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

1. Evidence has been provided for the transfer of phosphatidyl[14C]choline and [3H]cholesterol between bovine serum albumin and cauda epididymal rat spermatozoa in Krebs-Ringer bicarbonate medium, which can promote sperm capacitation. 2. An analysis of the lipid composition in both albumin and spermatozoa revealed that phospholipid levels decreased in the protein and increased by roughly comparable amounts in sperm cells during incubation in vitro. 3. Cholesterol (free + ester) increased in albumin and decreased in spermatozoa. Changes in the amount of esterified cholesterol were solely responsible for the increase associated with albumin, whereas whole sperm cell extracts showed a significant decline in free cholesterol. 4. The composition of albumin-bound fatty acids did not alter appreciably as a result of incubation with spermatozoa. 5. Rates of [14C]palmitic acid utilization by spermatozoa suggest that lipid synthesis accounted for less than 5% of the changes observed under the conditions of this study. 6. These results are interpreted as broadly supporting our previous proposal that lipid exchange between albumin and sperm cells is implicated in sperm capacitation in vitro. Specifically, the results are compatible with the idea that a decreased cholesterol/phospholipid ratio in the sperm plasma membrane facilitates this transformation.
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PMID:Studies on the mechanism of capacitation. II. Evidence for lipid transfer between plasma membrane of rat sperm and serum albumin during capacitation in vitro. 50 48

A study of the lipid composition of ram testicular and ejaculated spermatozoa was made in an attempt to resolve conflicting results in the literature. Testicular spermatozoa were found to contain more than double the amount of phospholipid present in ejaculated spermatozoa. Most phohpholipid components, including choline plasmalogen, decrease substantially in concentration during migration of the spermatozoa through the male reproductive tract. Phosphatidylserine, ethanolamine phosphoglycerides and cardiolipin components accounted for the greatest relative decreases in concentration, the former decreasing by approximately nine tenths. Of the phospholipid-bound fatty acids the most pronounced change occurs in palmitic during migration of spermatozoa through the reproductive tract. There is a net loss of approx. 500 mug of palmitic acid for every 10-9 spermatozoa. The loss of arachidonic acid was particularly interesting, and prompted a study of the prostaglandin content of testicular and epididymal fluids, since arachidonic acid can act as a precursor of prostaglandin. The concentration of prostaglandin F2alpha found in the testicular and epididymal fluid is considerably in excess of that found in venous plasma of the ram.
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PMID:Changes in phospholipids of ram spermatozoa during migration through the epididymis and possible origin of prostaglandin F2alpha in testicular and epididymal fluid. 112 97

Disaccharide effect of sucrose on lipid metabolism was confirmed in male Wistar rats (initial weight 119-127 g). The rats were given rations containing either sucrose (30% of total caloric++ value), or invert sugar, or starch only (control). The duration of the dietary period was 40 days. To study lipid metabolism the rats were injected i. p. with 1-14C-glucose and 3H-palmitic acid. 14C-radioactivity increased in the total lipid of serum and epididymal adipose tissue, in liver phospholipids and mostly in liver neutral lipids with the saccharose-supplemented diet but not with invert sugar-supplemented diet. In contrast, 3H-radioactivity in liver phospholipids decreased in rats that were given saccharose, no changes were recorded in the animals fed with invert sugar or starch.
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PMID:[Effect of sucrose on lipid metabolism in rats: confirmation of the disaccharide effect]. 224 62

The comparative bioavailability of cocoa butter (a predominantly saturated fat) and corn oil (a predominantly unsaturated fat) was determined in male Sprague-Dawley rats by analysis of total fecal lipids following ad libitum feeding of purified diets containing 5, 10 and 20% cocoa butter or corn oil for 2 wk. Fecal lipid elimination was significantly increased (P less than 0.05) in each cocoa butter group when compared with the corresponding corn oil group, resulting in lower digestibility coefficients for cocoa butter (59-72%) than for corn oil (93-97%). Body weight gain and food intake data were similar among all treatment groups. Fecal fatty acid profiles in rats fed corn oil diets consisted primarily of 27-34% palmitic acid (16:0), 22-32% stearic acid (18:0) and 25-37% oleic acid (18:1). Palmitic, oleic and linoleic acids were also the primary fatty acids stored in epididymal fat tissue from corn oil-fed rats. In contrast, fecal fatty acids in animals fed cocoa butter diets consisted of 31-37% palmitic acid and 58-64% stearic acid; oleic acid was the major fatty acid stored in epididymal fat tissue. These results indicate that the decreased digestibility of cocoa butter is largely a result of its fatty acid composition. This reduced bioavailability of cocoa butter may be at least partially responsible for its previously described neutral effect on serum cholesterol.
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PMID:Digestibility of cocoa butter and corn oil and their influence on fatty acid distribution in rats. 358 14

The mechanism of S-100 protein release from adipocytes, which is apparently coupled with lipolytic activity, was investigated in vitro using rat epididymal fat pads. The S-100 protein release was increased severalfold by 10 microM epinephrine in the medium containing a low concentration (less than 5 mg/ml) of albumin, but the release was enhanced only slightly when the medium contained a high concentration (more than 20 mg/ml) of albumin. On the other hand, the maximum rate of free fatty acid release measured simultaneously was observed in medium containing more than 20 mg/ml albumin. The rate of S-100 protein release was found to be closely related to the concentrations of both albumin added to the incubation medium and fatty acids released into it, and the rate was increased under conditions wherein the molar ratio of fatty acid/albumin was greater than 6. The S-100 protein release from fat pads was also enhanced solely by the addition of an excess amount (6 mM) of palmitic acid or oleic acid. The basal release of S-100 protein at a high concentration of albumin in the fat pads of diabetic or long-term starved rats, in which the fatty acid level in adipocytes is known to be enhanced, was about 7- and 2-fold higher, respectively, than that of control fed rats. These results suggest that S-100 protein in adipocytes is released under conditions in which the fatty acids being produced are not released promptly and are accumulated in the cells.
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PMID:Induction of adipose S-100 protein release by free fatty acids in adipocytes. 376 31

Using a recently developed technique of direct tracer injection into selective adipose tissue sites (Baker et al., Mech. Ageing Dev., 27: 295-313, 1984), we have studied the esterification of free fatty acids (FFA) to triglyceride fatty acids in the epididymal fat pads of normal and Ehrlich ascites carcinoma-bearing mice. We have tested the hypothesis that, during Ehrlich ascites carcinoma growth, a defect develops, resulting in the inhibition of the esterification and incorporation of FFA into adipose tissue diglyceride and triglyceride fatty acids. Our technique allowed the measurement of the disappearance of [1-14C]palmitic acid as FFA and its incorporation into di- and triglyceride fatty acids over 1 h. Multicompartmental analysis was used to compute the fractional rates of esterification and turnover. Using measured FFA pool sizes and assuming near-steady-state conditions, we estimated the transport rates (mass/time) of fatty acid esterification and turnover. Our results indicate that, compared to controls (normal mice), the epididymal fat pads of mice bearing early (5-day) and advanced (9-day) Ehrlich ascites carcinoma, respectively, show: 65% and near complete (congruent to 99%) decreases in the fractional rates of FFA esterification; about 2- and 24-fold increases in the FFA pool sizes; and 40% and 70% decreases in the transport rates of esterification.
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PMID:Inhibition of fatty acid incorporation into adipose tissue triglycerides in Ehrlich ascites tumor-bearing mice. 394 Jun 32

1. Mitochondrial and microsomal fractions of rat epididymal adipose tissue incorporated [1-(14)C]acetyl-CoA equally well into various fatty acids by a chain-elongation mechanism. C(18) and C(20) fatty acids were the two major products, and comprised about 80% of the total fatty acids synthesized in both particles. 2. When incubated in air, mitochondria synthesized stearic acid, octadecenoic acid and eicosamonoenoic acid in almost equal amounts (about 20% each), whereas in microsomal fractions, the synthesis of octadecenoic acid was more than fivefold the stearic acid formation. In both fractions, major components of synthesized monoenoic fatty acids were the Delta(11:12) isomers. Hexadecenoic acid and octadecenoic acid from whole adipose tissue contained approx. 11 and 14% of the Delta(11:12) isomer respectively. 3. When mitochondria or microsomal fractions were incubated in nitrogen, there was increased synthesis of stearic acid and palmitic acid and less of C(16) and C(18) monoenoic acids; synthesis of C(20) acids remained predominantly of the monoenoic acids. Determination of the position of the double bond in the monoenoic acids supported the view that the synthesis of hexadecenoic acid and octadecenoic acid involves a desaturase activity, whereas eicosamonoenoic acid and eicosadienoic acid are formed only by elongation of endogenous fatty acids. 4. Most of the radioactivity was found in free fatty acids (63%) and the phospholipid (26%) fraction. In phospholipids, phosphatidylcholine and phosphatidylethanolamine were the two major components. 5. Most of the fatty acids synthesized, including those not normally found in particle lipids (arachidic acid, eicosamonoenoic acid and eicosadienoic acid) were distributed fairly evenly in the phospholipid and free fatty acid fractions. However, stearic acid was found predominantly in the phospholipid fraction.
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PMID:Synthesis of fatty acids from (1- 14 C)acetyl-coenzyme A in subcellular particles of rat epididymal adipose tissue. 463 95

The effect was investigated of two different methods of preparing an albumin-palmitic acid complex on the tissue uptake of the palmitic acid, both in vivo and in vitro. Complex A was prepared by exposing monomolecular layers of palmitic acid-1-(14)C deposited on a solid surface to albumin dissolved in buffer. Complex B was prepared by the interaction of albumin with a micellar solution of palmitate-1-(14)C. The radioactivities and chemical compositions of the two complexes were almost identical. Rat epididymal fat pads took up, during a 1 hr incubation, about 2.5 times as much palmitic acid from complex A as from complex B; the extent of esterification of the incorporated label was equal for the two complexes. The fractional turnover rate of palmitic acid of complex A, administered intravenously to dogs, was about twice that of palmitic acid from complex B. The label of the two complexes recirculated in the esterified fatty acid fraction of plasma to an equal extent. It is proposed that differences in the orientation of the fatty acid molecules may affect their interaction with the binding sites of albumin and that the metabolic differences of the resulting complexes are related to differences in the ease of transfer of the fatty acid from the complex to receptor sites of tissues.
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PMID:Rates of tissue uptake of palmitic acid-1-14C complexed with albumin by two different procedures. 603 57

The metabolism of [14-14C]erucic acid and [U-14C]palmitic acid has been investigated in adipocytes isolated from rat epididymal fat. The rate of acylation of [14C]erucic acid in cellular lipids and oxidation to CO2 and acid-soluble activity was ca. 1/3 of the rate with [14C]palmitic acid as substrate. A maximal incorporation of fatty acids in triacylglycerol was found at a fatty acid concentration of 0.8 mM in the medium, both with [14C]erucic acid and [14C]palmitic acid as substrate. Glucose added to the medium increased the esterification and decreased the oxidation of both fatty acids. No significant chain-shortening of [14C]erucic acid to shorter monoenes was identified in the fat cells. Increasing concentrations of unlabeled palmitic acid in the incubation medium markedly inhibited the esterification of [14C]erucic acid, whereas unlabeled erucic acid had little effect on the rate of esterification of [14C]palmitic acid.
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PMID:Metabolism of erucic acid in adipocytes isolated from rat epididymal fat. 684 2

The inhibitory action of cholesterol-containing suspensions on fertilizing capacity in uterine-capacitated rabbit sperm cells showed a direct dependence on the concentration of sterol. Dispersion with synthetic phosphatidylcholine as a nonsonicated suspension or as liposomes did not alter this antifertilization effect. Esterification of the sterol, however, caused a complete loss of inhibitory activity. Cholesterol inhibited induction of the acrosome reaction among epididymal rat spermatozoa incubated under chemically defined conditions. Other agents with a negative effect on the acrosome reaction were seminal plasma membrane vesicles and palmitic acid. Egg lecithin-liposomes and bovine serum albumin, especially after being delipidated, facilitated it. These results corroborate the viewpoint that changes in the lipid bilayer of sperm plasma membrane significantly influence fertilizing capacity among mammalian spermatozoa.
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PMID:Interaction of lipids with the plasma membrane of sperm cells. I. The antifertilization action of cholesterol. 743 24


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