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B P Setchell

Publications and source records attributed to B P Setchell.

At least 19 recordsLinked to original sources
PubMed2002

Expression of a blood-brain barrier-specific antigen in the reproductive tract of the male rat.

The endothelial barrier antigen (EBA) is a protein expressed specifically by the endothelial cells of the rat brain barrier vessels. This antigen has been described as a 'barrier protein' and is used as a marker for the competent blood-brain barrier. A blood-testis barrier has also been described. However, unlike the blood-brain barrier, which is formed by endothelial cells, the blood-testis barrier is formed mainly by the Sertoli cells, which provide an isolated environment for spermatogenic cells within the seminiferous tubules. Testicular blood vessels express the erythroid glucose transporter protein and other markers, which are strongly expressed in brain blood vessels, and may contribute to the blood-testis barrier. This study was carried out to determine whether Sertoli cells or testicular blood vessels express EBA. Tissues of other organs were used as controls for EBA expression. EBA was expressed by the endothelial cells in most microvessels of the testis, and in a few vessels of the epididymis, seminal vesicle, prostate gland, vas deferens and bladder-neck region. Furthermore, EBA was strongly and consistently detected in epithelial cells of the rete testis and dorsolateral prostate gland, and in a few epithelial cells of the ventral prostate gland, the seminal vesicle and the coagulating gland. However, Sertoli cells, which are the main site of the blood-testis barrier, were negative for EBA. In conclusion, EBA may have a wider role in rat tissues than has been previously appreciated.

Animals↗
PubMed2002

Effect of local heating of rat testes after suppression of spermatogenesis by pretreatment with a GnRH agonist and an anti-androgen.

The effects of local heating of rat testes, in which spermatogenesis had been suppressed with injections of a GnRH agonist and an anti-androgen, were examined. Although the detrimental effects of heating were not as marked as those found in the testes of non-injected rats, the testes in which spermatogenesis was suppressed also showed a significant reduction in mass, the number of spermatozoa, tubular diameter and the percentage of normal tubular cross-sections at day 35 after heating. The results indicate that heating has an effect on cells in the testis other than those shown to be most susceptible to heat, namely pachytene spermatocytes and early spermatids, which were absent or markedly reduced in number when spermatogenesis was suppressed. The long-term effects of heating on the above parameters, as reported in a previous study, were also confirmed. However, in testes in which spermatogenesis was suppressed at the time of heating, there appeared to be no or a reduced long-term impairment of spermatogenesis, as determined by testis mass, the percentage of qualitatively normal tubules and epididymal sperm counts.

Analysis of Variance↗
PubMed2002

How much LH do the Leydig cells see?

The purpose of this study was to assess the concentrations of LH that Leydig cells are exposed to upon in vivo stimulation of steroidogenesis. The concentrations of LH were measured in rats in testicular interstitial extracellular fluid, seminiferous tubular fluid and blood plasma from testicular veins from one testis before and from the other testis of the same rats after an intravenous injection of gonadotrophin-releasing hormone (GnRH) or saline, and compared with the concentrations in blood plasma from a peripheral vein. The concentrations of LH in interstitial fluid surrounding the Leydig cells before the injections were about 10% of the levels in blood plasma, and showed no significant rise at 15 min and a much smaller rise at later times in rats injected with GnRH than those seen in blood plasma from either of the two sources, which were similar. The concentrations of LH in tubular fluid were even lower and showed no change after GnRH. Testosterone concentrations in testicular cells, interstitial fluid and testicular venous blood plasma were significantly increased by 15 min after GnRH, when compared with saline-injected controls, with no change in the levels in tubular fluid. The rise in testosterone concentrations in testicular venous plasma after GnRH was smaller than those in the cells and interstitial fluid. In conclusion, the concentrations of LH reaching the testicular interstitial fluid were only about one-tenth of that measured in the circulation, presumably because the endothelial cells restrict access of the hormone to the interstitial fluid. This indicated that either the Leydig cells are extremely sensitive to LH stimulation or that testicular endothelial cells modulate the action of LH on the Leydig cells.

Animals↗
PubMed2001

Endotoxin-induced interleukin 1 expression in testicular macrophages is accompanied by downregulation of the constitutive expression in Sertoli cells.

Interleukin-1alpha (IL-1alpha) is constitutively produced by Sertoli cells in adult rat testes. We demonstrate here that adult rats initiate expression of IL-1alpha and IL-1beta in testicular macrophages and decrease plasma testosterone by 60%, 2 h after administration of endotoxin. The macrophage activation was accompanied by downregulation of IL-1alpha mRNA expression in Sertoli cells. Despite increased tissue concentrations of IL-1alpha and IL-1beta immunoreactive protein, the level of bioactive IL-1 in the testis remained unchanged. Testes from prepubertal rats responded similarly to endotoxin, but lacked constitutive expression of IL-1alpha. We conclude that endotoxin-induced inflammation involves the testis by local macrophage activation and cytokine secretion. The paracrine mechanisms regulating IL-1 bioactivity in the testis are unknown but may represent a means to protect germ cells from noxious effects of inflammation.

Animals↗
PubMed2001

Reduction of long-term effects of local heating of the testis by treatment of rats with a GnRH agonist and an anti-androgen.

Heating the testes of anaesthetized adult rats to 43 degrees C for 30 min in a waterbath was followed by a large decrease in testis and epididymis mass and number of spermatozoa 35 days later. These parameters had recovered to some extent, but not completely, by days 70 and 97 after heating, but had decreased again in rats examined on day 182. There were no consistent effects of heating on androgen status, as determined by the concentrations of testosterone in blood and testis fluids, or by seminal vesicle mass, and interstitial fluid volume was increased in the heated testes. Treatment of rats with an implant of a GnRH agonist and daily injections of an anti-androgen for 14 days (sufficient in itself to cause large temporary decreases in tissue mass, number of spermatozoa and androgen status) did not reduce the initial decrease in testis mass or number of spermatozoa seen after heating, but reduced the later decreases in mass and number of spermatozoa significantly. These findings indicate that, as well as causing damage to spermatocytes and spermatids, as previously reported, heating also reduces the ability of spermatogonia to repopulate the seminiferous tubules at longer intervals after heating. Furthermore, it appears that this effect on the spermatogonia can be reduced by treating the animals with a GnRH agonist and anti-androgen, a treatment similar to that shown by other authors to improve recovery of the testis from irradiation or drug treatment.

Androgen Antagonists↗
PubMed2000

Effect of efferent duct ligation on the function of the blood-testis barrier in rats.

The function of the blood-testis barrier has been assessed from the ratio of the Cr-EDTA space in the parenchyma to the measured interstitial volume in the testes of rats at various times after unilateral ligation of the efferent ducts. The barrier remained effective during the phase of fluid accumulation and testicular mass gain, which was linear for at least 24 h, but the testis mass began to decrease between 32 and 40 h after efferent duct ligation, and the Cr-EDTA space at 40 and 48 h after efferent duct ligation exceeded the volume of the interstitial tissue. This finding indicated that, at these times, the barrier to Cr-EDTA, which is normally excluded from the tubules, had broken down and the marker was entering the tubules. Thereafter, the Cr-EDTA space decreased again to be less than the interstitial tissue volume, indicating a restoration of the barrier function, although degeneration of the seminiferous epithelium continued to become more obvious. The present study is the first report of a reversible breakdown of the barrier, but the relevance of the breakdown to the effects on spermatogenesis requires further study.

Analysis of Variance↗
PubMed2000

Testicular vasomotion in different mammals.

Vasomotion is a rhythmical variation in arterial blood flow present in many different organs among them the rat testis. Vasomotion is suggested to play an important role for the transvascular fluid exchange and the exchange of nutrients over the capillary wall as well as the formation of interstitial fluid. The present study was undertaken to elucidate whether vasomotion is present in the testes of different species independent of their anatomical vascular topography. Blood flow in the testes of mouse, brush-tailed possum, tammar wallaby, ram and human was investigated by using a laser Doppler flowmeter. Vasomotion was found in all the species investigated.

Animals↗
PubMed1998

Secretion of D-aspartic acid by the rat testis and its role in endocrinology of the testis and spermatogenesis.

The 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.

Animals↗
PubMed1998

Effect of compatible solutes and diluent composition on the post-thaw motility of ram sperm.

The effect of the compatible solutes proline, glycine betaine and trehalose in Tris-based diluents at varying pH, concentrations of egg yolk or glycerol on the post-thaw motility characteristics and fertility of ram sperm was examined. In addition, the amino acid glycine was compared with proline, glycine betaine and a standard Tris-based diluent. Post-thaw motility was assessed using a Hamilton-Thorn motility analyser. In the presence of glycerol and egg yolk, proline and glycine betaine improved the post-thaw motility characteristics of ram sperm. Regardless of the pH of the diluent at which semen was frozen, the percentage of motile sperm was higher when frozen in the presence of proline or glycine betaine than in their absence, whereas proline and glycine betaine only improved the progressive and rapid percentages of sperm for semen frozen in diluents at pH lower than 7.0. When semen was frozen in the absence of egg yolk or glycerol all the motility characteristics were reduced. Increasing the concentration of egg yolk in the diluent from 5% to 10, 15 or 20% had no effect on the post-thaw motility of sperm. The addition of 27 mM of proline or glycine betaine to the diluent also improved post-thaw motility. However, at a concentration of 81 mM, proline and glycine betaine had a detrimental effect on the percentage of motile sperm. Trehalose had no effect on the motility of sperm frozen in glycerol-containing diluents, but motility was lower after cryopreservation in glycine than in Tris-, proline- or glycine betaine-based diluents. There were no differences in the fertility of sperm frozen in Tris-, proline or glycine betaine diluents after cervical or laparoscopic insemination of ewes.

Animals↗
PubMed1998

Transient retardation in embryo growth in normal female mice made pregnant by males whose testes had been heated.

In three separate experiments, using three different strains of mice, when normal females were mated by males whose testes had been heated once to 42 degrees C for 20 min, the embryos at 10.5 days post-coitum were approximately 20% smaller than control embryos. In one experiment, the difference was still present, although proportionately less, at 15.5 and 18.5 days and, in another experiment, a difference could be seen in 11.5 and 13.5 day old embryos but not in 12.5, 14.5, 15.5 or 18.5 day old embryos. The frequency of mating and pregnancy rates were unaffected. In one experiment, the time available for mating was restricted to 4 h instead of overnight, without effect on the result. In another experiment, other males were heated for 30 min, and these showed a period of infertility from 10 to 32 days later, preceded and followed by the production of smaller than normal embryos; litter size was also reduced in the period after the return of fertility in these animals. The yolk sacs and the trophoblasts of the embryos sired by the heated males were also slightly smaller than those sired by the controls in the two experiments in which these were measured. The pattern of weight reduction is thus different from that seen in gynogenetic embryos or when the gene for insulin-like growth factor (IGF)-II is disrupted, and suggests a reduction in embryo growth at the earlier stages, with compensatory growth occurring later in pregnancy.

Animals↗
PubMed1998

Reduction in fluid secretion by rat testis by drugs that block potassium channels.

The effect of two class III antiarrhythmic drugs (Almokalant, Astra-Hässle and Dofetilide, Pfizer) on fluid secretion by rat testes has been examined. Both drugs reduced fluid secretion, whether this was measured by the amount of rete testis fluid that could be collected 22 h after unilateral efferent duct ligation, or by the difference in mass between the ligated and unligated testes, or by the difference in amount of supernatant fluid after the parenchyma of the ligated and unligated testes had been dispersed and centrifuged. The secretion of potassium, calculated from the amount of potassium in the supernatant fluids from the ligated and unligated testes was also reduced by the drugs, whereas the secretion of androgen-binding protein and inositol was unaffected. The concentration of potassium in the secreted fluid, calculated from the amount and composition of the supernatant fluids, was not affected by treatment of the rats with Almokalant, but was increased in rats treated with Dofetilide and, in these, the concentration of sodium was reduced and that of magnesium and inositol was increased and the concentration of total protein was unaffected. The concentration of androgen-binding protein in secreted fluid was increased in rats treated with Almokalant, while the concentration of testosterone was unaffected. Histological examination of testes from treated rats revealed phagocytosis of stage 19 spermatids in tubules at stages VIII-IX after 2 days, at stages IX-XI after 4 days and at stages VIII-XIV after 7 days, apparently owing to an effect on spermiation. It appears that these drugs interfere with potassium-mediated fluid secretion by the testis, leading to the other changes seen.

Analysis of Variance↗
PubMed1998

The Parkes Lecture. Heat and the testis.

The evidence for the lower temperature of the testes of many mammals is summarized, and the reasons suggested for the descent of the testes into a scrotum are discussed. Descriptions are given of the various techniques used for studying the effects of heat on the testis, whole body heating, local heating of the testes (by inducing cryptorchidism, scrotal insulation or immersion of the scrotum in a water bath), and heating of tissue or cell preparations in vitro. The effects of heat are discussed, effects on the testis (weight, histology, physiology, biochemistry and endocrinology), on the numbers and motility of spermatozoa in rete testis fluid and semen, on fertilizing ability of spermatozoa and on the subsequent development of the embryos produced when spermatozoa from heated testes are used to fertilize normal ova. The possible mechanisms for the damaging effects of heat are discussed, as well as the importance of heat-induced abnormalities in male reproduction in domestic animals and humans.

Animals↗
PubMed1997

Microvascular permeability to the F(ab')2 fragment of IgG in the male rat reproductive tract at puberty.

Development of contraceptive vaccines has recently raised much interest following the cloning of the sperm and oocyte components involved in the sperm-oocyte interaction. The main difficulty of immunocontraception in the male is the poor access of antibodies to the luminal compartment. As recent literature suggests that many substances are transported to the testis by receptor-mediated or fluid-phase transcytosis, the dependence of the transport of IgG on the Fc receptor was studied in the present investigation by comparing the penetration of whole IgG and the F(ab')2 fragment of IgG to the testis and epididymis. The maximum volume of distribution (Veq) for the F(ab')2 fragment was significantly higher than that for whole IgG in the testis of 30-60-day old rats, in the caput and cauda of 30- and 45-day old rats and the corpus of 45-day old rats. The speeds at which equilibrium between tissue extracellular fluid and serum was reached (K) for the F(ab')2 fragment and whole IgG were significantly different in the testicular capsule of the 60-day old, in the caput and corpus of the 45- and 60-day old and in the cauda of the 45-day old rats. The microvascular permeabilities (PE) to the F(ab')2 fragment were more than 2-fold higher than those to whole IgG in the testis of the 20-, 45- and 60-day old, in the testicular capsule of the 20- and 45-day old, in the caput of 20-, 30- and 60-day old and in the corpus of 20-day old rats. The PE to whole IgG was more than 2-fold higher than that to the F(ab')2 fragment in the cauda of the 45-day-old rats. The PE to the F(ab')2 fragment increased steadily from 20 to 60 days of age in the testis and caput, but in the corpus there was a more abrupt increase between 30 and 45 days of age. In the cauda, PE remained in the same range of magnitude throughout pubertal development. These results suggest that the F(ab')2 fragment reaches the lumen of the reproductive tract more easily than whole IgG from 30 days of age onwards in the testis, whereas in the caput, corpus and cauda epididymidis the rate at which F(ab')2 fragment reaches the lumen increases only temporarily at the time of appearance of spermatozoa in the lumen. Transport of IgG to the male reproductive tract is thus unlikely to be mediated by Fc receptors.

Aging↗
PubMed1997

Sperm counts in semen of farm animals 1932-1995.

In some countries, sperm counts in normal human semen seem to have declined over the last 50 years. If this decline is real and due to environmental factors, falls might also be seen in sperm numbers in the semen of farm animals. Sperm counts are available for bull, boar and ram from the early 1930s, obtained using techniques similar to those used for human semen. Data have been obtained from the literature between 1932 and 1995 from 137 studies involving bulls, 76 involving boars and 130 involving rams. All were normal adult animals, from which semen was collected regularly but at a frequency which would not be likely to cause a fall in sperm counts. The references were obtained systematically from Animal Breeding Abstracts, and where possible the original articles were consulted to obtain mean values for each study; where the original reference was not easily obtainable, values were taken from the abstract. The bull data showed no correlation of sperm count with year of publication (r2 = 0.000), for the boars there was a slight but non-significant positive correlation (r2 = 0.041), and for the sheep there was a slight, but significant, rise in sperm counts with time (r2 = 0.124 for sperm counts and 0.126 for total sperm per ejaculate; not all authors gave both values). It would appear that, if the fall in human sperm counts is real, then it must be due to something which is not affecting farm animals.

Animals↗
PubMed1997

Epididymal compounds and antioxidants in diluents for the frozen storage of ram spermatozoa.

The epididymal compounds taurine, hypotaurine and inositol, and the antioxidants carnosine and ascorbic acid, were added to Tris-based diluents containing varying concentrations of glycerol, and their effect on the post-thaw motility characteristics and fertility of ram spermatozoa was examined. Overall, the post-thaw motility characteristics of spermatozoa were better when semen was frozen in the presence rather than in the absence of glycerol. Only taurine protected spermatozoa during cryopreservation; the presence of 25 mM or 50 mM taurine significantly improved the post-thaw percentage of motile spermatozoa but this had no effect on fertility after cervical or laparoscopic insemination of ewes. Increasing the concentration of taurine to more than 100 mM significantly reduced the percentage of motile spermatozoa, compared with the lower concentrations of the amino acid. The presence of more than 50 mM carnosine or ascorbic acid significantly reduced all motility characteristics compared with the control diluent. Given that hypotaurine, carnosine, or ascorbic acid did not improve post-thaw motility, the cryoprotective effect of taurine may be attributable to its osmoregulation rather than to its antioxidant properties.

Animals↗
PubMed1996

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.

The 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 degrees 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.

Animals↗