Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P56851 (epididymal)
 11,273 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

L-Arabinose is a natural, poorly absorbed pentose that selectively inhibits intestinal sucrase activity. To investigate the effects of L-arabinose feeding on lipogenesis due to its inhibition of sucrase, rats were fed 0-30 g sucrose/100 g diets containing 0-1 g L-arabinose/100 g for 10 d. Lipogenic enzyme activities and triacylglycerol concentrations in the liver were significantly increased by dietary sucrose, and arabinose significantly prevented these increases. Arabinose feeding reduced the weights of epididymal adipose tissue. Moreover, plasma insulin and triacylglycerol concentrations were significantly reduced by dietary L-arabinose. These findings suggest that L-arabinose inhibits intestinal sucrase activity, thereby reducing sucrose utilization, and consequently decreasing lipogenesis.
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PMID:L-arabinose feeding prevents increases due to dietary sucrose in lipogenic enzymes and triacylglycerol levels in rats. 1123 61

Glucose metabolism is necessary for successful fertilization in the mouse. Both spermatozoa and oocytes metabolize glucose through the pentose phosphate pathway (PPP), and NADPH appears required for gamete fusion. The aims of this study were to further characterize the utilization of glucose by the fertilizing spermatozoon and the fertilized oocyte, to demonstrate the importance of the PPP in different steps of fertilization, and to examine whether the beneficial effect of glucose could be mediated by a NADPH-dependent enzyme involved in redox regulation. By using a fluorescent analog of 2-deoxyglucose, glucose uptake was evidenced in both the head and flagellum of motile spermatozoa. After sperm-oocyte fusion, an increase in glucose uptake by the fertilized oocyte was observed but not before the formation of the male and female pronuclei. By using a microphotometric technique, activity of glucose 6-phosphate dehydrogenase (G6PDH), the key enzyme of the PPP, was localized to the sperm head and midpiece. When epididymal spermatozoa were released into a glucose-containing medium, the NADPH/NADP ratio increased with capacitation. Sperm-oocyte fusion and meiosis reinitiation of the fertilized oocyte was inhibited by the PPP inhibitor 6-aminonicotinamide (6-AN); inhibition of sperm-oocyte fusion was relieved by NADPH. Sperm-oocyte fusion and meiosis reinitiation were also inhibited by diphenylamine iodonium, which is a flavoenzyme inhibitor reported to prevent reactive oxygen species (ROS) generation in mouse spermatozoa and embryos. These findings indicate that the PPP is involved in different steps of fertilization. Subsequent regulation of a NADPH-dependent flavoenzyme responsible of ROS production is envisaged.
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PMID:Involvement of the pentose phosphate pathway and redox regulation in fertilization in the mouse. 1568 28

Energy metabolism is a key factor supporting sperm function. Sustaining sperm motility and active protein modifications such as phosphorylation could be the reason why sperm require exceptionally more ATP than other cells. Many methods have been used to understand the relationship between energy metabolism and sperm function. These approaches have identified critical metabolic pathways that support specific processes during germ cell development and fertilisation. In round spermatids, lactate and pyruvate are the preferred substrates and the use of glucose is limited, however, during epididymal maturation sperm expand to use glycolysis. While the acrosome reaction requires lactate or pyruvate for ATP production by oxidative phosphorylation, gamete fusion requires glucose to produce NADPH by the pentose phosphate pathway. Sperm motility appears to be supported by relatively low ATP levels, but achievement of high ATP levels are essential for tyrosine phosphorylation linked to hyperactivation. Thus, each individual process and event requires a different substrate and metabolic pathway. Despite different preferences for energy substrates and metabolic pathways between species, analysis of knockout mice revealed that glycolysis is indispensable for mouse sperm function and that oxidative phosphorylation is not essential for male fertility. This suggests that glycolysis could compensate for the lack of oxidative phosphorylation and recover most sperm function. Spermatogenic cell-specific glycolytic enzymes may confer flexible use of substrates and adapt to unexpected conditions for substrates in the female reproductive tract.
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PMID:Energy metabolism and sperm function. 1764 71


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