Efeito de diferentes concentrações de melatonina em espermatozoides de carneiros sobre estresse oxidativo após criopreservação

Abstract

ABSTRACT.-Souza W.L., Moraes E.A., Costa J.M.S., Souza P.H.F., Lopes Junior E.S., Oliveira R. The aim was to evaluate the effect of adding different concentrations of melatonin in ram semen diluted after cryopreservation. Ten ejaculates were collected0 from three adult ram (n=30) by means of artificial vagina for sheep. The collected samples were diluted in Tris-egg yolk, to a final concentration 200x10 6 sptz/mL kept in water bath at 32°C, and melatonin added as treatments: control; 100pM; 100nM; 100μM and 1mM melatonin. Then, the samples were cooled in a cold chamber at 5°C for two hours, in straws of 0.5mL and sealed. They were stored under the liquid nitrogen vapor for 15 minutes to 8cm of liquid blade and frozen with liquid nitrogen. Samples were analyzed for sperm motility, membrane integrity, acrosomal membrane, mitochondrial activity, oxidative stress and quantification of the binding capacity. The variables were subjected to analysis of variance and the means were compared by Tukey test at 5% probability. The total and progressive motility of thawed sperm were higher in samples treated with 100pM melatonin (62.99 and 45.07%, respectively; P<0.05) when compared to other treatments. The addition of different concentrations of melatonin in semen diluted with the exception of 1mM concentration, a higher percentage of cells with intact plasma membrane, as compared with the control (P<0.05). The percentage of sperm with acrosome membrane integrity was higher in the semen with 100pM melatonin (P<0.05) than the other treatments. The high mitochondrial activity was higher in spermatozoa treated with 100pM melatonin (69.30%; P<0.05). Addition of 100nM melatonin reduced the amount of TBARS after cryopreservation (2.84, P<0.05) when compared with the other treatments. After thawing, the number of sperm which bind to the perivitelline membrane was higher in the melatonin treated with 100pM (155,73; P<0.05). Therefore, melatonin addition the semen diluted can be useful to enhance the cryopreservation of sheep semen, improving fertilization rates through artificial insemination.

Gene Expression Profile and Enzymatic Activities of Frozen Buck Sperm Supplemented with Melatonin in Cold and Hot Temperatures.

“…Succu, et al (2011) have indicated that supplementing melatonin in a dose of 1.0 mM to ram extender maintained progressive motility, intracellular ATP concentrations, DNA integrity and fertilization rate in comparison to other doses (0.001, 0.01, 0.1, and 10 mM). In contrast, Souza et al (2016) have stated that low concentration of melatonin (100 pM) increased the sperm motility, mitochondrial activity, integrity of plasma membrane and acrosome in ram semen in comparison to high concentrations (100 nM, and 100 μM). Moreover, supplementation of melatonin at low dose (0.1 mM) to semen extender of buffalo bulls maintained the ultrastructure integrity of the sperm and increased pregnancy rate in compared to control and high doses groups (0.250, 0.500, 0.750 and 1 mM) (EL-Raey et al, 2015).…”

Colesterol carregado pela ciclodextrina sobre a criopreservação dos espermatozoides de garanhões da raça Nordestina

“…Essa redução é esperada e pode ser atribuída ao declínio no metabolismo de energia dos espermatozoides que, ao serem expostos, por um longo período de incubação, acredita-se que ocorra um déficit de energia pela elevação do metabolismo celular e uma rápida utilização dos constituintes do diluente, implicando em danos diretos as organelas envolvidas na movimentação espermática, como a mitocôndria, prejudicando a atividade da cadeia de transporte de elétrons, consequentemente, provocando a redução na motilidade (Souza et al 2016b). Contudo, os resultados apresentados revelaram o sêmen com valores de motilidade espermática para garanhões, dentro do percentual exigido pelo CBRA (2013), inferindo assim, a sua aptidão para fecundação.…”

“…A integridade da membrana plasmática dos espermatozoides descongelados foi determinada pelo teste com sonda fluorescente. Para esta avaliação utilizou-se a associação de duas sondas fluorescentes, iodeto de propídio (IP) e Hoechst 33342 (H33342), conforme Souza et al (2016b). As amostras de cada tratamento foram colocadas em microtubos de 1,5mL após descongelação.…”

Evaluation of Solvent Toxicity of Plant Extract with Antiviral Action in Refrigerated Goat Semen

“…Fato esse não proporcionado pelo MEM, justificando assim a ocorrência de diferença estatística (P < 0,05) entre esses dois diluidores em todos os tratamentos. Na literatura, diversos trabalhos relataram a qualidade e eficiência do Tris Gema como diluente seminal [15,25,27,28], pois o mesmo além de atuar como uma substância tampão acarreta uma desaceleração do metabolismo da frutose pelo espermatozoide, de modo a contribuir para preservação energética da célula espermática [7]. Partindo dessa premissa, presume-se que possivelmente esse diluente seja o ideal a ser adotado em metodologias que busquem a inativação do CAEV no sêmen através de extratos naturais dissolvidos em DMSO, tornando uma ferramenta auxiliar no combate a artrite encefalite caprina.…”