Effects of prenatal exposure to Tityus bahiensis scorpion venom on rat offspring development.

Scorpion envenoming is a public health problem. In Brazil, the scorpion Tityus serrulatus is considered the most dangerous, but a large number of exposures also occur with Tityus bahiensis. There are quite a few studies in literature about the toxic effects of this venom but it is not known if the venom causes malformations or behavioral defects to the offspring of mothers exposed to the venom during pregnancy. The objective of this work was to determine, in rats, the possible toxic effects of T. bahiensis venom on offspring when injected into rats during different periods of fetal development. Rats were assigned to one of three groups: one control group and two experimental groups that were subcutaneously injected with venom (2.5mg/kg) on the 10th (GD10) or on 16th day (GD16) of gestation. Pups were evaluated for changes in physical and behavioral development. GD10 treatment group offspring showed an increase in body weight gain, earlier ear unfolding, incisor tooth eruption and vaginal opening. A decrease in the time of palmar grasp and surface-righting reflexes was observed only for males. In GD16 treatment group, earlier ear unfolding, incisor tooth eruption, and delay in eye opening were observed in the offspring. In female pups a decrease in weight gain and in time for palmar grasp reflex, and an increase in time for negative geotaxis were observed. In male pups a delay in the testis descent, decrease in the time of palmar grasp, increase in the time of negative geotaxis reflex and in the general and locomotor activities could be noticed. Therefore, we concluded that a moderate dose of scorpion venom administered to pregnant rats was able to elicit alterations in physical and behavioral development in the offspring during the postnatal period.

Developmental effects of Tityus serrulatus scorpion venom on the rat offspring.

Scorpion envenomation is a public health problem. Extensive research has been conducted to describe the systemic effects of scorpion venoms and their toxins, however, few reports are available about their effects on pre- and post-natal periods. Whole venom of the Tityus serrulatus scorpion was administered to rats on the 10th and 16th days of pregnancy to determine the effect on physical, reflexive and behavioral development of offspring. Thirty female Wistar rats were mated and distributed into three groups with one control group (C) and two experimental groups that were injected with venom (1mg/kg) on the 10th (GD10) or the 16th day (GD16) of pregnancy. After birth, the litter was standardized (eight pups for dam) and the rat pups were submitted to physical and behavioral analysis. A greater weight gain was observed on the 20th day of life (PN20) in the female and male pups of the two experimental groups compared to controls. In the GD16 group, a delay in ear opening and acceleration in ear unfolding were observed. In relation to reflexive development, an increased time for palmar grasp reflex was observed on PN8 in GD16. For this group, there was a decrease in the time of righting reflex on PN4 and PN6, and of negative geotaxis on PN6, PN8 and PN10. In conclusion, scorpion venom administered to pregnant rats on specific gestational days and at a dose that simulates a small accident, results in alterations in some reflex and physical parameters in their offspring.

Amphetamine-induced rapid-onset sensitization: role of novelty, conditioning and behavioral parameters.

BACKGROUND: Environmental factors may modulate sensitization to the locomotor-activating effects of psychostimulants. In addition, some parameters of locomotor activity seem to be more sensitive to detect cocaine-induced behavioral sensitization. We examined how novelty and conditioning can modulate a previously described rapid-onset type of behavioral sensitization to amphetamine (AMP) in mice, using total, peripheral and central open-field locomotion frequencies as experimental parameters. METHODS: In the first experiment, mice received an ip injection of saline (SAL) or 5.0 mg/kg AMP paired or not with the open-field or in their home-cages. Four hours later, all the animals received an ip SAL challenge injection and, 15 min later, were observed in the open-field for quantification of total, peripheral and central locomotion frequencies. The second experiment had a similar protocol, except that mice received a challenge injection of 1.5 mg/kg AMP. RESULTS: The priming AMP injection significantly increased all the parameters of locomotion of SAL-challenged mice firstly exposed to or previously paired (but not unpaired) with the open-field. AMP priming injection enhanced total and peripheral locomotion of all AMP-challenged mice but only increased central locomotion of mice submitted to novelty or environmental conditioning. CONCLUSION: Our results showed: 1) the development of an AMP-induced rapid-onset sensitization to novelty and rapid-onset environmental conditioning in mice, 2) the potentiation of the AMP-induced rapid-onset sensitization to an AMP challenge injection by novelty and environmental conditioning and 3) the importance of measuring different locomotor activity parameters in behavioral sensitization experiments.

Participaçäo de fatores exteroceptvos e interoceptivos na sensibilizaçäo comportamental induzida por anfetamina / Participation of exterorceptives and interoreceptives factors amphetamin-induced behavioral sensitization

O efeito estimulante motor induzido pela anfetamina em roedores intensifica-se após administraçoes repetidas. Diversas evidências experimentais sugerem que esse fenômeno, denominado Sensibilizaçao Comportamental, compartilha as bases mecanicísticas inerentes às propriedades reforçadoras da droga e, conseqüentemente, à dependência farmacológica. De importancia, tanto a sensibilizaçao como a dependência à anfetamina parecem ser marcantemente potencializada pelo pareamento entre o efeito da droga e condiçoes exteroceptivas específicas. Paralelamente evidências mais recentes sugerem que além dos fatores exteroceptivos, o condicionamento do efeito farmacológico de psicoestimulantes a fatores interoceptivos poderia ser fundamental para o desenvolvimento do fenômeno de Sensibilizaçao Comportamental. Nesse contexto, o presente trabalho teve como proposiçao geral verificar a possível participaçao de fatores exteroceptivos ambientais e sociais bem com de fatores interoceptivos relacionados à ativaçao do Sistema Nervoso Autonômico Simpático no fenômeno de sensibilizaçao ao efeito estimulante motor induzido pela anfetamina em camundongos. Com o a intuito de detectar nao apenas alteraçoes quantitativas como também modificaçoes qualitativas nesse fenômeno, diversos parâmetros da atividade geral dos animais em campo aberto foram analisados...(au)