Addition of synthetic amino acids in sheep semen improves its quality after cryopreservation / Adição de aminoácidos sintéticos no sêmen ovino melhora a qualidade espermática após a criopreservação do sêmen

Some amino acids can protect mammalian sperm cells against oxidation during thermal stress caused by freezing/thawing. Thus, the objective was to evaluate the protective action of the association of the amino acids L-proline (Pro) and L-glutamine (Glu) against the cryoinjury caused to sheep sperm after cryopreservation. Eight ejaculates were collected from four sheep (n=32) and diluted in Tris-Egg Yolk-Glycerol until the final concentration of 200 x106 sptz/mL and kept in a water bath at 32 °C. The amino acids were added as follows: control (without adding amino acids), Pro+Glu 1 (100 µM Pro + 500 µM Glu), Pro+Glu 2 (300 µMPro + 1000 µM Glu), Pro+Glu 3 (500 µM Pro + 1500 µM Glu) and Pro+Glu 4 (700 µM Pro + 2000 µM Glu). Afterwards, the semen was cooled to 5 °C for 2 h, after that period, filled in 0.5 mL straws and then placed under liquid nitrogen vapor (N2L), 8 cm from the liquid sheet for 15min, and then immersed on the N2L. The samples were analyzed for sperm motility, plasma membrane and acrosomal membrane integrity, mitochondrial activity and binding test. The variables were subjected to the normality tests (Lilliefors test) and homoscedasticity tests (Cochran and Bartlett test), afterwards the variables of normal distribution were subjected to analysis of variance and the means compared by the Tukey test with a significance level of 5%. The Pro+Glu 3 group exhibited sperm with a greater (P<0.05) motility after thawing. In addition, the highest percentage of plasma and acrosomal membrane integrity were obtained using Pro+Glu 1, Pro+Glu 2 and Pro+Glu 3; and Pro+Glu 2 and Pro+Glu 3, respectively. Amino acids also kept mitochondrial activity high compared to the control, with Pro+Glu 3 resulting in greater activity (P<0.05). Sperm viability was higher (P<0.05) with the use of Pro+Glu 2 and Pro+Glu 3 than in the control. The number of sperm that showed the ability to bind to the egg yolk perivitelline membrane was higher (P<0.05) in semen treated with amino acids. It is concluded that the addition of synthetic amino acids in the semen of sheep before cryopreservation improves sperm quality and fertilization potential and can thus be added in cryopreservation protocols.

Alguns aminoácidos podem proteger as células espermáticas de mamíferos contra a oxidação durante o estresse térmico causado na congelação/descongelação. Dessa forma, objetivou-se avaliar a ação protetora da associação dos aminoácidos L-prolina (Pro) e L-glutamina (Glu) contra as crioinjúrias causadas aos espermatozoides de ovino após a criopreservação. Foram coletados oito ejaculados de quatro carneiros (n=32) e diluídos em Tris-Gema de ovo-Glicerol até a concentração final de 200 x106 sptz/mL e, mantidos em banho maria a 32 °C. Os aminoácidos foram adicionados da seguinte forma: controle (sem adição de aminoácidos), Pro+Glu 1 (100 µM Pro + 500 µM Glu), Pro+Glu 2 (300 µM Pro + 1000 µM Glu), Pro+Glu 3 (500 µM Pro + 1500 µM Glu) e Pro+Glu 4 (700 µM Pro + 2000 µM Glu). Depois, o sêmen foi resfriado a 5 °C por 2 h, após esse período, envasado em palhetas de 0,5 mL e então acondicionado sob vapor de nitrogênio líquido (N2L), a 8 cm da lâmina líquida por 15 min, e depois imersos no N2L. As amostras foram analisadas quanto à motilidade espermática, integridade da membrana plasmática e da membrana acrossomal, atividade mitocondrial e teste de ligação. As variáveis foram submetidas aos testes de normalidade (Teste de Lilliefors) e homocedacidade (Teste de Cochran e Bartlett), posteriormente as variáveis de distribuição normal foram submetidas à análise de variância e as médias comparadas pelo teste de Tukey com nível de significância de 5%. O grupo Pro+Glu 3 exibiu espermatozoides com uma maior (P<0,05) motilidade após o descongelamento. Além disso o maior percentual de integridade da membrana plasmatica e acrossomal foram obtidos utilizando Pro+Glu 1, Pro+Glu 2 e Pro+Glu 3; e Pro+Glu 2 e Pro+Glu 3, respectivamente. Os aminoácidos também mantiveram alta a atividade mitocondrial em comparação com o controle, com Pro+Glu 3 resultando numa maior atividade (P<0,05). A viabilidade dos espermatozoides foi maior (P<0,05) com o uso de Pro+Glu 2 e Pro+Glu 3 do que no controle. O número de espermatozoides que apresentaram à capacidade de ligação a membrana perivitelina da gema de ovo foi maior (P<0,05) no sêmen tratado com aminoácidos. Conclui-se que, a adição dos aminoácidos sintéticos no sêmen de ovinos antes da criopreservação melhora a qualidade espermática e o potencial fecundante, podendo assim serem adicionados em protocolos de criopreservação.

Short-term buserelin administration induces apoptosis and morphological changes in adult rat testes

Abstract Purpose: To investigate the effect of buserelin on gonadal structure and function in adult male rats. Methods: Twenty-four adult Wistar male rats were divided into three groups: two treated groups and controls. The first and second treated groups received 300 (low dose) and 500 (high dose) µg/kg buserelin, respectively, and the control group received normal saline. All groups were treated subcutaneously for five days. Results: The seminiferous tubular epithelial thickness was significant decreased in the treated groups compared with those in the control. There was a significant increase in apoptotic cell death in high dose treated group compared with low dose treated and control groups. No significant difference in serum testosterone level was observed after one month in the three groups. Conclusion: Buserelin induces apoptotic cell death and decreased diameter and epithelium thickness of seminiferous tubules in the adult rat testes.

Effect of clomiphene citrate on sperm density in male partners of infertile couples.

Infertility is on the rise in today's world. A subnormal sperm count is frequently encountered in infertile couples. Clomiphene citrate, 1-[p-(beta-diethyl aminoethoxy) phenyl]-1,2-diphenyl chloroethylene, is an orally active nonsteroidal agent distantly related to diethylstilbestrol. It is thought to stimulate pituitary gonadotropin release by excluding estradiol from hypothalamic receptor sites. This interaction neutralizes the normal negative feedback control of estrogen and results in enhanced secretion of LH-RH, FSH-RH and gonadotropins. Testosterone is produced by the Leydig cells in response to LH secretion. The concentration of testosterone in the tubular environment is believed to maintain the gametogenic function of the testis. Clomiphene citrate in the dose of 25 mg daily for 25 days with five days rest was administered to 25 extreme oligozoospermic men (group I) and 40 moderate oligozoospermic men (group II) the cycle being continued for three months). Repeat semen analysis was done at the end of three months and all the routine seminal parameters were reevaluated. The data thus obtained was analyzed using Student's paired 't' test. The mean sperm count in Group I increased from 3.84 +/- 0.32 to 8.2 +/- 1.58 (P < 0.05) and in Group II from 13.05 +/- 0.48 to 24.55 +/- 1.73 (P < 0.001). The mean motile sperm count in Group I increased from 1.74 +/- 0.25 to 3.92 +/- 0.83 (P < 0.05) and in Group II from 8.27 +/- 0.40 to 10.05 +/- 0.56 (P < 0.01). Thus clomiphene citrate exerts its effect on spermatogenesis by raising the endogenous serum FSH, LH and testosterone levels to initiate and maintain gametogenesis (10). Researchers opined that this increase in endogenous gonadotrophins manifests itself in improving the sperm count, sperm motility and to certain extent morphology of the sperms, when there is no end-organ pathology.