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Diverse larval habitats significantly influence female mosquito oviposition. Utilizing traps that simulate these habitats is helpful in the study of the bioecology and characteristics of pathogen-transmitting species during oviposition. This study evaluated the feasibility of different traps in natural environments by comparing sampling methods and detecting the oviposition of epidemiologically important mosquitoes, with emphasis on Haemagogus species, in a fragment of the Atlantic Forest in Silva Jardim, Rio de Janeiro State, Brazil. Monthly collections were conducted from March 2021 to October 2023 using four types of traps: plastic containers, tires, bamboo, and sapucaia. Immatures were collected from these traps using a pipette, placed in plastic bags, and transported to the laboratory. Tire was the most efficient trap, showing the highest mosquito abundance (n = 1239) and number of species (S = 11). Conversely, the plastic container trap exhibited the lowest diversity (H = 0.43), with only two species and a low mosquito abundance (n = 26). The bamboo trap captured six species and recorded the second-highest diversity index (H = 1.04), while the sapucaia trap captured five species and had the third-highest diversity index (H = 0.91). Of the total immatures collected, 1817 reached adulthood, comprising 13 species, two of which are vectors of the sylvatic yellow fever virus: Haemagogus leucocelaenus and Haemagogus janthinomys . In conclusion, detecting key vectors of the sylvatic yellow fever virus in Brazil highlights the need for ongoing entomological and epidemiological surveillance in the study area and its vicinity. These efforts are crucial for monitoring vector presence and activity, identifying potential transmission hotspots, and devising effective control and prevention strategies.

Although tropical forests are home to most of the global diversity, they suffer from the most significant knowledge gaps concerning their fauna. Despite its high biodiversity, Brazil is facing an alarming destruction of habitats, with species becoming extinct before they can be discovered or described via science. Therefore, there is an urgent need to expand wildlife inventories, including entomofauna surveys. The present study aimed to analyze the bionomic aspects and the influence of abiotic factors on mosquito fauna whose immature phases develop in two bamboo species, Guadua tagoara and Bambusa vulgaris , in Tijuca National Park, Rio de Janeiro, Brazil. Immatures were collected in 10 artificially drilled bamboo plants, in five stalk internodes per plant, at two sampling points, from March 2022 to March 2023, during 23 collections. A total of 1845 immatures were obtained, 72.14% at sampling point 1 and 27.86% at sampling point 2. Of this, 1162 individuals reached adulthood, belonging to the following species: Culex iridescens , Culex neglectus , Haemagogus leucocelaenus , Orthopodomyia albicosta , Sabethes identicus , Sabethes melanonymphe , Sabethes purpureus , Toxorhynchites bambusicola , Toxorhynchites sp., Trichoprosopon compressum , Trichoprosopon pallidiventer , Wyeomyia arthrostigma , Wyeomyia codiocampa , Wyeomyia lutzi , Wyeomyia oblita , Wyeomyia personata , Wyeomyia serrata , and Wyeomyia sp. The Tijuca National Park is a tourist spot and receives a large number of visitors. Thus, humans can become an accessible food source for mosquitoes in this area, making the species survey critical since important arbovirus vectors have been recorded in Rio de Janeiro.

Significant pathogens that have resurfaced in humans originate from transmission from animal to human populations. In the Americas, yellow fever cases in humans are usually associated with spillover from non-human primates via mosquitoes. The present study characterized the prevalence of the yellow fever vector Haemagogus leucocelaenus in Rio de Janeiro, Brazil. The Atlantic Forest fragment chosen is an area of translocation of the golden lion tamarin (Leontopithecus rosalia), where 10 ovitraps were installed to collect mosquito eggs in Fazenda Três Irmãos, at Silva Jardim city, from March 2020 to October 2022. A total of 1514 eggs were collected, of which 1153 were viable; 50% belonged to medically important mosquito species and 24% to the yellow fever vector species, Hg. leucocelaenus. The months of December 2020 (n = 252), November 2021 (n = 188), and January 2022 (n = 252) had the highest densities of this vector. Haemagogus leucocelaenus was positively correlated with temperature (r = 0.303) and humidity (r = 0.48), with eggs hatching up to the 15th immersion with higher abundance of females. Implementing mosquito monitoring for arbovirus activity can help protect both the golden lion tamarin and human populations from the threat of arbovirus transmission., (© 2023. Springer Nature Limited.)

Culicid species, which include potential vectors of yellow fever, are diverse and abundant, with species commonly co-occurring in certain sites. Studying these species can provide important insights into their vector potential and, consequently, epizootic cycles of arboviruses carried about by these vectors. Here, we evaluated the vertical distribution and temporal segregation of mosquito oviposition with emphasis on arbovirus vectors in a fragment of the Atlantic Forest in Casimiro de Abreu, Rio de Janeiro, Brazil. Two sampling points were selected: Fazenda Três Montes and the Reserva Natural de Propriedade Privada Morro Grande. Collections were carried out at two sites using 10 ovitraps installed on the vegetation cover at different heights (0, 2, 4, 6, and 8 m above ground level) and monitored monthly from July 2018 to December 2020. The hypotheses of temporal and vertical stratification were tested through a PERMANOVA, and the relationship of each species with the vertical distribution was evaluated individually through a correlation analysis. We collected a total of 3075 eggs, including four species of medical importance: Haemagogus leucocelaenus ( n = 1513), Haemagogus janthinomys ( n = 16), Aedes albopictus ( n = 1097), and Aedes terrens ( n = 449). We found that Hg. leucocelaenus had a positive relationship with height, exhibiting behavior that appears to benefit from higher heights. The abundance of Ae. terrens seemed to follow Hg. leucocelaenus , although we did not find a relationship with height for the former species. On the other hand, Ae. albopictus exhibited a negative relationship with height, becoming absent or outnumbered at higher strata. Our study site has already presented evidence of recent transmission of the wild yellow fever virus, supporting the need to carefully monitor the emergence of febrile diseases among residents in the surrounding areas and the local population.

Some Aedinii mosquitoes are of high importance in the transmission of the sylvatic YFV. Usually, their eggs are very resistant and depend on the rain for their hatching. The present study evaluated the effect of multiple mosquito-egg immersions and the sex ratio of male and female specimens from Atlantic Forest remnants in the state of Rio de Janeiro, Brazil. Three sampling sites were selected in the municipality of Casimiro de Abreu, where 50 ovitraps were randomly installed to collect eggs from the ground level up to different heights, from August 2018 to December 2020. The mosquito sex ratios were compared between seasons and forest sites, using the generalized linear mixed model (GLMM), which included sampling months and trees as random effects. A total of 33,091 mosquito eggs were collected, of which 6152 eggs were already hatched (18%) and 26,939 were unhatched; of these, approximately 76% subsequently hatched. We found that 25% of the eggs corresponded to four species: Aedes albopictus (n = 1277), Ae. terrens (n = 793), Haemagogus janthinomys (n = 89), and Hg. leucocelaenus (n = 3033). The sex ratio (male:female) was variable concerning the sampling sites and the season. For most species, GLMM estimates found no difference in the variation of the average sex ratio as a function of these predictors, and there was no evidence of temporal autocorrelation in the mosquito data. The number of immersions necessary for hatching the eggs differed between mosquito species, and eggs collected in the dry season hatched both in the first immersions and the subsequent events. Co-occurrence of Aedes terrens and Hg. leucocelaenus was the most frequently observed pairwise species combination. Considering recurrent arbovirus outbreaks in Brazil and their burden on the human population, our study helps to shed light on how these vectors behave in nature; therefore, they can be used in surveillance programs.

The yellow fever virus is estimated to cause 30,000 deaths each year worldwide, with the majority of cases and deaths occurring in Africa. The virus is also endemic to Central and South America, including northern and western Brazil. The sylvatic cycle of the virus is related to wild and rural areas, with nonhuman primates as the primary host and wild mosquitoes, specifically from the genera Haemagogus, as vectors. The diversity of the mosquito community plays a significant role in the increase of pathogen transmission to humans. In the present study, we detected fluctuation in populations of vector mosquitoes using ovitraps for Culicidae egg collection. The study area is a forest fragment of the Atlantic Forest, one of the most threatened biomes in Brazil. This biome has been suffering significant deforestation due to anthropic activity. Worryingly, the proximity of human populations to forest environments increases the risk of spreading disease from forest fragments to urban areas. Our findings showed that the highest egg abundance occurred in December 2019, with a significant difference (p = 0.005) between rainy and dry seasons. Most eggs were collected during the rainy period. Subsequent quantification of specimens from epidemiologically relevant species hatched from field-collected eggs resulted in 1,131 (86%) Haemagogus leucocelaenus (Dyar & Shannon, 1924), 111 (8%) Aedes terrens (Walker, 1856), 47 (4%) Aedes albopictus (Skuse, 1894), and 21 (2%) Haemagogus janthinomys (Dyar, 1921). Finally, we assessed the behavior of different vector species performing oviposition on the same breeding site. The highest correlation coefficient was observed between Ae. albopictus and Ae. terrens (rho = 0.52) concerning other Culicidae species. Therefore, we believe that Culicidae population surveillance is crucial for disease monitoring since the increase in specimens of a number of vector species influences the emergence of yellow fever cases in nonhuman primates and human populations., (© The Author(s) 2022. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Arbovirus infections, such as dengue, zika, chikungunya, and yellow fever, are a major public health problem worldwide. As the main vectors, mosquitoes have been classified by the Center for Disease Control and Prevention as one of the deadliest animals alive. In this ecological study, we analyzed the population dynamics of important genera and species of mosquito vectors. Mosquito immatures were collected using ovitraps and at natural breeding sites: bamboos and bromeliads. Adult mosquitoes were captured using CDC traps with CO 2 , Shannon traps, and manual suction tubes. Collections took place during the rainy and dry seasons from 2019 to 2020 in the Serra dos Órgãos National Park, Rio de Janeiro state, Brazil. The highest number of species was recorded in the ovitraps, followed by CDC and bromeliads. The breeding site with the lowest diversity was bamboo, though it showed the highest level of evenness compared to the other breeding sites. The medically important genera reported were Haemagogus spp., Aedes spp., Culex spp., and Wyeomyia spp. Culicid eggs increased in the rainy season, with a peak in November 2019 and January and February 2020, and lower abundance in the dry season, from September to October 2019. Mosquito eggs had a strong positive correlation (ρ = 0.755) with temperature and a moderate positive correlation (ρ = 0.625) with rainfall. This study shows how environmental variables can influence the ecology of disease-vector mosquitoes, which are critical in the maintenance of arbovirus circulation in a threatened biome within the most densely populated region of Brazil.

This work aimed to evaluate the spatial distribution of mosquitoes in different seasonal periods and the interaction between climatic factors and the abundance of mosquitoes, especially those belonging to the tribe Mansoniini in the area surrounding the Amazon hydroelectric production region (Jirau-HP) of Rondônia state, Brazil. Mosquito specimens were collected in May, July, October, and December 2018, and April, July, September, and November 2019, over periods of three alternating days during the hours of 6:00 p.m. to 8:00 p.m. Mosquito sampling was performed using automatic CDC and Shannon light traps. Canonical correspondence analysis (CCA), combined with Monte Carlo permutations, was used to evaluate the correlation between climatic variables and species distribution. In addition, non-metric multidimensional scaling (NMDS) was used to verify the similarity among the sampled communities from the different collections. After analyzing the total mosquito fauna at all sampling points, 46,564 specimens were identified, with Mansonia dyari showing the highest relative abundance in 2018 (35.9%). In contrast, Mansonia titillans had the highest relative abundance in 2019 (25.34%), followed by Mansonia iguassuensis (24.26%). The CCA showed that maximum temperature significantly influenced the distribution of mosquito populations in the study area (p = 0.0406). The NMDS showed that sampling carried out in the rainy and dry seasons formed two distinct groups. There was a significant correlation between species richness and cumulative precipitation 15 days before the sampling period (R 2  = 58.39%; p = 0.0272). Thus, both temperature and precipitation affected mosquito population dynamics. The effect of rainfall on mosquito communities may be due to variations in habitat availability for immature forms., (© 2022. The Author(s).)

This study investigated the composition of mosquito species in different kinds of breeding sites in a tropical forest remnant of the Atlantic Forest and identified species of public health concern therein. Collections of immature forms of mosquitoes were carried out monthly at the Poço das Antas Biological Reserve in southeastern Brazil, between June 2014 and June 2015. Samples were collected from four types of breeding sites: bamboos, bromeliads, puddles, and a lake. A total of 1,182 specimens of mosquitoes belonging to 28 species and 13 genera were collected. Three species, Ad. squamipennis, An. neglectus, and Wy. arthrostigma represented 64.8% of the captured specimens. Only three species were found in more than one type of breeding site: Ps. ferox, An. triannulatus, and Tx. trichopygus. Two species of public health concern were found breeding in bamboo (Ae. aegypti and Ae. albopictus) and one in the lake (An. darlingi). Bamboo had the highest species richness, Shannon diversity, abundance of individuals and number of dominant species of all breeding sites. Similar Simpson diversity was obtained for bamboo and bromeliads, with higher values than those obtained for puddles and the lake. The significance of the four breeding sites, especially bamboos, is discussed in the context of controlling populations of sylvatic species of mosquitoes in Atlantic Forest areas., Competing Interests: NO authors have competing interests Enter: The authors have declared that no competing interests exist.

The yellow fever (YF) virus has been detected throughout Brazil, with the occurrence of human cases, cyclic epizootics, and its isolation from Haemagogus janthinomys and Hg. leucocelaenus . We assessed the seasonal occurrence, egg abundancy, and oviposition interaction of mosquito vector species captured at a Private Natural Heritage Reserve in the Atlantic Forest biome. A total of 2943 eggs and 1538 mosquito larvae were collected from which 1231 belonged to entomologically important species. Ovitraps were used to collect immature mosquitoes from September 2019 to January 2021. The Mann-Whitney test was used to assess the differences in the abundance of eggs between rainy and dry seasons. Kruskal-Wallis and Dunn's post hoc tests were used to evaluate the significance of the differences in the number of individuals from vector species. The highest percentage of mosquito vector eggs were collected during the rainy season, from December to February. Most eggs recovered from ovitraps belonged to the species Hg. leucocelaenus , representing 85% of all mosquito eggs identified. The other species had lower abundances and percentages: Aedes terrens (7%), Haemagogus janthinomys (5%) and Aedes albopictus (3%). The species that shared breeding sites with a higher frequency were Hg. leucocelaenus and Hg. janthinomys , with a statistically positive correlation (ρ = 0.74). This finding suggests that maybe the presence of Hg. leucocelaenus eggs acted as an attractant for Hg. janthinomys or vice versa. An understanding of mosquito oviposition behavior is necessary for the development of surveillance and control approaches directed against specific pathogen vectors of medical and veterinary importance.

This study registers the diversity of Culicidae in the Bom Retiro Private Natural Heritage Reserve (RPPNBR), Rio de Janeiro state, Brazil, based on the collection of the immature stages in natural and artificial larval habitats. Larvae and pupae were collected monthly at two sites of the RPPNBR from May 2014 to July 2015 using dippers and aquatic pipettes. The diversity of the mosquito community was described using the Shannon-Wiener Diversity Index (H'), as well as diversity, richness, and dominance of species found in different larval habitats (lake, bamboos, bromeliads, and artificial vessels). The Mann-Whitney test was used to calculate differences between the two natural and artificial habitats. Overall, 15,659 specimens belonging to 25 species, ten genera, and two subfamilies were collected. The most abundant species collected at sites that were reforested recently were Culex pleuristriatus Theobald, 1903, Limatus durhamii (Theobald, 1901), Aedes albopictus (Skuse, 1895), Culex neglectus (Lutz, 1904), and Culex retrosus (Lane & Whitman, 1951). In a forest preserved site, the most abundant species were Cx. neglectus, Culex iridescens (Lutz, 1905), Sabethes identicus (Dyar & Knab, 1907), Wyeomyia arthrostigma (Lutz, 1905), and Li. durhamii. With respect to larval habitats, 0.1% of the specimens were collected along the edge of a lake, 5.5% in bamboos, 35.9% in bromeliads, and 58.4% in artificial containers. Only 5.5% of the specimens were collected in the forest preserved site, with the remaining samples from the site with altered vegetation. A greater species richness and diversity were found in forest-altered sites compared to the forest preserved site. Several species were collected in the water accumulated in the nylon lids of plastic water tanks. Such vessels can promote an increase in mosquito population density in the environment surrounding the study area., (© The Author(s) 2022. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Mansonia amazonensis (Theobald, 1901) is one of 15 species of the subgenus Mansonia Blanchard, 1901. It is essentially a Neotropical species, recorded in Bolivia, Peru and Brazil. In the highly seasonal Amazon region, Mansonia species find ideal environmental conditions for reproduction, development and establishment. Considering that climate significantly influences the size and behavior of mosquitoes, and insects in general, we analyzed the influence of seasonality on wing morphological variability in populations of Ma. amazonensis. Captures were carried out near the banks of the Madeira River in Rondnia State, Brazil during the dry, rainy and transition periods between seasons during 2018 and 2019. Morphometric characters of 181 wings were analyzed using morphological methods. The results show that wing size of Ma. amazonensis increases following a relatively gradual trend, from smaller wings during the dry period to larger ones in the rainy season. This study provides the first evidence, detected using geometric morphometry, of seasonally associated phenotypic variability in the wing conformation of Ma. amazonensis.

Mansonia spp. are voracious hematophagous mosquitoes whose mature stages usually breed in freshwater bodies containing aquatic vegetation. The reduction in water flow leads to a proliferation in aquatic plants, increasing their populations. Besides, some species are potential vectors of pathogens such as arboviruses and microfilariae. We evaluated the degree of active dispersion of females of Mansonia spp. in the surrounding area of the Jirau hydroelectric power plant in the Amazon, Rondônia, Brazil, using mark-release-recapture techniques. The flight behavior of the recaptured specimens was summarized with a set of average and maximum distances traveled. We show that the dispersal movement of Mansonia spp. is predominantly performed by random, low, and short flights, with a tendency to remain near the breeding sites in certain vegetation fragments. However, the maximum distances traveled were 2000 m from the release point for Mansonia amazonensis during 2018 and Mansonia humeralis during 2019., (© 2021. The Author(s).)

The present study aims to analyze the effectiveness of ovitraps in the capture of Hg leucocelaenus eggs and evaluate the influence of the dry and rainy seasons on their abundance and hatching rates. The eggs were collected in the Atlantic Forest of State of Rio de Janeiro, Brazil, an area in which the yellow fever virus is known to circulate. We distributed 15 ovitraps in three sampling points, with five ovitraps per point. We distributed 15 ovitraps in three sampling points on trees within a forested area, which were sequentially numbered, monitored, and replaced every two weeks from October 2016 to April 2018. There was a high dominance of Hg. leucocelaenus eggs (98.4%) and a variation in egg hatching rates between the wet and dry seasons. These rates were 1.5 times higher in the rainy season than in the dry season. The rainy season also showed a greater abundance of eggs and higher values of ovitrap positivity and egg density indexes in the installed ovitraps. The abundances of Hg. leucocelaenus eggs were positively correlated with mean monthly temperature and air humidity but not significantly correlated with accumulated precipitation. These results, as well as their implications for the possible use of ovitraps to monitor vector mosquitoes of yellow fever in the study region, are discussed., Competing Interests: The authors have declared that no competing interests exist.

Living bamboo stalks are one of the most specialized habitats for mosquito oviposition and immature development. Most of the mosquito species that breed in these habitats are sylvatic, and some are of importance for public health as possible vectors of pathogens. Perforated internodes are a very specialized environment due to the difficulty of access. Furthermore, due to their relatively simple fauna, they represent a valuable model for ecological studies that may be applicable to more complex environments. This study aims to assess the mosquito bionomics of species raised in bamboo internodes. Therefore, the diversity of mosquito species and the influence of abiotic variables (pH and temperature) on the distribution of mosquitoes that breed in this habitat were analyzed. The study area is a fragment of Atlantic Forest within the Association of da Armada (ATA) in Nova Iguaçu, state of Rio de Janeiro, Brazil. Immature mosquitoes were sampled with suction tubes (mouth aspirators) between August 2017 and July 2018. A total of 3,170 larvae were collected in 5 bamboo plants, each with 8 stalks perforated. Of these, 688 larvae reached the adult stage, representing 10 genera and 19 species. The most common species were Culex neglectus (43%), Trichoprosopon digitatum (22%), Culex iridescens (8%), Sabethes identicus (7%), and Orthopodomyia albicosta (7%). The richness of the immatures collected in the ATA was 19 species, with a diversity of 1.10 and Shannon evenness of 0.57. A diverse composition of Culicidae in bamboo stalks was found, although dominance was low., (Copyright © 2021 by The American Mosquito Control Association, Inc.)

Background: Mosquito assemblages are organized along an ecological gradient, including small habitats where interspecific competition predominates and large permanent habitats where predation predominates. This study aimed to analyze the oviposition behavior of mosquitoes regarding the preference for traps installed at two different heights with regard to ground level and the tendency to share spawning sites in an Atlantic Forest fragment in Nova Iguaçu, State of Rio de Janeiro, Brazil., Methods: The eggs were collected from April 2018 to March 2019. Twelve ovitraps were used, randomly distributed in trees at ground level and at a height of 3 m in a forest environment., Results: They were sequentially numbered, monitored, and replaced every 2 weeks. Among the 5818 eggs collected, 3941 hatched, 3756 reached the pupa stage, and 2370 reached the adult stage. The most abundant species were Aedes albopictus (63%) and Haemagogus leucocelaenus (35%), followed by Aedes terrens (2%) and Haemagogus janthinomys (1%). Analyses showed a significant difference of (P = 0.02) between the number of mosquito species collected in the palettes at ground level and the number collected at the height of 3 m. Cluster analysis of species abundance showed that the eggs collected in the palettes at ground level were more abundant than those collected in the palettes at the height of 3 m. We detected co-occurrence of species in the oviposition palettes; according to the null model, such species distribution was not random., Conclusions: The exploitation of oviposition sites by mosquito species can represent an event forced by population density facilitated by the ecological valence of individuals of one species. Understanding the aggregate distribution of larvae at the oviposition site allows us to conduct more in-depth studies of the oviposition behavior of female mosquitoes., (© 2021. The Author(s).)

Although there are many studies on the control of mosquito vectors of the yellow fever virus (YFV) in tropical forests, there are still few ecological studies regarding abiotic factors effect on these mosquitoes. Here we characterize these effects on oviposition behavior, abundance, and diversity of mosquito vectors of YFV. The study was conducted in Córrego da Luz Municipal Park, in Casimiro de Abreu, Rio de Janeiro state, Brazil, from July 2018 to December 2019. Ovitraps were placed at ground level and 3 m high. The data were tested for normality using the Shapiro-Wilk test, followed by an independent sample analysis, the Mann-Whitney test. The Shannon Diversity Index was used to evaluate the abundance of mosquitos' eggs collected at both ground level and 3 m high. We highlight the presence of Haemagogus janthinomys and Hg. leucocelaenus, primary YFV vectors in forest areas. The abundance of Hg. leucocelaenus (63%), Hg. janthinomys (75%), and Aedes terrens (58%) was higher at the height of 3 m, while Ae. albopictus (52%) was higher at ground level. Aedes albopictus was positively correlated with temperature. Culicidae monitoring is essential for assessing the YFV transmission cycle in Atlantic forest fragments.

This study examined the ultrastructural characteristics of the egg of Coquillettidia venezuelensis (Theobald) (Diptera: Culicidae) with the aid of scanning electron microscopy. The eggs are elliptical and blackish, measuring on average 525.3 ± 12.8 μm in length and 94.9 ± 5.14 μm in width, with a length to width ratio of 5.54 ± 0.18. The anterior region of the egg is tubuliform, with a well-developed micropylar collar measuring approximately 2.54 ± 0.33 μm in thickness, the inner side of which is uniformly and deeply excavated, with a depression around the outer margin of the micropylar disc, which has a diameter of 29.4 ± 1.7 μm, an area of 234.4 μm2 ± 401.3 μm2 and a slightly elevated central region measuring 1.7 ± 0.5 μm in diameter that bears the central micropyle.

The ultrastructure and morphometry of the egg of Coquillettidia albifera (Prado) (Diptera: Culicidae) studied under scanning electronic microscopy is presented for the first time. The identification of the species was confirmed by examination of the genitalia of males collected with females. The male genitalia are redescribed and digital photographs are provided. The eggs are elliptical with the anterior region elongate and tubuliform, length 661 ± 2.59 µm and width 183 ± 2.59 µm (ratio length/width 3.61 ± 0.08). The dorsal surface is covered by a hexagonal, pentagonal and rectangular chorionic network with randomly distributed tubercles. The micropylar disc has a diameter of 18.91 ± 0.65 µm, surrounded by a continuous protuberant collar with a thickness of 4.4 ± 0.3 µm. No structure or vestige of cement related to egg attachment was observed.

Studies on the bioecology of Haemagogus leucocelaenus Dyar and Shannon 1924, Haemagogus janthinomys Dyar 1921, Aedes albopictus Skuse 1895 (Diptera: Culicidae) mosquitos are extremely important from an epidemiologic point of view, as they are known to be vectors of many important pathogens and, therefore, act as the main factor responsible for the maintenance of several zoonoses natural cycles. The present work aimed to elucidate their seasonal egg-hatching rate using the immersion method. Ovitraps were used to collect mosquito eggs from an Atlantic Forest fragment, in the State of Rio de Janeiro, Brazil, from November 2015 to November 2016. After collection, the eggs were immersed 40 times to assess their hatching rate and evaluate the number of immersions resulting in the highest hatchability during the study period. Differences in the proportion of hatched eggs between species and seasons (spring, summer, fall, winter) and in the numbers of immersions in which eggs hatched were assessed using odds ratios. Hg. leucocelaenus was the species with the highest number of eggs hatching in all sampling periods, followed by Ae. albopictus. Most Ae. albopictus eggs hatched on first immersion regardless of season. Both the numbers of eggs and the number of immersion in which the Haemagogus eggs hatched showed high variability within seasons. In spring, the proportion of eggs that hatched on the first compared to further immersions was similar, while in fall and winter a higher percentage (over 94%) of Hg. leucocelaenus eggs hatched on the first immersion; the opposite pattern was observed in the summer. These results differ from previous observations linking increased hatching to warmer months. The number of immersions in which Hg. leucocelaenus eggs hatched varied between seasons, however differences were not statistically significant. These results evidence the need for further studies to elucidate factors that influence hatching patterns.

The egg of Hulecoeteomyia koreica (Edwards) [=Aedes koreicus (Edwards)], an invasive mosquito in Europe, is described from material obtained in Italy. Eggs are cigar-shaped and tapered posteriorly. They are 667.5 ±47.27 µm in length, and the width posteriorly, in the middle and near the micropyle is, respectively, 113.18 ±10.07, 182.5 ±26.92 and 142.25 ±13.85µm. The outer chorion has groups of tubercles, 3 or 4 in an irregular row in the anterior region and 4-6 irregularly dispersed in cavities surrounded by a covering similar to a membrane. The micropyle is surrounded by an irregular collar, and groups of tubercles are less defined in this region. This pattern is different from the egg described for any other mosquito species.

A temporal observational study was conducted with the aim of characterizing Culicidae richness, diversity, abundance, and species similarity in fragments of Atlantic Forest within the Itatiaia National Park, state of Rio de Janeiro, Brazil. A total of 31 mosquito species were collected in 2 sampling stations, during the day and night, and the abundance index and dominance coefficient for each species were calculated. The results showed that the culicid density was higher during the day, and the time preference was directly influenced by the climate variables analyzed, which acted as limiting factors for mosquito occurrence. The mosquito fauna at the Itatiaia National Park presented high richness, including some epidemiologically important species: Anopheles cruzii, Haemagogus leucocelaenus, Aedes scapularis, and Sabethes identicus. Studies of this region supply information on biodiversity, and consequently help to understand epidemiological aspects of potential pathogen vector species.

Culex (Melanoconion) pedroiSirivanakarn & Belkin 1980 and Culex (Melanoconion) ribeirensisForattini & Sallum 1985 are two morphologically very similar species of the Pedroi subgroup of mosquitoes in the Spissipes section of the subgenus Melanoconion of the genus Culex L. 1758. We carried out an analysis of the mitochondrial cytochrome c oxidase I (COI) DNA variation between these two species. The recent observation of sympatric coexistence in a forested area of Rio de Janeiro State (Brazil) triggered the need to validate these two species previously identified based on morphology. We concluded that the COI is a useful tool for identification of Cx. pedroi and Cx. ribeirensis., (© The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

The present study aimed to determine the effects of seasonal variation on phenotypic variation in Culex bastagarius, using geometric morphometric analysis based on wing shape and size. Samples were collected in the Guapiaçu Ecological Reserve, in Rio de Janeiro, Brazil. Mosquitoes were captured once every 2 months (December 2012-January 2014) using light traps. The results of geometric morphometric analysis revealed variations in wing size; however, variability was not evident in wing shape. The present study provides novel data regarding phenotypic plasticity of Cx. bastagarius that have been scarcely addressed in the past.

To increase the knowledge of biodiversity and identify larval habitats used by immature mosquitoes in the Atlantic Forest, we conducted a study in areas with various stages of preservation within the Guapiaçu Ecological Reserve in Cachoeiras de Macacu, Rio de Janeiro state. The Culicidae fauna were sampled during February, April, June, August, October, and December 2012; February, March, April, May, June, August, October, and December 2013; and January and March 2014. Immature mosquitoes were collected with dippers and suction tubes (mouth aspirators). Over the sampling period, 2697 larvae of 56 species were collected, some of which are recognized vectors of human diseases. The larval mosquito community found in artificial habitats, temporary ground water, and phytotelmata differed between sites, except for the mosquito fauna in bromeliads, which were almost 80% similar. Species segregation was more evident between larval habitats than between sites. Culex usquatus was the dominant species and colonized the highest number of larval habitats. The artificial larval habitats found in REGUA were colonized by a great diversity of species and high abundance as well, thus human artifacts left by the public in the area that collect water may promote an increase in mosquito populations. Among the species collected, some are known or suspected vectors of pathogens to humans and/or veterinary relevance, and their medical relevance is discussed.

This study aimed to assess the vertical patterns of oviposition and temporal changes in the distribution of mosquito species in an area of the Atlantic Forest in Rio de Janeiro State, Brazil, and in particular, the behavior and oviposition of potential yellow fever virus vectors. Mosquito samples were collected from the Ecological Reserve Guapiaçu (REGUA, Brazil), which includes a somewhat disturbed forest, with a large diversity of plants and animals. In all, 5,458 specimens (ten species from seven genera) were collected. Haemagogus leucocelaenus was the most frequently captured species, representing 73% of the specimens collected. Species richness and diversity were the highest in the samples collected from the ground-level ovitraps and decreased with height. Species composition also differed significantly among heights. The largest species differences were detected between ovitraps set at the ground level and those set at 7 m and 9 m; Hg. leucocelaenus, Limatus durhamii, and Limatus paraensis contributed most to these differences. Sampling month and climatic variables had significant effects on species richness and diversity. Species diversity and richness decreased with height, suggesting that the conditions for mosquito breeding are more favorable closer to the ground. Species composition also showed vertical differences., (© 2016 The Society for Vector Ecology.)

A temporal observational study was conducted of the Culicidae fauna in a remnant area of Atlantic Forest within a private reserve (Guapiaçu Ecological Reserve-REGUA) presenting typical vegetation cover of dense rain forest, with some patches recovering a floristic composition similar to that of the original community. Research was carried out to analyze the influence of climatic factors (mean monthly temperature, rainfall, and air relative humidity) on the temporal dynamics of the mosquito communities that occur in the reserve. The completeness of the mosquito inventory was assessed with individual-based rarefaction-extrapolation curves. Differences in species composition between sites and months were tested with PERMANOVA. True diversities of orders 0, 1, and 2 (effective numbers) were estimated and compared between sites, months, and years. Multiple stepwise regressions were used to assess relationships between climatic variables, measures of diversity, and abundances of the most common species. There were significant interactive effects between year and site on measures of diversity. However, diversity estimates showed little variation among months, and these were weakly correlated with climatic variables. Abundances of the most common species were significantly related to temperature or relative humidity, but not rainfall. The presence of mosquito species known to be vectors of human diseases combined with an intermittent flow of visitors to the study area suggests there is a risk of disease transmission that warrants further monitoring.

In this study, the oviposition behavior of mosquito species exhibiting acrodendrophilic habits was investigated. The study was conducted near the Simplicio Hydroelectic Reservoir (SHR) located on the border of the states of Minas Gerais and Rio de Janeiro, Brazil. Samples were collected using oviposition traps installed in forest vegetation cover between 1.70 and 4.30 m above ground level during the months of April, June, August, October, and December of 2011. Haemagogus janthinomys (Dyar), Haemagogus leucocelaenus (Dyar and Shannon), Aedes albopictus (Skuse), and Aedes terrens (Walker) specimens were present among the collected samples, the first two of which being proven vectors of sylvatic yellow fever (SYF) in Brazil and the latter is a vector of dengue in mainland Asia. As the data set was zero-inflated, a specific Poisson-based model was used for the statistical analysis. When all four species were considered in the model, only heights used for egg laying and months of sampling were explaining the distribution. However, grouping the species under the genera Haemagogus Williston and Aedes Meigen showed a significant preference for higher traps of the former. Considering the local working population of SHR is very large, fluctuating, and potentially exposed to SYF, and that this virus occurs in almost all Brazilian states, monitoring of Culicidae in Brazil is essential for assessing the risk of transmission of this arbovirus.

Purpose: Statins are selective inhibitors of 3-hydroxyl-3-methyl-glutaryl coenzyme A (HMG-CoA) reductase, the rate-limiting enzyme of the mevalonate pathway for cholesterol biosynthesis. Increasing evidence indicates that statins, particularly atorvastatin, are neuroprotective in several conditions, including stroke, cerebral ischemia, traumatic brain injury, and excitotoxic amino acid exposure. However, only a few studies have investigated whether statins modulate seizure activity. In the current study we investigated whether atorvastatin or simvastatin alters the seizures induced by pentylenetetrazol (PTZ), a classical convulsant., Methods: Adult male Wistar rats were treated with atorvastatin or simvastatin for 7 days (10 mg/kg/day). Seizure activity was induced by PTZ (60 mg/kg, i.p.), and evaluated by behavioral and electrographic methods. Cholesterol levels were determined by a standard spectrophotometric method. Blood-brain barrier (BBB) permeability was assessed by the fluorescein method. Atorvastatin levels in the plasma and cerebral cortex were determined by high-performance liquid chromatography tandem mass spectrometry., Key Findings: We found that oral atorvastatin treatment increased the latency to PTZ-induced generalized seizures. In contrast, when the 7-day atorvastatin treatment was withheld for 1 day (i.e., atorvastatin withdrawal), PTZ-induced seizures were facilitated, as evidenced by a decrease in the latency to clonic and generalized tonic-clonic seizures induced by PTZ. In contrast, simvastatin treatment for 7 days (10 mg/kg/day, p.o.), with or without withdrawal, did not alter PTZ-induced seizures. Interestingly, the effects of atorvastatin treatment and withdrawal were not accompanied by changes in plasma or cerebral cortex cholesterol levels or in the BBB permeability. Atorvastatin levels in the plasma and cerebral cortex after 7 days of treatment were above the half maximal inhibitory concentration for inhibition of HMG-CoA reductase, whereas atorvastatin was not detectable in the plasma or cerebral cortex following a 24 h washout period (atorvastatin withdrawal)., Significance: We conclude that atorvastatin treatment and withdrawal have differential effects on pentylenetetrazol-induced seizures, which are not related to changes in plasma or cerebral cortex cholesterol levels or in BBB permeability. Additional studies are necessary to evaluate the molecular mechanisms underlying our findings as well as its clinical implications., (Wiley Periodicals, Inc. © 2011 International League Against Epilepsy.)

Unlabelled: Oxidative stress markers are thought to be related to nociception. Because thiolic compounds are important antioxidants, we investigated the relationship between thiols, endogenous or exogenous, and nociception. Systemic or spinal, but not peripheral, administration of the exogenous thiolic compound N-acetyl-L-cysteine (NAC) reduced nociception induced by intraplantar capsaicin injection. Moreover, we detected an increase in lipid peroxidation and 3-nitrotyrosine and a decrease in nonprotein thiolic levels in the lumbar spinal cord of capsaicin-injected animals. All these effects were prevented by NAC treatment (i.p. and i.t.). Our findings confirm a role for the spinal cord in NAC actions because systemic NAC administration also reduced the nociception trigged by intrathecal injection of capsaicin. Moreover, adjuvant-induced arthritis, but not paw incision, also -decreases nonprotein thiol levels in the spinal cord. Similarly, NAC produced antinociception in adjuvant-treated animals, but not in paw-incised animals. Finally, we investigated the role of endogenous thiol compounds in the nociceptive process administrating buthionine-suphoxamine (BSO), an inhibitor of glutathione-synthesis. Intrathecal BSO treatment decreased nonprotein thiol levels in the spinal cord, as well as induced mechanical allodynia and chemical and thermal hyperalgesia. In conclusion, our results indicate a critical role for nonprotein thiols in nociception at the level of the spinal cord., Perspective: The results presented here indicate that the loss of nonprotein thiols in the spinal cord is involved in pain development. Therefore, the administration of thiolic compounds or other strategies allow thiol levels to be maintained and could be a beneficial action in the therapy of painful conditions., (Copyright (c) 2010 American Pain Society. Published by Elsevier Inc. All rights reserved.)

Purpose: In the present study we decided to investigate whether physical exercise protects against the electrographic, oxidative, and neurochemical alterations induced by subthreshold to severe convulsive doses of pentyltetrazole (PTZ)., Methods: The effect of swimming training (6 weeks) on convulsive behavior induced by PTZ (30, 45, and 60 mg/kg, i.p.) was measured and different electrographic electroencephalography (EEG) frequencies obtained from freely moving rats. After EEG recordings, reactive oxygen species (ROS) generation, nonprotein sulfhydryl (NPS), protein carbonyl, thiobarbituric acid-reactive substances (TBARS), superoxide dismutase (SOD), catalase (CAT), Na(+), K(+)-ATPase activity, and glutamate uptake were measured in the cerebral cortex of rats., Results: We showed that physical training increased latency and attenuated the duration of generalized seizures induced by administration of PTZ (45 mg/kg). EEG recordings showed that physical exercise decreased the spike amplitude after PTZ administration (all doses). Pearson's correlation analysis revealed that protection of physical training against PTZ-induced seizures strongly correlated with NPS content, Na(+), K(+)-ATPase activity, and glutamate-uptake maintenance. Physical training also increased SOD activity, NPS content, attenuated ROS generation per se, and was effective against inhibition of Na(+), K(+)-ATPase activity induced by a subthreshold convulsive dose of PTZ (30 mg/kg). In addition, physical training protected against 2',7'-dichlorofluorescein diacetate (DCFH-DA) oxidation, TBARS and protein carbonyl increase, decrease of NPS content, inhibition of SOD and catalase, and inhibition glutamate uptake induced by PTZ., Conclusions: These data suggest that effective protection of selected targets for free radical damage, such as Na(+), K(+)-ATPase, elicited by physical training protects against the increase of neuronal excitability and oxidative damage induced by PTZ.

Traumatic brain injury (TBI) is a devastating disease that commonly causes persistent mental disturbances and cognitive deficits. Although studies indicate that oxidative stress and functional deficits occurring after TBI are interrelated events, the knowledge of the mechanisms underlying the development of such cognitive deficits has been limited. Thus, in the present study, we investigated the effect of fluid percussion brain injury (FPI) on a spatial learning task and levels of oxidative stress markers, namely, protein carbonylation and thiobarbituric acid-reactive substances (TBARS) and Na+,K+-ATPase activity 1 or 3 months after FPI in rats. Statistical analysis revealed that FPI increased the scape latency and mean number of error in Barnes maze test 1 and 3 months after FPI. We also found that protein carbonylation and TBARS content increased in the parietal cortex 1 and 3 months after FPI. In addition, 3 months after FPI, protein carbonylation levels increased both in ipsilateral and contralateral cortices of FPI animals. Indeed, statistical analysis revealed a decrease in Na+,K+-ATPase activity in the cerebral cortex of 1 month FPI animals. Furthermore, the decrease in enzyme activity found 3 months was larger, when compared with 1 month after FPI. These results suggest that cognitive impairment following TBI may result, at least in part, from increase of two oxidative stress markers, protein carbonylation and TBARS that occurs concomitantly to a decrease in Na+,K+-ATPase activity.

The studies of physiological roles for cellular prion protein (PrP(c)) have focused on possible functions of this protein in the CNS, where it is largely expressed. However, the observation that PrP(c) is expressed also in muscle tissue suggests that the physiological role of PrP(c) might not be limited to the central nervous system. In the present study, we investigated possible functions of PrP(c) in muscle using PrP(c) gene (Prnp) null mice (Prnp(0/0)). For this purpose, we submitted Prnp(0/0) animals to different protocols of exercise, and compared their performance to that of their respective wild-type controls. Prnp(0/0) mice showed an exercise-dependent impairment of locomotor activity. In searching for possible mechanisms associated with the impairment observed, we evaluated mitochondrial respiration (MR) in skeletal or cardiac muscle from these mice during resting or after different intensities of exercise. Baseline MR (states 3 and 4), respiratory control ratio (RCR) and mitochondrial membrane potential (DeltaPsi) were evaluated and were not different in skeletal or cardiac muscle tissue of Prnp(0/0) mice when compared with wild-type animals. We concluded that Prnp(0/0) mice show impairment of swimming capacity, perhaps reflecting impairment of muscular activity under more extreme exercise conditions. In spite of the mitochondrial abnormalities reported in Prnp(0/0) mice, our observation seems not to be related to MR. Our results indicate that further investigations should be conducted in order to improve our knowledge about the function of PrP(c) in muscle physiology and its possible role in several different neuromuscular pathologies.

Although the precise mechanisms underlying the CNS degeneration of patients with glutaryl-CoA dehydrogenase (GCDH) deficiency are still the subject of intense debate, many studies have highlighted that excitotoxicity plays a fundamental role in the neuropathology of this disease, particularly involving the N-methyl-D-aspartate receptor subtype of ionotropic glutamate receptors. Modulation of the glutamatergic system by these compounds involves an inhibition of glutamate uptake into synaptosomes and synaptic vesicles, and a decrease in glutamate binding. Furthermore, glutaric and 3-hydroxyglutaric acids inhibit glutamate decarboxylase, the key enzyme of GABA synthesis, and striatal GABAergic medium-spiny neurons are highly vulnerable to 3-hydroxyglutaric acid-induced neurotoxicity. In conclusion, glutaric acid and 3-hydroxyglutaric acid induce an imbalance in glutamatergic and GABAergic neurotransmission.

In vitro studies suggest that excitotoxic cell damage is an underlying mechanism for the acute striatal damage in glutaryl-CoA dehydrogenase (GCDH) deficiency. It is believed to result from an imbalance of glutamatergic and GABAergic neurotransmission induced by the accumulating organic acids 3-hydroxyglutaric acid (3-OH-GA) and to a lesser extent glutaric acid (GA). Stereotaxic administration of 3-OH-GA and GA into the rat striatum have confirmed these results, but may not truly represent the effect of chronic exposure to these compounds. In an attempt to better understand the pathophysiology of GCDH deficiency in vivo , two animal models have been utilized. A mouse that lacks GCDH activity in all tissues was generated by gene targeting in embryonic stem cells. These animals develop the characteristic biochemical phenotype of the human disease. Pathologically, these mice have a diffuse spongiform myelinopathy similar to that in human patients; however, there is no evidence for acute striatal damage or sensitivity to acute encephalopathy induced by catabolism or inflammatory cytokines. A naturally occurring animal model, the fruit-eating bat Rousettus aegypticus, lacks hepatic and renal GCDH activity, but retains cerebral enzyme activity. Like the mouse, these bats develop the characteristic biochemical phenotype of glutaryl-CoA dehydrogenase deficiency, but lack overt neurological symptoms such as dystonia. It is not known whether they also develop the spongiform myelinopathy seen in the Gcdh-deficient mice. Otherwise, these constellations would suggest that cerebral GCDH deficiency is responsible for the development of neuronal damage. The lack of striatal damage in these two rodent models may also be related to species differences. However, they also highlight our lack of a comprehensive understanding of additional factors that might modulate the susceptibiliy of neurons to accumulating 3-OH-GA and GA in GCDH deficiency. Unravelling these mechanisms may be the key to understanding the pathophysiology of this unique disease and to the development of neuroprotective strategies.

Undernutrition of dams and pups disrupts the retrieval efficiency of mothers. However, if the mothers are assessed in their home cages, they spend more time with their litters. In the present study the effect of test conditions on pup retrieval behavior of mothers receiving a 25% (well-nourished group) and 8% casein diet (undernourished group) was examined. In agreement with previous studies, undernourished mothers spent more time with their litters than well-nourished dams as lactation proceeded. Pup retrieval behavior varied with test conditions. In the first experiment, the maternal behavior of dams was assessed by the standard procedure (pups were separated from their mother and scattered over the floor of the home cage). The mother was then returned and the number of retrieved pups was recorded. From day 3 to 8, the retrieval efficiency of undernourished dams decreased, while the retrieval efficiency of well-nourished mothers did not vary. In the second experiment, mothers were subjected to a single retrieval test (on day 9 of lactation) using the procedure described for experiment 1. No difference between well-nourished and undernourished mothers was observed. In the third experiment, seven-day-old pups were separated from the mothers and returned individually to a clean home cage. Dietary treatment did not affect the retrieval efficiency. However, undernourished dams reconstructed the nest more slowly than did well-nourished dams. Taken together, these results suggest that pup retrieval behavior of the undernourished mother is not impaired by dietary restriction when the maternal environment is disturbed minimally.

Glutaryl-CoA dehydrogenase deficiency is an inherited neurometabolic disease complicated by precipitation of acute encephalopathic crises during a vulnerable period of brain development. These crises result in bilateral striatal damage and subsequently a dystonic dyskinetic movement disorder. In previous in vitro studies neuronal damage in this disease has been linked to an excitotoxic mechanism mediated in particular by one of the accumulating metabolites, 3-hydroxyglutaric acid. However, nothing is known about the in vivo effects of this organic acid. In the present study, we used a stereotaxic intrastriatal injection technique to investigate the behavioral and neurotoxic effects of 3-hydroxyglutaric acid exposure in rats. Here, we report that 3-hydroxyglutaric acid induced an increase in convulsion frequency and duration as determined by open field measurement. Nissl-stained coronal sections from treated rats revealed a pale lesion in the striatum following 3-hydroxyglutaric acid exposure. N-methyl-D-aspartate (NMDA) receptor blockade by MK-801 and stimulation of GABA(A) receptors by muscimol prevented the induction of convulsions and striatal damage by 3-hydroxyglutaric acid, whereas blockade of non-NMDA receptors by 6,7-dinitroquinoxaline-2,3-dione (DNQX) was not protective. We conclude that 3-hydroxyglutaric acid induces convulsions and striatal damage via initiation of an imbalance in the excitatory glutamatergic and the inhibitory GABAergic neurotransmission, resulting in an enhanced excitatory input in striatal neurons. These results support the hypothesis of NMDA receptor-mediated excitotoxic cell damage in glutaryl-CoA dehydrogenase deficiency and represent the basis for the development of new neuroprotective treatment strategies.

Neurological dysfunction is common in patients with maple syrup urine disease (MSUD). However, the mechanisms underlying the pathophysiology of this disorder are poorly known. In the present study we investigated the effect of intrastriatal administration of the alpha-keto acids accumulating in MSUD on the behavior of adult rats. After cannula placing, rats received unilateral intrastriatal injections of alpha-ketoisocaproic acid (KIC, 8 micromol), alpha-ketoisovaleric acid (KIV, 8 micromol), alpha-keto-beta-methylvaleric acid (KMV, 6 micromol) or NaCl. KIV elicited clonic convulsions in a dose-response manner, whereas KIC and KMV did not induce seizure-like behavior. Convulsions provoked by KIV were prevented by intrastriatal preadministration of muscimol (46 pmol) and MK-801 (3 nmol), but not by the preadministration of DNQX (8 nmol). These results indicate that among the keto acids that accumulate in MSUD, KIV is the only metabolite capable of causing convulsions in the present animal model and indicates that KIV is an important excitatory metabolite. Moreover, the participation of GABAergic and glutamatergic NMDA mechanisms in the KIV-induced convulsant behavior is suggested, since KIV-induced convulsions are attenuated by muscimol and MK-801. The authors suggest that KIV may play an important role in the convulsions observed in MSUD, and highlight its relevance to the understanding of the pathophysiology of the neurological dysfunction of MSUD patients.

The antinociceptive action of a novel pyrazole-derived compound, 3-methyl-5-hydroxy-5-trichloromethyl-1H-1-pyrazolcarboxyamide (MPCA) was evaluated using the formalin and tail-immersion tests in mice. Anti-inflammatory activity was assessed by paw plethysmometry in adult rats using the carrageenin-induced paw edema test. Subcutaneous administration of MPCA (22, 66, and 200 mg/kg) induced a dose-dependent decrease in the time spent licking during the neurogenic and inflammatory phases of the formalin test, and preadministration of naloxone (1 mg/kg, sc) did not prevent MPCA-induced (200 mg/kg, sc) antinociception. Naloxone decreased the spontaneous locomotor activity of mice, while MPCA had no effect on locomotion. In contrast, administration of the opioid antagonist caused a significant increase in the locomotor behavior of mice previously injected with MPCA. MPCA was devoid of antinociceptive action by the tail-immersion test and of anti-inflammatory activity. Moreover, MPCA had no effect on the motor performance of mice in the rotarod test. These results suggest that MPCA induces antinociception in the neurogenic and inflammatory phases of the formalin test, an effect that does not involve opioid receptors.

The involvement of glutamatergic and GABAergic mechanisms in the behavioral effects induced by the intrastriatal injection of 5-aminolevulinic acid (ALA) (1-8 mgr;mol/2 mgr;l), a metabolite that accumulates in porphyrias, was evaluated. ALA administration to adult female rats increased locomotor activity, induced clonic convulsions and elicited dose-dependent body asymmetry assessed by the elevated body swing test. ALA-induced convulsions were prevented by intrastriatal preadministration of the glutamate antagonists, 6, 7-dinitroquinoxaline-2,3-dione (8 nmol/0.5 microl) or dizocilpine (2. 5 nmol/0.5 microl), but not by the GABA agonist, muscimol (46 pmol/0. 5 microl). Body asymmetry was prevented only by 6, 7-dinitroquinoxaline-2,3-dione pretreatment. A higher dose of muscimol (92 pmol/0.5 microl) prevented both ALA-induced convulsions and body asymmetry. However, this dose of muscimol induced motor biases, which make difficult to ascertain the involvement of GABA(A) receptors in ALA-induced behavioral effects. This study suggests that glutamatergic mechanisms underlie the ALA-induced convulsions and body asymmetry. The present results may be of value in understanding the physiopathology of the neurological dysfunction occurring in acute porphyrias.

The effects of chronic administration of alpha-tocopherol or melatonin, or acute ascorbic acid administration on the convulsant action of methylmalonic acid (MMA) were investigated in adult male rats. Animals were chronically injected with alpha-tocopherol (40 mg kg(-1), i.p.), melatonin (5 mg kg(-1), i.p.) or vehicle for 7 days. Buffered MMA (6 micromol/2 microl) or NaCl (9 micromol/2 microl) was injected intrastriatally and the animals were observed for the appearance of clonic or tonic-clonic convulsions and rotational behavior. Ascorbic acid (100 mg kg(-1), s.c.) was administered 30 min before MMA injection. Alpha-tocopherol and ascorbic acid pretreatment decreased the duration of the convulsive episodes and the rotational behavior elicited by MMA. This study provides evidence that free radical generation may participate in the convulsant effects of methylmalonic acid.

The effect of intrastriatal administration of glutaric acid (GTR), a metabolite that accumulates in glutaric acidemia type I (GA-I), on the behavior of adult male rats was investigated. After cannula placing, rats received unilateral intrastriatal injections of GTR buffered to pH 7.4 with NaOH or NaCl. GTR induced rotational behavior toward the contralateral side of injection and clonic convulsions in a dose-dependent manner. Rotational behavior was prevented by intrastriatal preadministration of DNQX and muscimol, but not by the preadministration of MK-801. Convulsions were prevented by intrastriatal preinjection of muscimol. This study provides evidence for a participation of glutamatergic non-NMDA and GABAergic mechanisms in the GTR-induced behavioral alterations. These findings may be of value in understanding the physiopathology of the neurological dysfunction in glutaric acidemia.

Guanidino compounds play specific physiological and pathological roles in the central nervous system. We investigated the effect of an intrahippocampal infusion of GMP (a guanidino compound) administered immediately post-training on the inhibitory avoidance learning paradigm in rats. Bilateral intrahippocampal micro-injection of GMP (0-30 nmol) caused a dose-dependent increase in test step-down latencies which was completely reversed by intrahippocampal co-administration of muscimol or baclofen (GABA agonists) or preadministration (15 min pre-training, i.p.) of MK-801 (an NMDA antagonist). These results provide evidence for a participation of GABA and NMDA receptors in the GMP-induced increase in the test step-down latencies.

The effects of methylmalonic (MMA) and propionic acid (PPA), metabolites that accumulate in methylmalonic and propionic acidemia respectively, on [3H]glutamate binding, adenylate cyclase activity and [U-14C]acetate incorporation into lipids were investigated in rat cerebral cortex. Neither acid effected [3H]glutamate binding, regardless of the presence of sodium in the incubation medium. Also, the acids had no effect on basal or GMP-PNP-stimulated adenylate cyclase activity. These results suggest that MMA and PPA do not interact with glutamate binding sites and have no effect on basal or guanine nucleotide-stimulated adenylate cyclase activity. In contrast, [U-14C]acetate incorporation into brain lipids was significantly blocked by both acids, the effects being more pronounced with PPA, indicating an inhibition of brain lipid biosynthesis caused by MMA and PPA. These results may explain at least in part the hypomyelinization and/or demyelinization characteristic of patients affected by methylmalonic acidemia and propionic acidemia.