The Parkes Lecture Heat and the testis

Setchell, B. P.

doi:10.1530/jrf.0.1140179

Cited by 360 publications

(253 citation statements)

References 3 publications

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“…It is well known that the mammalian testis operates on the brink of hypoxia (Setchell 1998) and that testicular hyperthermia increases metabolism and hence O 2 consumption. However, blood flow is reported to remain relatively constant and therefore the resulting hypoxia is regarded as the basis for decreases in sperm motility and morphology (Waites and Setchell 1964;Paul et al 2009;Hamilton et al 2016).…”

Section: Discussionmentioning

confidence: 99%

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Hyperthermia and not hypoxia may reduce sperm motility and morphology following testicular hyperthermia

Kastelic¹,

Wilde²,

Rizzoto³

et al. 2017

Vet. Med.

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ABSTRACT:The mammalian testis typically operates on the brink of hypoxia; the long-standing dogma is that increased testicular temperature increases metabolism, but blood flow is unaffected and the resulting hypoxia reduces sperm motility and morphology. In rats and mice, oxygen (O 2 ) content of inspired air affected O 2 content of testes, enabling the latter to range from approximately 50 to more than 200% of physiologic concentrations. A ram model was used to test the hypotheses that hypoxia would disrupt sperm motility and morphology and that hyperoxia would prevent hyperthermia-induced reductions in sperm motility and morphology. Eighteen Canadian Arcott rams (approximately 10 months old) were used in a 2 × 3 factorial, with factors being scrotal insulation (insulated or not insulated) and O 2 concentrations in inspired air (14, 21 or 85%). Six rams, three with and three without scrotal insulation, were placed in each of three enclosed areas for 30 h to expose them to their respective oxygen concentrations, with scrotal insulation removed at the end of the exposure. Semen was collected by electro-ejaculation twice before insulation, bi-weekly for four weeks starting one week after exposures, and then once weekly for two weeks. There were effects of insulation, time and an insulation × time interaction for motile sperm and sperm that had normal morphology or head or midpiece defects (P < 0.01 for each). Sperm motility and morphology exhibited alterations between approximately two and five weeks after insulation, with mean progressively motile and morphologically normal sperm decreasing from approximately 55 to 35% and from 80 to 30%, respectively, and with head and midpiece defects increasing from approximately 3 to 50% and from 10 to 20% (P < 0.05 for each). The hypotheses that hypoxia would disrupt sperm quality and production, whereas hyperoxia would prevent hyperthermia-induced reductions in sperm quality and production, were not supported. This is apparently the first report that heat-stress induced damage to sperm was due to increased temperature per se and not testicular hypoxia, calling into question a long-standing paradigm.

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Section: Discussionmentioning

confidence: 99%

“…Consequently, the dogma is that decreased sperm motility and an increased proportion of morphologically abnormal sperm following increased testicular temperature are due to hypoxia (Setchell 1998;Paul et al 2009). Although this view is widely accepted, to our knowledge, this has apparently not been formally tested.…”

Section: Original Papermentioning

confidence: 99%

Hyperthermia and not hypoxia may reduce sperm motility and morphology following testicular hyperthermia

Kastelic¹,

Wilde²,

Rizzoto³

et al. 2017

Vet. Med.

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show abstract

“…Theoretically, this loss of testicular thermoregulation causes an increase in stage-specific apoptosis of germ cells at most susceptible stages of spermatogenesis, chronic hypoxia, and excessive production of reactive oxygen species. Excessive reactive oxygen species production that is not counterbalanced by antioxidant systems results in a number of deleterious effects to the sperm, including increased levels of sperm membrane lipid peroxidation, reduced motility, decreased mitochondrial activity, increased DNA fragmentation and apoptosis [2].…”

Section: Introductionmentioning

confidence: 99%

Study of the effect of varicocelectomy on sperm proteins expression in patients with varicocele and poor sperm quality by using two-dimensional gel electrophoresis

Hosseinifar

Sabbaghian

Nasrabadi

et al. 2014

J Assist Reprod Genet

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Purpose To compare proteomic profiles of spermatozoa from patients with varicocele and poor sperm quality before and after varicocelectomy. Methods This work was designed as a prospective and observational study. The study was based on 20 men with varicocele grade 3 and poor sperm quality undergoing varicocelectomy at the Fertility Unit of Royan institute in 2009. Two semen samples were collected, one before varicocelectomy and the other after surgery. Protein separation was done by two-dimensional protein electrophoresis, and analyzed by gel densitometry and mass spectrometry. Differential sperm protein expression levels were measured by gel densitometry. Results Comparison of the sperm parameters showed that sperm motility and concentration were increased after varicocelectomy. At the level of protein, a total of 3 protein spots were identified whose expression was significantly lower in sperm samples before varicocelectomy compared with after surgery including heat shock protein A5 (HSPA5), superoxide dismutase 1 (SOD1) and δ-subunit of the catalytic core of mitochondrial adenosine triphosphate synthase (ATP5D). Conclusions High grade varicocoele affects sperm protein expression presumably because of increasing testicular temperature. These proteins play essential roles in sperm production, DNA integrity protection, and sperm motility. This novel study demonstrates that varicocelectomy can improve both sperm quality and proteins expression.

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“…In addition, it alters the expression profiles of many genes [4,29,30]. In this regard, we previously showed high expression of heat shock 70 kDa protein 2 (HSPA2) in testicular tissue and caudal segment of epididymides in rat varicocele model [31].…”

Section: Discussionmentioning

confidence: 99%

An association between sperm PLCζ levels and varicocele?

Janghorban-Laricheh

Ghazavi-Khorasgani

Tavalaee

et al. 2016

J Assist Reprod Genet

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Purpose We aimed to compare the expression of phospholipase C ζ (PLCζ), as one of the main sperm factors involved in oocyte activation, at both RNA and protein levels in fertile men and those with varicocele. Methods This study included 35 individuals with male factor infertility presenting primary infertility with grade II and III unilateral varicocele and 20 fertile men without varicocele. Semen parameters were assessed according to WHO 2010. Sperm DNA fragmentation, relative expression of PLCζ at messenger RNA, and protein levels were evaluated by sperm chromatin structure assay (SCSA), real-time PCR, and Western blot analysis, respectively. Results The results of this study reveal that the mean relative expression of PLCζ was significantly lower in individuals with varicocele compared to fertile men at both transcription and translation levels. In addition, the percentage of DNA fragmentation was significantly higher in infertile men with varicocele compared to fertile men. Conclusions The findings of the present study illustrate that one of the etiologies of reduced fertility associated with varicocele is the low expression of PLCζ. This effect could subsequently reduce the sperm ability to induce oocyte activation. Therefore, these results hold promise to modify our understanding of reproductive physiology of varicocele state.

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The Parkes Lecture Heat and the testis

Cited by 360 publications

References 3 publications

Hyperthermia and not hypoxia may reduce sperm motility and morphology following testicular hyperthermia

Hyperthermia and not hypoxia may reduce sperm motility and morphology following testicular hyperthermia

Study of the effect of varicocelectomy on sperm proteins expression in patients with varicocele and poor sperm quality by using two-dimensional gel electrophoresis

An association between sperm PLCζ levels and varicocele?

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