Seroepidemiological evidence for Taenia solium taeniasis/cysticercosis in three Venezuelan rural communities.

Taenia solium is the most common parasite infection of the brain, causing neurocysticercosis and typically found in rural communities with free-ranging pigs. Identification of transmission in rural areas is essential for its control. Risk factors and transmission of the parasite were evaluated in three rural Venezuelan communities (Valle del Rio and Potrero Largo, Cojedes state; and Palmarito, Portuguesa state) by a questionnaire (112 households) and coprological (492 samples) and serological (433 human and 230 porcine sera) analysis, respectively. Typical risk factors were found in all three communities: free-foraging pig husbandry, deficient sanitary conditions, high open defecation and ignorance of the parasite life cycle. Coprological examinations revealed a high level of soil-transmitted parasites. Importantly, two T. solium adult worm carriers were identified in each of the three communities. Anti-metacestode antibodies and the HP10 secreted metacestode glycoprotein were detected at significant levels in human and porcine sera in Valle del Rio, Potrero Largo and Palmarito. In conclusion, these communities may be considered to be endemic for taeniasis/cysticercosis, and the instigation of an appropriate control programme is recommended.

Age-dependent effects of kappa-opioid receptor stimulation on cocaine-induced stereotyped behaviors and dopamine overflow in the caudate-putamen: an in vivo microdialysis study.

kappa-Opioid receptor stimulation attenuates psychostimulant-induced increases in extracellular dopamine in the caudate-putamen (CPu) and nucleus accumbens of adult rats, while reducing cocaine-induced locomotor activity and stereotyped behaviors. Because kappa-opioid receptor agonists (e.g., U50,488 or U69,593) often affect the behavior of preweanling rats in a paradoxical manner, the purpose of the present study was to determine whether kappa-opioid receptor stimulation differentially affects dopaminergic functioning in the CPu depending on age. In vivo microdialysis was used to determine whether U50,488 (5 mg/kg) attenuates cocaine-induced dopamine overflow in the dorsal CPu on postnatal day (PD) 17 and PD 85. In the microinjection experiment, cocaine-induced stereotyped behaviors were assessed in adult and preweanling rats after bilateral infusions of vehicle or U50,488 (1.6 or 6.4 microg per side) into the CPu. Results showed that U50,488 attenuated the cocaine-induced increases in CPu dopamine overflow on PD 85, while the same dose of U50,488 did not alter dopamine dialysate levels on PD 17. Cocaine also increased stereotyped behaviors (repetitive motor movements, behavioral intensity scores, and discrete behaviors) at both ages, but adult rats appeared to exhibit more intense stereotypic responses than the younger animals. Consistent with the microdialysis findings, bilateral infusions of U50,488 into the dorsal CPu decreased the cocaine-induced stereotypies of adult rats, while leaving the behaviors of preweanling rats unaffected. These results suggest that the neural mechanisms underlying kappa-opioid/dopamine interactions in the CPu are not fully mature during the preweanling period. This lack of functional maturity may explain why kappa-opioid receptor agonists frequently induce different behavioral effects in young and adult rats.

Postnatal manganese exposure alters dopamine transporter function in adult rats: Potential impact on nonassociative and associative processes.

In the present study, we examined whether exposing rats to a high-dose regimen of manganese chloride (Mn) during the postnatal period would depress presynaptic dopamine functioning and alter nonassociative and associative behaviors. To this end, rats were given oral supplements of Mn (750 microg/day) on postnatal days (PD) 1-21. On PD 90, dopamine transporter (DAT) immunoreactivity and [3H]dopamine uptake were assayed in the striatum and nucleus accumbens, while in vivo microdialysis was used to measure dopamine efflux in the same brain regions. The effects of postnatal Mn exposure on nigrostriatal functioning were evaluated by assessing rotorod performance and amphetamine-induced stereotypy in adulthood. In terms of associative processes, both cocaine-induced conditioned place preference (CPP) and sucrose-reinforced operant responding were examined. Results showed that postnatal Mn exposure caused persistent declines in DAT protein expression and [3H]dopamine uptake in the striatum and nucleus accumbens, as well as long-term reductions in striatal dopamine efflux. Rotorod performance did not differ according to exposure condition, however Mn-exposed rats did exhibit substantially more amphetamine-induced stereotypy than vehicle controls. Mn exposure did not alter performance on any aspect of the CPP task (preference, extinction, or reinstatement testing), nor did Mn affect progressive ratio responding (a measure of motivation). Interestingly, acquisition of a fixed ratio task was impaired in Mn-exposed rats, suggesting a deficit in procedural learning. In sum, these results indicate that postnatal Mn exposure causes persistent declines in various indices of presynaptic dopaminergic functioning. Mn-induced alterations in striatal functioning may have long-term impact on associative and nonassociative behavior.

Effects of aripiprazole and terguride on dopamine synthesis in the dorsal striatum and medial prefrontal cortex of preweanling rats.

The purpose of this study was to determine whether aripiprazole, a D2-like partial agonist increasingly prescribed to children, alters DA synthesis via actions at autoreceptors in the dorsal striatum and medial prefrontal cortex (mPFC) of preweanling rats. The ability of dopaminergic agents to alter DOPA accumulation in the striatum and mPFC was measured after NSD-1015 on postnatal day (PD) 20. Dopaminergic tone was manipulated by administering reserpine, gamma-butyrolactone (GBL), or through amphetamine withdrawal. Results showed that the partial agonists aripiprazole and terguride increased striatal DOPA accumulation under normosensitive conditions, but decreased DOPA accumulation in states of low dopaminergic tone. A different pattern of results was observed in the mPFC, because terguride and haloperidol, but not aripiprazole, increased DOPA accumulation under normosensitive conditions. In conclusion, the present data show that aripiprazole affects striatal synthesis modulating autoreceptors in an adult-typical manner during the late preweanling period. Unlike in adult rats, however, the mPFC of preweanling rats appears to contain transitory synthesis modulating autoreceptors that are sensitive to drug manipulation.

Vertical stratification and development aspects of phlebotomine sand flies (Diptera: Psychodidae) in an area of Atlantic Forest tree species in a metropolitan region in northeastern Brazil.

In the state of Rio Grande do Norte in northeast Brazil, cases of visceral leishmaniasis (VL) occur mainly in the periurban areas of the city of Natal. Lutzomyia longipalpis Lutz & Neiva 1912 (Diptera: Psychodidae), a vector of Leishmania chagasi (Protozoa: Trypanosomatidae) to humans, is found throughout the state. Flora and fauna influence the distribution of sand fly species, whose horizontal or vertical stratification can be used as a parameter for identifying potential vectors, considering the presence of vertebrate hosts in the area. The purpose of this study was to obtain information about the vertical stratification of phlebotomine sand flies in an endemic area of leishmaniasis in Rio Grande do Norte, and associate it with the presence of other animals in the peridomiciliary environment as well as to analyze, under laboratory conditions, aspects of L. longipalpis reproduction in wild females. The sand flies were captured with light traps hung at different heights in species of Atlantic Forest trees and in a peridomiciliary environment in animal shelters. The traps were placed between 17:30 and 6:00 of the following day, in a peridomiciliary and extradomiciliary area of a forest fragment in both dry and rainy months. In the extradomiciliary environment, the traps were installed at 1, 3 and 5 m above the ground. The biological cycle of L. longipalpis was followed from the eggs of 200 wild females. Specimens of L. lenti, L. walkeri, and L. migonei were captured. The comparison and statistical analysis showed that L. longipalpis is more abundant at a height of 3 m and L. evandroi at 1 m. In the animal shelters (chickens, horses, and armadillos), we captured mainly specimens of L. longipalpis and L. evandroi. The duration of the biological cycle of L. longipalpis was approximately 38 days at a temperature of 28 degrees C.

GABA imbalance in squirrel monkey after unilateral vestibular end-organ ablation.

Using an antibody against GABA conjugated to bovine serum albumin, GABA-like immunoreactivity was measured in vestibular nuclei and adjacent structures in normal and unilaterally vestibular-deafferentiated squirrel monkeys. Three and 6 days after end-organ ablation, GABA levels increased in lateral vestibular nucleus (LVN) on the side ipsilateral to the lesion, while GABA decreased in LVN on the side contralateral to the lesion. GABA levels in ventral cochlear nucleus or inferior cerebellar peduncle did not differ from normal in either case.

GABA-like immunoreactivity in the squirrel monkey organ of Corti.

The distribution of gamma-aminobutyric acid (GABA)-like immunoreactivity in the squirrel monkey organ of Corti was determined using an antiserum against GABA conjugated to bovine serum albumin. Immunoreactive labeling was seen in the region of the inner spiral bundle, the synaptic region below inner hair cells, in terminals contacting the basal part of outer hair cells, and in tunnel spiral fibers. Examples of each of these immunoreactive components could be observed in all cochlear turns. In the region of inner hair cells, immunoreactive labeling took the form of numerous small puncta randomly distributed below the base of the cells. In the region of outer hair cells, large globular immunoreactive structures reminiscent of terminal endings at the subnuclear level were observed. Since similar structures were seen at the base of outer hair cells in other cochleas processed for AChE, we conclude that GABA-like immunoreactivity was contained in efferent terminals which synapse on outer hair cells. These results strengthen previous evidence for the presence of GABA in the olivocochlear system of the mammalian cochlea.

Localization of GABA immunoreactivity in the auditory brainstem of guinea pigs.

Using an antibody against GABA, neurons within the guinea pig hindbrain, midbrain and forebrain auditory nuclei were identified which demonstrate GABA-like immunoreactivity. GABA-positive cells were localized in the cochlear nucleus, superior olivary complex, lateral lemniscus, inferior colliculus, and medial geniculate body. GABA-positive terminals could be seen surrounding globular and spherical cells in ventral cochlear nucleus and principal cells in medial nucleus of the trapezoid body. In addition, numerous positive, punctate terminals appeared throughout the hindbrain auditory nuclei and, although fewer in number, in midbrain and forebrain auditory nuclei.

The inability of squirrel monkeys to localize sound after unilateral ablation of auditory cortex.

The ability of squirrel monkeys to localize brief sounds was tested before and after unilateral ablation of auditory cortex. Results indicated that, after unilateral ablation of auditory cortex, monkeys could no longer localize sound accurately in the hemifield opposite to the side of lesion. These data demonstrate that contralaterally-directed functioning of auditory cortex occurs in primates.