Effect of external cryoprotectants on the in vitro viability of frozen spermatozoa of SWISS-ALBINA and BALB/c mice (Mus musculus). / Efeito de crioprotetores externos sobre a viabilidade in vitro de espermatozóides congelados de camundongos (Musmusculus) das linhagens SWISSALBINA e BALB/c.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

The genetic progress obtained with trangenesis required the development and consolidation of reproductive techniques such as in vitro embryo production and gamete cryopreservation. With the diversity of new models and genetic lines, it became critical to optimize the use of experimental techniques of cryopreservation of semen in different animal species. The objective of this study was to evaluate the effects of 3 disaccharides as extenders for frozen semen of SWISS-ALBINA (heterogenetic) and BALB/c (isogenetic) mice, using the fast freezing technique. The straws were exposed to vapor of N2 during 10 minutes, before the immersion in liquid N2. At thawing, semen samples were exposed to air during 5 seconds and then immersed in water at 37C during 2 minutes. To evaluate the effect of the different treatments (1: sucrose; 2: threalose; 3: lactose-SWISS-ALBINA; and 1:lactose; and 2:threalose-BALB/c), each semen sample was evaluated for progressive sperm motility (MOT) and vigor (VIG), in 3 different moments: after thawing (THAW); after centrifugation to remove the cryoprotectant and re-suspension in P-1 medium (CEN); and after 10 minutes of incubation in CO2 (10M). The fertilizing capacity of the cryopreserved semen was assessed through the cleavage rate (CR) after in vitro fertilization (IVF), on the two genetic lines and also on crossbred lines. On SWISSALBINA mice, the MOT in treatment 2 was higher (P <0.001) than in the other 2 treatments, in the 3 evaluations (47.0% at DES; 66.5% at CEN; and 67.2% at 10M). In treatment 1, mean MOT was 32.5 at DES, 51.5% at CEN and 47.7% at 10M. In treatment 3, mean MOT was 30.0%, 46.5% and 32.7% at DES, CON and 10M, respectively. For BALB/c mice, MOT in treatment 2 was also higher than for treatment 1 (P <0.001). The VIG did not differ among treatments in either genetic line (P <0.05). Also, the CR did not differ across treatments (P >0.05). For SWISSALBINA mice, mean CR were 38.2%, 46.0% and 43.4% for treatments 1, 2 and 3, respectively. Mean CR for BALB/c mice were 46.4% for treatment 1 and 35.7% for treatment 2. No treatment effect was observed in CR for crossbred lines (P >0.050. These results indicate that post-thawing in vitro viability was superior when using threalose rather than sucrose or lactose to extend frozen semen, but such effect was not followed by improvement in in vitro fertility in any of the evaluated genetic lines.

ASSUNTO(S)

camundongo mice veterinary sêmen criopreservação sacarose lactose, fertilização in vitro trealose veterinária lacotose sacarose mus musculus semen in vitro fertilization threalose mus musculus crioprotetores externos reproducao animal sperm motility

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