Influência da temperatura sobre a função testicular

As células da linhagem germinativa são sensíveis a ação do calor, sendo a termorregulação um fator determinante para o sucesso reprodutivo. O aumento da temperatura testicular pode ocorrer devido a fatores internos ou externos e contribui para o aumento da produção de espécies reativas de oxigênio e nitrogênio, induzindo, assim, a degeneração testicular e perda de células germinativas. Em adição, mudanças nos níveis de testosterona e de corticosteroides em animais submetidos ao estresse térmico podem ser observadas e interferem na capacidade reprodutiva dos mesmos. Por outro lado, em resposta ao calor e com finalidade protetora, há o aumento da síntese de proteínas de choque térmico (HSP). Desta forma, a quantidade e qualidade do sêmen e, consequentemente, a fertilidade são comprometidas pelo estresse térmico testicular, o que torna a realização de estudos que aprofundem o conhecimento sobre as alterações causadas indispensáveis, inclusive para a busca de terapias que preservem e reparem as funções testiculares.

Evaluation of Corpus Luteum Vascularization in Recipient Mares by Using Color Doppler Ultrasound

Background: Embryo transfer is one of the most commonly used reproductive biotechnique. The success of embryo transfer is also affected by the synchrony of estrus and ovulation between donor and recipient animals. In horse reproduction, ultrasonography has been used, among other purposes, to diagnose early pregnancy. However, only the color Doppler imaging mode makes it possible to evaluate the vascular architecture and the hemodynamic aspects of the vessels in several organs, especially the corpus luteum. The objective of this study was to evaluate, based on the color Doppler ultrasound, the corpus luteum vascularization and function from recipient mares at embryo transfer timing.Materials, Methods & Results: Mangalarga Machador mares from 5 to 10-year-old and a range of live weights of between 350 to 450 kg were used for this experiment, kept in pasture-based on mombaça grass (Panicum maximum) and were given ad libitum access to water and mineral supplementation. The animals (n = 15) were gynecologically examined and uterine consistency was evaluated by rectal palpation the same operator using an ultrasound system (SonoScape®) with a linear transducer, and operating frequency ranging from 5 to 10 Mhz. The uterine tone was classified between grades 1 and 4 and subjected to ovulation induction. The objective and subjective vascular perfusion of the corpus luteum was evaluated by color Doppler ultrasound on the day of embryo transfer and endometrium. The determination progesterone concentration on the day of the embryo transfer was performed by direct chemiluminescence assay. The arcsine (√P/100) transformation was applied to the percentage data, and the results were expressed as mean (.) ± standard error of the mean (SEM). Further, the assumptions of normality and homoscedasticity were verified, respectively, based on the Shapiro-Wilk and Lilliefors tests. Regarding the parametric and non-parametric variables, were applied, respectively, analysis of variance (ANOVA) followed by Tukey’s test, and the Kruskal-Wallis test followed by Dunn’s test. Pearson’s correlation coefficient was used to evaluate the relationship between the parameters. The statistical program SPSS 16.0 was used to perform the over-mentioned analyses, and a p-value 0.05).Discussion: Mares that later became pregnant showed a higher concentration of progesterone as an outcome of the higher vascularization in the corpus luteum. It can be supported by both the correlation between the progesterone concentration and the corpus luteum vascular perfusion, as well as by the higher values of the vascular perfusion in pregnant mares. Based on the results, it has been concluded that the color Doppler ultrasound evaluation is an accurate tool to determine the corpus luteum vascularization, whether considering the objective or subjective methods. Also, the vascular perfusion is the most efficient parameter to determine both the corpus luteum function and to predict the ability of the recipient mares to maintain pregnancy

The use of açaí as a potential antioxidant for bovine semen cryopreservation

Semen cryopreservation is an important tool for animal reproduction due to its potential for fast dissemination of genetics from males with high genetic merit. However, cryopreservation protocols continue to provoke negative effects on sperm cell structure and function, thus leading to lower viability. This reduction in viability is correlated with excessive production of reactive oxygen species (ROS) that generate oxidative stress, which is responsible for lowering sperm motility, alteration in plasma membrane fluidity, and lipidic peroxidation. Due to these facts, it becomes necessary to add substances with the antioxidant potential for semen cryopreservation to confer additional protection to sperm cells. A variety of compounds from plants and fruits have been incorporated to such media due to their antioxidant potential. In such context, açaí has gained attention by researchers due to its substantial antioxidant capacity, particularly attributed to its polyphenolic fraction, which is rich in anthocyanins. Moreover, it also contains resveratrol and quercetin in its composition, which has activity against free radicals. In general terms, the antioxidant of natural sources (i.e., açaí) deserves special attention since it contributes to the preservation of the national flora, also displays a significant potential to improve the quality of frozen-thawed bovine semen

Use of grayscale histogram to assess testicular changes in ram caused by heat stress

Because it detects discrete changes in tissue density, ultrasound allows an early diagnosis of physiologic changes, especially when dealing with subclinical changes. aimed to evaluate the use of quantitative analysis of the gray scale of ultrasound images of ovine testicles as a method for early diagnosis of testicular changes caused by heat stress. Testicles from ten ovine were insulated and then evaluated regarding echogenicity, echotexture, anatomical measurements, and seminal characteristics. Echogenicity was the first variable to show changes during the insulation period, as well as the first one to show evidence of regeneration of those changes. There was a correlation (p 0.05) in echotexture. Testicular measurements were only altered (p < 0.05) after insulation; however, the structural integrity of the seminiferous tubules was not altered. Echogenicity is an efficient ultrasound parameter for the early diagnosis of a testicular degenerative process as well as for the early diagnosis of its regeneration

Use of grayscale histogram to assess testicular changes in ram caused by heat stress

Because it detects discrete changes in tissue density, ultrasound allows an early diagnosis of physiologic changes, especially when dealing with subclinical changes. aimed to evaluate the use of quantitative analysis of the gray scale of ultrasound images of ovine testicles as a method for early diagnosis of testicular changes caused by heat stress. Testicles from ten ovine were insulated and then evaluated regarding echogenicity, echotexture, anatomical measurements, and seminal characteristics. Echogenicity was the first variable to show changes during the insulation period, as well as the first one to show evidence of regeneration of those changes. There was a correlation (p &lt; 0.05) between echogenicity and sperm vigor, motility, and mass sperm motility, as well as a correlation (p &lt; 0.05) between echotexture and motility. Echogenicity, motility, vigor, and mass sperm motility decreased (p &lt; 0.05) within four days of testicular insulation, and there was no change (p &gt; 0.05) in echotexture. Testicular measurements were only altered (p &lt; 0.05) after insulation; however, the structural integrity of the seminiferous tubules was not altered. Echogenicity is an efficient ultrasound parameter for the early diagnosis of a testicular degenerative process as well as for the early diagnosis of its regeneration.Because it detects discrete changes in tissue density, ultrasound allows an early diagnosis of physiologic changes, especially when dealing with sub-clinical changes. The study aimed to evaluate the use of quantitative analysis of the grayscale of ultrasound images of ovine testicles as a method for early diagnosis of testicular changes caused by heat stress. Testicles from ten rams were insulated and then evaluated regarding echogenicity, echotexture, anatomical measurements, and seminal characteristics. Echogenicity was the first variable to show changes during the insulation period, as well as the first one to show evidence of regeneration of those changes. There was a correlation (p &lt; 0.05) between echogenicity and sperm vigor, sperm motility, and mass sperm motility, as well as a correlation (p &lt; 0.05) between echotexture and motility. Echogenicity, sperm motility, vigor, and mass sperm motility decreased (p &lt; 0.05) within four days of testicular insulation, and there was no change (p &gt; 0.05) in echotexture. Testicular measurements were only altered (p &lt; 0.05) after insulation. Echogenicity is an efficient ultrasound parameter for the early diagnosis of a testicular degenerative process as well as for the early diagnosis of its regeneration

Evaluation of Corpus Luteum Vascularization in Recipient Mares by Using Color Doppler Ultrasound

Background: Embryo transfer is one of the most commonly used reproductive biotechnique. The success of embryo transfer is also affected by the synchrony of estrus and ovulation between donor and recipient animals. In horse reproduction, ultrasonography has been used, among other purposes, to diagnose early pregnancy. However, only the color Doppler imaging mode makes it possible to evaluate the vascular architecture and the hemodynamic aspects of the vessels in several organs, especially the corpus luteum. The objective of this study was to evaluate, based on the color Doppler ultrasound, the corpus luteum vascularization and function from recipient mares at embryo transfer timing.Materials, Methods &amp; Results: Mangalarga Machador mares from 5 to 10-year-old and a range of live weights of between 350 to 450 kg were used for this experiment, kept in pasture-based on mombaça grass (Panicum maximum) and were given ad libitum access to water and mineral supplementation. The animals (n = 15) were gynecologically examined and uterine consistency was evaluated by rectal palpation the same operator using an ultrasound system (SonoScape®) with a linear transducer, and operating frequency ranging from 5 to 10 Mhz. The uterine tone was classified between grades 1 and 4 and subjected to ovulation induction. The objective and subjective vascular perfusion of the corpus luteum was evaluated by color Doppler ultrasound on the day of embryo transfer and endometrium. The determination progesterone concentration on the day of the embryo transfer was performed by direct chemiluminescence assay. The arcsine (√P/100) transformation was applied to the percentage data, and the results were expressed as mean (.) ± standard error of the mean (SEM). Further, the assumptions of normality and homoscedasticity were verified, respectively, based on the Shapiro-Wilk and Lilliefors tests. Regarding the parametric and non-parametric variables, were applied, respectively, analysis of variance (ANOVA) followed by Tukey’s test, and the Kruskal-Wallis test followed by Dunn’s test. Pearson’s correlation coefficient was used to evaluate the relationship between the parameters. The statistical program SPSS 16.0 was used to perform the over-mentioned analyses, and a p-value &lt; 0.05 was taken as significant. Corpus luteum vascular perfusion, based on the objective and subjective evaluation methods, and the progesterone concentration were higher in the pregnant mares (P &lt; 0.05). The objective and subjective methods for evaluation of the vascular perfusion in the corpus luteum were positively correlated between themselves as well as to progesterone concentration (P &lt; 0.05). There was no significant difference between the groups considering the uterine tonus evaluation (P &gt; 0.05).Discussion: Mares that later became pregnant showed a higher concentration of progesterone as an outcome of the higher vascularization in the corpus luteum. It can be supported by both the correlation between the progesterone concentration and the corpus luteum vascular perfusion, as well as by the higher values of the vascular perfusion in pregnant mares. Based on the results, it has been concluded that the color Doppler ultrasound evaluation is an accurate tool to determine the corpus luteum vascularization, whether considering the objective or subjective methods. Also, the vascular perfusion is the most efficient parameter to determine both the corpus luteum function and to predict the ability of the recipient mares to maintain pregnancy