278 research outputs found
Secretion of D-aspartic acid by the rat testis and its role in endocrinology of the testis and spermatogenesis
No full textAbstractThe D-isomer of aspartic acid (D-Asp) has been found in rat testes. In the present study, samples of testicular venous blood plasma, rete testis fluid, interstitial extracellular fluid, luminal fluid from the seminiferous tubules, testicular parenchymal cells, epididymal spermatozoa and peripheral blood plasma were collected and analyzed for D-Asp by two methods, an enzymatic and a chromatographic HPLC method. The two methods gave very similar results for all samples. The highest concentrations of D-Asp (about 120 nmol/ml) were found in testicular venous blood plasma, with slightly lower concentrations in rete testis fluid (95 nmol/ml) and epididymal spermatozoa (80 nmol/g wet weight). Lower levels were found in testicular parenchymal cells (which would comprise mostly spermatids and spermatocytes), luminal fluid from the seminiferous tubules and interstitial extracellular fluid (26, 23 and 11 nmol/ml respectively). However, these values were all higher than those for peripheral blood plasma (6 nmol/ml). It would appear that D-Asp is being secreted by the testis mostly into the venous blood, passing thence into the rete testis fluid and being incorporated into the spermatozoa at the time or after they leave the testis. The distribution of D-Asp is thus quite different from that of testosterone, and its role and the reason for its high concentration in the male reproductive tract remain to be elucidated
Semen and its constituents
No full textAbstractThe chemical composition and characteristics of semen are presented.Brian P. Setchel
Interleukin-18 is expressed in rat testis and may promote germ cell growth
No full textMona-Lisa Strand, Aida Wahlgren, Konstantin Svechnikov, Cecilia Zetterstroma, Brian P. Setchell, Olle Sode
Unusual germ cell organization in the seminiferous epithelium of a murid rodent from southern Asia, the greater bandicoot rat, Bandicota Indica
No full textThe definitive version is available at www.blackwell-synergy.comIn the greater bandicoot rat, Bandicota indica, of south-east Asia, nine cell associations were documented in the testicular seminiferous epithelium. In about 10% of the tubule cross sections two or more cell associations occurred and, furthermore, some of the generations of germ cells within the cell associations were sometimes either out of phase, or missing, in the tubule cross sections. These features, together with the fact that this species has a highly pleiomorphic sperm head shape, are somewhat reminiscent of those of the seminiferous epithelium in humans and some other primates but not of common laboratory rodents. This species could thus be a good model for investigating irregular patterns of spermatogenesis in naturally occurring wild species of rodent.P. Worawittayawong, C. M. Leigh, G. Cozens, E. J. Peirce, B. P. Setchell, P. Sretarugsa, A. Dharmarajan, W. G. Bree
The effect of paternal diet-induced obesity on sperm function and fertilization in a mouse model
No full textAlthough obvious effects of obesity on female reproduction and oocytes are emerging, the effects on male fertility and sperm quality are less clear with studies reporting conflicting results. We hypothesize that male obesity affects sperm function and physiology probably as a result of elevated oxidative stress in spermatozoa and therefore elevated levels of sperm DNA damage and loss of function. Six-week-old C57/Bl6 male mice (n = 36) were randomly allocated to two groups: group 1 (n = 18) received a control diet, whereas group 2 (n = 18) received a high-fat diet (HFD). At the completion of a 9-week period, mice were sacrificed and spermatozoa were obtained. Sperm motility, concentration, intracellular reactive oxygen species (ROS) production and sperm DNA damage were measured. The ability of the sperm to undergo capacitation, acrosome reaction, sperm binding and ability to fertilize an oocyte were also assessed. The percentage of motile spermatozoa was decreased in the HFD group compared with controls (36 ± 2% vs. 44 ± 4%; p < 0.05). Intracellular ROS was elevated (692 ± 83 vs. 409 ± 22 units; p < 0.01) in the HFD group compared with controls. Sperm DNA damage was also increased (1.64 ± 0.6% vs. 0.17 ± 0.06%; p < 0.05) in the HFD group compared with the control group. Furthermore, the percentage of non-capacitated sperm was significantly lower compared with controls (12.34% vs. 21.06%; p < 0.01). The number of sperm bound to each oocyte was significantly lower (41.14 ± 2.5 vs. 58.39 ± 2.4; p < 0.01) in the HFD group compared with that in controls and resulted in significantly lower fertilization rates (25.9% vs. 43.9%; p < 0.01). This report provides evidence that obesity may induce oxidative stress and sperm DNA damage as well as decreased fertilizing ability. This is important as DNA damage in the sperm as a result of oxidative stress has been linked to poor reproductive outcomes.H. W. Bakos, M. Mitchell, B. P. Setchell and M. Lan
The recycling of carbon in glucose, lactate and alanine in sheep
No full textPregnant ewes with catheters implanted in an artery and the uterine and recurrent tarsal veins were infused at a constant rate with U−¹⁴C-labelled glucose, alanine or bicarbonate. Measurements were made of the overall and local fractional contribution of glucose and alanine to CO₂ production and of the extent of interconversion of these metabolites. In the whole animal, by coupling the results with the authors’ previous study of lactate metabolism, a solution was obtained to an open unrestricted 4-compartment model of the exchange of carbon between glucose, lactate, alanine and CO₂. A more limited study was made with non-pregnant sheep because complete data for lactate interactions with alanine were not available. Our analysis of glucose/lactate/alanine/CO₂ interactions in pregnant sheep suggests that about two-thirds of the glycogenic carbon was oxidised fairly directly to CO₂. There was relatively little recycling of glucose carbon through lactate and alanine so that most of the remaining glycogenic carbon was stored as product with relatively long turnover time. It is possible that much of this was in the form of muscle glycogen, and analysis of glycogenic carbon exchange across the hind limb muscle was consistent with this conclusion. In non-pregnant ewes, the findings, although incomplete, suggested that there were no great differences from the findings in pregnant ewes.Derek B. Lindsay, Patrick J. Barker, Andrew J. Northrop, Brian P. Setchell, Graham J. Faichne
Whole body heat exposure induces apoptosis in mouse caudal epididymal spermatozoa
No full textPaper 115, Abstracts only published 40th Annual Conference of the Society for Reproductive Biology
Introduction: The aim of the present study was to determine the immediate effects of whole body heating on sperm numbers, motility and apoptosis. Material and Methods: C57BL/6 mice (n=7) were exposed to 37-38oC (8 hours/day), for three consecutive days while control mice (n=7) were kept at 23-24oC. Caudal epididymal spermatozoa were collected from control and heat treated mice 16 hours after the last heat treatment to determine the sperm number and motility using a Neubauer haemocytometer and sperm apoptotic changes by dual colorflow cytometry using Annexin V/PE (Annexin V conjugated with phycoerythrin) and 7AAD (7-amino-actinomycin D) stains. Results: There were no significant differences (p>0.05) in sperm numbers between heat treated and control mice, however heating did result in a significant reduction in sperm motility (p<0.05). Apoptosis staining identified four different subpopulations of spermatozoa: (a) live spermatozoa (Annexin V-/7AAD-), (b) early apoptotic spermatozoa with exteriorized phosphotidylserine (PS) receptor and intact plasmalemma (Annexin V+/7AAD-), (c) late apoptotic spermatozoa with PS receptor translocation and leaky plasmalemma (Annexin V+/7AAD+) and (d) dead spermatozoa with damaged plasmalemma with no detectable PS receptor (Annexin V-/7AAD+). Heating resulted in significant reduction in the percentage of live spermatozoa (p<0.05), an increase in early apoptotic (p<0.05), late apoptotic (p<0.05), and dead spermatozoa (p<0.05). Conclusion: This study shows that mice exposed to whole body heat exposure of 37-38oC for 8 hours per day for three consecutive days exhibited early and late apoptotic changes to epididymal spermatozoa. These findings suggest possible adverse effects of exposure to high temperature on the viability of human spermatozoa in the epididymides. In addition, these findings reinforce the importance of temperature during sperm preparation procedures in infertility clinics, and research laboratories.
H. Wechalekar, B.P. Setchell, W. G. Breed, M. Ricci, C. Leigh and E. Peirc
The penetration of chromium-EDTA from blood plasma into various compartments of rat testes as an indicator of function of the blood-testis barrier after exposure of the testes to heat
No full textThe concentration of chromium⁵¹–EDTA in blood plasma after an intravenous infusion was found to be about 40 times that present in rete testis fluid and 20 times that in the additional seminiferous tubular fluid resulting from ligation of the efferent ducts. These values indicate the effectiveness of the blood–testis barrier to small water-soluble molecules, like Cr–EDTA. The volume of distribution in microlitres of Cr–EDTA in the parenchyma was about 60% of the volume of the interstitial tissue as determined on frozen sections by morphometry, and was similar, or slightly less, in the ligated testes, compared with the unligated testes. Heating the testes to 43°C for 30 min led to the expected reduction several days later in testis mass, but the volume of distribution of Cr–EDTA was no greater than that in the testes of control rats, and the ratio of Cr–EDTA space to interstitial tissue was not different, while the concentration of Cr–EDTA in the additional seminiferous tubular fluid increased only slightly as testis mass fell. These results indicate that the blood–testis barrier was only slightly less effective, if changed at all, during the period of spermatogenic disruption following local heating of the testis.B. P. Setchell, L. Tao and J. L. Zup
SIRT6 in mouse spermatogenesis is modulated by diet-induced obesity
No full textMale obesity is associated with reduced sperm function and increased incidence of sperm DNA damage; however, the underlying molecular mechanisms have not yet been identified. Mammalian SIRT6 protein is involved in caloric-dependant DNA damage repair in other tissue types, yet a possible role for SIRT6 in male obesity and subfertility has not been investigated previously. To assess SIRT6 levels and activity in the testes, male mice (n = 12 per diet) were fed either a control diet (CD; 6% fat) or a high-fat diet (HFD; 21% fat) for 16 weeks before the collection of testes and spermatozoa. SIRT6 protein was localised to the nucleus of transitional spermatids and the acrosome of mature spermatozoa, with levels significantly decreased in HFD-fed male mice (P < 0.05). This decrease in SIRT6 protein was associated with transitional spermatids having increased levels of acetylated H3K9 in the nucleus (P < 0.01) and increased DNA damage (P < 0.001). We propose a role for SIRT6 in spermiogenesis and potentially protamination processes, which are known to be compromised by male obesity.Nicole O. Palmer, Tod Fullston, Megan Mitchell, Brian P. Setchell and Michelle Lan
Whole-body heat exposure induces membrane changes in spermatozoa from the cauda epididymidis of laboratory mice
No full textThis study was carried out to determine if exposure to hot environmental temperatures had a direct, detrimental effect on sperm quality. For this the effect of whole-body heat exposure on epididymal spermatozoa of laboratory mice was investigated. C57BL/6 mice (n = 7) were housed in a microclimate chamber at 37ºC–38ºC for 8 h per day for three consecutive days, while control mice (n = 7) were kept at 23ºC–24ºC. Cauda epididymal spermatozoa were obtained 16 h after the last heat treatment. The results showed that sperm numbers were similar in the two groups (P = 0.23), but after heat treatment, a significant reduction in the percentage of motile sperm was present (P < 0.0001). Membrane changes of the spermatozoa were investigated by staining with phycoerythrin (PE)- conjugated Annexin V, which detects exteriorization of phosphotidylserine from the inner to the outer leaflet of the sperm plasma membrane, and 7-aminoactinomycin D (7-AAD), which binds to the sperm nucleus when the plasma membrane is damaged. The percentage of spermatozoa showing positive staining with Annexin V–PE or 7-AAD or both, was significantly higher (P < 0.05) in heat-exposed mice compared with controls. These results show that whole-body heat exposure to 37ºC–38ºC induces membrane changes in the epididymal spermatozoa of mice, which may lead to apoptosis.Harsha Wechalekar, Brian P. Setchell, Eleanor J. Peirce, Mario Ricci, Chris Leigh and William G. Bree
- …
