Jonathan Maia da Silva Costa

Características do sêmen a fresco e descongelado de garanhões da raça Nordestina

Este estudo descreveu as caracteristicas seminais, da membrana plasmatica e do acrossoma de espermatozoide congelado/descongelado de 19 ejaculados de garanhoes da raca Nordestina. Os aspectos analisados incluiram os parâmetros fisicos do semen fresco; a motilidade e a longevidade do semen diluido e descongelado; a morfologia espermatica, integridade funcional e estrutural da membrana plasmatica do espermatozoide e a habilidade de ligacao do espermatozoide a membrana perivitelina da gema do ovo de galinha do semen descongelado. As variaveis foram avaliadas pela ANOVA com post hoc teste de Student Newman-Keuls (P<0,05). A MT e a MP foram maiores (P<0,05) no semen diluido do que no descongelado. A percentagem media de defeitos maiores, menores e totais foi muito inferior ao limite recomendado pelo CBRA. A porcentagem de reativos ao HOST foi de 14,21±1,12% e a porcentagem media de membranas integras detectadas pelo teste supravital de 62,22±9,06% e pela sonda SYBR-14 de 81,47±26,90. O numero medio de espermatozoides ligados a MPV apos a descongelacao do semen foi de 230,39±57,09. A MT e MP no tempo 0 min do TTR foi superior (P<0,05) em relacao a 150 min, nao diferindo nos tempos 10 min e 30 min. Os resultados demonstram que a utilizacao dos testes laboratoriais adicionais ajudam no processo de avaliacao das amostras, possibilitando a obtencao de informacoes mais confiaveis e precisas. Embora a criopreservacao tenha provocado queda na motilidade seminal, o uso de diluidor contendo amidas minimizou os danos osmoticos nas celulas espermaticas e manteve a integridade morfologica, funcional e estrutural da membrana plasmatica do espermatozoide. Estes resultados sao um referencial em estudos futuros uma vez que, inexistem dados comparativos nesta raca.

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

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 200x106 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.