USO DA rbST NO DIA DO ESTRO EM RECEPTORAS DE EMBRIÃO BOVINO CRIOPRESERVADO

Estudou-se o efeito da administração de duas doses de rbST (250 e 500 mg) no dia do estro em receptoras de embrião bovino criopreservado na taxa de gestação e na concentração sérica de progesterona. No experimento I, 44 receptoras foram distribuídas em dois tratamentos: T1(n = 22, controle) e T2(n = 22), recebendo a administração subcutânea de 250 mg de rbST. No experimento II, 71 receptoras foram distribuídas em: T1(n = 31, controle) e T2(n = 40), recebendo 500 mg de rbST. Os diagnósticos de gestação foram realizados 30 dias após o estro. As taxas de gestação não diferiram entre tratamentos em ambos os experimentos (40,9%(T1) vs 50,0%(T2) e 48,4%(T1) vs 52,5%(T2) para os experimentos I e II, respectivamente). As concentrações séricas de progesterona (ng/mL de plasma), obtidas nas amostras de sangue coletadas no dia da inovulação, não diferiram entre tratamentos, sendo 5,92 ± 0,62(T1) vs 5,77 ± 0,48(T2) e 4,94 ± 0,54(T1) vs 4,77 ± 0,51(T2) para os experimentos I e II, respectivamente. Esses resultados indicam que a administração de 250 ou 500 mg de rbST, no dia do estro, não proporciona incremento tanto na taxa de gestação como na concentração sérica de progesterona de receptoras de embrião bovino criopreservado. PALAVRAS-CHAVE: bovino; receptora de embrião; taxa de gestação

Poly-lactic acid nanoparticles (PLA-NP) promote physiological modifications in lung epithelial cells and are internalized by clathrin-coated pits and lipid rafts

BackgroundPoly-lactic acid nanoparticles (PLA-NP) are a type of polymeric NP, frequently used as nanomedicines, which have advantages over metallic NP such as the ability to maintain therapeutic drug levels for sustained periods of time. Despite PLA-NP being considered biocompatible, data concerning alterations in cellular physiology are scarce.MethodsWe conducted an extensive evaluation of PLA-NP biocompatibility in human lung epithelial A549 cells using high throughput screening and more complex methodologies. These included measurements of cytotoxicity, cell viability, immunomodulatory potential, and effects upon the cells’ proteome. We used non- and green-fluorescent PLA-NP with 63 and 66 nm diameters, respectively. Cells were exposed with concentrations of 2, 20, 100 and 200 µg/mL, for 24, 48 and 72 h, in most experiments. Moreover, possible endocytic mechanisms of internalization of PLA-NP were investigated, such as those involving caveolae, lipid rafts, macropinocytosis and clathrin-coated pits.ResultsCell viability and proliferation were not altered in response to PLA-NP. Multiplex analysis of secreted mediators revealed a low-level reduction of IL-12p70 and vascular epidermal growth factor (VEGF) in response to PLA-NP, while all other mediators assessed were unaffected. However, changes to the cells’ proteome were observed in response to PLA-NP, and, additionally, the cellular stress marker miR155 was found to reduce. In dual exposures of staurosporine (STS) with PLA-NP, PLA-NP enhanced susceptibility to STS-induced cell death. Finally, PLA-NP were rapidly internalized in association with clathrin-coated pits, and, to a lesser extent, with lipid rafts.ConclusionsThese data demonstrate that PLA-NP are internalized and, in general, tolerated by A549 cells, with no cytotoxicity and no secretion of pro-inflammatory mediators. However, PLA-NP exposure may induce modification of biological functions of A549 cells, which should be considered when designing drug delivery systems. Moreover, the pathways of PLA-NP internalization we detected could contribute to the improvement of selective uptake strategies