Category: Epididymal

DISCUSSION(6)

Another potential source of PGH2 may be the spermatozoa themselves, since cyclooxygenases have also been localized in the male gamete. The hypothesis of a sperm PGH2 origin is reinforced by the fact that arachidonic acid (the substrate of COX activity) can be released from sperm membranes by phospholipase A2 during the loss of phospholipids as the gametes transit the epididymis. These hypotheses have to be investigated. antibiotics levaquin

PGDS is the only one of the lipocalins that is associated with enzyme activity. The lipocalin family consists of various small secretory proteins that share a common feature of binding and transport of lipophilic molecules. PGDS may act as a transporter of lipophilic substances, including prostaglandins. Moreover, PGDS was suggested to be a retinoid transporter with an affinity for retinoic acid as great as that of retinoic acid-binding protein. However, in the epididymis this function is more probably performed by the epididymal retinoic acid-binding protein that is secreted from the corpus to the cauda epididymidis in mammals.

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The role of PGDS in all the fluids of the genital tract is uncertain. No information is available in vivo about enzyme activity of the secreted luminal PGDS. However, PGD2 can be formed in vitro by glutathione-independent PGDS in rat epididymal tissue homogenates, and thus it is probable that PGDS is potentially active in the epididymis. Bull testicular, epididymal, and seminal isoforms have been found to be capable of transforming PGH2 to PGD2 in the fluids after dilution. However, the authors of this work suggested that an unknown inhibitor of PGDS may exist in vivo, at least in bull seminal plasma. Furthermore, the structural modifications observed in the ram and stallion when the protein passes through the epididymis (loss of about 5 kDa in both species and an increase in pI in the ram) may also alter the properties of this enzyme, as has been shown for other epididymal enzymes such as gamma-glutamyl transpeptidase during transit. ampicillin antibiotic

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DISCUSSION(4)

The origin of PGDS in the seminal plasma of the ram was the epididymis, since no PGDS mRNA was detected in the seminal vesicle tissue and the protein was not detectable in seminal vesicle secretions or in the seminal plasma of vas deferens-ligated rams (data not shown). Buy Advair Diskus Online

The regulation of expression and synthesis of PGDS in the anterior part of the epididymis is not dependent on testicular factors, since efferent duct ligation did not abolish mRNA expression or protein synthesis in the caput epidi-dymidis in either species studied. The reduction in PGDS expression and synthesis observed in the anterior caput in the ligated ram, and its disappearance from the efferent ducts of the ligated stallion, were probably a consequence of the general reduction in epithelial activities due to the suppression of testicular fluid.

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The presence of PGDS in ram and stallion epididymal fluids was related not only to epididymal activity but also to testicular activity, as it was detected in the RTF. This protein has also been found in the RTF of the bull. However, testicular PGDS has more acidic isoforms than the epididymal protein. As only one glutathione-independent PGDS gene has been observed to date, this polymorphism is probably due to differential degrees of gly-cosylation of the protein between tissues. Variations in the degree of glycosylation of PGDS have been found between blood and brain PGDS (p-trace protein) in humans. Such variations in protein glycosylation between the testis and the epididymis have also been found for other proteins secreted by the two organs, such as clusterin. Cheap Diskus Advair

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DISCUSSION(2)

The secretory activity was highly regionalized and was localized only in the initial segment (regions 0-1) of the ram epididymis and regions 0-2 (proximal and distal caput) of the stallion epididymis. Expression of mRNA for PGDS in ep-ididymal tissues was detected only in the caput epididymal region where the protein was secreted. The secretion of PGDS in both the ram and horse was among the highest in this region (around 20%), and PGDS was a major protein of the epididymis, accounting for nearly 8% of all proteins secreted by the epididymis. In both species, the highest amount of PGDS was found in the fluid of the anterior region (around 10%). This protein could be considered as a good marker of the secretory activity of the anterior region, as also proposed for GPX. buy flovent inhaler

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In the present study, a major secreted protein was identified in the testicular, epididymal, and seminal fluids of rams and stallions as the glutathione-independent lipocalin-type PGDS (prostaglandin-H2 D-isomerase; (5Z,13E)-(15S)-9a,11 a-epidioxy-15-hydroxyprosta-5,13-dienoate-D-isomerase, EC 5.3.99.2). We identified this compound by microsequencing the protein and by using polyclonal antisera obtained from a peptide deduced from the cDNA sequence of pig PGDS.

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RESULTS(4)

A 0.8-kilobase mRNA was detected only in the proximal caput epididymidis of both the ram (regions 0-1) (Fig. 4C) and the stallion (regions 0-2) (Fig. 7C). Testicular PGDS transcripts were found in stallions (not shown), but we were not able to detect signals in any rams. PGDS mRNA could be detected in the efferent ducts of all the horses studied, whereas the transcript was detected in only half the rams.

Regulation of the Expression and Synthesis of PGDS in the Vasa Efferentia and Epididymis

Regulation of PGDS expression by testicular factors and testosterone was studied with ipsilateral-ligated efferent ducts and with castrated and castrated-testosterone-supple-mented animals.

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