In the present study we developed a chemically induced experimental model for gestational hypermethioninemia in rats and evaluated in the offspring the activities of Na(+),K(+)-ATPase and Mg(2+)-ATPase, as well as oxidative stress parameters, namely sulfhydryl content, thiobarbituric acid-reactive substances and the antioxidant enzymes superoxide dismutase and catalase in encephalon. Serum and encephalon levels of methionine and total homocysteine were also evaluated in mother rats and in the offspring. Pregnant Wistar rats received two daily subcutaneous injections of methionine throughout the gestational period (21 days). During the treatment, a group of pregnant rats received dose 1 (1.34 μmol methionine/g body weight) and the other one received dose 2 (2.68 μmol methionine/g body weight). Control group received saline. After the rats give birth, a first group of pups was killed at the 7th day of life and the second group at the 21th day of life for removal of serum and encephalon. Mother rats were killed at the 21th day postpartum for removal of serum and encephalon. Both doses 1 and 2 increased methionine levels in encephalon of the mother rats and dose 2 increased methionine levels in encephalon of the offspring. Maternal hypermethioninemia also decreased the activities of Na(+),K(+)-ATPase, Mg(2+)-ATPase and catalase, as well as reduced total sulfhydryl content in the encephalon of the pups. This chemical model seems to be appropriate for studies aiming to investigate the effect of maternal hypermethioninemia on the developing brain during gestation in order to clarify possible neurochemical changes in the offspring.

The purpose of this study was to develop a chronic chemically induced model of mild hyperhomocysteinemia in adult rats. We produced levels of Hcy in the blood (30μM), comparable to those considered a risk factor for the development of neurological and cardiovascular diseases, by injecting homocysteine subcutaneously (0.03μmol/g of body weight) twice a day, from the 30th to the 60th postpartum day. Controls received saline in the same volumes. Using this model, we evaluated the effect of chronic administration of homocysteine on redox status in the blood and cerebral cortex of adult rats. Reactive oxygen species and thiobarbituric acid reactive substances were significantly increased in the plasma and cerebral cortex, while nitrite levels were reduced in the cerebral cortex, but not in the plasma, of rats subjected to chronic mild hyperhomocysteinemia. Homocysteine was also seen to disrupt enzymatic and non-enzymatic antioxidant defenses in the blood and cerebral cortex of rats. Since experimental animal models are useful for understanding the pathophysiology of human diseases, the present model of mild hyperhomocysteinemia may be useful for the investigation of additional mechanisms involved in tissue alterations caused by homocysteine.

No abstract

Depressive disorders, including major depression, are serious and disabling, whose mechanisms are not clearly understood. Since life stressors contribute in some fashion to depression, chronic variable stress (CVS) has been used as an animal model of depression. In the present study we evaluated some parameters of oxidative stress [thiobarbituric acid reactive substances (TBARS), catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPx)], and inflammatory markers (interleukin 6, C reactive protein, tumor necrosis factor-alpha and nitrites), as well as the activity of butyrylcholinesterase in blood of rats subjected to chronic stress. Homocysteine and folate levels also were measured. Stressed animals were submitted to different mild stressors for 40 days. After CVS, a reduction in weight gain was observed in the stressed group, as well as an increase in immobility time in the forced swimming test as compared with controls. Stressed animals presented a significant increase on TBARS and SOD/CAT ratio, but stress did not alter GPx activity and any inflammatory parameters studied. CVS caused a significant inhibition on serum butyrylcholinesterase activity. Stressed rats had higher plasmatic levels of homocysteine without differences in folate levels. Although it is difficult to extrapolate our findings to the human condition, the alterations observed in this work may be useful to help to understand, at least in part, the pathophysiology of depressive disorders.

ABSTRACT. Infl uence of host age and learning on chemotactic behavior and parasitism of Trichogramma pretiosum. Trichogramma pretiosum Riley, 1879 reared on Ephestia kuehniella Zeller, 1879 eggs, have been used in biological control of Spodoptera frugiperda (J. E. Smith, 1797). However, host age and experience just after emergence might have some infl uence on parasitism and parasitoid behavior. This study evaluated the infl uence of S. frugiperda host age and egg odor experience, on chemotactic behavior and parasitism of T. pretiosum. Spodoptera frugiperda eggs with 24, 48 and 72 hours were exposed to T. pretiosum females. Parasitoid time experience, in the same host, was evaluated within 1, 3, 4, 5, 6 and 24 hours, as well as, its host exposed time (1, 2, 3 and 24 hours). Chemotactic responses of T. pretiosum (experienced and inexperienced females) to S. frugiperda egg extracts were recorded in Y-tube olfactometer. We also observe parasitism rates (choice tests) in insects with and without experience. The parasitism average was higher in S. frugiperda eggs with 24 hours. Inexperienced females and those experienced for 1, 3 and 4 hours, parasitized less S. frugiperda eggs compared to those for 5, 6 and 24 hours. There was no diff erence in parasitism from females exposed for 2, 3 and 24 hours when compared to those exposed for one hour. Experienced females were more attracted to S. frugiperda eggs odor than to control (hexano). Parasitism percentage, by inexperienced parasitoids, was greater in E. kuehniella eggs (original host) than in S. frugiperda, however it was not observed in experienced females.KEYWORDS: Biological control, egg parasitoid, eggs extract.RESUMO. Trichogramma pretiosum Riley, 1879 mantido em ovos de Ephestia kuehniella Zeller, 1879, tem sido utilizado no controle biológico de Spodoptera frugiperda (J. E. Smith, 1797). No entanto, fatores como idade do hospedeiro e experiência prévia, podem infl uenciar o parasitismo e o comportamento do parasitoide. Esse estudo avaliou a infl uência da idade dos ovos e da experiência em ovos e extrato de ovos de S. frugiperda no comportamento quimiotáxico e no parasitismo de T. pretiosum. Ovos de S. frugiperda com 24, 48 e 72 horas, foram expostos a fêmeas de T. pretiosum. Também foi avaliado o tempo de experiência do parasitoide, no mesmo hospedeiro, por 1, 3, 4, 5, 6 e 24 horas, assim como, seu tempo de exposição (1, 2, 3 e 24 horas). As respostas quimiotáxicas de T. pretiosum (experiente e não experiente) em extrato de ovos de S. frugiperda foram observadas em olfatômetro tipo Y. As taxas de parasitismo foram registradas em teste de escolha, com insetos experientes e inexperientes com ovos e extrato de ovos de S. frugiperda. O parasitismo em S. frugiperda foi signifi cativamente maior em ovos com 24 horas de idade. Fêmeas inexperientes e experientes por 1, 3 e 4 horas, apresentaram uma menor taxa de parasitismo, quando comparadas a fêmeas expostas por 5, 6 e 24 horas. Não houve diferença de parasitismo em fêmeas expostas por 2, 3 e 24 horas, comparadas à...