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1.
The direct activation of sterol ester hydrolase (E.C. 3.1.1.13) in homogenates of bovine corpus luteum by N6O2′·dibutyryl cyclic adenosine 3′∶5′-phosphate, (dibutyryl cAMP), adenosine triphosphate (ATP), and Mg2+ has been demonstrated. Variability in the extent of activation by the additions was minimized by homogenization of the tissue
in 5 mM Mg2+. Baseline sterol ester hydrolase activity was primarily associated with the 105,000 × g soluble fraction, and significant
activation of the enzyme preparation preincubated with dibutyryl cAMP, ATP and Mg2+ occurred within the first 15 min, prior to addition of substrate. A requirement for protein kinase in the system was demonstrated
by blocking the cofactor-dependent enzyme activation with commercial protein kinase inhibitor. 相似文献
2.
The regulation of neutral cholesterol ester hydrolase activity by changes in its phosphorylation state was studied in rat
liver microsomes. Treatment with cAMP-dependent protein kinase resulted in increased enzyme activity, which was further enhanced
by the addition of cAMP and MgATP. Consistent activations were also achieved with MgCl2 and MgATP, the magnesium effect being abolished by ethylenediaminetetraacetic acid and adenosine triphosphate. Cholesterol
ester hydrolase was activated twofold by free calcium and Ca2+/calmodulin; this latter effect was blocked by the chelator ethyleneglycol-bis(β-aminoethyl ether)N,N,N′,N′-tetraacetic acid and the calmodulin antagonist trifluoperazine. The phosphatase inhibitors pyrophosphate and glycerophosphate
led to marked and dose-dependent increases in esterase activity, whereas okadaic acid elicited no effect. Furthermore, pyrophosphate
and okadaic acid did not change the increases in enzyme activity promoted by Ca2+, Ca2+/calmodulin, Mg2+ and MgATP. Cholesterol ester hydrolase was inactivated in a concentration-dependent manner by nonspecific alkaline phosphatases.
In cAMP-dependent protein kinase/cAMP- or Ca2+/calmodulin-activated microsomes, a time-dependent loss of activation in cholesteryl oleate hydrolysis was caused by alkaline
phosphatase. These findings suggest that microsomal cholesterol ester hydrolase is activated through cAMP and Ca2+/calmodulin phosphorylation, whereas enzyme deactivation is dependent on phosphatase action. 相似文献
3.
In the presence of hydroxylamine or ascorbic acid, the inhibitory effects of Cu2+ on lysosomal acid cholesteryl ester hydrolase (acid CEH) partially purified from rat liver were studied.
Hydroxylamine stimulated the inhibition of acid CEH activity by Cu2+ but not that by Zn2+, Fe2+, Co2+, Mn2+, Ca2+, Mg2+ and Hg2+. This Cu2+-dependent inhibition of acid cholesterol ester hydrolase (CEH) activity was completely prevented by ethylenediamine tetraacetic
acid (EDTA), EGTA and o-phenanthroline, a chelator with a stability constant for Cu2+, and also by sulfhydryl agents and cytoplasmic reducing agents such as cysteine, glutathione and mercaptoethanol. In addition,
the stimulative effects of hydroxylamine on Cu2+-dependent inhibition were maintained even after preincubation of Cu2+ with hydroxylamine.
On the other hand, ascorbic acid was found to replace the stimulation by hydroxylamine of the Cu2+-dependent inhibition of acid CEH activity but the effects of ascorbic acid progressively became smaller with prolongation
of the preincubation time. Moreover, addition of chemical radical scavengers to the reaction mixture did not prevent the Cu2+-dependent inhibition of acid CEH activity in the presence of ascorbic acid. These results suggest that Cu2+ causes inhibition of lysosomal acid CEH activity through the formation of Cu1+ in a reductive medium. 相似文献
4.
Kathleen M. Botham 《Lipids》1991,26(11):901-906
An acid cholesteryl ester hydrolase activity associated with a fraction containing mitochondria and lysosomes from rat lactating
mammary glands was found to have a pH optimum of 5.0. Its sedimentation pattern was closely related to that of the lysosomal
enzyme markers acid phosphatase and β-glucuronidase, suggesting that the activity is associated with the lysosomes. The enzyme
was strongly inhibited by Cu2+, but was inhibited little by other divalent metal ions. Acid cholesteryl ester hydrolase activity was almost completely abolished
byp-hydroxymercuribenzoate, but this effect was reversed in the presence of an equimolar concentration of reduced glutathione
(GSH), indicating that the enzyme requires free sulfhydryl groups for activity. These properties are similar to those of acid,
lysosomal cholesteryl ester hydrolases found in other tissues. Acid cholesteryl ester hydrolase activity was 8–14 fold higher
in mammary tissue from lactating as compared to virgin rats. Neutral cholesteryl ester hydrolase activities associated with
the microsomal and cytosolic subcellular fractions were also increased in lactating glands, but to a lesser extent. In addition,
a 2-fold increase in the activities of both the acid and microsomal neutral enzymes was seen during the first few days of
lactation, while the cytosolic neutral activity remained constant. These results suggest that mammary gland cholesteryl ester
hydrolases have a role in the regulation of cholesterol metabolism in mammary cells, and in the provision of cholesterol for
secretion into milk. 相似文献
5.
Diacylglycerol acyltransferase from rat adipose tissue is shown to be inactivated by 30 to 40% upon incubation with adenosine
5′-triphosphate (ATP) and Mg2+. The activity responsible for this inactivation is associated with the cytosolic fraction, specific for ATP, prevented when
ATP is substituted by β,γ-methylene-ATP, and partially blocked by 1 mM ethylenediaminetetraacetate or 40 mM NaF, but not by
inhibitors of adenosine 3′,5′-cyclic-monophosphate (cAMP)-dependent protein kinase and/or protein kinase C (PKC). The cytosolic
activity cannot be mimicked by (cAMP)-protein kinase nor by PKC. Inactivated diacylglycerol acyltransferase from ATP/cytosol-treated
microsomes can be reactivated by incubation with partially purified protein phosphate from rat liver, and can be inactivated
again by further addition of ATP in the presence of cytosol. The results suggest the existence in adipose tissue of a protein
kinase other than cAMP-protein kinase or PKC, which may be involved in the regulation of triacylglycerol synthesis. 相似文献
6.
Cholesteryl ester hydrolase (CEH) was measured at 32°C and 37°C, and with and without cofactors for stimulation of cyclic
AMP-dependent protein kinase, in 104,000×g supernatants from rats aged 14–365 days. Activity at the two temperatures was also partially resolved by cation exchange
FPLC. Total specific activity of CEH was relatively constant, with or without addition of cofactors, from 14 to 47 days, during
which time temperature labile CEH was a very small fraction of total CEH activity. At later times, 51–150 days, activity was
increased as much as two-fold, both with and without cofactors, with most of the increase occurring in the temperature labile
fraction. Activation of temperature stable and temperature labile activities, where present, by protein kinase cofactors could
be demonstrated in all age groups, but was highly variable as a function of age and protein concentration used in the assay.
Apparent induction of temperature labile activity over the interval 47–51 days coincides with reported increases in testosterone
synthesis and first appearance of spermatozoa in the testis. This and other lines of evidence suggest unique roles for these
enzymes in regulation of availability of free cholesterol for testosterone and membrane synthesis, respectively. 相似文献
7.
Johann Hofmann Florian Ueberall Lydia Posch Karl Maly Dieter B. J. Herrmann Hans Grunicke 《Lipids》1989,24(4):312-317
The new phospholipid analogue 3-hexadecylmercapto-2-methoxy-methyl-propyl-1-phosphocholine inhibits the phospholipid-calcium-dependent
protein kinase, partially purified from Walker carcinoma cells with a Ki value of 0.56 μM. The compound inhibits the phorbol ester stimulated phosphorylation of the ribosomal protein S6 indicating
that the depression of Ca2+-phospholipid-dependent protein kinase by the alkyl phospholipid also occurs in intact cells. The dose effect curve for the
inhibition of cell proliferation by 3-hexadecylmercapto-2-methoxy-methyl-propyl-1-phosphocholine in Walker cells exhibits
a close correlation to the dose effect curve for the depression of Ca2+-phospholipid-dependent protein kinase activity. Although alternative mechanisms cannot be excluded, the data suggest that
the growth inhibitory activity of 3-hexadecylmercapto-2-methoxy-methyl-propyl-1-phosphocholine correlates with the inhibition
of Ca2+-phospholipid-dependent protein kinase. The antiproliferative activity of 3-hexadecylmercapto-2-methoxymethyl-propyl-1-phosphocholine
is synergistically enhanced bycis-diamminedichloroplatinum(II). 相似文献
8.
Inhibition of the hormone-sensitive lipase in adipose tissue by long-chain fatty acyl coenzyme A 总被引:1,自引:0,他引:1
The effects of free fatty acids and fatty acyl esters of coenzyme A and carnitine on the activity of a hormone-sensitive lipase
preparation made from pigeon adipose tissue were determined. Oleic acid (100 μM) resulted in a 40% inhibition of lipase activity
A more potent inhibition of lipase activity was seen with long-chain fatty acyl CoA compounds. The concentration required
for half-maximal inhibition with oleoyl CoA and palmitoyl CoA was 25–40 μM, whereas palmitoyl carnitine stimulated lipase
activity. Activated lipase preparations (preincubated with Mg2+, ATP, cyclic AMP and protein kinase) were 4–6 times more sensitive to inhibition by oleoyl CoA than were nonactivated preparations.
An increase in cellular levels of fatty acyl coenzyme A could, therefore, contribute to the feedback inhibition of lipolysis
in adipose tissue. 相似文献
9.
Effects of hexadecylphosphocholine on protein kinase C and TPA-induced differentiation of HL60 cells
Mamoru Shoji Robert L. Raynor Edward A. M. Fleer Hansjörg Eibl William R. Vogler J. F. Kuo 《Lipids》1991,26(2):145-149
Several structural analogs of alkylphosphocholine (APC) were studied for their effects on protein kinase C (PKC) and 12-O-tetradecanoylphorbol-13-acetate (TPA) elicited biochemical and cellular events in HL60 cells. Hexadecylphosphocholine (He-PC2), the APC prototype, inhibited PKC competitively with respect to phosphatidylserine and noncompetitively with respect to
CaCl2, both with an apparent Ki of about 15 μM. Inhibition of PKC by He-PC2 was selective, since cyclic AMP dependent protein kinase and Ca2+/calmodulin dependent protein kinase II were relatively unaffected. He-PC2 inhibited TPA-induced depletion of PKC and TPA-stimulated phosphorylation of cellular proteins in HL60 cells. TPA-induced
differentiation of HL60 cells was also inhibited by He-PC2, and this inhibition was synergistic or additive to the effects of 1-(5-isoquinoline-sulfonyl)-2-methylpiperazine (H-7),
a PKC inhibitor. The present findings are consistent with the hypothesis that inhibition of PKC might be related, in part,
to the antineoplastic effect of He-PC2 and ether lipid analogs such as ET-18-OCH3 (1-octadecyl-2-methyl-glycero-3-phosphocholine). 相似文献
10.
Amedeo Biasi Valerio Marino Giuditta Dal Cortivo Paolo Enrico Maltese Antonio Mattia Modarelli Matteo Bertelli Leonardo Colombo Daniele DellOrco 《International journal of molecular sciences》2021,22(19)
Guanylate cyclase-activating protein 1 (GCAP1), encoded by the GUCA1A gene, is a neuronal calcium sensor protein involved in shaping the photoresponse kinetics in cones and rods. GCAP1 accelerates or slows the cGMP synthesis operated by retinal guanylate cyclase (GC) based on the light-dependent levels of intracellular Ca2+, thereby ensuring a timely regulation of the phototransduction cascade. We found a novel variant of GUCA1A in a patient affected by autosomal dominant cone dystrophy (adCOD), leading to the Asn104His (N104H) amino acid substitution at the protein level. While biochemical analysis of the recombinant protein showed impaired Ca2+ sensitivity of the variant, structural properties investigated by circular dichroism and limited proteolysis excluded major structural rearrangements induced by the mutation. Analytical gel filtration profiles and dynamic light scattering were compatible with a dimeric protein both in the presence of Mg2+ alone and Mg2+ and Ca2+. Enzymatic assays showed that N104H-GCAP1 strongly interacts with the GC, with an affinity that doubles that of the WT. The doubled IC50 value of the novel variant (520 nM for N104H vs. 260 nM for the WT) is compatible with a constitutive activity of GC at physiological levels of Ca2+. The structural region at the interface with the GC may acquire enhanced flexibility under high Ca2+ conditions, as suggested by 2 μs molecular dynamics simulations. The altered interaction with GC would cause hyper-activity of the enzyme at both low and high Ca2+ levels, which would ultimately lead to toxic accumulation of cGMP and Ca2+ in the photoreceptor outer segment, thus triggering cell death. 相似文献
11.
Experimental Mg2+ deficiency was induced in a group of rats by feeding them a Mg2+-deficient diet for 23 days. They were pair-fed to compare with a control group of rats fed a Mg2+-sufficient diet. In the Mg2+-deficient group the plasma total cholesterol and triglyceride levels were increased while HDL-cholesterol was decreased.
In the Mg2+-deficient group the plasma level of thiobarbituric acid reacting substances (TBARS) used as a measure for lipid peroxidation
was increased. The increase was attributed to the increased cytosolic Ca2+ in Mg2+-deficiency which can cause: 1) increase of hydro and endoperoxide levels as a consequence of the increase of arachidonic
acid release and eicosanoid synthesis in Mg2+-deficiency, and 2) inhibition of the mitochondrial respiratory activity and activation of Ca2+-dependent proteases which may activate the conversion of xanthine dehydrogenase to xanthine oxidase which generates active
O2 species. In the Mg2+-deficient group, the fatty acid composition of the liver microsomes indicated a slower rate of conversion of linoleic acid
to arachidonic acid which was consistent with the decrease of Δ6 desaturase activity in liver microsomes of Mg2+-deficient rats as measuredin vitro. The decrease of Δ6 desaturase activity was attributed to the lower concentration of actual enzyme molecules as a result
of the decreased rate of protein synthesis in Mg2+-deficiency. The possible effects of the increased catecholamine release in Mg2+-deficiency are discussed. 相似文献
12.
Norio Katoh 《Lipids》1993,28(10):867-871
The effect of sphingosine on the phosphorylation of endogenous proteins by protein kinase C (PKC) was investigated in bovine
mammary gland. Several proteins were shown to be substrates for PKC in both cytosolic and total particulate fractions by phosphorylation
in the absence or presence of 1-oleoy-2-acetyl-sn-glycerol, phosphatidylserine (PS) and Ca2+. At concentrations of 83 μM or less, sphingosine inhibited phosphorylation of several substrates for PKC in both fractions.
Phosphorylation of cytosolic 36 kDa, 21 kDa and particulate 36 kDa proteins was particularly sensitive to sphingosine. Cytosolic
97 kDa phosphorylation (which was enhanced by Ca2+ alone) was also sensitive to sphingosine. The inhibition was reversed by excess addition of lipid cofactors, particularly
PS, but not by Ca2+. At higher concentrations (167 and 417 μM), in addition to the inhibition seen at lower concentrations, sphingosine stimulated
phosphorylation of several proteins, including cytosolic 19 kDa and particulate 53 kDa, which were not detected in the absence
of sphingosine. The sphingosine-induced phosphorylation disappeared with excess addition of PS, but not with addition of Ca2+. The results point toward the importance of the interaction of sphingosine with membrane phospholipids in the signal transduction
pathway mediated by PKC-dependent phosphorylation in bovine mammary gland. 相似文献
13.
John F. Rees S. John Pirt 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1979,29(9):591-602
The stability of resting glycolytic activity (RGA) i.e. lactic acid production from glucose, in non-growing suspensions of Lactobacillus delbrueckii was examined. Non-growing conditions were imposed by removal of essential nutrients or by the addition of antibiotics. The stability of RGA was reduced in fast-grown chemostat cells. Mg2+, reducing agents, the rigorous exclusion of oxygen and a constant supply of energy source gave a five-fold increase in RGA and a 25-fold increase in stability in cells deprived of a nitrogen source. Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) activity severely limited RGA after about 8 h of incubation. No evidence of excessive ATP accumulation or ADP depletion was found. Addition of chloramphenicol, actinomycin D or mitomycin C decreased RGA stability over a 24-h period. Addition of yeast extract and tryptone to a mixture containing phosphate, Mg2+, thioglycollate and chloramphenicol gave a three-fold increase in RGA which lasted for about 1 h. Mg2+ is believed to stimulate the glycolytic sequence directly and oxygen probably inhibits GAPDH by interaction with the -SH groups of the enzyme. Tryptone and yeast extract probably stimulate pyruvate kinase activity, and this enzyme is also absolutely dependent on fructose-1, 6-diphosphate for activity. 相似文献
14.
Choline kinase was located in the cytosolic fractions of the filamentous, pathogenic fungi,Microsporum gypseum andEpidermophyton floccosum. A broad pH optima (6.0–9.0) was observed for theM. gypseum enzyme, but theE. floccosum enzyme was active at pH 8.4 as well as 10.5, the activity being higher at pH 8.4. Enzyme from both dermatophytes had Km value of 3.3×10?4 M for choline; however, for ATP, it was 6.6×10?4 M and 12.6×10?4 M forM gypseum andE. floccosum, respectively. Choline kinase of both dermatophytes showed SH-group requirement. TheM. gypseum choline kinase was inhibited to a greater extent by Mn2+, Ca2+ and Ba2+ than was theE. floccosum enzyme. In comparison to other nucleotides, ATP was the most effective phosphate donor for phosphorylating choline in both dermatophytes. Higher concentrations of ATP inhibited the enzyme inM. gypseum as well asE. floccosum. Phosphorylcholine inhibited the choline kinase activity from both fungi, whereas phosphoethanolamine and glycerol 3-phosphate were stimulatory. 相似文献
15.
The effect of ATP on the microsomal desaturation of linoleic acid to γ-linolenic acid was studied in a system in vitro with
the following results: (1) preincubation of rat liver microsomes with ATP alone in N2 or in the presence of CoA and Mg++ followed by subsequent incubation with 1-14C-linoleic acid plus NADH in O2 resulted in enhancement of 1-14C-linoleic acid desaturation when compared with control samples in which no preincubation was performed; (2) the preincubation
of the microsomes with ATP, Mg++ and CoA in the presence of 1-14C-linoleic acid decreased the desaturation of the labeled acid to γ-linolenic acid upon subsequent incubation with NADH, as
a consequence of incorporation of the acid into the microsomal lipids; (3) the increase of linoleic acid desaturation depended
on the ATP concentration during preincubation and followed a sigmoidal curve. It was specific for ATP, and neither GTP, CTP,
ADP nor AMP produced a similar effec. However, GTP or CTP could replace ATP as a cofactor in the microsomal desaturation of
free linoleic acid to γ-linolenic, suggesting that directly or indirectly they may activate conversion of the free acid to
linoleyl-CoA; (4) preincubation of microsomes with ATP activated the acylation of CoA. However, this activation showed no
quantitative correlation with enhancement of the desaturation reaction; (5) addition of ATP also stimulated conversion of
linoleyl-CoA to γ-linolenic acid. This enhancement was not related to inhibition of the linoleyl-CoA hydrolase; (6) however,
in spite of these results, preincubation with ATP did not increase the initial velocity of linoleic acid or linoleyl-CoA desaturation;
(7) preincubation of microsomes with ATP also increased the 6-desaturation of oleic acid and α-linolenic acid but did not
increase the 9-desaturation of plamitic and stearic acid. 相似文献
16.
Cholesterol ester hydrolase activity has been studied in mammary glands of rats. Subcellular fractionation of the glands obtained
in mid-lactation indicated that around 80% of the recovered activity was associated with particulate fractions. Two distinct
cholesterol ester hydrolase activities were identified, one with an optimum pH of 7.5–9.0 and the second (approximately 5%
of the total activity) with a more acidic pH optimum. Although the neutral cholesterol ester hydrolase had some properties
in common with the lipoprotein lipase in mammary tissue, it was shown to be a separate entity by several criteria. Its activity
could be increased following treatment with Mg-ATP and cAMP-dependent protein kinase, suggesting identity with the hormone
sensitive lipase of adipose tissue. The cholesterol ester hydrolase activity in mammary glands just after parturition was
greater than in glands obtained either from late-pregnant or midlactating animals. The subcellular distribution of the neutral
cholesterol ester hydrolase suggested that it may have a different function to the neutral cholesterol ester hydrolase of
adrenals and other tissues. Nevertheless the fact that the activity of the enzyme can be modulated by cAMP-dependent protein
kinase suggests the possibility that hormonal control of this enzyme may be involved in the regulation of cholesterol metabolism
in the mammary gland. 相似文献
17.
Jacqueline Goddat Hervé Coste Isabelle Vilgrain Edmond Chambaz Hugues Driguez 《Lipids》1992,27(5):331-338
Twelve analogs of 1,2-di-O-octanoylglycerol modified at C-3 and three quaternaryN-alkyl-ammonium derivatives of glycerol were synthesized. The compounds were testedin vitro as potential modulators of the calcium activated, phospholipid dependent protein kinase C (PKC) and diacylglycerol (DAG)
kinase activities in order to understand the molecular interactions of these enzymes with their natural activators, inhibitors,
or substrates. PKC activity was assayed by measuring histone H1 phosphorylation, and the compounds synthesized were tested either in the presence (inhibitors) or in the absence (activators)
of 1,2-di-O-octanoyglycerol analogs with the phosphatidylserine/Ca2+ mixture. DAG kinase activity was measured by the incorporation of phosphate into 1,2-di-O-oleoyl-sn-glycerol in the presence of the various analogs synthesized. In regard to PKC activity, the assays revealed that 1,2-di-O-octanoylglycerol analogs are inactive when modified at C-3 with groups which do not permit hydrogen bonding. Under our conditions,
di-O-octanoylthioglycerol, which has been reported as inactive, was able to activate PKC in the presence of phosphatidylserine.
It has been shown to give a synergistic activation with diacylglycerol and had no affinity for the phorbol ester receptor
binding site, suggesting thatO-octanoylthioglycerol interacts with the enzyme at a different site from the phorbol ester receptor binding site. PKC and
DAG kinase activities are inhibited byN-alkyl-ammonium compounds (IC50 24 μM) only when either two 8-carbon alkyl or acyl chains are present at the 1- and 2-positions of the glycerol backbone.
The fact that these compounds have a strong effect on the binding of [3H]phorbol 12,13-dibutyrate to protein kinase C, and also inhibit DAG kinase, may suggest binding to the DAG site of the regulatory
domain of PKC. 相似文献
18.
The activity that has been previously reported to reversibly inactivate adipose glycerolphosphate acyltransferase (GPAT) and
diacylglycerol acyltransferase (DGAT)in vitro in the presence of ATP is shown here to be partially purified from adipose tissue with an apparent molecular weight of 68
kDa. The activity responsible for inactivating DGAT is associated with a kinase activity as determined by phosphate incorporation
both into microsomal proteins and into a synthetic tyrosine-containing peptide as substrate for protein tyrosine kinase. Two
microsomal polypeptides of 53 and 69 kDa are major substrates of this kinase. Both DGAT inactivating and kinase activities
assayed from the purified sample have been found to be insensitive to the Ser/Thr kinase inhibitor H-7 while being sensitive
to genistein and tyrphostin-25. A crude protein phosphatase preparation from liver was capable of reversing the effects of
both activities. The purified sample was also shown to inactivate GPAT in the presence of ATP. These results suggest that
a protein tyrosine kinase, in concert with a protein tyrosine phosphatase, may regulate the activities of DGAT and GPAT by
a phosphorylation-dephosphorylation mechanism. 相似文献
19.
Magnesium and Morphine in the Treatment of Chronic Neuropathic Pain–A Biomedical Mechanism of Action
Kamila Kulik Barbara yyska-Granica Agnieszka Kowalczyk Przemysaw Kurowski Magorzata Gajewska Magdalena Bujalska-Zadrony 《International journal of molecular sciences》2021,22(24)
The effectiveness of opioids in the treatment of neuropathic pain is limited. It was demonstrated that magnesium ions (Mg2+), physiological antagonists of N-methyl-D-aspartate receptor (NMDAR), increase opioid analgesia in chronic pain. Our study aimed to determine the molecular mechanism of this action. Early data indicate the cross-regulation of µ opioid receptor (MOR) and NMDAR in pain control. Morphine acting on MOR stimulates protein kinase C (PKC), while induction of NMDAR recruits protein kinase A (PKA), leading to a disruption of the MOR-NMDAR complex and promoting functional changes in receptors. The mechanical Randall-Selitto test was used to assess the effect of chronic Mg2+ and morphine cotreatment on streptozotocin-induced hyperalgesia in Wistar rats. The level of phosphorylated NMDAR NR1 subunit (pNR1) and phosphorylated MOR (pMOR) in the periaqueductal gray matter was determined with the Western blot method. The activity of PKA and PKC was examined by standard enzyme immunoassays. The experiments showed a reduction in hyperalgesia after coadministration of morphine (5 mg/kg intraperitoneally) and Mg2+ (40 mg/kg intraperitoneally). Mg2+ administered alone significantly decreased the level of pNR1, pMOR, and activity of both tested kinases. The results suggest that blocking NMDAR signaling by Mg2+ restores the MOR-NMDAR complex and thus enables morphine analgesia in neuropathic rats. 相似文献
20.
Incubation of Caco-2 cells, a human intestinal cell line, with 25-hydroxycholesterol (25-HOC) markedly enhanced cellular cholesteryl
ester formation determined by incorporation of [14C]oleic acid into intracellular cholesteryl [14C]oleate. The stimulation by 25-HOC of cholesteryl ester formation was suppressed by staurosporine, a kinase inhibitor, but
not by cycloheximide or actinomycin D. The specific activity of microsomal acyl-coenzyme A:cholesterol acyltransferase (ACAT)
increased two-fold in cells treated with 10 μM 25-HOC for 5 h. ACAT activity decreased when microsomes were incubated without
sodium fluoride, a phosphatase inhibitor, but the decrease in ACAT activity in cells stimulated with 25-HOC was more pronounced.
The results suggest that protein phosphorylation may be involved in the stimulation of cholesteryl ester formation by 25-HOC
in Caco-2 cells. 相似文献