Streptozotocin-induced mechanical hypernociception is not dependent on hyperglycemia

Since streptozotocin (STZ)-induced diabetes is a widely used model of painful diabetic neuropathy, the aim of the present study was to design a rational protocol to investigate whether the development of mechanical hypernociception induced by STZ depends exclusively on hyperglycemia. Male Wistar rats (180-200 g; N = 6-7 per group) received a single intravenous injection of STZ at three different doses (10, 20, or 40 mg/kg). Only the higher dose (40 mg/kg) induced a significant increase in blood glucose levels, glucose tolerance and deficiency in weight gain. However, all STZ-treated rats (hyperglycemic or not) developed persistent (for at least 20 days) and indistinguishable bilateral mechanical hypernociception that was not prevented by daily insulin treatment (2 IU twice a day, sc). Systemic morphine (2 mg/kg) but not local (intraplantar) morphine treatment (8 µg/paw) significantly inhibited the mechanical hypernociception induced by STZ (10 or 40 mg/kg). In addition, intraplantar injection of STZ at doses that did not cause hyperglycemia (30, 100 or 300 µg/paw) induced ipsilateral mechanical hypernociception for at least 8 h that was inhibited by local and systemic morphine treatment (8 µg/paw or 2 mg/kg, respectively), but not by dexamethasone (1 mg/kg, sc). The results of this study demonstrate that systemic administration of STZ induces mechanical hypernociception that does not depend on hyperglycemia and intraplantar STZ induces mechanical sensitization of primary sensory neurons responsive to local morphine treatment.

Effect of blood components, abdominal distension, and ecdysone therapy on the ultrastructural organization of posterior midgut epithelial cells and perimicrovillar membranes in Rhodnius prolixus

The effects of blood components, nerve-cord severance, and ecdysone therapy on the posterior midgut epithelial cells of 5th-instar Rhodnius prolixus nymphs 10 days after feeding were analyzed by transmission electron microscopy. Cutting the nerve-cord of the blood-fed insects partially reduced the development of microvilli and perimicrovillar membranes (PMM), and produced large vacuoles and small electrondense granules; insects fed on Ringer's saline diet exhibited well developed microvilli and low PMM production; swolled rough endoplasmatic reticulum and electrondense granules; Ringer's saline meal with ecdysone led to PMM development, glycogen particles, and several mitochondria in the cytoplasm; epithelial cells of the insects fed on Ringer's saline meal whose nerve-cord was severed showed heterogeneously distributed microvilli with reduced PMM production and a great quantity of mitochondria and glycogen in the cytoplasm; well developed microvilli and PMM were observed in nerve-cord severed insects fed on Ringer's saline meal with ecdysone; Ringer's saline diet containing hemoglobin recovered the release of PMM; and insects fed on human plasma showed slightly reduced PMM production, although the addition of ecdysone in the plasma led to a normal midgut ultrastructural organization. We suggest that the full development of microvilli and PMM in the epithelial cells depends on the abdominal distension in addition to ingestion of hemoglobin, and the release of ecdysone.

Influência da privaçäo de sono sobre os efeitos de drogas dopaminérgicas em voluntários / The influence of sleep deprivation on dopaminergic drugs effects in volunteers

Avaliam-se os efeitos de uma noite de privaçäo de sono em 40 voluntários sadios e sua interaçäo com drogas dotadas de atividade dopaminérgica: metanfetamina, nomifensina e bromocriptina e também placebo, como controle. Verifica-se que a privaçäo de sono, por si só, näo alterou o tempo de execuçäo e o número de erros nos testes de atençäo utilizados, assim como näo modificou o desempenho em um teste de performance motora. De modo geral, as drogas utilizadas näo interferiram nos resultados dos testes acima citados. A metanfetamina fez reverter os escores de "sedaçäo" conseqüentes à privaçäo de sono (na escala para estados subjetivos, de Norris); o mesmo näo aconteceu para a nomifensina e a bromocriptina

Escalas de avaliacao. / Rating scales

Descrevem-se brevemente as vantagens e desvantagens das escalas de auto-avaliacao e de avaliacao por um observador treinado. Traduziu-se para o portugues a BPRS e foi feito um estudo de confiabilidade e validacao em nosso meio. Enumeram-se as dificuldades encontradas creditando-as ao estagio de desenvolvimento de pesquisas no Brasil