Regulació energètica als espermatozoides

Investigadors de la Facultat de Veterinària han aprofundit en la comprensió dels mecanismes que utilitzen els espermatozoides dels porcs per a obtenir i regular la seva energia. La recerca mostra que el procés està regulat, principalment, per l'activitat d'un enzim, l'hexoquinasa, i pel nivell energètic de l'espermatozoide.Investigadores de la Facultat de Veterinària han profundizado en la comprensión de los mecanismos que utilizan los espermatozoides de los cerdos para obtener y regular su energía. La investigación muestra que el proceso está regulado, principalmente, por la actividad de una enzima, la hexoquinasa, y por el nivel energético del espermatozoide

La importància de la dopamina en la reproducció mamífera

Les funcions reproductives dels mamífers esdevenen un mecanisme biològic força complex i del que encara queda molt per saber. Tot i així, des de la Facultat de Veterinària de la Universitat Autònoma de Barcelona, amb col·laboració amb la Universidad Austral de Xile, han descobert quelcom que podria implementar els mecanismes de fecundació 'in vivo' d'alguns mamífers, incloent-hi l'home també. Són les catecolamines. Unes substàncies -entre les quals es troba la dopamina- que, tot i que són conegudes per la seva funció neurotransmissora, ara s'ha demostrat que la seva funcionalitat va més enllà. El motiu: la presència dopaminèrgica en el tracte vaginal d'algunes femelles, així com de receptors de dopamina de tipus 2 (DRD2) en espermatozoides. Aquest fet atorga una importància indubtable a les catecolamines durant el camí dels espermatozoides a través del tracte vaginal, donat que millora la viabilitat, la motilitat i la capacitació espermàtica. O almenys això s'ha demostrat en la incubació porcina mitjançant dopamina.Las funciones reproductivas de los mamíferos resultan ser un mecanismo biológico bastante complejo y del que aún queda mucho por saber. Aún así, desde la Facultad de Veterinaria de la Universitat Autònoma de Barcelona, con la colaboración de la Universidad Austral de Chile, han descubierto algo que podría implementar los mecanismos de fecundación 'in vivo' de algunos mamíferos, incluyendo al hombre también. Son las catecolaminas. Unas sustancias -entre las que se encuentra la dopamina-que, aunque son conocidas por su función neurotransmisora, ahora se ha demostrado que su funcionalidad va más allá. El motivo: la presencia dopaminérgica en el tracto vaginal de algunas hembras, así como de receptores de dopamina de tipo 2 (DRD2) en espermatozoides. Este hecho otorga una importancia indudable a las catecolaminas durante el camino de los espermatozoides a través del tracto vaginal, dado que mejora la viabilidad, la motilidad y la capacitación espermática. O al menos eso se ha demostrado en la incubación porcina mediante dopamina

Millorar el semen dels porcs per filtracions

La cria selectiva del ganat porcí no passa pels seus millors moments. Malgrat seleccionar els individus més productius i dessitjables des d'un punt de vista ramader, la qualitat de l'esperma dels mascles està disminuint a un ritme alarmant. Aquesta recerca ha desenvolupat un tractament per aplicar al semen, que consisteix en filtrar-lo a través d'unes resines concretes de sefarosa. Els resultats mostren una millora significativa en la qualitat de l'esperma i la mobilitat dels espermatozoides, doncs les resines emprades impedeixen el pas dels espermatozoides de menor qualitat.La cría selectiva del ganado porcino no pasa por sus mejores momentos. A pesar de seleccionar a los individuos más productivos y deseables desde un punto de vista ganadero, la calidad del esperma de los machos está disminuyendo a un ritmo alarmante. Esta investigación ha desarrollado un tratamiento para aplicar al semen, que consiste en filtrarlo a través de unas resinas concretas de sefarosa. Los resultados muestran una mejora significativa en la calidad del esperma y la movilidad de los espermatozoides, pues las resinas utilizadas impiden el paso de los espermatozoides de menor calidad

Criopreservació dels espermatozoides porcins

La inseminació artificial té una gran importància en el sector porcí i la criopreservació del semen és bàsica, sempre i quan es garanteixi una qualitat òptima dels espermatozoides. Durant el procés de congelació i descongelació, les condicions tèrmiques, hídriques i de l'equilibri osmòtic, posen a prova la resistència dels espermatozoides porcins. Aquesta recerca ha estudiat el paper que juguen els mitocondris en la regulació de la formació de substàncies oxidants, responsables de la degradació cel·lular.La inseminación artificial tiene una gran importancia en el sector porcino y la criopreservación del semen es básica, siempre y cuando se garantice una calidad óptima de los espermatozoides. Durante el proceso de congelación y descongelación, las condiciones térmicas, hídricas y de equilibrio osmótico, ponen a prueba la resistencia de los espermatozoides porcinos. Esta investigación ha estudiado el papel que juegan las mitocondrias en la regulación de la formación de sustancias oxidantes, responsables de la degradación celular

La funció dels sucres del semen dels mamífers

El semen dels mamífers conté sucres molt diversos, des de la glucosa, fins a la fructosa (sucre bàsicament d'origen vegetal, que rarament trobem en teixits animals) i les proporcions de cadascun divergeixen molt en cada espècie de mamífer, sense estar clara quina és la funció que hi desenvolupen. L'opció més òbvia semblava ser la de constituir un substrat energètic. Aquest estudi ha permès inferir que la principal funció que tenen els monosacàrids dins del plasma seminal de mamífers no és simplement la de base energètica, sinó la de reguladors funcionals dels espermatozoides rere l'ejaculació.El semen de los mamíferos contiene azúcares muy diversos, desde la glucosa, hasta la fructosa (azúcar básicamente de origen vegetal, que raramente encontramos en tejidos animales) y las proporciones de cada uno divergen mucho en cada especie de mamífero, sin estar clara cuál es la función que desarrollan. La opción más obvia parecía ser la de constituir un sustrato energético. Este estudio ha permitido inferir que la principal función que tienen los monosacáridos en el plasma seminal de mamíferos no es simplemente la de base energética, sino la de reguladores funcionales de los espermatozoides tras la eyaculación

Red-Light Irradiation of Horse Spermatozoa Increases Mitochondrial Activity and Motility through Changes in the Motile Sperm Subpopulation Structure

Previous studies in other mammalian species have shown that stimulation of semen with red-light increases sperm motility, mitochondrial activity, and fertilizing capacity. This study sought to determine whether red-light stimulation using a light emitting diode (LED) at 620-630 nm affects sperm motility and structure of motile subpopulations, sperm viability, mitochondrial activity, intracellular ATP levels, rate of O consumption and DNA integrity of horse spermatozoa. For this purpose, nine ejaculates were collected from nine different adult stallions. Upon collection, semen was diluted in Kenney extender, analyzed, its concentration was adjusted, and finally it was stimulated with red-light. In all cases, semen was packaged in 0.5-mL transparent straws, which were randomly divided into controls and 19 light-stimulation treatments; 6 consisted of a single exposure to red-light, and the other 13 involved irradiation with intervals of irradiation and darkness (light-dark-light). After irradiation, sperm motility was assessed using a Computerized Semen Analysis System (CASA). Flow cytometry was used to evaluate sperm viability, mitochondrial membrane potential and DNA fragmentation. Intracellular levels of ATP and O consumption rate were also determined. Specific red-light patterns were found to modify kinetics parameters (patterns: 4, 2-2-2, 3-3-3, 4-4-4, 5-1-5, and 5-5-5 min), the structure of motile sperm subpopulations (patterns: 2, 2-2-2, 3-3-3, and 4-1-4 min), mitochondrial membrane potential (patterns: 4, 3-3-3, 4-4-4, 5-1-5, 5-5-5, 15-5-15, and 15-15-15 min), intracellular ATP levels and the rate of O consumption (pattern: 4 min), without affecting sperm viability or DNA integrity. Since the increase in some kinematic parameters was concomitant with that of mitochondrial activity, intracellular ATP levels and O consumption rate, we suggest that the positive effect of light-irradiation on sperm motility is related to its impact upon mitochondrial activity. In conclusion, this study shows that red LED light stimulates motility and mitochondrial activity of horse sperm. Additional research is needed to address the impact of red-light irradiation on fertilizing ability and the mechanisms through which light exerts its effects

Presence and Function of Dopamine Transporter (DAT) in Stallion Sperm : Dopamine Modulates Sperm Motility and Acrosomal Integrity

Dopamine is a catecholamine with multiple physiological functions, playing a key role in nervous system; however its participation in reproductive processes and sperm physiology is controversial. High dopamine concentrations have been reported in different portions of the feminine and masculine reproductive tract, although the role fulfilled by this catecholamine in reproductive physiology is as yet unknown. We have previously shown that dopamine type 2 receptor is functional in boar sperm, suggesting that dopamine acts as a physiological modulator of sperm viability, capacitation and motility. In the present study, using immunodetection methods, we revealed the presence of several proteins important for the dopamine uptake and signalling in mammalian sperm, specifically monoamine transporters as dopamine (DAT), serotonin (SERT) and norepinephrine (NET) transporters in equine sperm. We also demonstrated for the first time in equine sperm a functional dopamine transporter using 4-[4-(Dimethylamino)styryl]-N-methylpyridinium iodide (ASP+ ), as substrate. In addition, we also showed that dopamine (1 mM) treatment in vitro, does not affect sperm viability but decreases total and progressive sperm motility. This effect is reversed by blocking the dopamine transporter with the selective inhibitor vanoxerine (GBR12909) and non-selective inhibitors of dopamine reuptake such as nomifensine and bupropion. The effect of dopamine in sperm physiology was evaluated and we demonstrated that acrosome integrity and thyrosine phosphorylation in equine sperm is significantly reduced at high concentrations of this catecholamine. In summary, our results revealed the presence of monoamine transporter DAT, NET and SERT in equine sperm, and that the dopamine uptake by DAT can regulate sperm function, specifically acrosomal integrity and sperm motility

The increase in phosphorylation levels of serine residues of protein HSP70 during holding at 17ºC is concomitant with a higher cryotolerance of boar spermatozoa

Boar-sperm cryopreservation is not usually performed immediately after semen collection, but rather a holding time (HT) of 4 h-30 h at 17 u C is spent before starting this procedure. Taking this into account, the aim of this study was to go further in- depth into the mechanisms underlying the improving effects of HT at 17 u C on boar-sperm cryotolerance by evaluating the effects of two different HTs (3 h and 24 h) on overall boar-sperm function and survival before and after cryopreservation. Given that phospho/dephosphorylation mechanisms are of utmost importance in the overall regulation of sperm function, the phosphorylation levels of serine residues (pSer) in 30 different sperm proteins after a 3 h- or 24 h-HT period were also assessed. We found that a HT of 24 h contributed to a higher sperm resistance to freeze-thawing procedures, whereas mini-array protein analyses showed that a HT of 24 h induced a significant (P,0.05) increase in pSer (from 100.06 1.8 arbitrary units in HT 3 h to 150.2 65.1 arbitrary units in HT 24 h) of HSP70 and, to a lesser extent, in protein kinases GSK3 and total TRK and in the cell-cycle regulatory protein CDC2/CDK1. In the case of HSP70, this increase was confirmed through immunoprecipation analyses. Principal component and multiple regression analyses indicated that a component explaining a percentage of variance higher than 50% in sperm cryotolerance was significantly correlated with pSer levels in HSP70. In addition, from all the parameters evaluated before freeze-thawing, only pSer levels in HSP70 resulted to be able to predict sperm cryotolerance. In conclusion, our results suggest that boar spermatozoa modulate its function during HT, at least partially, by changes in pSer levels of proteins like HSP70, and this is related to a higher cryotoleranc

The Effects of Red Light on Mammalian Sperm Rely upon the Color of the Straw and the Medium Used

Several studies have shown that the exposure of semen to red light improves sperm quality and fertilizing ability, which could improve the efficiency of assisted reproductive techniques with irradiated semen. However, despite being considered as possible sources of variation, the effects of the color of the container (straws) or the medium have not yet been evaluated. In this study, 13 ejaculates from different stallions were split into equal fractions, diluted either with Kenney or Equiplus extender, and subsequently packed into straws of five different colors. After storage at 4 °C for 24 h, the sperm were irradiated and different variables, including sperm motility, plasma membrane integrity, and mitochondrial membrane potential, were evaluated. Our results confirm that irradiation increases some motion characteristics and mitochondrial membrane potential without affecting sperm viability and demonstrate that the effects depend on the color of the straw and the extender used. Previous research has determined that irradiation of mammalian sperm with red light increases motility, mitochondrial activity, and fertilization capacity. In spite of this, no study has considered the potential influence of the color of the straw and the extender used. Therefore, this study tests the hypothesis that the response of mammalian sperm to red light is influenced by the color of the straw and the turbidity/composition of the extender. Using the horse as a model, 13 ejaculates from 13 stallions were split into two equal fractions, diluted with Kenney or Equiplus extender, and stored at 4 °C for 24 h. Thereafter, each diluted fraction was split into five equal aliquots and subsequently packed into 0.5-mL straws of red, blue, yellow, white, or transparent color. Straws were either nonirradiated (control) or irradiated with a light-dark-light pattern of 3-3-3 (i.e., light: 3 min, dark: 3 min; light: 3 min) prior to evaluating sperm motility, acrosome and plasma membrane integrity, mitochondrial membrane potential, and intracellular ROS and calcium levels. Our results showed that irradiation increased some motion variables, mitochondrial membrane potential, and intracellular ROS without affecting the integrities of the plasma membrane and acrosome. Remarkably, the extent of those changes varied with the color of the straw and the extender used; the effects of irradiation were more apparent when sperm were diluted with Equiplus extender and packed into red-colored straws or when samples were diluted with Kenney extender and packed into transparent straws. As the increase in sperm motility and intracellular ROS levels was parallel to that of mitochondrial activity, we suggest that the impact of red light on sperm function relies upon the specific rates of energy provided to the mitochondria, which, in turn, vary with the color of the straw and the turbidity/composition of the extender

The addition of reduced glutathione to cryopreservation media induces changes in the structure of motile subpopulations of frozen-thawed boar sperm

Adding cryopreservation media with reduced glutathione (GSH) has previously been shown to maintain the motility, membrane integrity and fertilizing ability of frozen-thawed boar sperm, although the effects of GSH on good (GFE) and poor freezability (PFE) ejaculates rely upon the intrinsic ejaculate freezability. The resilience to withstand freeze-thawing procedures has previously been related to the existence of a specific distribution of motile sperm subpopulations, which differs between GFE and PFE. Thus, the main aim of this study was to determine whether the addition of GSH to freezing media has any impact on the distribution of motile sperm subpopulations in GFE and PFE. With this purpose, 18 GFE and 13 PFE were cryopreserved with or without 2 mM GSH. Sperm quality and motile subpopulations were evaluated at 30 min and 4 h post-thawing. Three subpopulations were identified and the percentages of spermatozoa belonging to the fastest and most linear subpopulation, which was referred as 'SP1', decreased over post-thawing time. Good freezability ejaculates that were cryopreserved in the presence of 2 mM exhibited a significantly higher percentage of spermatozoa belonging to SP1 than the other combinations of treatment and freezability both at 30 min (mean ± SEM: GFE-C: 16.6 ± 0.4; GFE-GSH 27.7 ± 0.6) and 4 h post-thawing (GFE-C: 7.8 ± 0.2 vs