Abstract Although a considerable number of studies have investigated the effects of lipopolysaccharide (LPS) on the reproductive performance of dairy cows, the response of ovine oocytes to LPS during their in vitro maturation and development is not well defined yet. Ewe’s ovaries were obtained from a slaughterhouse, the oocytes were collected and matured in the presence of increasing concentrations (0, 0.01, 0.1, 1 and 10 µg/mL) of LPS in order to evaluate the meiotic maturation by measuring the proportion of oocytes reaching the MII stage. The concentration of intracellular glutathione (GSH) was measured in oocytes following maturation in vitro. In addition, concentrations of selected metabolites including glucose, pyruvate, lactate and glutamine were quantified in the medium following maturation. A number of treated matured oocytes along with the control group were subsequently fertilized using frozen semen and assessed for the rate of cleavage and for the proportion reaching the blastocyst stage. The number of oocytes in MII stage was significantly reduced in response to the increasing concentrations of LPS (77.83%, 70.64%, 68.86%, 66.32%, respectively, in case of 0.01, 0.1, 1 and 10 µg/mL LPS when compared to the control group, 76.34%; P<0.05). There were no differences neither in the intracellular concentration of GSH in the oocytes nor in case of the metabolites in the maturation medium. Although the rate of cleaved oocytes was not affected by increasing levels of LPS, the blastocyst rate was reduced in a dose dependent manner (36.69%, 34.21%, 30.35%, 17.27% and 14.03% for the control, 0.01, 0.1, 1 and 10 µg/mL LPS, respectively (P<0.05). These results demonstrate that the developmental competence of ovine oocytes may be affected detrimentally by LPS and such deleterious effects could be related to the maturation process.

RESUMO A indução de potenciação de longo prazo (LTP) aumenta a capacidade de armazenamento das sinapses no giro denteado (DG) do hipocampo. A irisina é uma miocina gerada a partir do FNDC5 (um precursor genético) durante o exercício. Embora a administração intra-Cornu Ammonis1 de irisina fortaleça a LTP em camundongos com doença de Alzheimer, os efeitos da injeção intra-denteada de irisina sobre a LTP em ratos ainda precisam ser elucidados in vivo. Neste estudo, ratos Wistar machos foram divididos aleatoriamente em um grupo controle (solução salina), irisina (0,5, 1 e 1,5 μg / rato) e dimetilsulfóxido (DMSO). Após o tratamento, a amplitude do pico populacional (PS) e a variação dos potenciais pós-sinápticos excitatórios (EPSP) foram medidos no DG de ratos in vivo. Além disso, após a conclusão das experiências, os locais de estimulação e registro no hipocampo foram confirmados histologicamente a partir de secções do cérebro. Adicionalmente, ensaios bioquímicos como malondialdeído (MDA), capacidade antioxidante total (TAC) e status oxidante total (TOS) foram avaliados (os marcadores antioxidantes foram analisados no plasma). Nossos resultados sugerem que todas as doses de irisina (0,5, 1, 1,5 μg / rato) causaram um aumento na variação da EPSP e na amplitude da PS quando comparadas com o grupo controle. Além disso, os resultados obtidos mostraram que a irisina diminuiu os níveis de TOS e MDA, enquanto aumentou os níveis de TAC como um marcador da peroxidação lipídica no plasma. O presente estudo fornece evidências diretas de que a irisina afeta a plasticidade sináptica dependente de atividade no DG.

ABSTRACT Induction of long-term potentiation (LTP) increases the storage capacity of synapses in the hippocampal dentate gyrus (DG). Irisin is a myokine generated from FNDC5 (a gene precursor) during exercise. Although intra-cornu ammonis 1 administration of irisin fortifies LTP in mice with Alzheimer's disease, the effects of intra-DG injection of irisin on the LTP in rats remains to be elucidated in vivo. In this study, male Wistar rats were randomly divided into a control group (saline), irisin (0.5, 1, and 1.5 μg/rat), and dimethyl sulfoxide (DMSO). After treatment, the population spike (PS) amplitude and slope of excitatory postsynaptic potentials (EPSP) were measured in the DG of rats in vivo. Moreover, following completion of the experiments, the stimulating and recording sites in the hippocampus were confirmed histologically from brain sections. Furthermore, biochemical assays like malondialdehyde (MDA), total antioxidant capacity (TAC), and total oxidant status (TOS) were evaluated (the antioxidant markers were analyzed in the plasma). Our results suggest that all doses of irisin (0.5, 1, 1.5 μg/rat) caused an increase in the EPSP slope and PS amplitude when compared with the control group. In addition, the results obtained showed that irisin decreased TOS and MDA levels while increasing TAC levels as a marker of lipid peroxidation in plasma. The present report provides direct evidence that irisin affects the activity-dependent synaptic plasticity in the dentate gyrus.