Browsing by Author "Santos, Tasso Moraes"

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    Dose-dependent effect of carbamazepine on weanling rats submitted to subcutaneous injection of tityustoxin.
    (2008) Guidine, Patrícia Alves Maia; Assumpção, Gioconda; Santos, Tasso Moraes; Massensini, André Ricardo; Chianca Júnior, Deoclécio Alves; Moraes, Márcio Flávio Dutra
    The scorpion envenoming syndrome is a serious public health matter in Brazil. The most severe cases occur during childhood and elderly. Previous results from our laboratory suggest that the effects of scorpion toxins on the central nervous system play a major role on the lethality induced by scorpion envenoming. The aim of this work is to evaluate the therapeutic potential of carbamazepine (CBZ) injected i.p. 90 min before s.c. tityustoxin (TsTX) injection in weanling rats. Rats were divided into six experimental groups according to s.c. injection (saline or TsTX) and i.p. treatment (vehicle or CBZ 12, 50 and 100 mg/kg): Sal/Veh group (n = 4); Sal/CBZ100 (n = 4); TsTX/CBZ12 (n = 6); TsTX/CBZ50 (n = 8); TsTX/CBZ100 (n = 8) and, at last, TsTX/Veh (n = 8). The dose of TsTX was the same for all groups: 6.0 mg/kg, twice the DL50 for weanling rats. Video images were recorded until death or for a maximum period of 240 min. Lungs were excised and weighed to evaluate edema. The results showed that CBZ (12, 50 and 100 mg/kg) was able to increase the survival rate and latency-to-death of the rats. Only the group treated with 100 mg/kg of CBZ had a decrease in the pulmonary edema. The known effect of CBZ reducing neuronal excitability most likely protected the neural substrates targeted by TsTX. Although treatment was performed before TsTX inoculation, the results are promising regarding CBZ as a therapeutic coadjuvant in the treatment of scorpion poisoning. The pharmacokinetics of CBZ can be very much improved by either changing the form of administration or encapsulating the drug in order to enhance solubility.
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    Malnutrition alters the cardiovascular responses induced by central injection of tityustoxin in Fischer rats.
    (2013) Silva, Fernanda Cacilda dos Santos; Guidine, Patrícia Alves Maia; Ribeiro, Mara Fernandes; Fernandes, Luciano Gonçalves; Xavier, Carlos Henrique; Menezes, Rodrigo Cunha Alvim de; Silva, Marcelo Eustáquio; Santos, Tasso Moraes; Moraes, Márcio Flávio Dutra; Chianca Júnior, Deoclécio Alves
    Scorpion envenoming and malnutrition are considered two important public health problems in Brazil, involving mainly children. Both these conditions are more common among the economically stratified lower income portion of the population, thus suggesting that these factors should be analyzed concomitantly. It is known that cardiorespiratory manifestations, as cardiac arrhythmias, arterial hypertension and hypotension, pulmonary edema and circulatory failure are the main “causa mortis” of scorpion envenomation. Additionally, there are evidences in the literature that deficiencies in dietary intake endanger the CNS and modify the cardiovascular homeostasis. Then, the objective of this work is to evaluate the protein malnourished effect on cardiovascular responses induced by tityustoxin (TsTX, an a-type toxin extracted from the Tityus serrulatus scorpion venom). Fischer rats (n ¼ 20) were injected i.c.v. with TsTX and divided in control and malnorished groups, which were, respectively, submitted to a control and a low-protein diet. Arterial pressure recordings were done until death of the animals. Although both groups presented an increased mean arterial pressure after TsTX injection, this increase was smaller and delayed in malnourished rats, when compared to control rats. In addition, heart rate increased only in rats from the control group. Finally, malnourished rats had an increase in survival time (9:9/13.5
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    Malnutrition during central nervous system growth and development impairs permanently the subcortical auditory pathway.
    (2013) Penido, Alexandre Batista; Rezende, Gustavo Henrique de Souza; Abreu, Renata Viana; Oliveira, Antônio Carlos Pinheiro de; Guidine, Patrícia Alves Maia; Pereira, Grace Schenatto; Chianca Júnior, Deoclécio Alves; Massensini, André Ricardo; Santos, Tasso Moraes; Moraes, Márcio Flávio Dutra
    The brain that grows and develops under the continued influence of malnutrition presents permanent impairment on functioning and neurotransmitter release. The aim of this study was to investigate the chronic effects of neonatal food restriction on neurochemical and neurodynamical aspects within the primary auditory sensory pathway. Our working hypothesis is that neonatal malnutrition may affect the flow of primary sensory information both at a neurochemical and neurodynamical level. To test this hypothesis, three groups of rats were assigned, from birth to 370 days of life, to the following dietary scheme: a wellnourished (WN) group fed ad libitum lab chow diet; an undernourished (UN) group fed 60% of diet consumed by WN group; and a rehabilitated group, undergoing same dietary restriction as undernourished until 42 days of age and thereafter fed ad libitum until the end of the experiment. At 370 days of age, the animals were submitted to brainstem auditory-evoked potentials (BAEPs) recordings and sacrificed for neurochemical evaluation of glutamate release. Undernutrition decreased glutamate release in the cortex, hippocampus, midbrain and brainstem, and significantly increased the latency of BAEP wave V. In addition; the re-establishment of the dietary conditions was not sufficient to reverse the neurochemical and electrophysiological alterations observed in the UN group. Taken altogether, our results suggest that malnutrition imposed at a critical development period caused an irreversible effect within the auditory primary sensory pathway.
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    The role of dorsomedial hypotalamus ionotropic glutamate receptors in the hypertensive and tachycardic responses evoked by Tityustoxin intracerebroventricular injection.
    (2015) Silva, Fernanda Cacilda dos Santos; Guidine, Patrícia Alves Maia; Machado, Natália Lima Santos; Xavier, Carlos Henrique; Menezes, Rodrigo Cunha Alvim de; Santos, Tasso Moraes; Moraes, Márcio Flávio Dutra; Chianca Júnior, Deoclécio Alves
    The scorpion envenoming syndrome is an important worldwide public health problem due to its high incidence and potential severity of symptoms. Some studies address the high sensitivity of the central nervous system to this toxin action. It is known that cardiorespiratory manifestations involve the activation of the autonomic nervous system. However, the origin of this modulation remains unclear. Considering the important participation of the dorsomedial hypotalamus (DMH) in the cardiovascular responses during emergencial situations, the aim of this work is to investigate the involvement of the DMH on cardiovascular responses induced by intracerebroventricular (icv) injection of Tityustoxin (TsTX, a a-type toxin extracted from the Tityus serrulatus scorpion venom). Urethane-anaesthetized male Wistar rats (n = 30) were treated with PBS, muscimol or ionotropic glutamate receptor antagonists, bilaterally in DMH and later, with an icv injection of TsTX, or treated only with PBS in both regions. TsTX evoked a marked increase in mean arterial pressure and heart rate in all control rats. Interestingly, injection of muscimol, a GABAA receptor agonist, did not change the pressor and tachycardic responses evoked by TsTX. Remarkably, the injection ionotropic glutamate receptors antagonists in DMH abolished the pressor and the tachycardic response evoked by TsTX. Our data suggest that the central circuit recruited by TsTX, whose activation results in an array of physiological and behavioral alterations, depend on the activation of DMH ionotropic glutamate receptors. Moreover, our data provide new insights on the central mechanisms involved in the development of symptoms in the severe scorpion envenomation syndrome