Microbial source tracking and antimicrobial resistance in one river system of a rural community in Bahia, Brazil / Rastreamento de fontes microbianas e resistência antimicrobiana em um sistema fluvial de uma comunidade rural da Bahia, Brasil

Use of antibiotics inevitably leads to antimicrobial resistance. Selection for resistance occurs primarily within the gut of humans and animals as well as in the environment through natural resistance and residual antibiotics in streams and soil. We evaluated antimicrobial resistance in Gram negative bacteria from a river system in a rural community in Bahia, Brazil. Water was collected from the Jiquiriçá and Brejões rivers and the piped water supply. Additionally, stools were collected from a random sample of residents, cows, pigs and horses near the river. The samples were screened for bacteria resistant to ciprofloxacin, cefotaxime, and meropenem and identified biochemically at the genus and species levels. Microbial source tracking demonstrated that ruminant and human fecal contamination increased as the rivers neared the village center and decreased after the last residence. Antibiotic bacteria were identified from all samples (n = 32). No bacteria were resistant to carbapenems, but the majority of the enterobacteria were resistant to ciprofloxacin, even though this class of antibiotics is not commonly used in food animals in this region. Considering these facts, together with the pattern of human fecal contamination, a human source was considered most likely for these resistant isolates.

O uso de antibióticos inevitavelmente leva à resistência antimicrobiana. A seleção para resistência antimicrobiana ocorre principalmente no intestino de seres humanos e animais, bem como no meio ambiente, através da resistência natural e resíduos de antibióticos nos esgotos e no solo. Avaliamos a resistência antimicrobiana em bactérias Gram-negativas de um sistema fluvial em uma comunidade rural da Bahia, Brasil. A água foi coletada nos rios Jiquiriçá e Brejões e no abastecimento de água encanada. Além disso, foram coletadas amostras randomizadas de fezes de moradores, vacas, porcos e cavalos próximos ao rio. As amostras foram triadas para bactérias resistentes à ciprofloxacina, cefotaxima e meropenem e identificadas bioquimicamente nos níveis de gênero e espécie. O rastreamento de fontes microbianas demonstrou que a contaminação fecal de ruminantes e humanos aumentou à medida que os rios se aproximavam do centro da vila e diminuía após a última residência. Bactérias resistentes a antibióticos foram identificadas em todas as amostras (n = 32). Nenhuma bactéria demonstrou ser resistente aos carbapenêmicos testados, contudo, foi encontrado enterobactérias resistentes à ciprofloxacina, ainda que essa classe de antibióticos não seja comumente usada na medicina veterinária dos animais dessa região. Considerando esses fatos, juntamente com o padrão de contaminação fecal avaliado, a fonte de contaminação humana foi considerada a mais provável na interação desses isolados resistentes.

Microbial source tracking and antimicrobial resistance in one river system of a rural community in Bahia, Brazil

Abstract Use of antibiotics inevitably leads to antimicrobial resistance. Selection for resistance occurs primarily within the gut of humans and animals as well as in the environment through natural resistance and residual antibiotics in streams and soil. We evaluated antimicrobial resistance in Gram negative bacteria from a river system in a rural community in Bahia, Brazil. Water was collected from the Jiquiriçá and Brejões rivers and the piped water supply. Additionally, stools were collected from a random sample of residents, cows, pigs and horses near the river. The samples were screened for bacteria resistant to ciprofloxacin, cefotaxime, and meropenem and identified biochemically at the genus and species levels. Microbial source tracking demonstrated that ruminant and human fecal contamination increased as the rivers neared the village center and decreased after the last residence. Antibiotic bacteria were identified from all samples (n = 32). No bacteria were resistant to carbapenems, but the majority of the enterobacteria were resistant to ciprofloxacin, even though this class of antibiotics is not commonly used in food animals in this region. Considering these facts, together with the pattern of human fecal contamination, a human source was considered most likely for these resistant isolates.

Resumo O uso de antibióticos inevitavelmente leva à resistência antimicrobiana. A seleção para resistência antimicrobiana ocorre principalmente no intestino de seres humanos e animais, bem como no meio ambiente, através da resistência natural e resíduos de antibióticos nos esgotos e no solo. Avaliamos a resistência antimicrobiana em bactérias Gram-negativas de um sistema fluvial em uma comunidade rural da Bahia, Brasil. A água foi coletada nos rios Jiquiriçá e Brejões e no abastecimento de água encanada. Além disso, foram coletadas amostras randomizadas de fezes de moradores, vacas, porcos e cavalos próximos ao rio. As amostras foram triadas para bactérias resistentes à ciprofloxacina, cefotaxima e meropenem e identificadas bioquimicamente nos níveis de gênero e espécie. O rastreamento de fontes microbianas demonstrou que a contaminação fecal de ruminantes e humanos aumentou à medida que os rios se aproximavam do centro da vila e diminuía após a última residência. Bactérias resistentes a antibióticos foram identificadas em todas as amostras (n = 32). Nenhuma bactéria demonstrou ser resistente aos carbapenêmicos testados, contudo, foi encontrado enterobactérias resistentes à ciprofloxacina, ainda que essa classe de antibióticos não seja comumente usada na medicina veterinária dos animais dessa região. Considerando esses fatos, juntamente com o padrão de contaminação fecal avaliado, a fonte de contaminação humana foi considerada a mais provável na interação desses isolados resistentes.

Microbial source tracking and antimicrobial resistance in one river system of a rural community in Bahia, Brazil.

Use of antibiotics inevitably leads to antimicrobial resistance. Selection for resistance occurs primarily within the gut of humans and animals as well as in the environment through natural resistance and residual antibiotics in streams and soil. We evaluated antimicrobial resistance in Gram negative bacteria from a river system in a rural community in Bahia, Brazil. Water was collected from the Jiquiriçá and Brejões rivers and the piped water supply. Additionally, stools were collected from a random sample of residents, cows, pigs and horses near the river. The samples were screened for bacteria resistant to ciprofloxacin, cefotaxime, and meropenem and identified biochemically at the genus and species levels. Microbial source tracking demonstrated that ruminant and human fecal contamination increased as the rivers neared the village center and decreased after the last residence. Antibiotic bacteria were identified from all samples (n = 32). No bacteria were resistant to carbapenems, but the majority of the enterobacteria were resistant to ciprofloxacin, even though this class of antibiotics is not commonly used in food animals in this region. Considering these facts, together with the pattern of human fecal contamination, a human source was considered most likely for these resistant isolates.

Influence of apical enlargement and complementary canal preparation with the Self-Adjusting File on endotoxin reduction in retreatment cases.

AIM: To compare the effectiveness of large apical preparations and complementary canal preparation with the Self-Adjusting File (SAF) in removing endotoxins from the root canal of teeth with apical periodontitis. METHODOLOGY: Ten single-rooted and single-canaled teeth with post-treatment apical periodontitis were selected. Endotoxin samples were taken after removal of the root filling (S1), after chemomechanical preparation (CMP) using 2.5% NaOCl and an R25 file (S2), after CMP using 2.5% NaOCl and an R40 file (S3) and after complementary CMP using the SAF system (S4). Limulus amebocyte lysate (LAL) was used to measure endotoxin levels. The Friedman and Wilcoxon tests were used to compare endotoxin levels at each clinical intervention (P < 0.05). RESULTS: After root filling removal, endotoxin was detected in 100% of the root canals (S1, 4.84 EU mL-1 ). CMP with the R25 file was able to significantly reduce endotoxin levels (P < 0.05). Increased levels of endotoxin removal were achieved by apical preparation with the R40 file (P < 0.05). Complementary CMP with SAF did not significantly reduce endotoxin levels (P > 0.05) following the use of the R40 instrument. CONCLUSIONS: Apical enlargement protocols were effective in significantly reducing endotoxin levels. Complementary preparation with the SAF system failed to eliminate residual endotoxin contents beyond those obtained with the R40 instrument.

Relationship between function, strength and electromyography of upper extremities of persons with tetraplegia.

STUDY DESIGN: Cross-sectional. OBJECTIVE: To analyze the relationships between functional tests, arm strength and root mean square of surface electromyography (EMG). SETTING: Sao Paulo, Brazil. METHODS: Twenty-four individuals with chronic tetraplegia participated. Upper extremity motor score (UEMS), functional independence measure (FIM) motor score, spinal cord independence measure III and capabilities of upper extremity (CUE) were performed. Muscle strength of the right elbow flexors-extensors was assessed using dynamometry and manual muscle test (MMT) and EMG of right biceps and triceps brachii were performed. Spearman's rank correlation coefficients and Mann-Whitney's U-test were used. RESULTS: Functional tests and UEMS correlated strongly among them. UEMS highly correlated with triceps dynamometry and EMG. The dynamometry showed a very high correlation with MMT on the extensor group and a moderate correlation with flexor group. Triceps EMG showed moderate correlation with FIM and CUE. High correlations between triceps EMG and elbow extensors dynamometry and MMT were observed. A significant better performance on functional tests was observed on lower ASIA motor levels. The low-tetraplegia group showed a significant higher score on triceps EMG and dynamometry. CONCLUSION: Arm strength and EMG seem to be related to functional capabilities and independence in chronic tetraplegia.

Construction materials as a waste management solution for cellulose sludge.

Sustainable waste management system for effluents treatment sludge has been a pressing issue for pulp and paper sector. Recycling is always recommended in terms of environmental sustainability. Following an approach of waste valorisation, this work aims to demonstrate the technical viability of producing fiber-cement roof sheets incorporating cellulose primary sludge generated on paper and pulp mills. From the results obtained with preliminary studies it was possible to verify the possibility of producing fiber-cement sheets by replacing 25% of the conventional used virgin long fiber by primary effluent treatment cellulose sludge. This amount of incorporation was tested on an industrial scale. Environmental parameters related to water and waste, as well as tests for checking the quality of the final product was performed. These control parameters involved total solids in suspension, dissolved salts, chlorides, sulphates, COD, metals content. In the product, parameters like moisture, density and strength were controlled. The results showed that it is possible to replace the virgin long fibers pulp by primary sludge without impacts in final product characteristics and on the environment. This work ensures the elimination of significant waste amounts, which are nowadays sent to landfill, as well as reduces costs associated with the standard raw materials use in the fiber-cement industrial sector.

Pulp and paper plant wastes valorisation in bituminous mixes.

Nowadays, the increasing amount of wastes is a concerning reality and the environmental aspects has become a major priority. Following this worry, the purpose of this experimental study was to investigate the possibility of using pulp and paper inorganic wastes, named dregs and grits, in bituminous mixtures as aggregate replacement to reduce environmental effects of these wastes disposal. First, the wastes were chemically and physically characterized and also tested primarily taking into account the requirements for aggregates in bituminous mixtures. Then, formulations were prepared replacing aggregates with wastes in different amounts. The mechanical properties of these mixtures containing wastes were compared with reference samples based on standard methods. According to the results it was possible to verify that grits had a good performance and it might be directly tested industrially as an aggregate in road construction. On the other hand, dregs need to be treated before incorporation to guarantee stable mixes in terms of water sensitivity.

Behavioral and biochemical effects of neonicotinoid thiamethoxam on the cholinergic system in rats.

Thiamethoxam is a neonicotinoid insecticide, a group of pesticides that acts selectively on insect nicotinic acetylcholine receptors (nAChRs), with only a little action on mammalian nAChRs. Nevertheless, the selectivity of neonicotinoids for the insect nAChRs may change when these substances are metabolized. Therefore, we aimed to determine the potential effects of thiamethoxam on mammalian brain, testing the performance in the open field and elevated plus-maze of rats exposed to this insecticide and, in order to establish the neurochemical endpoints, we measured the acetylcholinesterase activity in different brain regions (hippocampus, striatum and cortex) and the high-affinity choline uptake (HACU) in synaptosomes from rat hippocampus. Treated animals received thiamethoxam (25, 50 or 100mg/kg) for 7 consecutive days. The results showed that treatment with thiamethoxam induced an increase in the anxiety behavior at two doses (50 or 100mg/kg). Moreover, there was a significant decrease in both HACU and acetylcholinesterase activity. Our hypothesis is that thiamethoxam (or its metabolites) could be acting on the central rats nAChRs. This would produce an alteration on the cholinergic transmission, modulating the anxiety behavior, acetylcholinesterase levels and HACU.

A novel dry active electrode for EEG recording.

The design and testing of a "dry" active electrode for electroencephalographic recording is described. A comparative study between the EEG signals recorded in human volunteers simultaneously with the classical Ag-AgCl and "dry" active electrodes was carried out and the reported preliminary results are consistent with a better performance of these devices over the conventional Ag-AgCl electrodes.

The relationship of optimism, pain and social support to well-being in older adults with osteoarthritis.

Improving the psychological well-being of individuals with osteoarthritis (OA) is an important concern because the condition is highly prevalent and has no known cure. Few studies have assessed the joint contribution of social, personality, and physical factors in relation to well-being for OA patients. In a cross-sectional sample of older adults with OA (n = 73, 73% female), we assessed the role of support perceptions, optimism and pain in depressive symptoms and life satisfaction. Greater optimism and support were significantly related to both greater life satisfaction and lower depressive symptoms. Further, optimism partially mediated the relationship of pain to life satisfaction, while support partially mediated the role of pain in depressive symptoms. The interplay of these variables in relation to well-being is discussed in the context of chronic illness and older adulthood.

Antinociceptive effect of the aqueous extract obtained from roots of Physalis angulata L. on mice.

In this study, we attempted to identify the possible antinociceptive action of aqueous extract (AE) obtained from roots of Physalis angulata, known in Brazil as "Camapu", used to treat various pain-related physiological conditions. The AE of Physalis angulata (10-30 mg/kg) given by i.p. or p.o. route, 0.5 and 1h prior, produced significant inhibition of abdominal constrictions caused by acetic acid, with ID(50) values of 18.5 (17.4-19.8) and 21.5 (18.9-24.4)mg/kg and inhibitions of 83+/-8 and 66+/-5%, respectively. The AE (10-60 mg/kg, i.p.) also caused significant inhibition of the late-phase of formalin-induced pain, with an ID(50) value of 20.8 (18.4-23.4)mg/kg and inhibition of 100%. Treatment of mice with AE (60 mg/kg, i.p.) or with morphine (10mg/kg, i.p.) produced a significant increase of the reaction time in the hot-plate test. These results demonstrate, for the first time, that the AE of Physalis angulata produce marked antinociception against the acetic acid-induced visceral pain and inflammatory pain responses induced by formalin in mice. The mechanism by which the AE produces antinociception still remains unclear. However, pharmacological and chemical studies are continuing in order to characterize the mechanism(s) responsible for the antinociceptive action and also to identify the active principles present in Physalis angulata. Moreover, the antinociceptive action demonstrated in the present study supports, at least partly, the ethnomedical uses of this plant.

Natural history of the lizard Enyalius brasiliensis (Lesson, 1828) (Leiosauridae) from an Atlantic forest of southeastern Brazil.

Information on the ecology of lizard species from the Brazilian Atlantic Forest is scarce and almost nothing is known about the ecology of lizards of the genus Enyalius. In this study, we provide information about some aspects of the natural history of E. brasiliensis from an area of Atlantic Forest in Ilha Grande, RJ. Enyalius brasiliensis (N = 15) feeds mainly on arthropods. The most frequent food items were insect larvae, orthopterans, and ants; in terms of volume, larvae and termites were the most important food items; ants and termites were the most numerous prey categories. Two females were reproductive (one had 10 and the other, five vitellogenic follicles); the smallest measured 92.4 mm in SVL. Seven lizards were found on forest leaf litter. The other microhabitats used were vines, fallen logs, branches, and a crevice on a slope.

Natural history of the lizard Enyalius brasiliensis (Lesson, 1828) (Leiosauridae) from an Atlantic Forest of southeastern Brazil

Informaçäes sobre a ecologia de espécies de lagartos da Floresta Atlântica brasileira são raras. Quase nada é conhecido sobre a ecologia de lagartos do gênero Enyalius. Com este estudo fornecemos informaçäes sobre alguns aspectos da história natural de E. brasiliensis de uma área de Mata Atlântica da Ilha Grande, RJ. Os indivíduos de E. brasiliensis (N = 15) se alimentaram principalmente de artrópodos. As presas ingeridas com maior freqüência foram larvas de insetos, ortópteros e formigas; em termos volumétricos, larvas e cupins foram os itens mais importantes; e formigas e cupins foram as presas mais numerosas. Das 10 fêmeas encontradas, duas estavam reprodutivas (uma tinha 10 e a outra, 5 folículos vitelogênicos); a menor delas media 92,4 mm de tamanho corporal. Sete dos 15 lagartos foram encontrados sobre folhiço no chão da mata. Os outros micro-habitats utilizados foram cipós, troncos caídos, galhos e um barranco de terra dentro de uma fenda de rocha.

Ionotropic glutamate receptor subunit expression in the rat hippocampus: lack of an effect of a long-term ethanol exposure paradigm.

BACKGROUND: Studies have shown that acute ethanol exposure inhibits ionotropic glutamate receptor function and that long-term ethanol exposure results in maladaptive increases in the expression of some of these receptors in neurons. It has been postulated that these changes, when unopposed by ethanol, contribute, in part, to the hyperexcitability associated with ethanol withdrawal. In this study, we compared the effect of long-term ethanol exposure on the hippocampal expression levels of subunits belonging to the three families of ionotropic glutamate receptors. METHODS: Adult male Sprague-Dawley rats were fed an ethanol-containing diet for 16 days. This diet contained 0% ethanol on days 1 and 2, 3% on days 3 and 4, 5% on days 5 to 7, and 6.7% on days 8 to 16. Control rats received an equivalent amount of an isocaloric diet without ethanol. Rats were killed on day 16 at the peak of ethanol consumption. Hippocampal homogenates were prepared by sonication and analyzed by Western immunoblotting techniques. On a separate group of rats, we measured withdrawal scores and audiogenic seizures on day 17. RESULTS: Ethanol-exposed rats had significantly higher withdrawal scores, and a significantly higher percentage of them developed audiogenic seizures; this indicates that the 16-day ethanol diet induces ethanol dependence. Unexpectedly, we found that expression of NR1 (including the expression of NR1 subunits containing the N1, C1, and C2 inserts), NR2A, NR2B, NR2C, GluR1, GluR2/3, GluR5, GluR6/7, and KA2 subunits was not altered in hippocampal homogenates from ethanol-exposed rats. CONCLUSIONS: These results indicate that maladaptive changes in the hippocampal expression levels of ionotropic glutamate receptor subunits do not always occur in ethanol-dependent rats. Consequently, other mechanisms must mediate the hyperexcitability state associated with ethanol withdrawal in these animals.

Effects of central and systemic injections of peripheral benzodiazepine receptor ligands on the anxiolytic actions of ethanol in rats.

The influence of peripheral benzodiazepine receptor ligands Ro5-4864 (0.05 or 1.0 mg/kg, i.p.) or PK11195 (0.05 or 1.0 mg/kg, i.p.) on the anxiolytic effect of ethanol (1.2 g/kg; 14% p/v; i.p.) was investigated in rats tested on the elevated plus-maze. Other animals were injected through intrahippocampal administrations of the ligands (0.5 or 1.0 nmol/0.5 &mgr;l) before ethanol (1.2g/kg; 14% p/v; i.p.) and submitted to the elevated plus-maze test. The results showed that the systemic administration of either ligands 24 hours before the ethanol treatment resulted in a reduced anxiolytic effect of this drug. Only PK11195 reversed the effect of ethanol after intrahippocampal injection. These data suggest that peripheral benzodiazepine receptors play a role in ethanol anxiolysis.

Fetal alcohol exposure alters neurosteroid modulation of hippocampal N-methyl-D-aspartate receptors.

The actions of ethanol on brain ligand-gated ion channels have important roles in the pathophysiology of alcohol-related neurodevelopmental disorders and fetal alcohol syndrome. Studies have shown that N-methyl-d-aspartate (NMDA) receptors are among the ligand-gated ion channels affected by prenatal ethanol exposure. We exposed pregnant dams to an ethanol-containing liquid diet that results in blood ethanol levels near the legal intoxication limit in most states (0.08%). Primary cultures of hippocampal neurons were prepared from the neonatal offspring of these dams, and NMDA receptor function was assessed by patch clamp electrophysiological techniques after 6-7 days in culture in ethanol-free media. Unexpectedly, we did not detect any changes in hippocampal NMDA receptor function at either the whole-cell or single-channel levels. However, we determined that fetal alcohol exposure alters the actions of the neurosteroids pregnenolone sulfate and pregnenolone hemisuccinate, which potentiate NMDA receptor function. Western immunoblot analyses demonstrated that this alteration is not due to a change in the expression levels of NMDA receptor subunits. Importantly, in utero ethanol exposure did not affect the actions of neurosteroids that inhibit NMDA receptor function. Moreover, the actions of pregnenolone sulfate on type A gamma-aminobutyric acid and non-NMDA receptor function were unaltered by ethanol exposure in utero, which suggests that the alteration is specific to NMDA receptors. These findings are significant because they provide, at least in part, a plausible mechanistic explanation for the alterations in the behavioral responses to neurosteroids found in neonatal rats prenatally exposed to ethanol and to other forms of maternal stress (Zimmerberg, B., and McDonald, B. C. (1996) Pharmacol. Biochem. Behav. 55, 541-547).

[Variables associated with underreporting of AIDS patients in Rio de Janeiro, Brazil, 1996]. / Fatores associados à subnotificação de pacientes com Aids, no Rio de Janeiro, RJ, 1996.

OBJECTIVE: The underreporting of AIDS cases in the municipality of Rio de Janeiro, Brazil, is significant. The study intends to analyze the factors associated to this event. METHODS: Using data provided by the Hospital Information System for the year of 1996, in Rio de Janeiro city, and by the National Surveillance System, patients were randomly selected and their medical records reviewed to verify an AIDS diagnosis. A multinomial model was used to perform an analysis of the variations on the chances of underreporting of AIDS cases versus reporting and on the chances of underreporting without evidences to fulfill the case definition of AIDS versus reporting. RESULTS: No significant associations were found between the variables such as "age", "marital status", "level of education", "occupation", and "severity of illness" and the underreporting of AIDS cases. The variable "female gender" showed a strong association with hospitalization without evidence of an AIDS diagnosis. A strong association was found between two or more admissions in an inpatient unit care and reporting. The existence of a epidemiological surveillance department in the hospital is inversely associated with the underreporting of AIDS cases. CONCLUSION: The significant association between organizational variables and underreporting of AIDS cases found in the study point out to the need of standardization of the surveillance procedures, the especial need for the creation and maintenance of surveillance departments in hospitals to improve the quality of the health information system and, therefore, AIDS prevention and care.

Dexamethasone reverses the ethanol-induced anxiolytic effect in rats.

The effects of intraperitoneal and intrahippocampal administration of the glucocorticoid dexamethasone were assessed regarding ethanol-induced anxiolysis in the elevated plus-maze in rats. Animals pretreated with systemic injections of dexamethasone (0.5, 1. 0, or 2.0 mg/kg, IP) 15 min before ethanol (1.2 g/kg, 14% w/v, IP) administration showed a significant dose-dependent attenuation of the increased percentage of frequency and time spent on open arms of the maze. However, IP dexamethasone treatment 4 h before the test had no effect. Unilateral intrahippocampal injection of dexamethasone (2 and 20 nmol in 0.5 microl) also significantly attenuated the increased exploration of the open arms induced by ethanol. The results are interpreted in terms of the modulation of the anxiolytic effects of ethanol by glucocorticoids and the possible involvement of hippocampus in this response. The rapid blockade of ethanol induced anxiolysis by dexamethasone strengthens the suggestion that a nongenomic mechanism may underlie this response.

[Evaluation of under-reporting of AIDS cases in the city of Rio de Janeiro based on data from the hospital information system of the Unified Health System]. / Avaliação da subnotificação de casos de Aids no Município do Rio de Janeiro com base em dados do sistema de informações hospitalares do Sistema Unico de Saúde.

Data from the Hospital Information System (SIH-SUS) were linked to data from the AIDS Case Reporting System (Sinan) to assess the level of under-reporting of AIDS cases in the city of Rio de Janeiro. A high level of unreported cases(42.7%) was observed for patients treated in hospitals under Brazil's Unified Health System in the city of Rio. Bivariate analysis showed an association between reporting to the Sinan and age, principal diagnosis, and type of hospital.

Role of nitric oxide-dependent pathways in ethanol-induced anxiolytic effects in rats.

BACKGROUND: Nitric oxide (NO) is a neuromodulator and an intercellular and retrograde messenger that mediates several functions in the central nervous system. The effects of ethanol (EtOH) on neuronal NO-dependent pathways have been the focus of recent research. Most studies have concentrated on the actions of chronic EtOH exposure. In this study, we examined the role of NO-dependent pathways in the acute actions of EtOH. METHODS: We used the elevated plus-maze test to study the role of NO-dependent pathways in the behavior of rats treated with acute EtOH. We tested the effects of 7-nitroindazole, a reversible competitive inhibitor of nitric oxide synthase. We also studied the effects of the cyclic guanylate monophosphate (cGMP) analog, 8-Bromoguanosine cyclic 3',5'-monophosphate sodium salt, and the NO donors S-nitroso-N-acetylpenicillamine or sodium nitroprusside. RESULTS: When injected by either intraperitoneal (6 mg/kg) or intrahippocampal (20 nmol) routes, 7-nitroindazole increased the percentage of open arm entries and time spent in open arms for rats injected with EtOH (1.0 g/kg, ip). This dose of EtOH did not produce an anxiolytic effect when administered alone. Additional experiments were performed with a dose of 1.2 g/kg of EtOH (ip), which produced an anxiolytic effect. Intrahippocampal administration of the cGMP analog, 8-Bromoguanosine cyclic 3',5'-monophosphate sodium salt (40 nmol), or the NO donors S-nitroso-N-acetylpenicillamine (20 or 40 nmol) or sodium nitroprusside (20 or 40 nmol) blocked the anxiolytic effect of this dose of EtOH. CONCLUSIONS: These results indicate that inhibition of NO-dependent pathways enhances, whereas stimulation of these pathways decreases, the efficacy of EtOH to produce anxiolytic effects in rats. We postulate that NO-dependent increases in guanylate cyclase activity and cGMP levels oppose the anxiolytic effects produced by acute EtOH administration.