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)

Continuous low-dose gamma-irradiation of mature rats induced a progressive degeneration of the germ cells. Blood FSH increased by 127, 176 and 214%, respectively, after 55, 70 and 85 days of treatment when compared to FSH levels in control rats (8.50 +/- 0.60 ng/ml); conversely, serum LH and testosterone levels were unchanged. The Sertoli cell function was affected by the treatment from 70 days on, as attested by androgen binding protein (ABP) and transferrin secretions which diminished 35-40%. Serum ABP levels were not altered, whatever the duration of irradiation, even though epididymal ABP contents (as well as concentrations) diminished 34-60% when compared to those of the controls. Moreover, in purified Leydig cells, LH-stimulated intracellular cAMP levels, which were decreased by seminiferous tubule medium (STM) from control rats, were enhanced in presence of STM from treated animals. Testosterone output was stimulated 9-fold in presence of oLH and further increased (46-76%) from stages XIV-V by STM prepared from control and irradiated rats, respectively. After 85 days the STM effects on both cAMP and testosterone syntheses were zero. These results demonstrate a probable alteration of Sertoli cell function after irradiation, but also a role of the germ cells in the regulation of the synthesis of ABP, transferrin and Sertoli cell paracrine factors.
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PMID:Effect of continuous low-dose gamma-irradiation on rat Sertoli cell function. 314 90

Free Ca2+ changes the curvature of epididymal rat sperm flagella in demembranated sperm models. The radius of curvature of the flagellar midpiece region was measured and found to be a continuous function of the free Ca2+ concentration. Below 10(-7) M free Ca2+, the sperm flagella assumed a pronounced curvature in the same direction as the sperm head. The curvature reversed direction at 2.5 x 10(-6) M Ca2+ to assume a tight, hook-like bend at concentrations of 10(-5) to 10(-4) M free Ca2+. Sodium vanadate at 2 x 10(-6) M blocked flagellar motility, but did not inhibit the Ca2+-mediated change in curvature. Nickel ion at 0.2 mM and cadmium ion at 1 microM interfered with the transition and induced the low Ca2+ configuration of the flagellum. The forces that maintain the Ca2+-dependent curvature are locally produced, as dissection of the flagella into segments did not significantly alter the curvature of the excised portions. Irrespective of the induced pattern of curvature, the sperm exhibited coordinated, repetitive flagellar beating in the presence of ATP and cAMP. At 0.3 mM ATP the flagellar waves propagated along the principal piece while the level of free Ca2+ controlled the overall curvature. When Ca2+-treated sperm models with hooked midpieces were subjected to higher concentrations of ATP (1-5 mM), some cells exhibited a pattern of movement similar to hyperactivated motility in capacitated live sperm. This type of motility involved repetitive reversals of the Ca2+-induced bend in the midpiece, as well as waves propagated along the principal piece. The free Ca2+ available to the flagellum therefore appeared to modify both the pattern of motility and the flagellar curvature.
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PMID:Calcium regulation of flagellar curvature and swimming pattern in triton X-100--extracted rat sperm. 318 Feb 54

The effect of halothane on isoproterenol-stimulated lipolysis was determined in isolated rat epididymal fat cells. The maximal lipolytic response (Emax) activated by isoproterenol was 350 +/- 61 nmol of glycerol/10(5) cells/hr with an EC50 of 5.1 X 10(-9) M. When the adipocytes were simultaneously bubbled with 2.5% halothane, the Emax decreased to 158 +/- 43 nmol of glycerol/10(5) cells/hr and the dose response curve for isoproterenol was shifted to the right (EC50 3.5 X 10(-8) M, p less than 0.05). When lipolysis was maximally stimulated with (-)-isoproterenol (10(-6)M), the inhibitory effect of halothane was found to be both dose dependent (IC50 approximately 2.5%, v/v) and reversible following washout. Neither the nonhydrolyzable cAMP analog, 8-(4-chlorophenylthio) adenosine 3',5'-cyclic monophosphate (2 X 10(-3)M), nor forskolin (10(-6) M) was able to normalize lipolysis in the presence of halothane. The activation of cAMP-dependent protein kinase (EC 2.7.1.37) activity by isoproterenol was not different in halothane-exposed cells when compared to unexposed cells. When control adipocytes were exposed to isoproterenol (10(-6) M), there was a 2.5-fold increase in the activity of hormone-sensitive lipase (EC 3.1.1.3) from 0.64 +/- 0.13 to 1.53 +/- 0.32 pkat (pmol/sec) per mg (p less than 0.005, n = 10). However, in the presence of halothane (2.5%, v/v) isoproterenol stimulation of hormone-sensitive lipase was attenuated by 50% to values of 1.06 +/- 0.23 pkat/mg (p less than 0.01, n = 10). Halothane had no direct inhibitory effect on hormone-sensitive lipase since this enzyme's activity was unaffected when homogenates of isoproterenol-stimulated control cells were incubated with halothane. These studies suggest that halothane impairs the activation of hormone-sensitive lipase by cAMP-dependent protein kinase and in this manner inhibits beta-adrenergic-stimulated lipolysis.
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PMID:Mechanism of halothane-induced inhibition of isoproterenol-stimulated lipolysis in isolated rat adipocytes. 335 97

1. The effect of neonatal monosodium-L-glutamate (MSG) treatment on lipolysis in rat epididymal adipose tissue was studied. A reduction in the basal lipolysis was observed in the MSG-treated rats. 2. This was accompanied by a decrease lipolytic response to isoprenaline, adrenocorticotropic hormone, forskolin, isobutylmethylxanthine and dibutyryl-cAMP. 3. The addition of adenosine deaminase, which inactivates endogenous adenosine in the medium, did not normalize the basal and the hormone stimulated lipolytic responses. 4. The maximal lipolysis stimulated by adenosine deaminase or 8-(p-sulfophenyl)-theophylline (8-SPT), an adenosine antagonist, was significantly lower in the MSG-treated rats. 5. Moreover, there was no change in the sensitivity of adenosine receptors to its antagonist as reflected by the similar potency of 8-SPT in eliciting the lipolytic response in both the control and MSG-treated rats. 6. In conclusion, neonatal MSG treatment in rats induced a general reduction of lipolytic response in the epididymal adipocytes which cannot be explained by an enhancement of the adenosine inhibitory system.
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PMID:Neonatal monosodium-L-glutamate treatment reduced lipolytic response of rat epididymal adipose tissue. 341 Feb 73

Effects of glucagon on insulin action in rat epididymal adipocytes were studied in vitro. [125I]iodoinsulin binding to isolated adipocytes was inhibited by preincubation of the cells with isoproterenol, epinephrine, or glucagon. Fifty percent inhibition was observed with 2 X 10(-8) M glucagon, 10(-6) M isoproterenol, and 10(-7) M epinephrine. Maximal (90%) inhibition induced by glucagon was observed at 10(-6) M. In Scatchard analysis, [125I]iodoinsulin competition data generated curvilinear plots in buffer- and glucagon-treated cells. Pretreatment of the cells with (Bu)2cAMP reduced insulin binding activity. However, the simultaneous addition of (Bu)2cAMP with [125I]iodoinsulin did not produce the inhibition of the binding when the cells were not pretreated with the agent. cAMP level in the cells was increased by incubation with glucagon. 3-O-[Methyl-3H]methylglucose uptake by isolated adipocytes was inhibited by pretreatment of the cells with glucagon. These results suggest that glucagon regulates insulin action through decrease in insulin receptor activity, and that it is possible that the inhibition is mediated by cAMP production in adipocytes.
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PMID:Glucagon alters insulin binding to isolated rat epididymal adipocytes: possible role of adenosine 3',5'-monophosphate in modification of insulin action. 352 8

Earlier studies have shown increased adenylate cyclase (AC) activity in epididymal mouse sperm incubated under capacitating conditions in vitro. The present study investigated the effect on AC activity of excluding calcium and/or glucose from the sperm incubation medium, which would modulate expression of fertilizing potential. AC activity was higher in sperm incubated for 120 than 30 min, and was higher in sperm incubated in calcium-containing than calcium-free media for all except acrosome-reacted populations. Calcium added at the time of assay stimulated AC activity, the degree of this response being independent of the functional state of the sperm population. The guanine nucleotide analogue Gpp(NH)p slightly enhanced AC activity, but did not alter the stimulatory effect of calcium. Since calcium can increase AC activity, possibly by interaction with a divalent cation allosteric site on the catalytic subunit of the enzyme, a rise in intracellular calcium levels during capacitation may mediate the increased activity of AC, allowing expression of cAMP dependent events which are a prerequisite for fertilization.
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PMID:Adenylate cyclase activity of mouse sperm during capacitation in vitro: effect of calcium and a GTP analogue. 374 87

Rat caput and cauda epididymal sperm cAMP-dependent and cAMP-independent protein kinase activity was determined in three buffers with and without calcium. In all buffers, higher enzymatic activity for both enzymes was found in cauda than in caput sperm. Maximum protein kinase activities were found in a sucrose-magnesium phosphate buffer. A Krebs Ringer phosphate buffer distinguished cAMP-dependent and cAMP-independent activity in cauda but not caput sperm. Sucrose-TRIS buffer was shown to be of little value for measuring enzyme activity in either cell type. When protein phosphorylation was examined with 0.5 mM calcium and 2.5 mM cAMP, inhibition of both caput and cauda sperm phosphorylation occurred. When cAMP concentration was lowered to microM, or nM, or pM levels, cAMP-dependent protein phosphorylation was restored.
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PMID:Epididymal sperm cAMP-dependent and cAMP-independent protein kinase activity and phosphorylation in the rat. 377 19

In the presence of 10-100 microM monensin (a monovalent cation ionophore), a considerable amount of 125I activity of iodoinsulin accumulated in isolated rat epididymal adipocytes during a 30-min incubation. The accumulation was secondary to the action of monensin to inhibit dissociation of a certain fraction of the cellbound 125I activity. This monensin effect was reversible. The accumulation of 125I activity was ATP dependent and so was the discharge of the accumulated radioactivity. Approximately 91% of the accumulated radio-activity was precipitable with trichloroacetic acid, and at least 84% was reactive to anti-insulin antibody. Monensin at 100 microM appeared to have only mild effects on the cellular activities of glucose transport and cAMP phosphodiesterase. Nevertheless, when cells were first exposed to 10 nM insulin in the presence of 100 microM monensin and then transferred into a hormone-free buffer that contained monensin, the phosphodiesterase activity in cells remained partially activated as if cells were kept exposed to approximately 0.5 nM insulin. Under similar conditions, glucose transport activity remained partially activated as if cells were incubated with approximately 70 pM insulin. Monensin did not inhibit the reversal of the insulin effect per se. Like monensin, 20-100 microM chloroquine (a lysosomotropic inhibitor) induced a considerable accumulation of [125I] iodoinsulin. However, cells that had been exposed to insulin in the presence of chloroquine retained little hormonal effect after washing. Based on these observations and on the reported biological effects of monensin, it is suggested (a) that monensin may induce intracellular accumulation of the insulin-receptor complex by blocking the acidification of endocytic vesicles and (b) that the accumulated insulin-receptor complex may retain a weak, but significant, capacity to stimulate both glucose transport and phosphodiesterase activities.
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PMID:Effects of monensin on insulin processing in adipocytes. Evidence that the internalized insulin-receptor complex has some physiological activities. 388 3

It was possible to demembrante and reactivate not only freshly collected testicular, cauda epididymal, and ejaculated ram sperm but also sperm that had been stored for several days at 0 degrees C and for several months at -196 degrees C in rete testis fluid or egg yolk citrate media. Sperm were usually washed free of seminal plasma before demembranation, but this was not essential for reactivation. Bovine serum albumin (1.0%) in the wash medium increased the survival of sperm, but more than 0.25% in the extraction medium decreased reactivation. A macro-molecular component of cauda epididymal fluid also inhibited the reactivation of testicular sperm. Triton X-100 concentrations between 0.01% and 1.00% in the extraction medium were satisfactory for demembranating the sperm. Rapid cooling (i.e., cold shock) mimicked the effect of detergent in making the sperm responsive to added ATP and demonstrated that damage to ram sperm in cold shock does not involve the axoneme. Ejaculated and cauda sperm were reactivated immediately on addition of ATP and activity persisted for up to 10 min. Testicular sperm, on the other hand, required about 4 min to become fully reactivated. The optimal ATP concentration for activation of sperm was 0.1-1.0 mM. Magnesium ions (0.1-1.0 mM) were important for reactivation, and testicular sperm required a higher magnesium concentration than did cauda or ejaculated sperm. Manganese ions were almost as effective as magnesium for reactivating cauda epididymal and ejaculated sperm. Cobalt and cadmium ions were much less active for cauda and ejaculated sperm and none of these ions were effective for testicular sperm. Fluoride (25-50 mM) inhibited reactivation. The presence of 50 microM cAMP in the extraction medium or preincubation of testicular sperm with theophylline or caffeine increased low levels of activation, but this was not evident with ejaculated or cauda sperm. We conclude that the motor apparatus is already functionally assembled in spermatozoa on leaving the testis, but some fine adjustment must take place during maturation in the epididymis.
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PMID:ATP-induced reactivation of ram testicular, cauda epididymal, and ejaculated spermatozoa extracted with Triton X-100. 395 35

The changes in intracellular calmodulin levels and cAMP-dependent protein kinase activities have been studied in the testis of normally developing and hypophysectomized rats. It appears that the onset of spermatogenesis which occurs on the first days of the postnatal development, is associated with a major (over fivefold) increase in the calmodulin level and enhancement of the cAMP-dependent protein kinase activity. On the contrary, hypophysectomy of adult animals is associated with a progressive decline in the calmodulin level and a rapid and regular decrease in the cAMP-dependent protein kinase activity. Moreover, measurements of the intracellular calmodulin level and cAMP-dependent kinase activity of isolated testicular germ cells or epididymal spermatozoa have shown that testosterone, administered to hypophysectomized rats as subcutaneous implants, maintains the concentration of these regulatory proteins to normal values.
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PMID:Calmodulin level and cAMP-dependent protein kinase activity in rat spermatogenic cells and hormonal control of spermatogenesis. 397 73


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