Influence of gender and estrous cycle in the forced swim test in rats

The present work aimed at studying the influence of the estrous cycle in the forced swim test, an animal model of depression. For this, 44 male and female Wistar rats were divided into five groups according to the hormonal state in the first day of the study: metaestrus (N = 12), diestrus (N = 8), proestrus (N = 7), estrous (N = 6) and males (N = 11). They were housed in groups of five, with water and food ad libitum under a 12/12 h light/dark cycle. Females were screened daily for the estrous cycle. The animals were subjected to two swimming sessions in a glass cylinder with water up to 15 cm at 28±2º C. The data of the first five minutes of a 15-min first session were compared to those of a 5-min second session 24 h later. The results indicate that the latency to the first immobility was substantially reduced in the second session and was longer for females in diestrus and proestrus in the first session. The results also indicate that females in diestrus and proestrus exhibited less immobility than males in the first session; females in diestrus also exhibited less immobility than females in metaestrus. Females in metaestrus and diestrus, as well as males, did not present the decrease in total immobility times in the second session. The present results are analyzed in terms of differential effects of progesterone and estrogen on a learning component and an affective component.

The effects of diazepam on the elevated T-maze are dependent on the estrous cycle of rats

In order to determine the modulation of anxiolytic and panicolytic-like effects of diazepam by the hormonal cycle of female rats, male and female rats – the latter divided per estrous cycle phase (estrus, diestrus, metaestrus and proestrus) – were tested in the elevated T-maze, a behavioral model of panic and anxiety. Diazepam (0.5, 1.0 and 2.0 mg/kg) or saline solution was injected in individual animals that were submitted to one session in the elevated T-maze 25 min after drug/saline administration. The test consisted of three avoidance trials and one escape trial, separated by a 30 s interval, during which the animals were isolated in individual cages. The avoidance trials began with the animal being placed at the end of the maze's enclosed arm. The time necessary for the animal to leave the central square was considered as the response's latency. The trials that exceeded 300 s were considered as failures. Results demonstrate a decrease in the effects of diazepam in inhibitory avoidance (anxiety) trials in females in diestrus and proestrus, but no relation of gender or estrous cycle on diazepam effects on escape trials (fear). The results support the hypothesis that down-regulation of GABAA receptors by activation of nuclear estrogen receptors and induction of PKC-mediated GABAA receptor phosphorylation by activation of surface estrogen receptors in raphe neurons underlie the modulation of diazepam sensitivity by estrogen.

Uso da morfina no período gestacional e lactação: efeitos sobre o desenvolvimento do sistema nervoso central e comportamento

O uso de substâncias psicoativas é um dos maiores problemas da sociedade moderna, causando transtornos sociais, econômicos e à saúde do usuário. Em 2010, 26,4-36 milhões de pessoas utilizaram analgésicos opióides para fins não-terapêuticos, sendo a frequência de uso nocivo por profissionais de saúde, cinco vezes maior quando comparados a população geral, devido ao acesso facilitado. A prevalência no uso durante a gravidez apresenta taxas que variam de 1% a 21%, representando preocupação na sociedade, uma vez que os efeitos ocasionados no desenvolvimento do feto ainda não estão bem elucidados. O objetivo deste estudo foi avaliar as respostas neurocomportamentais de ratos adultos após exposição crônica à morfina, durante o período intrauterino e lactação. Ratas grávidas receberam durante 42 dias, via subcutânea, morfina 10 mg/kg/dia. A prole foi pesada nos dias D1, D5, D10, D15, D20, D30, D60, e os ensaios comportamentais realizados com a prole aos 2,5 meses de idade, os quais consistiram no modelo do campo aberto, labirinto em cruz elevado, nado forçado e rota-rod. Os resultados demonstraram que a exposição à morfina promoveu redução no ganho de peso da prole após o nascimento e inclusive após o desmame, aumento da locomoção espontânea das fêmeas, bem como aumento do comportamento do tipo ansiogênico e comportamento do tipo depressivo, independente do sexo, porém sem prejuízo motor associado.

New experimental model of exposure to environmental tobacco smoke

PURPOSE: To describe a new model to passive smoking for rodents. METHODS: Twenty rats were distributed into two study groups (N=10): control group (CG), that was not exposed to tobacco smoke and used as normal standard for biochemical and histological analysis; Experimental Group (EG), that Animals were exposed to the passive smoking; Euthanasia was performed after 14 days of exposure. The serum level of nicotine and histological analysis were performed. RESULTS: There was a statistical difference on the nicotine serum levels between Experimental and Control group, with level of 286 ±23 nanograma/mL in the EG and undetectable on CG (p<0.01). The histological study suggested the model efficacy producing alveolar destruction and emphysema in the EG compared with the insignificant lesions in the CG's lung. CONCLUSION: The model of exposure to environmental tobacco smoke for rodents induced easily the changes related to secondhand smoke.

Copaiba oil effect on experimental jaw defect in Wistar rats

PURPOSE: To evaluate the effects of copaiba oil on jaw defects repair in Wistar rats treated with bioglass or adipose tissue. METHODS: A jaw defect was randomly created in forty-two rats and filled with bioglass or adipose tissue. The two groups (Gbio and Gcell) were subdivided in three subgroups with seven animals each according to gavage administration: control (distillated water), oil (copaiba oil) and melox (meloxicam). Euthanasia was performed after forty post-operative days. The bone formation was analyzed regarding the histological aspects. RESULTS: The osteoclasts activity was observed only in four subgroups (p=0.78). Regarding the osteoblasts presence, it was very similar between the subgroups, the difference was due to Gcell-melox (p=0.009) that presented less osteoblastic activity. The inflammatory cells were more evident in Gcell-melox subgroup, however, there was no difference in comparison with the other subgroups (p=0.52). Bone formation was observed in all subgroups, just two animals showed no bone formation even after 40 days. More than 50% of bone matrix mineralization was observed in 56% (23 animals) of the analyzed areas. The bone matrix mineralization was not different between subgroups (p=0.60). CONCLUSIONS: The subgroups that received copaiba oil showed bone repair, although not statistically significant in comparison to subgroups treated whit meloxicam or controls. Copaiba oil administered by gavage had no effect on bone repair in this experimental model.