Avaliação das características do espermatozóide eqüino congelado submetido a inclusão e remoção do colesterol das membranas

• Ano de defesa: 2007
• Autor(a) principal: Camila Haddad de Oliveira
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; UFMG
• Palavras-chave em Português: metil-â-ciclodextrina; sêmen congelado; colesterol; eqüino; Veterinária; Eqüino Reprodução; Sêmen congelado; Espermatozóides; Colesterol
• Link de acesso: http://hdl.handle.net/1843/SSLA-7UDHRY

Cholesterol incorporation to the sperm membranes has been reported as an alternative to improve the membrane stability of several species spermatozoa during the cryopreservation. However, in vivo fertility is reduced compared to cryopreservation of control sperm (without cholesterol). The aim of the present study was to evaluate the progressive motility, the functional and physical integrity of the plasma membrane (hyposmotic swelling test and evaluation with Propidium iodide, respectively), the acrossomal integrity (evaluation with FITC-PNA) and the ability of sperm to acrosome react (induction of the acrosome reaction with calcium ionophore - A23187), after incorporating and removing the cholesterol from sperm membranes. One ejaculate of twelve stallions was collected. Semen was submitted to four treatments: (1) conventional cryopreservation; (2) semen treated with cholesterol; (3) treatment 2 following removal of the cholesterol post-thawing with 0,052 mg of methyl-â-cyclodextrin/50 x 106 sperm; (4) treatment 2 following removal of the cholesterol post-thawing with 0,156 mg of methyl- â-cyclodextrin/50 x 106 sperm. No differences were observed in relation to progressive motility and plasma membrane functionality of sperm between treatments. However, it was observed fewer sperm with intact plasma membrane in treatments 1, 3, and 4, when compared to treatment 2, suggesting a toxic effect of cyclodextrin in the last two treatments. Cholesterol incorporation increased the percentage of sperm with intact acrosome after induction of the acrosome reaction. Nevertheless, no reduction was observed in the rates of sperm with intact acrosome after cholesterol removal with the two different cyclodextrin concentrations. Since induced acrosome reaction rate in vitro can be indicative of in vivo fertility, more studies should be performed to enhance the acrosome reaction rate in vitro without reducing plasma membrane integrity