Browsing by Author "Palacios Aguilar, María Paula"

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    Efecto de la suplementación de L-carnitina a diluyentes a base de leche desnatada sobre la criosupervivencia de esperma equino
    (Universidad de Cuenca, 2021-10-20) Palacios Aguilar, María Paula; Peláez Zhingri, Gabriela Micaela; Galarza Lucero, Diego Andrés
    L-carnitine(LC) plays a key role in sperm metabolism based on energy production (-oxidation) and reduction of lipid availability for peroxidation. In this sense, this research evaluated the effect of LC supplemented to two skimmed milk-based extenders on cryosurvival of chilled and frozen-thawed Peruvian Paso horse spermatozoa. A first experiment assessed the optimal LC dose (1, 5, 10, 25 and50 mM) added to INRA-96®-and UHT-extenders (plus 6% egg yolk) in 9 individual fresh and chilled for 96 h semen ejaculates. A second experiment evaluated the effect of LC added to extenders: INRA-96 or UHT, and INRA-Freeze®or UHT (plus 5% glycerol), in 16 ejaculatespooled (n=8 pools, 2 ejaculates/pool)either chilled or frozen, respectively. The results demonstrated that 25 mM LC, successfully preserved the kinetics and integrity of plasma and acrosomal membranes in individual samples of cold-stored equine semen for 48 and 96 h. In pooled samples, diluted with INRA (96 or Freeze) and supplemented with LC, the sperm characteristics were better maintained than UHT-extender up to 72 h of cold storage. After the freezing-thawed process, LC supplementation to INRA-Freeze extender improved motility and plasma membrane integrity, while the addition to UHT-extender improved acrosomal membrane integrity. In conclusion, the addition of L-carnitine to skimmed milk-based extenders has a positive effect on the kinetics and integrity of plasma and acrosomal membranes of chilled and frozen-thawed equine sperm.
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    Effect of melatonin and caffeine supplementation to freezing medium on cryosurvival of peruvian paso horse sperm using a two-step accelerating cooling rate
    (2022) Dorado , Jesús; Saa, Luis Rodrigo; Galarza Lucero, Diego Andrés; Santiago Moreno, Julián; Tamay Siguenza, Erika Fabiola; Palacios Aguilar, María Paula; Pelaez Zhingri, Gabriela Micaela
    This research examined the antioxidant and cryoprotective effects of melatonin (ME) and caffeine (CAF) supplementation in freezing medium on the cryosurvival of Peruvian Paso horse sperm using a two-step accelerating cooling rate. Twenty ejaculates from four adult and fertile stallions were recovered, initially diluted with INRA-96 , and finally frozen with INRA-Freeze  with either no supplementation (as control), 1 mM ME, or 2mM CAF using a two-ramp freezing system content inside a cryogenic-box and liquid nitrogen vapors. The sperm kinematic parameters and integrity of the plasma and acrosomal membranes of fresh semen and cryopreserved samples were evaluated using the CASA system (SCA-Evolution  2018) and PI/fluorescein isothiocyanate-conjugated peanut (Arachis hypogaea) agglutinin double fluorescent test, respectively. The oxidative stress of post-thaw sperm samples was also assessed using the CellRox Deep Red fluorescence test. The results showed that curvilinear velocity and average-path velocity were greater ( p < 0.05) after freezing with CAF than the control group. In addition, there were significance differences ( p < 0.01) between stallions (1–4) in post-thaw kinematic parameters regardless of ME or CAF addition. Both ME and CAF improved (p < 0.05) the proportion of sperm with intact plasma membranes and intact acrosomes. Nevertheless, neither CAF nor ME improved the oxidative stress after the cryopreservation process.