltin (MBT) were detected in 10, 3 and 31 out of 33 stations surveyed. TBT, DBT, and MBT were in the range of non detectable (n.d.)-122 ng Sn/g, n.d.-84 ng Sn/g, and n.d.-41 ng Sn/g respectively. t-octylphenol, nonylphenol and bisphenol-A were in range of 0.1–15.4 ng/g, 3–1070 ng/g and 0.2–15.9 ng/g, respectively. These levels are lower than in other Korean bays. Station K8, located close to a wastewater reservoir showed the highest concentration. Molecular tracers such as nonylphenol, t-octylphenol, bisphenol-A, indicated that PCBs and PAHs entered the bay through sewage discharge, while butyltins, DDTs and HCHs entered either through atmospheric depositions or from shipping activities. According to international sediment quality guidelines, the noted concentrations may not impact benthic life.     

Human health risk of polychlorinated biphenyls and organochlorine pesticides resulting from seafood consumption in South Korea, 2005–2007

Organochlorines (OCs) such as polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs), were measured in 26 species of seafood commonly consumed by the Korean population. PCBs and DDTs were the predominant contaminants with concentrations from 0.2 to 41 ng/g wet wt and from < 0.04 to 37 ng/g wet wt, while CHLs (<0.01–1.9 ng/g wet wt), HCB (<0.004–1.0 ng/g wet wt), and HCHs (<0.02–0.4 ng/g wet wt) were 1–2 orders of magnitude lower than the concentrations of PCBs and DDTs. The dominant PCBs and OCPs were PCB 153, 187, 138, and 118 and p,p′-DDE, HCB, p,p′-DDT, and p,p′-DDD, respectively. Dietary intakes of OCs for the general population, males, and females were estimated as 69, 78, and 60 ng/kg body weight/week, respectively. Mackerel, tuna, and hairtail were the main contributors to the dietary intakes of OCs. Among the eight age groups investigated, infants <2 years had the highest dietary exposure to OCs. Hazard ratios of non-cancer risk of all of the OCs were less than one, while the lifetime cancer risks of PCBs and DDTs were all greater than unity for Korean populations.     

PCDDs, PCDFs, PCBs, OC pesticides and mercury in fish and osprey eggs from Willamette River, Oregon (1993, 2001 and 2006) with calculated biomagnification factors

The osprey (Pandion haliaetus) population nesting along the main stem Willamette River and lower Santiam River was first studied to evaluate contaminants and reproductive rates in 1993 when 78 occupied nests were present. By 2001, the population increased to 234 occupied nests, a 13.7% annual rate of population increase. A sample egg was collected from each of a series of nests along the Upper River (river mile 55–187) in 1993, 2001 and 2006 to evaluate trends of persistent contaminants (organochlorine [OC] pesticides, polychlorinated biphenyls [PCBs], polychlorinated dibenzo-p-dioxins [PCDDs], and polychlorinated dibenzofurans [PCDFs]). Nearly all OC pesticide residues decreased significantly, e.g., p, p′-DDE (DDE) from 2,350 to 1,353 to 210 μg/kg wet weight (ww). PCBs followed a similar pattern over time, e.g., ΣPCBs 688 to 245 to 182 μg/kg ww, while PCDDs and PCDFs showed a more precipitous decline (often 85–95%) between 1993 and 2001, with no egg analyses warranted in 2006. During 2001–2002, sample osprey eggs were also collected from nests at three Headwater Reservoirs and two lower reaches (Newberg Pool and Tidal Portland) of the Willamette River, as well as the lower portion of the Santiam River to evaluate spatial residue patterns. Significant differences were seldom detected among the different sampling areas for OC pesticides (probably due to small sample sizes), although higher concentrations were often seen in the lower reaches, e.g., DDE 901 μg/kg ww (Headwater Reservoirs), 1,353 (Upper River), 1,384 (Newberg Pool) and 2,676 (Tidal Portland). PCB congener concentrations in eggs were usually higher in the Tidal Portland reach than at other locations and often significantly higher than at the Headwater Reservoirs or Upper River. Mercury (first analyzed in eggs in 2001), PCDDs and PCDFs were extremely low in 2001/2002 with no significant spatial patterns. Whole fish composite samples of largescale sucker (Catastomus macrocheilus) and northern pikeminnow (Ptychocheilus oregonensis), which account for about 90% of the biomass in the diet of this osprey population, were also collected from the Willamette River in 1993 and 2001 and analyzed for the same contaminants as osprey eggs. Contaminant residues in fish from the Upper River decreased between 1993 and 2001, paralleling findings for osprey eggs. Likewise, spatial patterns for fish residues paralleled findings for osprey eggs from the different reaches in 2001. A second empirical estimate of biomagnification factors (BMFs) from fish to osprey eggs for OC pesticides, PCBs, PCDDs and PCDFs (ww and lipid weight [lw] basis) was calculated based on residue data collected in 2001. The two independent BMF estimates (1993 and 2001) for each contaminant from the Upper River provide a measure of consistency, e.g., DDE (ww) 87 and 79, (lw) 103 and 112; ΣPCBs (ww) 11 and 8.4, (lw) 13 and 12. Mercury did not biomagnify from fish to osprey eggs (BMF = 0.60). Legacy contaminants investigated had limited (perhaps only DDE), if any, effects on reproductive success of the increasing osprey population nesting along the Willamette River by 2001.     

The role of CYP1A inhibition in the embryotoxic interactions between hypoxia and polycyclic aromatic hydrocarbons (PAHs) and PAH mixtures in zebrafish (<Emphasis Type="Italic">Danio rerio</Emphasis>)

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental pollutants with elevated concentrations in waters that may also experience hypoxia. Previous research has shown interactions between hypoxia and some PAHs (fluoranthene, α-naphthoflavone) but no interaction with others (benzo[a]pyrene (BaP), β-naphthoflavone). Here we examine how hypoxia (7.4% oxygen, ~35% of normoxia) affects the embryotoxicity of PAHs that act through different mechanisms and the role that CYP1A inhibition may play in these interactions. About 500 μg/l BaP and 1–200 μg/l benzo[k]fluoranthene (BkF) interacted synergistically with hypoxia to induce pericardial edema in developing zebrafish (Danio rerio). Hypoxia protected from the embryotoxicity of pyrene (PY) and had no effect on the toxicity of polychlorinated biphenyl-126. Despite previous reports of other CYP1A inhibitors interacting with hypoxia, up to 2,000 μg/l dibenzothiophene, 2-aminoanthracene (AA), and carbazole (CB) all failed to induce embryotoxicity under normoxic or hypoxic conditions. The toxicity of PAH mixtures—including binary mixtures of BaP/AA and BaP/CB and two environmentally relevant, complex mixtures—were exacerbated severely by hypoxia to induce or worsen pericardial edema and cause mortality. The interactions between hypoxia and BkF and PY were closely mimicked by morpholino knockdown of CYP1A, indicating a potential role for metabolism of these compounds in their toxicity. Our results indicate that various PAHs may exhibit synergistic, antagonistic or additive toxicity with hypoxia. The enhanced toxicity of environmental mixtures of PAHs under hypoxia suggests that risk assessments that do not take into account potential interactions with hypoxia may underestimate the threat of PAHs to fish in contaminated sites.     

Molecular dosimetry of DNA adducts in rainbow trout (Oncorhynchus mykiss) exposed to benzo(a)pyrene by different routes

 Farm raised rainbow trout (Oncorhynchus mykiss) were exposed by various routes to benzo(a)pyrene (BP) as a representative carcinogenic polycyclic aromatic hydrocarbon (PAH). Following exposure of fish to the chemical by intraperitoneal (i.p.) injection, ³²P-postlabelling studies indicated that non-feral trout were relatively resistant to the formation of BP-DNA adducts in liver. No adducts were detected in fish exposed to single doses (20 mg/kg) of BP. Multiple exposures (e.g. 2×25 mg/kg) were necessary in order for adducts to be detected, indicating that induction of the metabolising enzymes required for the bioactivation of BP is necessary. These studies provided reference information on DNA adducts for comparison with data from subsequent experiments at environmentally realistic low level exposures. Two types of low level aquatic exposure were carried out. The first procedure exposed fish for 30 days to a nominally constant low level (1.2 and 0.4 μg/l) of a homogeneous dispersion of BP in water, to simulate low level aquatic environmental exposures. Following ³²P-postlabelling analysis of the liver DNA of exposed fish, BP-DNA adducts were not detected. In the second procedure, fish were exposed to a constant low level of BP (ca. 0.5 μg/l) for 15 days then to a pulse (60 μg/l) which was allowed to naturally decline (to ca. 2 μg/l) during a further 15 days. Following this exposure, significant levels of BP-DNA adducts were detected in livers of trout. The effect of dietary exposures was investigated by feeding trout a diet containing either 58 μg or 288 μg BP per day for 6 days, equivalent to total doses of 43 mg/kg and 216 mg/kg. In both cases BP-DNA adducts were detected in livers of exposed fish. The results provide useful information on the types of exposures to PAHs which may pose a genotoxic risk to fish in the environment. Received: 5 April 1994 / Accepted: 31 May 1994     

Exposure and recovery response of isomers of HCH,metabolites of DDT and estradiol-17β in the female catfish,Heteropneustes fossilis

Effects of 40 days of exposure and 20 days of recovery response at sublethal concentration of technical grades of gamma isomer of hexachlorocyclohexane (γ-HCH, 0.025 ppm, 99.8%) and dichlorodiphenyltrichloroethane (DDT, 5.0 ppm) in tissue (liver, brain and ovary) bioconcentrations, gonadosomatic index (GSI) and plasma levels of estradiol-17β (E2) have been estimated during prespawning phase in the catfish Heteropneustes fossilis (Bloch). The results indicated that the tissue bioconcentrations of both HCHs (HCH isomers) and DDTs (metabolites of DDT) in liver, brain and ovary were in preferential order (liver > brain > ovary). The GSI and plasma levels of E2 were declined in response to exposure of γ-HCH and DDT. On withdrawal of exposure of pesticide there was recovery of HCHs in exposed fish for all tissues studied, whereas DDTs exposed fish showed recovery only in liver. Recovery of E2 production was also recorded in γ-HCH exposed fish whereas very little recorded in DDT exposed fish. It is suggested that HCHs and DDTs have preferential order (liver > brain > ovary) of their tissue bioconcentrations and HCH/DDT-withdrawal-dependent recovery during studied phase.     

Evaluation of risk associated with organchlorine pesticide contaminated sediment of the Lake Lianhuan watershed

Characteristics and risk evaluation of organchlorine pesticides (OCPs) in the sediments of four lakes located in the Lake Lianhuan area were conducted to observe the risks on ecological system and identify the sources of pollutants. Measurement of eleven OCPs, four hexachlorocyclohexane (HCH) isomers (α-HCH, β-HCH, γ-HCH, δ-HCH), three dichlorodiphenyltrichloroethane (DDT) homologues (p,p′-DDT, p,p′-DDD, p,p′-DDE), and four cyclodienes (Aldrin, Dieldrin, Endrin and Heptachlor), indicated that concentrations of OCPs, HCHs and DDTs ranged from 0.04 to 9.95, 0 to 7.40 and 0 to 2.44 ng/g, respectively. The most dominant pollutants were the HCHs, high proportions of γ-HCH isomer indicating the recent input of lindane. The ratios of α-HCH/γ-HCH of four lakes are all lower than that in technical HCH mixtures indicated that there was input of lindane in the past several years, or that significant α-HCH evaporation into the atmosphere occurred. The ratios of (p,p′-DDE + p,p′-DDD)/p,p′-DDT in four sediments are all <1, and the mean ratios of (DDE + DDD)/∑DDT are all <0.5, suggesting recent DDT compounds input. The risk assessment was based on ERL and ERM values obtained by the approach used for assessment of ocean risk. The results suggest that OCPs in sediments of the Lake Lianhuan system poses a potential hazard to human health and environment.     

The role of cysteine conjugation in the detoxification of microcystin-LR in liver of bighead carp (Aristichthys nobilis): a field and laboratory study

The role of glutathione (GSH) and cysteine (Cys) conjugates in the detoxification of microcystin-LR (MC-LR) in bighead carp (Aristichthys nobilis) was examined under laboratory and field conditions. Wild individuals of bighead carp were collected from 5 eutrophic lakes along the Yangtze River, while in laboratory experiment, bighead carp were injected intraperitoneally with 500 μg purified MC-LR/kg body weight (bw). Contents of MC-LR and its glutathione (MC-LR-GSH) and cysteine conjugates (MC-LR-Cys) in the liver of bighead carp were determined by liquid chromatography electrospray ionization mass spectrum (LC–ESI–MS). In laboratory experiment, low concentrations of MC-LR-GSH (mean: 0.042 μg/g dry weight (DW)) were always detectable, and the mean ratio of MC-LR-Cys to MC-LR-GSH was 6.55. While, in field study, relatively high MC-LR-Cys concentration (mean: 0.22 μg/g DW) was detected, whereas MC-LR-GSH was occasionally detectable, and the average ratio of MC-LR-Cys to MC-LR-GSH was as high as 71.49. A positive correlation was found between MC-LR-Cys concentration in the liver of bighead carp and MC-LR content in seston from the five lakes (r = 0.85). These results suggest that MC-LR-Cys might be much more important than MC-LR-GSH in the detoxification of MC-LR in fish liver, and that cysteine conjugation of MC-LR might be a physiological mechanism for the phytoplanktivorous bighead carp to counteract toxic cyanobacteria.     

Chemical contamination and associated liver diseases in two species of fish from San Francisco Bay and Bodega Bay

Starry flounder (Platichthys stellatus), white croaker (Genyonemus lineatus) and sediments were collected annually from selected sites within San Francisco Bay, and a reference site in Bodega Bay between 1984--1991. Fish livers were examined for toxicopathic lesions and analysed for selected chlorinated hydrocarbons (CHs) such as PCBs, DDTs, chlordanes and dieldrin; sediment and fish stomach contents were analysed for polycyclic aromatic hydrocarbons (PAHs) and CHs; and bile was analysed for PAH metabolites. Sediment concentrations of PAHs, PCBs and DDTs; bile concentrations of PAH metabolites; and liver concentrations of PCBs, dieldrin and chlordanes were generally significantly higher at all San Francisco Bay sites compared to the Bodega Bay reference site. For both species, hydropic vacuolation of biliary epithelial cells was the most prevalent liver lesion detected and was statistically associated with sediment and tissue concentrations of PAHs or their metabolites, PCBs, DDTs, chlordanes and dieldrin. Temporal trends analyses showed that at Hunters Point, sediment PAHs and CHs increased between 1984--1991, while liver concentrations of CHs decreased. Liver concentrations of dieldrin in starry flounder decreased at all three San Francisco Bay sites     

Intravenous self-administration of etonitazene alone and combined with cocaine in rhesus monkeys: comparison with heroin and antagonism by naltrexone and naloxonazine

Rationale  In humans, μ opioid–cocaine combinations (speedballs) have been reported to heighten pleasurable effects and result in greater abuse potential compared to either drug individually. Emerging evidence in animals suggests that the ability of μ opioids to enhance the reinforcing effects of cocaine might be independent of their μ intrinsic efficacy even though μ agonist efficacy appears to be a determinant in the reinforcing effects of μ opioids themselves. Objectives  This study examined the relationship between agonist efficacy, self-administration, and the enhancement of cocaine self-administration using the high-efficacy μ agonist etonitazene. Materials and methods  Rhesus monkeys self-administered cocaine, heroin, etonitazene, and opioid–cocaine combinations under a progressive-ratio schedule of intravenous drug injection. Results  Unlike cocaine and heroin, etonitazene did not maintain consistent self-administration at any dose tested (0.001–1.0 μg/kg/injection). However, combining etonitazene (0.1–1.0 μg/kg/injection) with cocaine (0.01 and 0.03 mg/kg/injection) enhanced cocaine self-administration, and this enhancement was attenuated by naltrexone. These effects are similar to those obtained by combining non-reinforcing doses of heroin and cocaine. Antagonism of etonitazene–cocaine and heroin–cocaine self-administration by naloxonazine was short lasting and was not maintained after 24 h (when naloxonazine’s purported μ₁ subtype antagonist effects are thought to predominate). Conclusions  The results suggest that high μ agonist efficacy does not guarantee consistent drug self-administration and that the ability of μ agonists to enhance cocaine self-administration does not depend exclusively on reinforcing efficacy. Moreover, the results do not support a major role for μ₁ receptor mechanisms in either etonitazene- or heroin-induced enhancement of cocaine self-administration.     

Hypothalamic–pituitary–adrenal axis and ethanol modulation of deoxycorticosterone levels in cynomolgus monkeys

Rationale The metabolites of deoxycorticosterone (DOC) and progesterone, allotetrahydrodeoxycorticosterone and allopregnanolone, are potent endogenous neuroactive steroids that are increased in rodent brain and plasma after hypothalamic–pituitary–adrenal (HPA) axis activation by acute stress or ethanol administration. However, little data are available for male nonhuman primates.Objective To determine DOC concentrations in plasma samples from 11 monkeys following challenge of the HPA axis with naloxone, corticotropin-releasing factor (CRF), dexamethasone, adrenocorticotropic hormone (ACTH) following dexamethasone pretreatment and ethanol.Methods DOC levels were measured in monkey plasma by radioimmunoassay.Results DOC levels were increased after naloxone (125 μg/kg and 375 μg/kg, respectively) and CRF administration (1 μg/kg), and decreased following dexamethasone (130 μg/kg) administration. ACTH (10 ng/kg) challenge, 4–6 h after 0.5 mg/kg dexamethasone, and administration of ethanol (1.0 g/kg and 1.5 g/kg) had no effect on DOC concentrations. DOC levels were positively correlated with cortisol and ACTH levels after the naloxone (375 μg/kg), CRF, and ACTH challenges. Finally, the suppression of DOC levels measured after dexamethasone was negatively correlated with subsequent alcohol self-administration.Conclusions These results suggest that DOC levels in monkeys are regulated by the HPA axis and may contribute to physiological responses following activation.     

Polychlorinated biphenyls,dioxins, furans,and organochlorine pesticides in spotted sandpiper eggs from the upper Hudson River basin,New York

In 2004, spotted sandpipers (Actitis macularia) were studied on the Hudson River near Fort Edward south to New Baltimore, NY and on two river drainages that flow into the Hudson River. Concentrations of 28 organochlorine pesticides, 160 polychlorinated biphenyl (PCB) congeners, and 17 dioxin and furan (PCDD-F) congeners were quantified in eggs collected on and off the Hudson River. The pattern of organochlorine pesticides and PCDD-F congeners did not differ significantly between eggs collected on and off the Hudson River. In contrast, the pattern of PCB congeners differed significantly between the Hudson River and other rivers. Total PCBs were significantly greater in eggs from the Hudson River (geometric mean = 9.1 μg PCBs/g wet weight) than from the other two rivers (0.6 and 0.6 μg PCBs/g wet weight). Seven of 35 (20%) eggs exceeded 20 μg PCBs/g wet weight, the estimated threshold for reduced hatching in tree swallows (Tachycineta bicolor) and some raptor species; the maximum concentration was 72.3 μg PCBs/g wet weight. Models that predicted nest survival and egg success (the proportion of eggs hatching in a clutch if at least one egg hatched) as functions of contaminant levels were poorly distinguished from models that presumed no such associations. While small sample size could have contributed to the inability to distinguish among contaminant and no toxicant models, we cannot rule out the possibility that contaminant concentrations on the Hudson River were not sufficiently high to demonstrate a relationship between contaminant concentrations and reproductive success.     

Polycyclic aromatic hydrocarbons in surface sediments of the Jialu River

The Jialu River, an important branch of the Huaihe River in China, was seriously polluted because of rapid economic growth and urbanization. In order to evaluate the potential for serious environmental consequences as a result of anthropogenic contamination, the distribution of polycyclic aromatic hydrocarbons (PAHs) has been investigated in surface sediment samples collected in connection with field surveys of 19 sites along the Jialu River. The total concentration of the 16 USEPA priority PAHs ranged from 466.0 to 2605.6 ng/g dry weight with a mean concentration of 1363.2 ng/g. Sediment samples with the highest PAH concentrations were from the upper reaches of the river, where Zhengzhou City is located; the PAH levels in the middle and lower reaches were relatively low. According to the observed molecular indices, PAHs originated largely from the high-temperature pyrolytic process. According to the numerical effect-based sediment quality guidelines (SQGs) of the United States, the levels of PAHs in the Jialu River should not exert adverse biological effects. The total benzo[a]pyrene toxicity equivalent (TEQ) values calculated for samples varied from 50.4 to 312.8 ng/g dry weight with an average of 167.4 ng/g. The relationships between PAHs and environmental factors, including chemical properties of sediments, water quality, aquatic organisms, hydrological conditions, and anthropogenic activities, are also discussed. PAHs exerted a potential negative impact on the benthos. Settlement percentage, population density and industrial GDP per capita had a significant influence on the distribution of PAHs.     

Bioaccumulation of microcystin and its oxidative stress in the apple (<Emphasis Type="Italic">Malus pumila</Emphasis>)

The bioaccumulation and harmful effects of microcystins (MCs) and the activity of peroxidase (POD) and superoxide dismutase (SOD) were examined in the apple (Malus pumila) exposed in vitro with the crude extract of toxic cyanobacterial blooms from Dianchi Lake in southwestern China. The results showed that the growth and proliferation of M. pumila shoots in vitro decreased markedly after exposure to microcystins above 0.3 μg/ml. Recovered microcystins determined by enzyme-linked immunosorbent assay (ELISA) in M. pumila shoot cultures increased with exposure time and concentration. After 14 days exposure to the concentration of 3 μg/ml microcystins, M. pumila shoot cultures accumulated microcystins up to a concentration of 510.23 ± 141.10 ng MC-LR equiv/g FW (fresh weight), equivalent to an accumulation rate of 36.45 ng/g day. POD activity was significantly increased after 7 days exposure to 3 μg/ml microcystins. After 14 days of exposure, microcystins caused POD to increase significantly at the concentration of 0.3 and 3 μg/ml. The activity of SOD was not affected by microcystins at concentrations up to 3 μg/ml on 7 days. After 14 days exposure to microcystins, SOD activity increased significantly at the concentration of 0.3 and 3 μg/ml in M. pumila shoot cultures.     

Interaction between noradrenaline and corticotrophin-releasing factor in the reinstatement of cocaine seeking in the rat

Rationale  Corticotropin-releasing factor (CRF) and noradrenaline (NA) have been shown in independent studies to mediate stress-induced reinstatement of drug seeking. To date, however, a functional interaction between the systems in reinstatement has not been demonstrated. Objectives  The objectives of this study were to determine whether CRF and NA systems can interact to influence reinstatement responding and, if so, in what direction the interaction occurs. Materials and methods  Rats were trained to self-administer cocaine (0.23 mg/kg per infusion) for 8–10 days. Subsequently, responding for drug was extinguished, and tests for reinstatement were conducted following: (1) pretreatment with the CRF receptor antagonist, d-Phe CRF_12–41 [1 μg, intracerebroventricular (i.c.v.)], prior to i.c.v. injections of NA (10 μg; Experiment 1); (2) pretreatment with the α₂ adrenoceptor agonist, clonidine (40 μg/kg, i.p.), prior to i.c.v. injections of CRF (0.5 μg; Experiment 2); (3) pretreatment with d-Phe (1, 5 μg, i.c.v.), prior to systemic injections of the α₂ adrenoceptor antagonist, yohimbine (1.25 mg/kg; Experiment 3A); or (4) pretreatment with clonidine (40 μg/kg, i.p.) prior to systemic injections of yohimbine (0.625 mg/kg, 1.25 mg/kg; Experiment 3B). Results  NA reliably induced reinstatement, an effect that was blocked by pretreatment with d-Phe. In contrast, CRF-induced reinstatement was not attenuated by pretreatment with clonidine. Pretreatment with neither d-Phe nor clonidine was effective in blocking yohimbine-induced reinstatement. Conclusion  Together, the present findings suggest a functional interaction between NA and CRF systems in mediating stress-induced reinstatement of cocaine seeking, whereby activation of CRF receptors occurs subsequent to, and downstream of, the sites of action of NA.     

Selective mu- and kappa-opioid receptor antagonists administered into the nucleus accumbens interfere with rapid tolerance to ethanol in rats

Background  Previous findings have shown that intra-accumbens injection of naltrexone, a non-selective opioid antagonist, blocks the acquisition of rapid tolerance to ethanol in rats. This study investigates the effects of intra-accumbens injection of the selective mu-, delta-, and kappa-opioid antagonists, respectively, naloxonazine, naltrindole, and nor-binaltorphimine, on rapid tolerance to ethanol. Methods  Male Wistar rats with guide cannulae directed to the shell or the core portions of the nucleus accumbens received a microinjection of naloxonazine (2–4 μg), naltrindole (2–4 μg), nor-binaltorphimine (2.5–5 μg), or vehicle. After 5 min, each group was divided in two groups that received ethanol (2.7 g/kg i.p.) or saline. Rats were then tested for motor coordination on the tilting plane apparatus. Twenty four hours later, all rats received a challenge dose of ethanol (2.7 g/kg i.p.) and were tested on the tilt plane again. Results  Repeated injections of ethanol caused a reduction in motor impairment suggesting the development of tolerance. However, rats injected with 4 μg naloxonazine into either core or shell portions of the nucleus accumbens did not exhibit tolerance when challenged with ethanol on day 2. Rats treated with 5 μg nor-binaltorphimine into accumbens core plus intraperitoneal saline on day 1 showed reduced motor impairment when challenged with ethanol on day 2, suggesting cross-tolerance to ethanol. Conclusions  Taken together, our results suggests that mu-opioid receptors in both shell and core portions of the nucleus accumbens, and possibly kappa-opioid in the core, participate in the modulation of rapid tolerance to ethanol.     

Occurrence and spatial distribution of organic contaminants in sediments from Chinhae Bay, Korea

Persistent organic pollutants (POPs) were monitored in surface sediment of Chinhae Bay, Korea. Sum (Σ) concentration (minimum, maximum and average — ng/g dry weight) ranged: ΣBTs (ng Sn/g): 12, 1230, 221; ΣPAHs: 54, 632, 182; nonylphenol: 107, 207, 148; bisphenol A: 4.36, 135, 83; T-PCBs: 0.64, 18, 3.49; ΣDDT: 0.19, 7.36, 1.15; ΣCHL: 0, 0.49, 0.06; ΣHCH: 0.03, 0.36, 0.10. Among them BTs, PAHs, nonylphenol and bisphenol A were detected in all locations. Chlordanes, HCHs and DDTs were at low levels. Levels of tributyltin remained similar to levels in 1987-94. PAHs were within national average. Chinhae Bay derives its pollution from a) two poβible point sources, namely, industrial and urban activities from inner Masan Bay and shipping activities from Kohyon Bay; b) diffuse sources of various sorts. Spatial distribution and chemical composition of POPs together with their inter-relationships were investigated.     

Pharmacological evidence for the presence of functional β3-adrenoceptors in rat retinal blood vessels

The aim of this study was to examine whether stimulation of β₃-adrenoceptors dilates rat retinal blood vessels and how diabetes affects the vasodilator responses. Images of ocular fundus were captured with an original high-resolution digital fundus camera in vivo. The retinal vascular responses were evaluated by measuring diameter of retinal blood vessels contained in the digital images. Both systemic blood pressure and heart rate (HR) were continuously recorded. The β₃-adrenoceptor agonist CL316243 (0.3–10 μg/kg/min, i.v.) increased diameter of retinal arterioles (at 10 μg/kg/min, a 31% increase) and decreased mean blood pressure (at 10 μg/kg/min, a 21% decrease) in a dose-dependent manner. CL316243 produced a small but significant increase in HR (at 10 μg/kg/min, a 9% increase). Both SR59230A (1 mg/kg, i.v.) and L-748337 (50 μg/kg, i.v.), β₃-adrenoceptor antagonists, significantly prevented CL316243-induced retinal vasodilator responses. Similar observations were made with another β₃-adrenoceptor agonist, BRL37344. The β₂-adrenoceptor agonist salbutamol also increased diameter of retinal arterioles (at 10 μg/kg/min, a 43% increase), whereas the drug produced greater decrease in blood pressure (at 10 μg/kg/min, a 46% decrease) and increase in HR (at 10 μg/kg/min, a 16% increase), compared with β₃-adrenoceptor agonists. The retinal vasodilator responses to CL316243 and BRL37344 observed under blockade of β₁/β₂-adrenoceptors with propranolol (2 mg/kg, i.v. bolus followed by 100 μg/kg/min infusion) were unaffected 2 weeks after induction of diabetes by the combination of streptozotocin treatment and d-glucose feeding. On the other hand, the vasodilator responses to salbutamol of retinal arterioles were significantly reduced in diabetic rats. These results suggest that stimulation of β₃-adrenoceptors causes the vasodilation of retinal arterioles in vivo and the vasodilator responses are unaffected at the early stage of diabetes.     

Are uranium-contaminated soil and irrigation water a risk for human vegetables consumers? A study case with Solanum tuberosum L., Phaseolus vulgaris L. and Lactuca sativa L.

The knowledge of uranium concentration, in the products entering the human diet is of extreme importance because of their chemical hazard to health. Controlled field experiments with potatoes, beans and lettuce (Solanum tuberosum L., Phaseolus vulgaris L. and Lactuca sativa L.) were carried out in a contaminated soil used by local farmers located near a closed Portuguese uranium mine (Cunha Baixa, Mangualde). The soil with high average uranium levels (64–252 mg/kg) was divided in two plots, and irrigated with non-contaminated and uranium-contaminated water (<20 and >900 μg/L). Uranium maximum average concentration in the edible vegetables parts (mg/kg fresh weight) ranged in the following order: lettuce (234 μg/kg) > green bean (30 μg/kg) > potatoes without peel (4 μg/kg). Although uranium in soil, irrigation water and vegetables was high, the assessment of the health risk based on hazard quotient indicates that consumption of these vegetables does not represent potential adverse (no carcinogenic) effects for a local inhabitant during lifetime.     

Comparative toxicity of hydrophobic contaminants to microalgae and higher plants

To enable rapid and sensitive screening of phytotoxic compounds in terrestrial system, a 4 day solid-phase microalgal bioassay was developed. Three species of microalgae (Selenastrum capricornutum, Chlorococcum hypnosporum and Chlorococcum meneghini) were chosen to investigate their responses to DDTs (DDT, DDD and DDE) and PAHs (naphthalene, phenanthrene and pyrene) spiked sands. The bioassay results showed that PAHs and DDTs were toxic to microalgae in a 4-day exposure tests but not to seed germination of ryegrass (Lolium perenne). Phenanthrene was the most phytotoxic. Among three investigated endpoints, fluorescence emissions by microalgae were less sensitive than cell density (optical density OD₆₅₀) and chlorophyll a concentration as endpoints. In general, S. capricornutum was the most sensitive species for PAHs (EC₅₀ for phenanthrene = 9.4 mg kg⁻¹), while C. meneghini for DDTs (EC₅₀ for DDE = 20.0 mg kg⁻¹). Comparison of the microalgal tests with US EPA standard seed germination/root elongation test (using Lolium perenne) demonstrated the superior screening potential of phytotoxic hydrophobic compounds using the proposed bioassay. Using OD₆₅₀ as the endpoint, EC₁₀ of selected microalgae for PAHs and DDTs were 0.43–64.3 mg kg⁻¹ and 0.67–117 mg kg⁻¹ respectively, which were much lower than the EC₁₀ of L. perenne for both PAHs (94–187 mg kg⁻¹) and DDTs (113–483 mg kg⁻¹). The results encourage further studies involving wider types of vascular plants and more comparison with standard phytotoxicity tests from different authorities using contaminated soils to verify the effectiveness of the microalgal bioassay.