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

Insulin stimulation of hydrogen peroxide production by rat epididymal fat cells was investigated by studying the oxidation of formate to CO2 by endogenous catalase. Under optimal concentrations of formate (0.1 to 1 mM) and glucose (0.275 mM), insulin stimulated formate oxidation 1.5- to 2.0-fold. Inhibitors of catalase activity, including nitrite and azide, inhibited both basal and insulin-stimulated formate oxidation at concentrations that did not interfere with insulin effects on glucose C-1 oxidation or glucose H-3 incorporation into lipids. The addition of exogenous catalase increased formate oxidation only slightly, while exogenous H2O2 (0.5 mM) stimulated formate oxidation by endogenous catalase strongly. These data indicate that the insulin-stimulated H2O2 production was intracellular. Insulin dose-response curves for formate oxidation were identical with those for glucose H-3 incorporation into lipids. The dependence of relative insulin effects on the logarithm of the glucose concentration was bell-shaped for formate oxidation and correlated highly with the coresponding dependences of glucose C-1 oxidation and glucose H-3 incorporation into lipids. This suggests that insulin stimulation of intracellular H2O2 production is linked to glucose metabolism. Since it is known that extracellular H2O2 can mimic insulin in several respects, these observations suggest that H2O2 may act as a "second messenger" for the observed effects of insulin.
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PMID:Insulin-stimulated intracellular hydrogen peroxide production in rat epididymal fat cells. 42 81

1. 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) produces atrophy, morphological changes, impaired spermatogenesis, and epididymal lesions in testis of experimental animals. The effects of TCDD administration to male rats on various parameters in the testes were examined. 2. Nine days after TCDD administration, significant decreases in body and testes weights occurred. However, the testes weight as a percent of body weight was higher in treated than control animals. 3. An increase in lipid peroxidation (content of thiobarbituric acid reactive substances) occurred in conjunction with the decrease in testicular weights. 4. TCDD administration produced a 3-fold increase in protein kinase C activity, small but significant decrease is superoxide dismutase and glutathione peroxidase activities, and no effect on catalase, glutathione reductase or glutathione S-transferase activities in the testes. 5. Nine days after treatment with TCDD, in the testes the iron content of whole tissue and cytosol increased while a decrease in microsomal iron was observed. The copper content of mitochondria and microsomes decreased with a corresponding increase in cytosol copper content. A small increase in the zinc content of whole testes occurred. 6. The data indicate that testicular atrophy due to TCDD may be associated with lipid mobilization and peroxidation.
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PMID:2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD)-induced alterations in lipid peroxidation, enzymes, and divalent cations in rat testis. 324 26

A peroxisomal fraction with catalase and CN- -insensitive palmitoyl CoA beta-oxidative activity different from the CN- -sensitive mitochondrial palmitoyl CoA beta-oxidative activity was purified from rat epididymal and perirenal white adipose tissue by differential and sucrose density gradient centrifugations. The degree of purification of this fraction as compared to the nuclei-free and fat-free homogenate was 10 and 34 for catalase and palmitoyl CoA beta-oxidative activity, respectively. The finding that it was devoid of urate oxidase activity suggests that white adipose tissue peroxisomes are anucleoid. The contributions of the peroxisomes and of the mitochondria to total beta-oxidative activity in white adipose tissue were 65 and 35%, respectively. Hypothyroidism induced a 2.0- and 2.4-fold decrease of mitochondrial and peroxisomal beta-oxidation specific activities, respectively. These results are discussed in terms of a possible thermogenic role for white adipose tissue peroxisomes.
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PMID:Peroxisomal and mitochondrial palmitoyl coenzyme A beta-oxidation activities in rat white adipose tissue and their regulation in hypothyroidism. 684 94

We have previously reported that endothelial cell (EC) xanthine dehydrogenase/xanthine oxidase (XD/XO) activity correlates inversely with the O2 tension to which the cells are exposed. Whether this effect is related to the production of reactive O2 species is unclear. We exposed bovine pulmonary artery EC to various conditions that altered the redox status of the cells: 1) hypoxia (3% O2) and normoxia (20% O2); 2) menadione (MEN), known to generate O2 radicals; 3) catalase (CAT) and reduced glutathione (GSH), which detoxify H2O2; and 4) various NO-generating systems. Changes in intracellular XO and XO + XD activities were correlated with rates of extracellular H2O2 release from the same cells. Conditions that decreased extracellular H2O2 release (hypoxia, CAT, and GSH) produced significant and parallel increases in intracellular XO and XO + XD activities in a time-dependent fashion. MEN treatment increased extracellular release of H2O2 and subsequently reduced intracellular XO and XO + XD activities. NO-generating agents did not change extracellular release of H2O2 but significantly reduced XO and XO + XD activities. The latter effect was prevented by reduced hemoglobin. Scavengers of hydroxyl radicals reversed the inhibition of XO and XO + XD activities produced by MEN but not that produced by NO. While NO significantly inhibited XD/XO activity from rat epididymal fat pad, it did not affect XD/XO mRNA expression in these cells. We conclude that intracellular XD/XO activity is sensitive to changes in oxidant-generating and protective systems. Inhibition of XD/XO activity by NO may be mediated through direct binding of NO to the enzyme iron-sulfur moiety or to its sulfhydryl groups.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effect of nitric oxide and cell redox status on the regulation of endothelial cell xanthine dehydrogenase. 776 82

Several studies indicate that reactive oxygen species (ROS) are involved in defective sperm function pathophysiology. In this study we attempted to determine differentially the effects of xanthine (0.12 mM) plus xanthine oxidase (0.035 U/mL) (X+XO, a ROS promoter system), ROS scavengers (Tiron (TIR, 15 mM); catalase (CAT, 10 micrograms/mL); dimethylsulfoxide (DMSO, 140 mM)), and X+XO plus scavengers on several epididymal mouse spermatozoa functional parameters, incubated in NTPC medium, for 29 min. In the presence of X+XO, progressive gametes significantly diminished. TIR or CAT attenuated this effect, but DMSO did not. Inversely, X+XO increased the bending-forms population; only TIR reversed this phenomenon. The ROS promoter system diminished the viable cell population; all scavengers assayed maintained sperm viability at levels similar to control ones. When exposed to hypoosmotic shock after 29 min incubation with X+XO, the percentage of swollen cells decreased; TIR, CAT, or DMSO did not prevent this effect. Our experiments demonstrate that it is possible to differentiate the deleterious ROS effects upon sperm functional activity. O-2. and H2O2 preferentially seem to modify sperm motility, O-2. exhibiting the greatest ability for generating bending-form gametes, OH-being the most lethal ROS. In addition, sperm membrane clearly appears as the most damaged structure.
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PMID:Differential effects of pharmacologically generated reactive oxygen species upon functional activity of epididymal mouse spermatozoa. 916 98

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

1. The acute effect of hexachlorocyclohexane (HCH) administration (i.p.) on testicular antioxidant system and lipid peroxidation (LPX) in immature and mature rats (15- and 90-day-old, respectively) were compared. 2. In both the age groups, the level of LPX in crude homogenate of testis (endogenous, as well as FeSO4, and ascorbic acid-stimulated) was increased after 6 hr of HCH treatment and remained high till 24 hr. However, FeSO4 and ascorbic acid-stimulated LPX was higher in 90-day-old rats in comparison to 15-day-old rats. HCH treatment also resulted in elevation of LPX level in testicular subcellular (nuclear, mitochondrial and microsomal) fractions by 6 hr of treatment. However, the magnitude of increase was greater in case of 90-day-old rats. 3. Activities of testicular cytosolic superoxide dismutases (total and CN(-)-resistant) of rats of 15- and 90-day-old age groups decreased significantly after 6 hr of HCH treatment, and remained decreased till 24 hr of the pesticide treatment. The percentage of decrease was higher in 15-day-old rats than 90-day-old rats. CN(-)-sensitive SOD activity of testis was found to decrease by 12 and 24 hr after the pesticide treatment in 15- and 90-day-old rats, respectively. The activity of catalase decreased 6 hr after the pesticide treatment in both the age groups. However, the magnitude of decrease was similar for both age groups of rats. 4. Testicular glutathione content, as well as levels of glutathione metabolizing enzymes (glutathione peroxidase and glutathione reductase), did not change in response to HCH treatment, whereas ascorbic acid content decreased by 12 and 6 hr after HCH treatment in 15- and 90-day-old rats, respectively. The level of H2O2 was found to be elevated after 6 hr of the pesticide treatment in both age groups. 5. Total epididymal sperm number was comparable in all experimental groups. However, the percentage of dead and damaged spermatozoa was significantly enhanced in HCH treated rats. 6. Acute HCH administration to rats results in induction of oxidative stress in the testis which depends upon the age of the animal.
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PMID:Comparison of hexachlorocyclohexane-induced oxidative stress in the testis of immature and adult rats. 946 84

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

Effect of repeated oral administration of hexachlorocyclohexane (HCH; 10 and 20 mg/kg body weight per day for 7, 15 and 30 days) on antioxidant defence system and lipid peroxidation (LPX) in the testis was compared between immature (15-day-old) and mature (90-day-old) rats. In both age-groups of rats, the pesticide elicited a significant decrease in the activities of cytosolic superoxide dismutase (SOD; total and CN(-)-resistant) and catalase, and ascorbic acid content together with an increase in the levels of LPX (both in crude homogenate and subcellular fractions) and H2O2. Testicular glutathione peroxidase (GPx; total and non-selenium-dependent) activity was enhanced in both the age-groups of rats while the testicular glutathione content as well as glutathione reductase activity remained unaltered. HCH treatment resulted in a decrease of total epididymal sperm number with a higher incidence of dead and damaged spermatozoa, and sperms having anomalous head. Statistical analyses suggest that the alterations in the testicular antioxidant defence profile in the rat are not only dependent on the duration of pesticide treatment, but also influenced by age.
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PMID:Age-related changes in rat testicular oxidative stress parameters by hexachlorocyclohexane. 1035 Jan 90

The metabolism, rate of intracellular accumulation of sugars, motility and ultrastructure of ejaculated tammar sperm were impaired by swim-up into artificial media, particularly when the cells were subsequently exposed to N-acetyl-D-glucosamine (NAG). The inclusion of hyaluronate, serum albumin, catalase or Desferal in swim-up media helped prevent deterioration of sperm motility, but failed to prevent detrimental NAG-induced metabolic and ultrastructural changes. However, the sperm were unavoidably diluted during swim-up into artificial media and their behavioural properties were modified by dilution. Thus, sperm collected from the cauda epididymidis were immotile and their rate of oxygen uptake was low in undiluted caudal epididymal semen (CES). Nevertheless, these sperm were viable, and vigorous motility was induced by 5- to 50-fold dilution in Krebs-Ringer phosphate (KRP). Sperm respiration also dramatically increased with moderate dilution (5- or 15-fold) in KRP, but decreased again at higher rates (50-fold). This suggested that motility and the metabolic properties of tammar sperm are modified both by dilution and on leaving the suppressing conditions of the epididymis. Diluted tammar epididymal sperm also displayed a Pasteur effect, but rapidly lost capacity for motility in an oxygen-depleted atmosphere. It was concluded that swim-up procedures compromise ejaculated tammar sperm by promoting dilution-induced changes. This may alter the permeability of the membrane with loss of the enzymes that process the ammonia generated during the metabolism of NAG in seminal plasma. Subsequent exposure to NAG further promotes ultrastructural damage culminating in loss of viability.
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PMID:The ultrastructure and metabolism of ejaculated tammar wallaby sperm are impaired by swim-up procedures when compared with sperm from the cauda epididymidis. 1089 91


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