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Query: UNIPROT:P56851 (epididymal)
 11,273 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Capacitation is defined as the series of transformations that spermatozoa normally undergo during their migration through the female genital tract, in order to reach and bind to the zona pellucida, undergo the acrosome reaction, and fertilize the egg. During this process, extensive changes occur in all sperm compartments (head and flagellum; membrane, cytosol, cytoskeleton), factors originating from epididymal fluid and seminal plasma are lost or redistributed and membrane lipids and proteins are reorganized; ion fluxes induce biochemical modifications and controlled amounts of reactive oxygen species are generated; spermatozoa develop hyperactivated motility; and complex signal transduction mechanisms are initiated. The main purpose of capacitation is to ensure that spermatozoa reach the eggs at the appropriate time and in the appropriate state to fertilize these eggs, by finely-controlling the rate of the changes necessary to prime spermatozoa and by activating all the mechanisms needed for the subsequent acrosome reaction. The reversibility of some of the mechanisms leading to sperm capacitation may therefore be a very important aspect of the fine regulation and perfect timing of this process.
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PMID:Capacitation as a regulatory event that primes spermatozoa for the acrosome reaction and fertilization. 923 44

The relationships between blood lead, sperm lead, sperm reactive oxygen species (ROS) level, and sperm fertile capability were investigated to understand the effects of lead exposure on sperm function and the mechanism of these effects. Male Sprague-Dawley rats, 7 weeks old, were randomly divided into control group and lead-treated group. The controls and lead-treated animals received intraperitoneal injection of 10 mg sodium acetate and 10 mg lead acetate/kg body weight, respectively, weekly for 6 or 9 weeks. The blood lead and epididymal sperm lead were analyzed by graphite furnace atomic absorption spectrophotometer. Chemiluminescence was measured to evaluate the generation of sperm ROS. Sperm-oocyte penetration rate (SOPR) was measured to evaluate sperm function. After 6 weeks of lead exposure, the rats had average blood lead levels of 32 microg/dl, sperm lead levels of 0.67 +/- 0.11 microg/10(9) sperm, unchanged epididymal sperm counts, percent of motile sperms, and motile epididymal sperm counts compared with control animals. However, after 9 weeks of lead exposure, the rats had average blood lead levels of 48.0 +/- 4.3 microg/dl, sperm lead levels of 0.88 +/- 0.16 microg/10(9) sperm, statistically lower epididymal sperm counts, and lower motile epididymal sperm counts. There was a good correlation between the blood lead and sperm lead(r2 = 0.946, P < 0.001). The sperms of lead-exposed rats produced significantly higher counts ofchemiluminescence than did those from the control rats (P < 0.001). The chemiluminescence counts were positively associated with sperm lead level (r2 = 0.613, P < 0.001). Epididymal sperm counts, motility and motile epididymal sperm counts were negatively associated with sperm chemiluminescence (r2 = 0.255, 0.152, and 0.299; P < 0.01, 0.05, and 0.01, respectively). The SOPR were positively associated with epididymal sperm counts, motility and motile epididymal sperm counts (r2 = 0.136, 0.285, and 0.264; P < 0.05, 0.01, and 0.001, respectively). The sperm chemiluminescence was negatively associated with SOPR (r2 = 0.519, P < 0.001). It is concluded that lead exposure probably affected the sperm function by activating one of the pathways of ROS generation.
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PMID:Lead exposure causes generation of reactive oxygen species and functional impairment in rat sperm. 927 9

Spermatozoa are highly sensitive to oxidative stress. The epididymis, a natural sperm reservoir, has maturational and storage functions. The epididymis may also protect spermatozoa from oxidative injury by elaborating scavengers of reactive oxygen species (ROS). Therefore, we have evaluated the mRNA expression of antioxidant enzymes in the normal rat epididymis and the effects of efferent duct ligation no the expression of these enzymes. Adult rat epididymides were harvested, divided into caput, corpus and cauda and processed for RNA extraction. Additional adult rats were subjected to unilateral efferent duct ligation and the epididymides harvested at 1, 4, 8, 16 or 28 days after the procedure. Antioxidant enzyme mRNA expression was assessed by Northern blot analysis using 32P-labelled DNA probes derived from known cDNA sequences for classical cellular glutathione peroxidase (GSHPx), phospholipid hydroperoxide glutathione peroxidase (PHGPX), secretory epididymal glutathione peroxidase (E-GPX), copper-zinc superoxide dismutase (SOD), secretory epididymal superoxide dismutase (E-SOD) and catalase. Specific mRNA levels were measured, with gene expression evaluated relative to total RNA, not per organ. Variations in lane loading were controlled by measuring the levels of 28S ribosomal RNA. GSHPx, PHGPX, SOD and catalase mRNA were detected in the caput, corpus and cauda epididymis. E-GPX mRNA was only detected in the caput, whereas E-SOD mRNA was primarily detected in the corpus. At 28 days after efferent duct ligation, epididymal weight decreased by 34% relative to controls (p < 0.05). With the exception of PHGPX, the relative mRNA levels of the antioxidant enzymes studied did not change after efferent duct ligation. This study demonstrates that mRNAs for multiple antioxidant enzymes are expressed in the epididymis and that the relative expression of these enzymes remains largely unchanged in response to efferent duct ligation. Taken together, these results suggest that antioxidant enzymes may play an important, region-specific role in epididymal function. Expression of the secretory antioxidant enzymes E-SOD and E-GPX is region-specific, indicating that the need for antioxidant enzymes may vary along the length of the epididymis.
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PMID:Identification and characterization of antioxidant enzyme mRNAs in the rat epididymis. 929 18

Involvement of reactive oxygen species has been implicated in the process of hyperactivation and capacitation of sperm. Nitric oxide has recently been found to function both as an intracellular and extracellular messenger, with its synthetic enzyme found in several cell types, including male and female genital tract organs. The objective of the present study was to investigate the role of nitric oxide in hamster sperm hyperactivation. Caudal epididymal contents of mature golden hamster sperm were diluted with human tubal medium supplemented with a sperm motility preparation. Inhibitors of nitric oxide synthase (nitro-L-arginine, methyl-L-arginine, and 1,3-phenylene-bis[1,2-ethenediyl]-bis-isothiourea) were added to incubation media in various doses. Alternatively, a nitric oxide donor, sodium nitroprusside, was used. The percentage motile and grade of movement were recorded at intervals encompassing the normal period of capacitation and hyperactivation. Acrosomal status was evaluated by phase contrast microscopy. Inhibition of nitric oxide synthesis did not affect motility during early capacitation but dramatically inhibited later hyperactivation. An inactive stereo-enantomere of the inhibiting drug had no effect. Addition of nitric oxide to nonstimulated sperm induced hyperactivation in a similar time course. In conclusion, nitric oxide plays a significant role in hyperactivation of hamster epididymal sperm.
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PMID:Evidence for nitric oxide regulation of hamster sperm hyperactivation. 953 92

We have previously shown human lipid-mobilizing factor (LMF) to be homologous with the plasma protein Zn-alpha2-glycoprotein in amino acid sequence, electrophoretic mobility, and immunoreactivity. In this study, both LMF and Zn-alpha2-glycoprotein have been shown to stimulate glycerol release from isolated murine epididymal adipocytes with a comparable dose-response profile. Both LMF and Zn-alpha2-glycoprotein caused a stimulation of adenylate cyclase in murine adipocyte plasma membranes in a GTP-dependent process, with maximum stimulation at 0.1 microM GTP and with saturation at protein concentrations of >5 microg/assay. Administration of LMF to exbreeder male mice over a 89-h period produced a decrease in body weight without a change in food and water intake. Body composition analysis showed a 42% reduction in carcass lipid when compared with controls. Treatment of ob/ob mice with human LMF over a 160-h period also produced a decrease in body weight, with a 19% reduction in carcass fat, without a change in body water or nonfat mass. Serum levels of glycerol and 3-hydroxybutyrate were significantly increased, as was oxygen uptake by interscapular brown adipose tissue, providing evidence of increased lipid mobilization and utilization. Human white adipocytes responded to both LMF and isoprenaline to the same extent, although the maximal response was lower than that for murine white adipocytes. These results suggest that LMF not only has the capacity to induce lipid mobilization and catabolism in mice, but it also has the potential to exert similar effects in cachectic cancer patients.
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PMID:Biological evaluation of a lipid-mobilizing factor isolated from the urine of cancer patients. 962 75

Mammalian caput and cauda epididymidal spermatozoa exhibit diverse stages of maturation, and their plasma membrane shows diverse composition and stability levels, thus enabling these spermatozoa to undergo the acrosomal reaction after transit through the epididymis. As a result, the study of antiperoxidative mechanisms is quite relevant, since epididymal spermatozoa must be properly protected against agents such as reactive oxygen species, which can impair the complex maturation process. We considered activities of certain enzymes (glutathione peroxidase [GPx], phospholipid hydroperoxide glutathione peroxidase [PHGPx], glutathione reductase [GR], superoxide dismutase [SOD], and catalase [CAT]) and the vitamin E content in isolated rat caput and cauda epididymidal spermatozoa. The results indicate that caput epididymidal sperm have significantly greater PHGPx (3.5x), GPx (2.4x), and SOD (1.7x) activities, as well as a greater amount of vitamin E (3.8x). There were no detectable differences in the GR and CAT activities of caput and cauda epididymidal spermatozoa. The substantial drop in PHGPx activity during epididymal transit is discussed in relation to an additional function of this enzyme: the use of caput sperm protamines as a sulfhydryl substrate. In vitro peroxidation of the two sperm populations by the free radical generator (azo-initiator) 2,2'-azobis(2-amidinopropane) dihydrochloride revealed that only about 13% of the vitamin E content of the caput epididymidal spermatozoa was consumed, which contrasts with the greater consumption (about 70%) of the vitamin in cauda epididymidal spermatozoa. Selective inhibition of PHGPx, SOD, or CAT did not change this picture. The higher susceptibility of cauda epididymidal spermatozoa to radicals is discussed in relation to the diverse enzymatic activities, vitamin E content, and peroxidative response. These factors are correlated with the different stages of sperm cell maturation, which are characterized-from caput to cauda epididymidis-by progressive destabilization of the plasma and acrosomal membranes.
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PMID:Antioxidant systems in rat epididymal spermatozoa. 974 22

The relationships between sperm reactive oxygen species (ROS) generation, the capacitation process and acrosome reaction, and the spermoocyte penetration rate (SOPR) were investigated to understand the effect of lead toxicity on sperm functions and the mechanisms of these effects. Male Sprague-Dawley rats received weekly intraperitoneal injections of 20 mg or 50 mg lead acetate/kg or 20 mg or 50 mg sodium acetate/kg (control) for 6 wk. Serum testosterone was measured by radioimmunoassay. In cauda epididymal spermatozoa, the chemiluminescence was measured to evaluate the sperm ROS generation. Chlortetracycline fluorescence assay was used to study the status of capacitation and acrosome reaction on fresh cauda epididymal spermatozoa and after 2, 4, or 24 h of incubation with 5 mg/ml bovine serum albumin. In lead-exposed rats, the serum testosterone levels were reduced, and the percentage of capacitation and the chemiluminescence were significantly increased in fresh cauda epididymal spermatozoa. The serum testosterone levels were negatively associated with the percentage of acrosome-reacted spermatozoa. Sperm chemiluminescence was positively correlated with the percentage of both capacitated and acrosome-reacted spermatozoa. The SOPR was negatively associated with the percentage of both capacitated and acrosome-reacted spermatozoa. In summary, this study showed that male rats exposed to lead had decreased serum testosterone levels and that this metal produced early onset of capacitation by one of the pathways of ROS generation. These effects might consequently result in premature acrosome reaction and reduced zona-intact oocyte-penetrating capability.
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PMID:Lead-induced changes in spermatozoa function and metabolism. 974 3

This study was undertaken to investigate whether treatment with vitamin E (VE) and/or vitamin C (VC) protects rat sperm by inhibiting reactive oxygen species generation induced by lead (Pb) exposure. Male Sprague-Dawley rats were assigned to the following five groups: vitamin-unsupplemented; 150 mg VE/kg chow supplemented; 300 mg VE/kg chow supplemented; 500 mg VC/l drinking water supplemented and 150 mg VE/kg chow + 500 mg VC/l drinking water supplemented group. Rats in each group were divided into Pb-unexposed and Pb-exposed subgroups, received weekly intraperitoneal injection of 10 mg sodium acetate or 10 mg Pb acetate/kg for 6 weeks, respectively. The blood and sperm Pb levels were analyzed by graphite furnace atomic absorption spectrophotometer. Chemiluminescence was measured to evaluate the generation of sperm reactive oxygen species (ROS). Motility and sperm-oocyte penetration rate (SOPR) were measured. In Pb-unexposed rats, epididymal sperm counts, motility, ROS, and SOPR were not different in the five supplemented groups. Lead exposure might decrease the defense capacity of sperm to the oxidative stress and therefore elevate the ROS generation, reduce sperm motility, and reduce SOPR. Supplementation with VE and/or VC reduced ROS generation, prevented loss of motility and capacity of oocyte penetration in Pb-exposed rats. This study suggests that supplementation with VE and/or VC inhibits Pb-related ROS generation, protects spermatozoa from loss of motility and oocyte penetration capability.
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PMID:Effects of vitamin E and/or C on reactive oxygen species-related lead toxicity in the rat sperm. 975 40

We have recently shown that leptin enhances systemic insulin sensitivity and whole body glucose utilization in the rat. This study examines our hypothesis that leptin has differential effects in regulating glucose utilization among the tissues, i.e. stimulating glucose utilization in brown adipose tissue (BAT) and skeletal muscle but suppressing glucose utilization in white adipose tissue (WAT) in normal male rats (275-350 g BW). The rats were treated with s.c. infusion of recombinant murine leptin (4 mg/kg x day) or vehicle (V) with Alzet osmotic pumps or with vehicle and pair-feeding (PF) for 7 days. Leptin significantly decreased food intake (leptin, 11.5 +/- 0.4 g/day; V, 16.8 +/- 1.5 g/day; P < 0.05) and body weight (maximum change, 5.0 +/- 0.2%; P < 0.05 vs. V) and lowered plasma triglyceride, insulin, and glucose levels, but raised beta-hydroxybutyrate levels. Glucose utilization by individual tissues was determined with an i.v. bolus of [1-(14)C]2-deoxyglucose (2-DG) after a 90-min hyperinsulinemic (2 mU/kg x min) euglycemic clamp. With leptin treatment, the 2-DG-determined glucose utilization in interscapular BAT was almost 3-fold that in V-treated rats and 70% greater than that in PF rats. In contrast, in the epididymal WAT, glucose utilization was reduced by leptin treatment to only 34% that in V-treated rats and 45% that in PF rats. Leptin increased 2-DG uptake by extensor digitorum longus muscle and soleus muscle compared with that in the V and PF groups. With leptin treatment, the GLUT4 glucose transporter mRNA and protein levels were increased in BAT, but decreased in WAT (both P < 0.05). There was no significant change in GLUT4 mRNA and protein expression in extensor digitorum longus muscle and soleus muscle. Oxygen consumption was significantly increased (32.1 +/- 7.4%) in BAT (139.0 +/- 8.2 nmole O2/30 min x 10(6) cells) of leptin-treated rats vs. that in V control rats (105.3 +/- 6.7 nmole O2/30 min x 10(6) cells). In conclusion, leptin has differential, tissue-specific effects on glucose and oxygen utilization, which contribute to the reduction in whole body adiposity by enhancing energy consumption in BAT and muscle while attenuating energy storage in WAT.
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PMID:Differential effects of leptin in regulation of tissue glucose utilization in vivo. 1021 62

Leptin inhibits food intake and increases metabolic rates in adult mice. Neonatal mice need to maximize food intake and also maintain high thermoregulatory metabolic rates to optimize survival, suggesting that leptin may function differentially in neonatal versus adult animals. The efficacy of exogenous leptin to alter these two physiological functions during development was thus examined in C57BL/6J lean (+/+ or ob/+) and ob/ob (leptin-deficient) mice. Intraperitoneal leptin administration (1 mg/kg body wt) to lean and ob/ob pups from 7 to 10 days of age did not affect milk intake, oxygen consumption, body weight, or epididymal fat pad weights. Intracerebroventricular injection of 1 microg leptin to 9-day-old pups also failed to influence milk intake or oxygen consumption. Because neither lean nor ob/ob pups responded to exogenous leptin, high endogenous plasma leptin concentrations per se in these lean mice do not explain their resistance to leptin. Leptin administered intracerebroventricularly also failed to alter milk/food intakes of 17-day-old pups but markedly increased oxygen consumption of these older mice. By 28 days of age, intracerebroventricular leptin inhibited food intake. The well-defined actions of leptin to reduce food intake and enhance metabolic rates do not develop synchronously. The ability of leptin to accelerate metabolic rates is acquired early in life and independent of its anorectic action, which may promote survival of neonates.
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PMID:Leptin alters metabolic rates before acquisition of its anorectic effect in developing neonatal mice. 1048 91


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