Unmasking of latent synaptic connections in the cortex of the rat, elicited by a facial nerve transection

Peripheral nerve injury elicits plastic changes in the cortex, resulting in reorganization of the somatotopic representation maps. These processes begin within minutes after nerve injury, and last for weeks. Although the mechanisms leading to these plastic changes are not known in a detail, a number of results suggest that the key element in the starting of these processes is a decrease in the function of the cortical GABAergic system, which allows the unmasking of pre-existing but normally silent synapses. The somatosensory and motor cortices of the rat brain are involved in strong and mutual interaction. This study of the early changes induced in this relationship by unilateral facial nerve transection (N7x) revealed that the disinhibition of associational and commissural connections caused by N7x allowed the appearance and enhancement of potentials in the motor cortices on both sides, evoked by right-side trigeminal stimulation, though these responses were strictly lateralized in normal animals. In response to the juxtacellular application of GABA and muscimol, reversal was observed in a small population of neurons (3 out of 84) tested with microelectrode recordings and pressure microinjections. These results suggest that a peripheral nerve injury (N7x) rapidly induces GABA(A) receptor-dependent disinhibition in the cortex

Bioecologia de ácaros da cultura da soja e influência da transgenia

As cultivares geneticamente modificadas alteram o manejo da cultura da soja (Glycine max L. Merril: Fabaceae). O aumento no uso de agroquímicos decorrentes do plantio de transgênicos é exemplo de prática que coloca em cheque o futuro dos solos e biodiversidade. Dentre as espécies de ácaros fitófagos que causam danos à cultura destacam-se Mononychellus planki McGregor e Tetranychus ludeni Zacher. O Caliothrips phaseoli Hood (Thysanoptera: Thripidae) também pode atingir nível de praga nestas plantações. Estes ácaros e inseto se alimentam das folhas da soja causando clorose e perda na produção de grãos. Neoseiulus californicus McGregor (Acari: Phytoseiidae) é utilizado no controle de populações de ácaros praga em culturas agrícolas, porém não são conhecidos seus parâmetros biológicos quando alimentados com M. planki e C. phaseoli. O objetivo deste trabalho foi conhecer os parâmetros biológicos de N. californicus quando alimentado de M. planki, T. ludeni e C. phaseoli sobre folhas de soja nas condições de laboratório e avaliar a influência da transgenia sobre o ciclo biológico de T. ludeni. Os ácaros foram coletados em plantações de soja da cidade de Lajeado - RS. No estudo com o predador foram utilizados ovos individualizados em arenas com M. planki, T. ludeni e C. phaseoli como alimento. Foram realizados estudos observando o desenvolvimento e reprodução de T. ludeni sobre soja convencional Fundacef 44, RR Nideira 5909, resistente ao glifosato e BT Rota 54, resistente ao glifosato e ao ataque de lagartas. A viabilidade total de ovo-adulto para o predador se alimentando de T. ludeni, M. planki e C. phaseoli foram 96.66%, 76.67% e 53.33%, respectivamente. O predador não completou seu desenvolvimento sendo alimentado com C. phaseoli, pois não houve oviposição. A capacidade de aumentar em número (rm) foi de 14.46 fêmeas/fêmeas/dias com T. ludeni e 13.39 com M. Planki. A transgenia na soja não demonstrou interferir na biologia de T. ludeni. Esta espécie pode estar em fase de adaptação à cultura, pois teve parâmetros de reprodução menores que o esperado. Os resultados poderão subsidiar trabalhos de controle biológico na soja e outras culturas que apresentarem as mesmas espécies herbívoras em nível de praga. Também contribuir para as discussões acerca do uso de transgênicos.The genetically modified cultivars change management culture of soybean, Glycine max L. Merri: Fabaceae. The dramatic increase in the use of agrochemicals arising from the planting of GM crops is practical example that puts in check the future of soil and agricultural biodiversity. Among the species of phytophagous mites that cause damage to culture, include Mononychellus planki McGregor, Tetranychus ludeni Zacher and Tetranychus urticae Koch. Caliothrips phaseoli Hood (Thysanoptera: Thripidae) is a species of insect that can also reach plague level in these plantations. The species lay their eggs on the leaves of soybeans and feed her causing chlorosis and loss in grain production. Neoseiulus californicus McGregor is already used in the control of pest mites in different cultures, but are not known their biological parameters feeding on M. planki and C. phaseoli. The aim of this study was to evaluate the biological parameters of N. californicus feeding on M. planki, T. ludeni and C. phaseoli in soybean leaves and the influence of transgenic on an herbivore, T. ludeni. The mites were collected in soy plantations in the city of Lajeado-RS. In the study with the predator, individualized eggs were used in arenas with M. planki, T. ludeni and C. phaseoli as food. Noted the development and reproduction of t. ludeni in different soybean cultivars, these being, conventional soybeans Fundacef 44, and of two types of genetically modified soybeans, RR Nideira 5909 glyphosate resistance e BT Rota 54 glyphosate resistant and the attack of caterpillar. The total egg viability-adult for the predator feeding on T. ludeni, M. planki and C. phaseoli was 96.66% respectively, 76.67% and 53.33%. The predator has not completed its development being fed with C. phaseoli, do you ovipositou. The ability to increase in number (rm) was 14.46 with T. ludeni and 13.39 female/female/day with M. planki. The varieties in soybeans has not shown to interfere with the biology of T. ludeni. Is species may be in the process of adaptation to the culture, as it had playback parameters smaller than expected. The results may subsidize works of biological control in soybeans and other crops which submit same herbivore species pest level. Also, contribute to discussions about the use of transgenic crops.CAPE

Weak if any effect of estrogen on spatial memory in rats

In a number of species, males appear to have spatial abilities that are superior to those of females. The favored explanation for this cognitive difference is hormonal: higher testosterone levels in males than in females. An alternative explanation focuses on the role of varying levels of estrogens in females during the estrus cycle; females perform as well as males on days of low estrogen, but more poorly on days of high estrogen. Other investigators have reported that estrogens improve both types of memory processes, which depend on the striatal (nonspatial navigation) and hippocampal (spatial) memory systems. Additionally, estrogens have been found to protect the working memory. These contradictory results initiated the present study, in which ovariectomized female rats were trained to escape in a Morris water maze. The daily trials were preceded by estradiol application in low doses (Experiment I) or in higher doses (Experiment II). In Experiment I, no differences at all were found between the latencies of the treated and control groups to reach a submerged platform in a Morris water maze. In Experiment II, however, the animals treated with the higher dose of estradiol showed a small deficit in the acquisition of the Morris water maze task. This study indicates that estradiol at around the physiological level has no effect on spatial learning and memory functions