Putative melatonin receptor in human spermatozoa

Vuuren, Renier J.J. van; Pitout, M.J.; Aswegen, C. H. Van; Theron, Jacques

doi:10.1016/0009-9120(92)80056-m

Cited by 75 publications

(48 citation statements)

References 9 publications

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“…Naturally, seminal fluid contains melatonin (Bornman et al, 1989) and the spermatozoa reportedly possess membrane melatonin receptors (Bornman et al, 1989;Van Vuuren et al, 1992). Removing of buffalo seminal plasma during the cryopreservation process deprives the sperm cells from important elements in between melatonin.…”

Section: Discussionmentioning

confidence: 99%

Evidences for the Role of Melatonin as a Protective Additive During Buffalo Semen Freezing

Raey¹,

Badr²,

Rawash³

et al. 2014

American Journal of Animal and Veterinary Sciences

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Till now, the exact role of melatonin in male infertility hasn't been fully discovered. Moreover, the intracellular signaling pathways activated by melatonin in buffalo spermatozoa especially on the level of cryopreservation process haven't been reported. The current study aimed simply to clarify the precise role of this hormone during buffalo semen cryopreservation. Semen samples were obtained randomly from 6 fertile buffalo bulls (aged 3 to 5 years). Weekly, two consecutive ejaculates were collected from each bull for successive six weeks duration using an artificial vagina. The ejaculates were pooled to eliminate variability between the evaluated samples. After that, semen samples were subjected to extension with Tris-based extender supplemented with different concentrations of melatonin (0.1, 0.25, 0.5, 0.75 and 1 mM) Vs. Trisbased extender only (control). Then they were processed to cryopreservation and thawing to assess the different semen characteristics. It had been found that 0.1 mM of melatonin significantly (p<0.05) improved post thawing motility, viability index, acrosomal integrity, total antioxidant capacity, superoxide dismutase and glutathione reductase activity. On the other hand, it significantly (p<0.05) decreased the rate of lipid peroxidation, aspartate amino transferase, alanine aminotransferase, alkaline phosphatase and DNA fragmentation. All of these previously enhanced semen characteristics were reflected positively on its in vitro fertilizing capacity, as well as the percent of harvested embryos. In conclusion melatonin supplementation to the extension media of buffalo semen during processing significantly enhanced its characteristics. Moreover, the preceding results focusing more light on the potential roles of melatonin in regulating male reproduction.

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Section: Discussionmentioning

confidence: 99%

Evidences for the Role of Melatonin as a Protective Additive During Buffalo Semen Freezing

Raey¹,

Badr²,

Rawash³

et al. 2014

American Journal of Animal and Veterinary Sciences

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“…Testosterone is metabolized to estrogens by aromatase [37], and estrogens seem to regulate ejaculated sperm motility [38]. The presence of testosterone and estrogen receptors in human spermatozoa [39,40] and the strong correlation found between the aromatase expression and motility in human [41] and buffalo [42] ejaculated sperm suggest that aromatase could be involved in the modulation of sperm motility by metabolization of seminal plasma testosterone into estrogens. Therefore, the higher ram sperm quality [43] and fertilization rate [16] observed during the breeding season could be partially caused by high levels of testosterone in ram seminal plasma, which could be transformed into estrogens by aromatase and improve motility parameters.…”

Section: Discussionmentioning

confidence: 99%

Seasonal variations of melatonin in ram seminal plasma are correlated to those of testosterone and antioxidant enzymes

Casao

Cebrián

Asumpção

et al. 2010

Reprod Biol Endocrinol

104

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Background: Some breeds of sheep are highly seasonal in terms of reproductive capability, and these changes are regulated by photoperiod and melatonin secretion. These changes affect the reproductive performance of rams, impairing semen quality and modifying hormonal profiles. Also, the antioxidant defence systems seem to be modulated by melatonin secretion, and shows seasonal variations. The aim of this study was to investigate the presence of melatonin and testosterone in ram seminal plasma and their variations between the breeding and nonbreeding seasons. In addition, we analyzed the possible correlations between these hormones and the antioxidant enzyme defence system activity. Methods:Seminal plasma from nine Rasa Aragonesa rams were collected for one year, and their levels of melatonin, testosterone, superoxide dismutase (SOD), glutathione reductase (GRD), glutathione peroxidase (GPX) and catalase (CAT) were measured.Results: All samples presented measurable quantities of hormones and antioxidant enzymes. Both hormones showed monthly variations, with a decrease after the winter solstice and a rise after the summer solstice that reached the maximum levels in October-November, and a marked seasonal variation (P < 0.01) with higher levels in the breeding season. The yearly pattern of GRD and catalase was close to that of melatonin, and GRD showed a significant seasonal variation (P < 0.01) with a higher activity during the breeding season. Linear regression analysis between the studied hormones and antioxidant enzymes showed a significant correlation between melatonin and testosterone, GRD, SOD and catalase. Conclusions:These results show the presence of melatonin and testosterone in ram seminal plasma, and that both hormones have seasonal variations, and support the idea that seasonal variations of fertility in the ram involve interplay between melatonin and the antioxidant defence system. BackgroundMelatonin plays a central role in fine-tuning circadian rhythms [1] and seasonal changes [2] through its daily nocturnal increase in the blood [3]. In seasonally breeding mammals that use changes in the photoperiod to time

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“…Despite the fact that the receptors are yet to be immunolocated, MT 1 and MT 2 receptor activity has been demonstrated in hamster and human spermatozoa by the use of 2-[ 125 I]-iodomelatonin binding (van Vuuren et al 1992) and competitive antagonists (van Vuuren et al 1992;Fujinoki 2008;Espino et al 2011).…”

Section: Introductionmentioning

confidence: 99%

Identification and immunolocalisation of melatonin MT1 and MT2 receptors in Rasa Aragonesa ram spermatozoa

Casao

Gallego

Abecia

et al. 2012

Reprod. Fertil. Dev.

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The reproductive seasonality of sheep suggests that melatonin receptors may be present in ram spermatozoa. The present study confirms the presence of melatonin MT(1) and MT(2) receptors. The MT(1) receptor was detected using immunocytochemistry, with four sperm subpopulations identified based on the following labelling patterns: (1) one small subpopulation with labelling over the entire head and tail; (2) one of two main subpopulations that exhibited reactivity at the equatorial, post-acrosomal, neck and tail regions; (3) another main subpopulation with equatorial and tail labelling only; and (4) a subpopulation in which staining was detected only in the tail. Immunocytochemistry revealed the presence of the melatonin MT(2) receptor, with intense staining on the acrosome, post-acrosomal region and neck and tail regions of all cells, but not in the equatorial region. Western blot identification of ram protein extracts revealed a 39-kDa band compatible with both MT(1) and MT(2) receptors, a 75-kDa band compatible with MT(1)/MT(2) heterodimerisation, a 32-kDa band compatible with MT(1) receptor activation and a double band of 45-55 kDa that is compatible with MT(2) receptor homodimerisation or heterodimerisation with other G-proteins. In conclusion, we provide evidence of the presence of MT(1) and MT(2) receptors in ram spermatozoa, although the biochemical pathway triggered by these receptors and their function in terms of fertility remains to be elucidated.

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Putative melatonin receptor in human spermatozoa

Cited by 75 publications

References 9 publications

Evidences for the Role of Melatonin as a Protective Additive During Buffalo Semen Freezing

Evidences for the Role of Melatonin as a Protective Additive During Buffalo Semen Freezing

Seasonal variations of melatonin in ram seminal plasma are correlated to those of testosterone and antioxidant enzymes

Identification and immunolocalisation of melatonin MT1 and MT2 receptors in Rasa Aragonesa ram spermatozoa

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