RESUMO
In vitro trypanocidal and leishmanicidal activities of the flavonoids hispidulin, from Ambrosia tenuifolia, and santin, from Eupatorium buniifolium, are reported. A sensitive technique that takes advantage of ((3)H)thymidine uptake by dividing trypanosomatids has been adjusted for quantification of the parasiticidal effect of the natural products. The IC(50) values for hispidulin and santin on Trypanosoma cruzi epimastigotes were 46.7 and 47.4 muM, respectively. On trypomastigotes, the IC(50) values were 62.3 microM for hispidulin and 42.1 microM for santin. Hispidulin was more active than santin on promastigotes of Leishmania mexicana (IC(50) = 6.0 microM versus 32.5 microM). No cytotoxic activity was observed on lymphoid cells, making hispidulin and santin potential lead compounds for the development of new natural drugs. This is the first report on the trypanocidal and leishmanicidal activities of these flavonoids and on the presence of santin in E. buniifolium.
Assuntos
Ambrosia/química , Eupatorium/química , Flavonas/farmacologia , Flavonoides/farmacologia , Leishmania mexicana/efeitos dos fármacos , Trypanosoma cruzi/efeitos dos fármacos , Animais , Argentina , Avaliação Pré-Clínica de Medicamentos , Feminino , Flavonas/toxicidade , Flavonoides/toxicidade , Concentração Inibidora 50 , Leishmania mexicana/crescimento & desenvolvimento , Leishmania mexicana/isolamento & purificação , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Linfócitos T/efeitos dos fármacos , Timidina/farmacocinética , Trítio , Trypanosoma cruzi/crescimento & desenvolvimento , Trypanosoma cruzi/isolamento & purificaçãoRESUMO
A practical method for the radioisotope labeling aimed at the study of the proliferative behavior of astrocytes was described. It consisted in injecting 20 microCi of (3)H-thymidine into the vitreous body and tracing by autoradiography labeled astrocytes located both inside and outside the retina, e.g. optic nerve and neighboring parts of the central nervous system. The paraffin sections were immunostained for glial fibrillary acidic protein (GFAP) previous to autoradiographic processing. The semiquantitative analysis of labeled astrocytes was carried out on autoradiographs of semithin sections of rabbits killed as early as 6 h and as late as 3 months after the single intravitreal injection of (3)H-thymidine. Compared with the technique of labeling astrocytes by systemic administration (single injection or continuous infusion) of (3)H-thymidine into small animals, the method described herein has the following outstanding features: (i) it is much more economical in terms of the amount of labeled precursor used per animal; (ii) the labeling of the astrocytes is obtained as early as 6 h and remains up to 3 months after injection; (iii) the immunolabeling of the astrocytes is compatible with autoradiography; (iv) it is less risky to the experimental animal and to the environment; (v) it can be used in animals much larger than rats or mice.
Assuntos
Astrócitos/efeitos dos fármacos , Divisão Celular/efeitos dos fármacos , Retina/efeitos dos fármacos , Timidina , Trítio , Corpo Vítreo/efeitos dos fármacos , Animais , Artefatos , Astrócitos/citologia , Astrócitos/metabolismo , Autorradiografia , Axônios/efeitos dos fármacos , Axônios/metabolismo , Axônios/ultraestrutura , Divisão Celular/fisiologia , Núcleo Celular/efeitos dos fármacos , Núcleo Celular/metabolismo , Núcleo Celular/ultraestrutura , Proteína Glial Fibrilar Ácida/metabolismo , Imuno-Histoquímica , Masculino , Coelhos , Retina/citologia , Retina/metabolismo , Timidina/farmacocinética , Fatores de Tempo , Trítio/farmacocinética , Corpo Vítreo/metabolismoRESUMO
Two classes of retinal neurons in the chick retina, the horizontal and the amacrine cells, are GABAergic. This study evaluates the neurogenesis of glutamic acid decarboxylase immunoreactive cells in the chick retina. Twenty-five microCi [3H]thymidine was injected into eggs of 2-10 days and the embryos were sacrificed at embryonic day 18 (E18). Glutamic acid decarboxylase immunohistochemistry was revealed by avidin-biotin complex method followed by autoradiography of thymidine. We used the cumulative method for counting autoradiographic grains. At E3, 10% of the amacrine cells were thymidine negative/glutamic acid decarboxylase positive and this rate remained constant until E6. From E6 to E8 about 80% of the amacrine cells were thymidine negative/glutamic acid decarboxylase positive. At E9, 100% of these neurons had been generated. On the other hand, at E3 only 1.5% of the horizontal cells had been generated (thymidine negative/glutamic acid decarboxylase positive) while at E6 this number increased to 10%. From E6 to E9 the neurogenesis pattern was similar to that found for amacrine cells. Our data show that the great majority (80%) of glutamic acid decarboxylase positive amacrine and horizontal cells proliferate between E6 and E9, i.e. the last 3 days of the neurogenesis period. From E3 to E6 only 20% of the glutamic acid decarboxylase positive amacrine and horizontal cells are generated, which suggests that glutamic acid decarboxylase positive cells may require a specific signal at about E6, which triggers their withdrawal from the cell cycle.
Assuntos
Retina/citologia , Retina/embriologia , Ácido gama-Aminobutírico/fisiologia , Animais , Autorradiografia , Diferenciação Celular/fisiologia , Divisão Celular/fisiologia , Embrião de Galinha , Glutamato Descarboxilase/análise , Retina/enzimologia , Timidina/farmacocinética , TrítioRESUMO
We evaluated the effects of angiotensin II (ANG II) and its antagonists on prolactin release, intracellular calcium ([Ca2+]i) mobilization, and [3H]thymidine uptake in cells from normal rat pituitaries and from estrogen-induced pituitary tumors. ANG II (10(-7) to 10(-9) M) increased prolactin release significantly in control and not in tumoral cells. In control cells, ANG II (10(-6) to 10(-9) M) produced an immediate spike of [Ca2+]i followed by a plateau. Spike levels rose significantly between 10(-10) and 10(-8) M ANG II, whereas the onset of the spike was retarded with decreasing concentrations. In tumoral cells, ANG II did not produce a spike phase even at 10(-6) M. ANG II-induced prolactin release and calcium mobilization were blocked by losartan (AT1 receptor antagonist) and not by PD-123319 (AT2 antagonist). Finally, [3H]thymidine uptake was not modified by ANG II (10(-7) to 10(-10) M) or its antagonists in either group. Our results suggest that chronic in vivo estrogenic treatment alters in vitro pituitary response to ANG II. Alterations might function to limit excessive prolactin secretion of hypersecreting tumors. Besides, ANG II does not modify DNA synthesis in vitro of cells from normal or tumor-derived hypophyses.
Assuntos
Angiotensina II/farmacologia , Cálcio/metabolismo , Adeno-Hipófise/metabolismo , Neoplasias Hipofisárias/metabolismo , Prolactina/metabolismo , Animais , Células Cultivadas , Replicação do DNA , Estrogênios , Feminino , Hiperplasia/metabolismo , Adeno-Hipófise/efeitos dos fármacos , Prolactinoma/metabolismo , Ratos , Ratos Sprague-Dawley , Timidina/farmacocinéticaRESUMO
Se realizó un estudio in vitro para conocer el efecto farmacológico de prazicuantel sobre los trofozoítos de Giardia intestinalis cepa P-1. Después de cultivarlos axénicamente, con cinco diferentes concentraciones de prazicuantel (de 0.32 hasta 1.62 nM/mL) durante 24 h a 37ºC, la viabilidad y la CI50 evaluada por la captación de colorante fluorogénico con citometría de flujo mostró un desplazamiento logarítmico de 10º a 10 a la tercera lo que correspondió a una concentración de 1.28 nM/mL. La incorporación de H3 metil-timidina como parámetro de crecimiento celular a 50 por ciento alcanzó 1.20 nM/mL de prazicuantel y el efecto citotóxico calculado por la capacidad de lisar células CHO (células de ovario de hámster chino) marcados con Cr51 se observó para la CI50 en una concentración de 1.05 nM/mL. Con estos tres parámetros se puede inferir qué viabilidad a 50 por ciento se observó a concentraciones más altas de prazicuantel comparadas con la capacidad para dividirse, así como el efecto citolítico, en donde la concentraciones más altas de prazicuantel comparadas con la capacidad para dividirse, así como el efecto citolítico, en donde la concentración de prazicuantel fue la más baja a lo que se atribuye la cualidad de apagar radicales libres, sin embargo, esto no fue proporcional al incrementar la concentración suponiéndose una importante capacidad detoxificante en Giardia. Se concluye que prazicuantel desarrolló actividad farmacológica en protozoarios, lo que le hace susceptible de emplearse contra la giardiasis
Assuntos
Cricetinae , Praziquantel/análise , Praziquantel/farmacocinética , Timidina/farmacocinética , Sobrevivência Celular/efeitos dos fármacos , Cricetulus , Giardia lamblia/citologia , Giardia lamblia/efeitos dos fármacos , Técnicas In VitroRESUMO
The kinetics of (3)H-tymidine and (3)H-proline incorporated by ameloblasts and enamel, were studied in undecalcified mouse incisors from birth to 6 days of age. Serial cross sections of unfixed right incisors were cut with a cryotome. The left incisors were fixed in paraformaldehyde, embedded in polybed as to get sagital 1 mum-thick sections. (3)H-thymidine was used to determine the apparent daily migration rate of ameloblasts, which was 513 mum in the unfixed sections and 610 mum/p.d. in the fixed ones. The semi-thin epon-embedded sections were also used to measure the lengths of the regions of the secretory and post-secretory zone of amelogenesis and to determine their growth during the experimental period. (3)H-proline was used to show the fate of the enamel proteins by correlating the radiactivity, determined by silver grain counts, with the migration rate of the ameloblasts. The results showed that the (3)H-proline labeled protein reached a peak of radiactivity at 4 h over ameloblasts and between 24 and 48 h after injection over enamel. In the unfixed section of the righ incisor a second peak of reaction was shown at48 h over ameloblasts and at72 h over enamel matrix. All these peaks were related to ameloblasts and enamel of the secretory zone. These results were interpreted as the evidence of reabsorption and reutilization of labeled proteins broken down in the young enamel, but may also be explained as secretion of low molecular weight proteins which are not kept by fixation. Another evidence of reutilization of labeled compounts for the biosynthesis of enamel proteins were given by the labeling of ameloblasts and enamel formed after birth at a considerable time after the pulse of (3)H-proline.