Possible Involvement of Aquaporin-7 and -8 in Rat Testis Development and Spermatogenesis

Calamita, Giuseppe; Mazzone, Amelia; Bizzoca, Antonella; Svelto, María

doi:10.1006/bbrc.2001.5810

Cited by 87 publications

(79 citation statements)

References 27 publications

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“…When AQP7 was first identified and localized in round and elongated spermatids, it was natural for the authors to propose a role in the reduction of cell volume in the development of round spermatids into testicular spermatozoa [70,71]. However, this assigned significance in spermiogenesis cannot be substantiated by the Aqp7 −/− mice, which show only a mild phenotype with normal testicular and epididymal morphology [72], normal testicular weight, normal daily sperm production, normal sperm morphological and kinematic characteristics, as well as in vitro and in vivo fertility [73].…”

Section: Aqp7mentioning

confidence: 99%

Aquaporins in spermatozoa and testicular germ cells: identification and potential role

Yeung¹

2010

Asian J Androl

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Mammalian spermatozoa have relatively high water permeability and swell readily, as in the hypo-osmotic swelling test used in the andrology clinic. Physiologically, spermatozoa experience changes in the osmolality of the surrounding fluids in both the male and the female tracts on their journey from the testis to the ovum. Sperm volume regulation in response to such osmotic challenges is important to maintain a stable cell size for the normal shape and function of the sperm tail. Alongside ion channels for the fluxes of osmolytes, water channels would be crucial for sperm volume regulation. In contrast to the deep knowledge and numerous studies on somatic cell aquaporins (AQPs), the understanding of sperm AQPs is limited. Among the 13 AQPs, convincing evidence for their presence in spermatozoa has been confined to AQP7, AQP8 and AQP11. Overall, current findings indicate a major role of AQP8 in water influx and efflux for sperm volume regulation, which is required for natural fertilization. The preliminary data suggestive of a role for AQP7 in sperm glycerol metabolism needs further substantiation. The association of AQP11 with the residual cytoplasm of elongated spermatids and the distal tail of spermatozoa supports the hypothesis of more than just a role in conferring water permeability and also in the turnover and recycling of surplus cellular components made redundant during spermiogenesis and spermiation. This would be crucial for the maintenance of a germinal epithelium functioning efficiently in the production of spermatozoa.

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Section: Aqp7mentioning

confidence: 99%

Aquaporins in spermatozoa and testicular germ cells: identification and potential role

Yeung¹

2010

Asian J Androl

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“…AQP7 has been localized in germ cells and is mostly expressed in post meiotic male germ cells. In particular, it has been identified in the plasma membrane of elongated spermatids and maturing spermatozoa from rat testis [Ishibashi et al 1997;Suzuki-Toyota et al 1999;Calamita et al 2001;Kageyama et al 2001] and even in the residual bodies remaining in the seminiferous epithelium [Suzuki-Toyota et al 1999;Calamita et al 2001]. In addition, Hermo and Smith [2011] observed an AQP7 immunoreaction over the whole cytoplasm of late elongating spermatids located near the lumen of rat seminiferous epithelium.…”

Section: Introductionmentioning

confidence: 96%

“…AQP8 was observed in all germ cell lines of rat testicular epithelium [Calamita et al 2001], whereas Yeung et al identified this protein channel exclusively in early and late spermatids in mouse testis [2009] and in all germ cells of human testis [2010]. AQP7 has been localized in germ cells and is mostly expressed in post meiotic male germ cells.…”

Section: Introductionmentioning

confidence: 99%

Immunolocalization of aquaporin 7 in human sperm and its relationship with semen parameters

Moretti

Terzuoli²,

Mazzi³

et al. 2011

Systems Biology in Reproductive Medicine

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Aquaporins (AQPs) are a family of 13 small hydrophobic transmembrane proteins expressed in numerous tissues and cells. Some AQPs work as strict water channels, others are permeable to a range of substances, including glycerol. In the male reproductive system their localization in testis, efferent ducts, epididymis, and spermatozoa has been described. We studied the distribution of AQP7 in ejaculated human sperm and the relationship between AQP7 labeling and sperm characteristics. Semen samples from 33 men were examined by light and transmission electron microscopy (TEM). TEM data were quantified using a mathematical formula that calculates a fertility index (FI) and the percentages of sperm apoptosis, immaturity, and necrosis. Immunocytochemistry with a polyclonal antibody anti-AQP7 was performed on the sperm samples. Normal sperm were labeled in the pericentriolar area, midpiece, equatorial segment, and weakly in the tail (grade 1). Abnormal sperm showed a diffuse low intensity of fluorescence evident in the cytoplasmic residues, coiled tails, in the entire head, and acrosome (grade 2). A high number of motile sperm obtained by swim up were labeled in a dotted manner in the mitochondria. A significant positive correlation was found between the spermatozoa with AQP7 grade 1 labeling and the percentage of normal form (P < 0.008), progressive motility and FI (P < 0.005); a negative correlation was noted with the percentages of cytoplasmic residues (P < 0.010) and immaturity (P < 0.006) and coiled tails (P < 0.012). The link between AQP7 distribution and sperm morphology and the particular dotted labeling in swim up selected motile sperm are novel and deserve additional studies.

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“…AQP8 is reportedly permeable to ammonia [3] . The majority of aquaporins are constitutively expressed in the plasma membrane (AQP0, 1,3,4,7,8,9,10), while others are almost exclusively restricted to intracellular membranes (AQP6, 11,12) [4] .…”

Section: Introductionmentioning

confidence: 99%

“…In addition, the cytoplasmic localization of AQP8 may also hint at its involvement in intracellular osmoregulation [9] . Subsequent studies [10][11][12][13][14][15][16] have shown that AQP8 has a wide tissue distribution in mammals, with expression noted in the testis, kidney, heart, gastrointestinal tract, airway, salivary gland, pancreas and placenta. In the reproductive system, AQP8 is strongly expressed in the testis and sperm in the male and in the ovary, oviduct, uterus, placenta, amnion, chorion and cervix in the female [16][17][18][19][20][21][22][23][24][25] .…”

Section: Introductionmentioning

confidence: 99%

Pregnant phenotype in aquaporin 8-deficient mice

et al. 2011

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Aim: Aquaporin 8 (AQP8) is expressed within the female reproductive system but its physiological function reminds to be elucidated. This study investigates the role of AQP8 during pregnancy using AQP8-knockout (AQP8-KO) mice. Methods: Homozygous AQP8-KO mice were mated, and the conception rate was recorded. AQP8-KO pregnant mice or their offspring were divided into 5 subgroups according to fetal gestational day (7, 13, 16, 18 GD) and newborn. Wild type C57 pregnant mice served as the control group. The number of pregnant mice, total embryos and atrophic embryos, as well as fetal weight, placental weight and placental area were recorded for each subgroup. The amount of amniotic fluid in each sac at 13, 16, and 18 GD was calculated. Statistical significance was determined by analysis of variance of factorial design and chi-square tests. Results: Conception rates did not differ significantly between AQP8-KO and wild type mice. AQP8-KO pregnant mice had a significantly higher number of embryos compared to wild type controls. Fetal/neonatal weight was also significantly greater in the AQP8-KO group compared to age-matched wild type controls. The amount of amniotic fluid was greater in AQP8-KO pregnant mice than wild type controls, although the FM/AFA (fetal weight/amniotic fluid amount) did not differ. While AQP8-KO placental weight was significantly larger than wild type controls, there was no evidence of placental pathology in either group. Conclusion: The results suggest that AQP8 deficiency plays an important role in pregnancy outcome.

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Possible Involvement of Aquaporin-7 and -8 in Rat Testis Development and Spermatogenesis

Cited by 87 publications

References 27 publications

Aquaporins in spermatozoa and testicular germ cells: identification and potential role

Aquaporins in spermatozoa and testicular germ cells: identification and potential role

Immunolocalization of aquaporin 7 in human sperm and its relationship with semen parameters

Pregnant phenotype in aquaporin 8-deficient mice

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