有机阳离子转运子2在人类附睾中的表达及其意义

目的:研究人类附睾有机阳离子转运子2(OCTN2)mRNA的表达,探讨附睾肉碱转运机制,为探索男性避孕节育新技术提供理论依据。方法:应用RT-PCR方法检测人类附睾头、体、尾组织中OCTN2 mRNA的表达。结果:人类附睾头、体、尾组织中都存在OCTN2 mRNA表达。结论:人类附睾可能依赖OCTN2转运肉碱进入附睾管,为精子提供能量,促进精子成熟。对人类附睾OCTN2的进一步研究,将成为男性节育研究中新的分子靶标。     

Epididymal carbohydrate metabolism in experimental hypercorticosteronism: studies on mature male rats

Corticosterone induced changes in serum hormonal profiles and the key enzymes involved in glycolytic and pentose phosphate pathways were studied in caput, corpus and cauda epididymides of mature male rats (200–250 g body weight). Corticosterone (3.5 mg/100 g body weight sc. for 20 days) treatment was found to depress serum testosterone and prolactin while the gonadotrophins were unaltered. Enzymes of both the glycolytic and pentose phosphate pathways were significantly decreased in caput epididymidis. But in corpus and cauda epididymides only the glycolytic enzymes were reduced. Withdrawal of treatment (for 20 days), resulted in restoration of the glycolytic enzymes to normalcy. The serum hormonal profiles were also found to be within the normal range. The pentose phosphate pathway in caput epididymidis showed a significant increase in enzyme activities following withdrawal of treatment. From the present investigation it is clear that hypercorticosteronism had a definite influence on epididymal enzymes involved in carbohydrate metabolism.     

Gamma-glutamyl transpeptidase activity in the epididymis during fetal and postnatal development in rats.

The histochemical and biochemical distributions of gamma-glutamyl transpeptidase (gamma-GT) were investigated in the epididymis of rats during fetal and postnatal development. In the epididymal homogenates, gamma-GT activity was detected on the fifth day after birth. A sharp increase was observed after 30 days of life in the caput homogenates. Moderate levels of the enzyme were found in the cauda epididymis. Gamma-GT is histochemically detected from the 15th day of gestation in Wolffian ducts and in 17- to 18-day-old fetuses in newly differentiated epididymal tubules. Enzyme activity, was associated with the plasma membranes (apical, lateral, and basal), was preponderant on the apical part of the epithelial cells. During the first 15 days of the postnatal life, the histochemical reaction intensities were identical from the caput to the cauda epididymidis. From the 18th day onwards, enzyme activity decreased in the corpus and in the cauda, while gamma-GT increased in the caput epididymidis, and a strong activity was found on the apical surface of epithelial cells. Weak or moderate gamma-GT activity of spermatozoa in the caput tubules, increasing steadily from caput to cauda epididymidis, suggests that gamma-GT may be related to the functional maturation of spermatozoa.     

Electrolyte and Water Transport in Rat Epididymis; Its Possible Role in Sperm Maturation

Electrolyte and water transport in different regions of the rat epididymis has been studied using a microperfusion technique. The caput and proximal corpus epididymides were found to absorb NaCl and water and secrete K⁺ at a lower rate than the cauda epididymidis. The secretion rate of protein was the same in both regions. In the caput and proximal corpus, reabsorption of chloride was hypertonic. Reabsorption of sodium could not account for water reabsorption. In contrast, water reabsorption in the cauda epididymidis was dependent upon the intraluminal sodium ions. Amiloride inhibited both the Na⁺ and water reabsorption in this region. It was concluded that in the proximal regions of the rat epididymidis, water reabsorption may be secondary to an active transport of chloride, whereas in the cauda, a net transepithelial transport of sodium ions is the driving force for water reabsorption.
Transport of electrolytes and water across the perfused rat cauda epididymidis has also been studied under various experimental conditions. Treatment of rats with alpha-chlorohydrin (9 mg/kg/day) for 7 days inhibited the rate of sodium and water reabsorption without affecting the secretion of proteins. Ligation of the testicular efferent duct or the corpus epididymidis had no significant effect on the transport functions of the cauda epididymidis. When cyproterone acetate (10 mg/rat/day) was injected into male rats, the rate of sodium and water reabsorption was reduced. This effect was accompanied by a loss of sperm motility. It is concluded that the transport functions of the cauda do not require the normal flow of testicular fluid, but may depend on the supply of circulating androgen in the blood. Alpha-chlorohydrin and cyproterone acetate may affect sperm maturation by disrupting the normal milieu of the epididymal duct.     

Glutathione peroxidase activity in cell cultures from different regions of human epididymis

AIM: To study the secretory activity and androgen regulation of glutathione peroxidase (GPx) in epithelial cell cultures from human epididymis. METHODS: Tissue was obtained from patients undergoing therapeutic orchidectomy for prostatic cancer. Epithelial cell cultures were obtained from the caput, corpus and cauda epididymides. Enzymatic activity was measured in conditioned media by colorimetric methods in absence or presence of 1, 10 or 100 nmol/L testosterone. The effect of 1 micromol/L flutamide was also evaluated. RESULTS: GPx activity was higher in cultures from corpus and cauda than caput epididymidis. The presence of different concentrations of testosterone increase enzyme activity in cell cultures from all epididymal regions. Addition of flutamide reverses the androgen dependent increase of GPx activity. CONCLUSION: GPx activity is secreted from human epididymal cells in a region dependent manner and is regulated by androgens.     

TGF-beta could be involved in paracrine actions in the epididymis of the marmoset monkey (Callithrix jacchus).

The transforming growth factor-beta1 (TGF-beta1) and the transforming growth factor-beta receptor type II (TGF-betaRII) were studied in the epididymis of sexually mature marmoset monkeys (Callithrix jacchus) by immunohistochemical localization of the protein and by polymerase chain reaction (PCR) analysis of the mRNA level. In order to specify reactive cell types, the morphology of all three segments (caput, corpus, and cauda epididymidis) was evaluated by light microscopy. Six different cell types could be distinguished: principal, basal, apical, and clear cells, as well as intraepithelial lymphocytes and macrophages. Using immunohistochemistry, specific staining for TGF-beta1 in the caput was found in 47% of the apical cells, whereas the TGF-betaRII was located in the apical portion of 91% of all principal cells. In the corpus epididymidis, 20% of the apical cells were immunopositive for TGF-beta, and binding of the receptor antibody occurred in 17% of the principal cells (all numbers based on counts of counterstained nuclei). All differences between percentages in the caput and corpus were significant as determined by chi-square test. PCR analysis revealed detectable levels of TGF-beta1 mRNA in the marmoset epididymis. Our results indicate for the first time that TGF-beta1 is synthesized in the marmoset epididymis, possibly in a different subpopulation of epididymal cells than the TGF-beta receptor type II. Thus, TGF-beta might be of functional relevance in the primate epididymis.     

Tissue Specificity of the Epididymal Androgen Dependent Phospholipase A

The effect of androgens on phospholipase A in the rat epididymis, liver, heart, kidney, prostate and epididymal fat pad has been investigated both in the cytosol and in a postmitochondrial partiulate cell fraction.
In both cell fractions, phospholipase A activity was 10–15 times higher in the cauda epididymidis than in the other organs, including the caput epididymidis, while the corpus showed an intermediate activity. In the cauda and corpus, castration reduced phospholipase A activity in both subcellular fractions to the same level as found in the other organs, and testosterone supplementation restored the enzyme activity. No evidence of a similar androgen controlled phospholipase A was found in any other tissue examined, including the prostate.     

Sperm maturation in dogs: sperm profile and enzymatic antioxidant status in ejaculated and epididymal spermatozoa

Spermatozoa become more susceptible to the attack of reactive oxygen species during maturation. To avoid oxidative damage, the epididymis must provide the necessary antioxidant protection. The aim of this study was to compare the canine sperm profile and the enzymatic antioxidant status of the ejaculated fractions and samples collected from the different segments of the epididymis (caput, corpus and cauda). Five adult dogs were used, and after 1–3 weeks, subsequently to bilateral orchiectomy and epididymal storage, sperm samples were collected from the different segments of the epididymis. Samples were evaluated for conventional microscopy and computer‐assisted motility analysis: sperm plasma membrane permeability and the activity of the antioxidant enzymes catalase, glutathione peroxidase (GPx) and superoxide dismutase (SOD). Samples collected from the caput and corpus showed lower values for most of the motility variables evaluated, indicating different levels of immaturity. Catalase activity was observed only in ejaculated samples. Conversely, GPx activity was higher in the cauda epididymidis. Correlations were found between SOD and GPx and SOD and sperm motility in the epididymal cauda and corpus, highlighting the importance of the enzymes for the protection of spermatozoa during the transit along the epididymis.     

Origin of the luminal fluid proteins of the rat epididymis

Using a combined microperfusion and high resolution gel electrophoresis technique, the origin of the epididymal fluid proteins of the rat has been investigated. Some proteins originate from the testis, others are secreted by the epididymis or are released by spermatozoa. Of particular interest is a 32 000 dalton protein found to be actively secreted by the caput epithelium in situ and concenrated in the lumen. The cauda epididymidis contained the highest concentration of this protein. Radioactive labelling of the sperm surface proteins revealed that this protein was present on the surface of the mature cauda but not on the immature caput or corpus sperm, suggesting its acquisition by the sperm surface during epididymal transit. Another sperm surface protein of interest (MW 40 000) is present only on the plasma membrane of the cauda but not on that of the caput or corpus sperm. Since this protein was not identified in the epididymal perfusates or luminal fluids, its presence may result from some modification events taking place in the sperm membrane during maturation.     

Protein profiles in various epididymal segments of normal and castrated rats

Aim: Epididymal proteins are known to play an important role in the maturation of spermatozoa. We ought to determine if there are regional differences in androgen-dependent epididymal proteins. Methods: A group of adult rats was castrated and epididymides were removed three days following castration. The epididymides were dissected into caput,corpus and cauda segments, homogenized, and proteins were fractionated by anion exchange HPLC. Proteins in selected fractions were resolved by SDS-PAGE and visualized by silver staining. Results: It was observed that the levels of multiple proteins drastically reduced in the various regions of epididymis of the orchiectomized rats. Conclusion: The epididymal proteins appear to be useful markers to study androgenic action in the epididymis. ( Asian J Androl 2000 ;2: 57-64)     

Physiological significance of nitrergic transmission in human penile erection

The corpora cavemosa (CC) muscles of the human penis and their structural arrangements are essential for the physiology of erection. Contraction of this muscle causes detumescence, and relaxation, tumescence. The motor excitatory neurotransmission is adrenergic, acting through the alpha adrenoceptors. Continuous adrenergic transmitter (noradrenaline) release is necessary for the maintenance of non-erectile (contractile) state of the penis. The inhibitory neurotransmitter that relaxes CC muscle to produce erection is nitrergic i.e., the chemical messenger being nitric oxide (NO). The latter can also be released from cavernous endothelium. Presence of NO increases intracellular cGMP through activation of the enzyme guanylate cyclase. This causes relaxation of CC muscle. Phosphodiesterase type 5 (PDE5) is responsible for the degradation of cGMP and regulation of CC muscle tone. Specific PDE inhibitors such as sildenafil enhance the intracellular cGMP to improve erection. Increase in intracellular cAMP can also bring about pharmacological erection in man (eg. PGE1, papaverine and histamine). Inhibition of excessive adrenergic tone with appropriate alpha - adrenergic blocking agents (eg. phentolamine) can also contribute to the onset of pharmacological erection. ( Asian J Androl 2000 ; 2 : 51 - 56 )     

Two-dimensional gel electrophoretic analysis of rat sperm membrane interaction with cauda epididymal fluid

Two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) was used to analyze the polypeptide composition of rat cauda epididymal fluid, blood serum and membrane-enriched fractions of caput, corpus, and cauda epididymal spermatozoa. Several polypeptides were found in both cauda fluid and blood serum, and in both cauda fluid and epididymal spermatozoa. Prominent cauda epididymal fluid polypeptides that were associated with caput, corpus, and cauda sperm membranes were 32 and 33 kDa. Passage of spermatozoa from the caput to the cauda epididymidis was characterized by the loss of three glycopolypeptides of 32, 30 and 29 kDa, and by the addition of a 37-kDa glycopolypeptide. Incubation of intact caput, corpus and cauda spermatozoa with cauda epididymal fluid revealed major changes in the polypeptide maps of the incubation fluid and the membrane-enriched fractions of caput and corpus, but not cauda spermatozoa. The incubation of cauda fluid with caput and corpus sperm cells was characterized by a loss of several polypeptides and the addition of a 24-kDa glycopolypeptide. The most striking change in spermatozoa incubated with cauda epididymal fluid was the addition of two glycopolypeptides of 32 and 33 kDa to the polypeptide maps of caput sperm cells. These data demonstrate that rat spermatozoa undergo surface modifications during epididymal maturation and that these modifications can be influenced by epididymal fluid.     

The ultrastructure of dog epididymis

Summary The ultrastructure of the epididymal duct and ductuli efferentes in the dog has been studied by electron microscopy. The epididymidis can be separated into the classical divisions of caput, corpus and cauda epididymidis on the basis of general morphology and ultrastructure. The ductuli efferentes have a low epithelium with pronounced cilia at the apices of cells and appear to provide primarily a transport role for spermatozoa. In the epididymis proper the caput region is characterized by an extremely large Golgi apparatus with large numbers of lysosomes and nuclear inclusions. Secretory activity appears to be most common in the corpus region. Absorption and secretion are most active in the first two segments while in the cauda epideidymidis the long-term storage of spermatozoa in the lumen is associated with many dense crystalline bodies formed in the epithelial cells within the Golgi apparatus and possibly deriving from absorbed macromolecular material from the lumen. The theory of whole sperm cell resorption by the epididymal duct is not supported by this study.     

An assessment of the fertilizing ability of spermatozoa in the epididymis of the marmoset monkey (Callithrix jacchus)

The fertilizing ability of spermatozoa from different regions of the epididymis of the marmoset monkey, Callithrix jacchus , was assessed by determining their rate of fusion with zonaless hamster ova in vitro. This technique tests for functional competence and was validated using epididymal spermatozoa of the hamster whose fertility have been measured previously by in vivo fertilization experiments. The results suggest that some marmoset spermatozoa first acquire the ability to fertilize in the distal caput and proximal corpus epididymidis although the majority become fertile on reaching the proximal cauda region. Acquisition of fertilizing capacity was associated with a change in the degree and character of sperm motility. However, it is considered that modifications to the sperm plasmalemma which allow capacitation and the acrosome reaction to occur are of primary importance for sperm fertility. The development of sperm fertilizing ability in the marmoset is discussed in relation to that in other primates.     

Investigation of epididymal sperm maturation in the golden hamster

During passage of hamster spermatozoa through the epididymis their maturation is shown to involve changes in the sperm head, midpiece (mitochondria) and tail. The sum of these changes results in a dramatic increase in the fertilizing potential of the spermatozoa. When comparable numbers of spermatozoa from the caput or corpus epididymis were injected into one uterine horn of mature females, following ovulation induction, and spermatozoa from the cauda epididymis were injected into the contralateral horn, no fertilization was observed with caput epididymal spermatozoa, 1.7% of oocytes were fertilized by corpus epiddymal spermatozoa, whereas 79.5% fertilization was obtained with cauda epididymal spermatozoa. Total sperm numbers increased from caput to corpus to cauda [28.3 ± 12.2, 40.6 ±20.8, 1434 ±62 mihon, respectively]. The percentage of progressively motile spermatozoa increased from 27.9 ±6.4 to 33.8 ± 4.8 to 70 ± 10.7 during this passage. Viability, measured by exclusion of the dye, propidium iodide, was significantly less in spermatozoa from the cauda than from the proximal or mid-caput epididymis. The percentage of the live cells that were stained intensely by rhodamine-123 (a measure of mitochondrial membrane potential) increased during epididymal passage from 22.8 ±7.8% in the proximal caput epididymis to 57.2 ± 16.5% in the cauda epididymis. Staining with acridine orange (a measure of DNA packaging in the sperm head) indicated an increase in chromatin condensation in cauda epididymal spermatozoa, when compared to those obtained from the caput or corpus.     

Sperm structural and motility changes during aging in the Brown Norway rat

The Brown Norway rat provides a useful model to study aging of the male reproductive tract because of the selective age-dependent pathological changes that are found in the testis, epididymis, and prostate. In the testis, there is a clear age-dependent decrease in both steroidogenesis and spermatogenesis. In the epididymis, some striking segment-specific changes occur at the histological and biochemical levels prior to the major loss of spermatogenesis. We hypothesized that formation of spermatozoa in the testis and maturation of spermatozoa in the epididymis (ie, acquisition of motility and loss of the cytoplasmic droplet) may be altered during aging. Changes in the morphology of spermatozoa were assessed by light and electron microscopy. Using computer-assisted sperm analysis, the motility parameters of spermatozoa obtained from the caput and cauda epididymidis of young and old Brown Norway rats were compared. In old animals, we also compared the motility of spermatozoa from epididymides adjacent to regressed testes with those from epididymides adjacent to nonregressed testes. There was a marked increase with age in the number of spermatozoa with abnormal flagellar midpieces; the nature of these defects did not change with age. In caput epididymidis, the percentage of motile sperm was similar in young and old rats. In contrast, the percentage of motile spermatozoa was significantly decreased in cauda epididymidis of old rats; spermatozoa from the regressed testis side had altered motility characteristics. Furthermore, in the cauda epididymidis on the regressed testis side of aged Brown Norway rats, the proportion of spermatozoa that retained their cytoplasmic droplet was markedly elevated. Some of these effects are likely due to changes taking place in spermatozoa during the process of spermatogenesis in the testis (eg, formation of the flagellum), whereas others could occur during sperm maturation in the epididymis (eg, acquisition of motility). The multiple effects of aging on sperm morphology, the acquisition of motility, and the shedding of the cytoplasmic droplet clearly indicate that the quality of spermatozoa is affected by aging.     

Transepithelial movement of non-polar and polar compounds in male rat reproductive tubule examined by in vivo microperifusion and in vivo micropuncture

Proluminal movement of 3H-testosterone and 3H-sucrose from peritubular to intratubular fluids of the adult rat testis and epididymis was investigated by using in vivo microperifusion and subsequent micropuncture of seminiferous tubules and caput, corpus, and cauda epididymal tubules. Tubules were perifused with Minimum Essential Medium containing 3H-testosterone or 3H-sucrose. 14C-polyethyleneglycol was included in the perifusion fluid as a marker for contamination of intraluminal fluid by interstitial fluid. Radioactivity of isotopes in perifusion and intraluminal fluids was determined at one and two hours after perifusion and the percentage of peritubular isotopes appearing in intraluminal fluid was determined. Net entry of 3H-sucrose into the seminiferous and epididymal tubules was significantly reduced. Proluminal movement of 3H-androgen across the seminiferous epithelium was also restricted. In contrast, intraluminal 3H-androgen concentrations in caput epididymal fluid were 200 to 300% of those in peritubular fluid at both one and two hours after perifusion. Similar results were found in the corpus epididymidis. 3H-androgen concentrations in cauda epididymal fluid were approximately 125% of peritubular isotope concentrations. The exact mechanism underlying this uphill proluminal movement of 3H-androgen into the rat epididymal lumen remains to be elucidated.     

In vitro Metabolism of (3H)-Androstenedione in the Rat Epididymis and Vas Deferens

The in vitro metabolism of (3H)-androstenedione in the epididymis and vas deferens of intact and castrated rats was investigated and the metabolites formed were identified by radio gas chromatography. Incubation of slices of caput epididymidis for 2 hr at 34 degrees C metabolised 90% androstenedione. Similar incubations of tissue samples from cauda epididymidis and vas deferens metabolized 60 and 25% of androstenedione respectively. The major metabolites formed in the epididymis were androstanedione (caput: 48%; cauda: 33%) and androsterone (caput: 35%; cauda: 13%). These metabolites appeared in much less concentration in the incubations with vas deferens (about 8% each). In general, conversion to testosterone and dihydrotesterone was low in all the three organs examined. Castration did not significantly alter the metabolic pattern in the caput epididymidis and vas deferens but promoted the formation of androsterone (38%) in the cauda epididymidis. The conversion of androstenedione, a weak androgen to testosterone, dihydrotestosterone and 3 alpha/3 beta-diols in the epididymidis and vas deferens of castrated rats may be of physiological significance. In addition, androsterone appears to be an important androgenic metabolite in the epididymis.     

流式细胞术测定睾丸和附睾中生精细胞DNA含量

目的 :观察睾丸和附睾各段组织管腔内生精细胞DNA含量的变化。　方法 :利用流式细胞术 (FCM) ,对15例有生育能力、意外死亡的青年捐献者的右侧新鲜睾丸和附睾 (头、体、尾 )组织管腔内生精细胞的DNA含量进行测定。　结果 :从睾丸至附睾尾均存在单倍体 (1n)、二倍体 (2n)和四倍体 (4n) 3种细胞。 1n细胞由 (2 4 .87±7.2 8) %增至 (96 .33± 1.5 8) % ,其中睾丸至附睾每段之间的差异有极显著性 (P <0 .0 1) ,附睾体与附睾尾之间也有明显差别 (P <0 .0 5 )。 2n和 4n细胞的比例分别由 (6 3.0 7± 8.96 ) %、(9.4 3± 3.83) %下降至 (2 .4 7± 0 .93) %、(1.17± 0 .95 ) %。睾丸至附睾每段之间 2n细胞的比例差异有极显著性 (P <0 .0 1) ,附睾体与附睾尾之间也有明显差别(P <0 .0 5 ) ;除睾丸与附睾头之间的 4n细胞变化不明显外 (P >0 .0 5 ) ,其他各段之间的 4n细胞比例差异也有显著性 (P <0 .0 5 )。　结论 :未成熟生精细胞比例在附睾转运过程中逐渐减少