Relationship between lead concentration in blood and the activities of erythrocyte pyrimidine 5′-nucleotidase and delta-aminolevulinate dehydratase in the mice exposed to lead

The relationship between the activities of both pyrimidine 5-nucleotidase (Py5N) and delta-aminolevulinate dehydratase (ALA-D) in erythrocytes and the concentration of lead in blood was investigated in the mice which were given ad libitum a drinking water containing lead of 10 to 500 ppm, for 30 days.From these results, it was demonstrated that the erythrocyte PySN activity is inhibited by lead and its activity level is negatively correlated with the concentration of lead in blood (r=–0.78). In addition, it was suggested that the erythrocyte Py5N activity is a better indicator in the exposure to relatively high lead concentration while the ALA-D is a more sensitive indicator for evaluating the lead exposure of low and moderate levels.     

A role of red cell pyrimidine 5′-nucleotidase in experimental lead poisoning

Intravenous administration of lead acetate to rabbits for 10 weeks at 2 week intervals resulted in significantly elevated blood lead levels, slight anemia with marked microspherocytosis and moderate basophilic stippling, and marked depression of red cell-aminolevulinic acid (ALA) dehydratase activity. However the decrease in red cell pyrimidine 5-nucleotidase (P5N) activity was slight when compared to the red cell P5N activity of comparable reticulocyte-rich blood, and intracellular accumulation of pyrimidine nucleotides could not be demonstrated. In the in vitro inhibition test the same degree of inhibition of red cell P5N activity seen in hereditary red cell P5N deficiency was obtained by using a lead concentration 200–400 times higher than the lead levels detected in human plumbism. Most importantly, there were no differences in the lead-induced inhibition of human and rabbit red cell P5N.From the results of the in vitro inhibition test, lead-induced red cell P5N deficiency appears to be one of several pathogenic mechanisms in chronic lead exposure associated with the accumulation of lead in bone marrow. A decrease in red cell P5N activity could not be demonstrated despite the marked depression in red cell ALA dehydratase activity, and slight anemia with marked microspherocytosis and moderate basophilic stippling in this experiment. These results suggest that lead affects red cells at multiple metabolic loci.     

Stimulation of the plasma membrane enzyme, 5′-nucleotidase,by ethanol exposure to neural cells in culture

• 1.1. Neural cells grown in culture have been employed to investigate the interaction between exposure to ethanol and enzyme activity at the plasma membrane of intact cells.
• 2.2. Continuous exposure of rat glioma cells (line C6) to ethanol induced a rise in the ecto-5′-nucleotidase enzyme activity. This activity appeared cell density-dependent and was reversible upon ethanol withdrawal.
• 3.3. Acute exposure to ethanol was also found to cause a dose-dependent stimulation in enzyme activity.
• 4.4. The stimulation of enzyme activity after chronic ethanol exposure was not a direct consequence of the acute presence of ethanol but appeared as an adaptation to the acute effect. Tolerance to the acute stimulation by ethanol was observed in cells chronically treated with ethanol.
• 5.5. A possible mechanism involving a change in membrane fluidity is proposed which will accomodate the data obtained from both acute and chronic studies.
• 6.6. Neural cells in culture have been found to react to the presence of ethanol in their media in a manner similar to animals and appear useful for delineating plasma membrane effects of ethanol without damage to cellular integrity.

     

Effect of nicardipine on learning and memory in mice

AIM: To study if nicardipine could improve learning and memory in mice. METHODS AND RESULTS: Nicardipine (0.5mg·kg~(-1)or 0.2 mg·kg~(-1), po) was shown to improve learning and memory in Y mize in mice, which increased passive avoidane response. Nicardipine was capable of antagonizing pentobarbital (15 mg·kg~(-1), ip)-in     

Effect of The effects of Δ 9-tetrahydrocannabinol on the metabolism of norepinephrine in rat brain on the morphine-induced hyperactivity of mice

The effect of ⁹-tetrahydrocannabinol (THC) on the locomotor activity-stimulating action of morphine has been investigated in mice. THC (10 mg/kg) has been found to potentiate morphineinduced hyperactivity. On the other hand, the stimulating action of morphine on motor activity strongly diminished in mice rendered tolerant by the implantation of a morphine pellet. The pretreatment of morphine-tolerant mice with the same dose of THC did not change the effect of morphine on the motor activity. These results suggest that tolerance also developed to the potentiating action of THC on morphine-induced hyperactivity during the development of tolerance to this action of morphine.     

Effect of some cyclooxygenase inhibitors on the increase in guanosine 3′:5′-cyclic monophosphate induced by NO-donors in human whole platelets

1. The effect of the NSAIDs indomethacin, indoprofen, diclofenac and acetylsalicylic acid on the increase in guanosine 3′:5′-cyclic monophosphate (cyclic GMP) induced by nitric oxide-donor agents was tested in human whole platelets and in platelet crude homogenate.
2. In whole platelets, indomethacin reduced the increase in cyclic GMP induced by the nitric oxide-donors (NO-donors) sodium nitroprusside (NaNP) and S-nitroso-N-acetylpenicillamine (SNAP) in a dose-dependent way, its IC₅₀ being 13.7 μM and 15.8 μM, respectively.
3. Of the other cyclooxygenase inhibitors tested, only indoprofen reduced the increase in cyclic GMP induced by both NO-donors in a dose-dependent way (IC₅₀=32.7 μM, NaNP and 25.0 μM, SNAP), while acetylsalicylic acid (up to 1000 μM) and diclofenac (up to 100 μM) were ineffective.
4. However, in platelet crude homogenate neither indomethacin nor indoprofen reduced the cyclic GMP production.
5. Indomethacin (10 μM), indoprofen (30 μM), diclofenac (100 μM) and acetylsalicylic acid (1000 μM) showed a comparable efficacy in inhibiting platelet thromboxane B₂ (TXB₂) production, suggesting that the inhibitory effect of indomethacin and indoprofen on the increase in cyclic GMP induced by both NO-donors was not mediated by inhibition of cyclooxygenase.
6. In vitro, the NSAIDs analysed did not interfere with nitrite production of SNAP.
7. The unhomogeneous behaviour of NSAIDs on the increase in cyclic GMP induced by NO-donors in whole platelets may contribute to the different pharmacological and toxicological characteristics of the drugs, providing new knowledge on the effect of indomethacin and indoprofen.

     

Tolerance to the effects of Δ 9-tetrahydrocannabinol in mice on intestinal motility,temperature and locomotor activity

The onset and duration of tolerance to three effects of ⁹-tetrahydrocannabinol ( ⁹-THC) given orally to mice were compared. The effects of ⁹-THC studied were: hypothermia, the depression of intestinal motility and the effect on spontaneous locomotor activity. When mice were dosed and tested at 24 hrs intervals it was apparent that tolerance was complete to its hypothermic and locomotor depressant effects after the first doses and to depression of intestinal motility after the fourth dose. Duration of tolerance also differed so that the normal hypothermic response had returned after 12 dose-free days, but not after 5 drug-free days; the effect on locomotor activity had returned within 4 days; and, apparent partial tolerance to the depressant effect of an acute challenging dose of ⁹-THC on intestinal motility still existed after 19 dose-free days.It is apparent that the time of onset and the duration of tolerance to ⁹-THC in mice showed a different pattern in the three parameters studied. It seems unlikely therefore that any one mechanism, such as metabolic tolerance, explains all the results observed and that several mechanisms should be explored to explain the phenomenon of tolerance to ⁹-THC.     

Effects of some GABA-mimetic drugs on the antinociceptive activity of morphine and β-endorphin in rats

Summary Intracerebroventricular administration of muscimol, a potent GABA-receptor agonist, counteracted the antinociceptive effect of morphine or -endorphin in rats as measured by the tail flick method. Muscimol's activity was reversed by bicuculline. Isoguvacine, another GABA agonist, as well as nipecotic acid and guvacine, two inhibitors of neuronal and glial uptake of GABA, also antagonized morphine's antinociceptive effect. A role of the central GABA-ergic system in mediating opiate antinociception is proposed.This study was supported by C.N.R. grant no. CT 77.01401.04     

Involvement of δ-opioid receptors in the effects of morphine on locomotor activity and the mesolimbic dopaminergic system in mice

Naltrindole (NTI) and naltriben (NTB), a benzofuran derivative of NTI, were recently synthesized as highly selective -opioid receptor antagonists. Both NTI and NTB failed to suppress the antinociceptive effect induced by morphine. In contrast, both NTI and NTB significantly suppressed the morphine-induced hyperlocomotion and increase in turnover of dopamine (DA) in the mouse limbic forebrain. These results suggest that -opioid receptors play, at least in part, a role in the morphine-induced hyperlocomotion and excitation of mesolimbic DA systems, but not antinociception.     

The effect of glibenclamide on the production of interstitial adenosine by inhibiting ecto-5′-nucleotidase in rat hearts

1. Adenosine exerts cardioprotective effects on the ischaemic myocardium. The production of adenosine in the ischaemic myocardium is attributed primarily to the enzymatic dephosphorylation of adenosine 5′-monophosphate (AMP) by 5′-nucleotidase. We determined the activity of 5′-nucleotidase in rat hearts. The objective of the study was to determine the effects of ATP-sensitive K⁺ (K_ATP) channel antagonists (glibenclamide and 5-hydroxydecanoate) on the production of adenosine, by use of a flexibly mounted microdialysis technique.
2. Rats were anaesthetized and the microdialysis probe was implanted in the left ventricular myocardium, followed by perfusion with Tyrode solution. The baseline level of dialysate adenosine was 0.51±0.09 μM (n=16). Introduction of AMP (100 μM) through the probe increased the dialysate adenosine markedly to 9.79±0.43 μM (n=12, P<0.001 vs baseline), and this increase was inhibited by the ecto-5′-nucleotidase inhibitor, α,β-methyleneadenosine 5′-diphosphate (100 μM), to 0.76±0.12 μM (n=8). Thus, the dialysate adenosine noted during the perfusion of AMP originated from dephosphorylation of AMP by ecto-5′-nucleotidase, and the dialysate level of adenosine attained reflects the ecto-5′-nucleotidase activity in the tissue in situ.
3. Glibenclamide (0.1–100 μM) decreased the adenosine concentration measured during the perfusion of AMP (100 μM) in a concentration-dependent manner (IC₅₀=10.5 μM). In contrast, 5-hydroxydecanoate (10–100 μM) did not affect the concentrations of dialysate adenosine, measured in the presence of AMP (100 μM). These results suggest that glibenclamide inhibits the activity of endogenous ecto-5′-nucleotidase and decreases the concentration of adenosine in the interstitial space of rat ventricular muscles in situ.

     

Effect of catecholamic acid on detoxication and distribution of NiCl_2 in mice and rats

目的：研究双酚胺酸（ＣＢＭＩＤＡ）对氯化镍的解毒作用．方法：ＮｉＣｌ２中毒后，立即给予ＣＢＭＩＤＡ，记录动物存活数；小鼠ｉｖ６３ＮｉＣｌ２后给药，测定２４ｈ组织中６３镍；用整体放射自显影术，显示小鼠体内６３镍分布．结果：ｓｃＣＢＭＩＤＡ０５－１５ｇ·ｋｇ－１对ｉｐＮｉＣｌ２５００ｍｇ·ｋｇ－１有解毒作用；小鼠ｉｐＮｉＣｌ２ＬＤ５０为８２８ｍｇ·ｋｇ－１，给药１５或２５ｇ·ｋｇ－１，ＬＤ５０分别为７８９和８２０ｍｇ·ｋｇ－１；大鼠ｉｍＣＢＭＩＤＡ５００ｍｇ·ｋｇ－１使ＮｉＣｌ２的ＬＤ５０提高８倍；组织中６３镍测定和定位显示，ＣＢＭＩＤＡ减少肺和血液中６３镍，增加了骨中６３镍，２４ｈ尿、粪６３镍排出与对照组无明显差异．结论：ＣＢＭＩＤＡ有效地解除镍毒性，提高动物存活率，降低镍在肺部的滞留．     

Interaction between Δ 9-tetrahydrocannabinol and morphine on the motor activity of mice

The present experiments dealt the effects of ⁹-tetrahydrocannabinol (THC) on the locomotor activity stimulating action of morphine in mice. In the first series of experiments, the pretreatments of mice by THC in doses up to 20 mg/kg have been found to potentiate the morphine-induced hyperactivity in dose-dependent manner, but higher doses of THC did not produce such an action. In the second series of experiments the dose-response curve of morphine for the motor activity has been found to shift to the left by the pretreatment of mice with 10 mg/kg of THC. These results show a synergism between morphine and THC and suggest that both drugs may share some common site of action.     

Gender-related difference in the toxicity of 2-(2′-hydroxy-3′,5′-di-tert-butylphenyl)benzotriazole in rats: Relationship to the plasma concentration,in vitro hepatic metabolism,and effects on hepatic metabolizing enzyme activity

Previously, we showed that the toxic susceptibility of male rats to an ultraviolet absorber, 2-(2′-hydroxy- 3′,5′-di-tert-butylphenyl)benzotriazole (HDBB), was nearly 25 times higher than that of females. The present study aimed to clarify the mechanism of gender-related differences in HDBB toxicity. Male and female rats were given HDBB by gavage at 0.5, 2.5, or 12.5?mg/kg/day for 28 days, and plasma HDBB levels were measured at various time points by using liquid chromatography–tandem mass spectrometry. HDBB was rapidly absorbed and eliminated from the plasma in both sexes, and no sexual variations were found in the plasma levels. In the plasma, HDBB metabolites were not detected at any dose by the liquid chromatography–photodiode array detector. In an in vitro metabolic study using hepatic microsomes from male and female rats, HDBB was slightly metabolized, but no sexual differences were found in the residual HDBB ratio after a 60-minute incubation with an NADPH-generation system. Following 28-day HDBB administration, sexually different changes were found in cytochrome P450–dependent microsomal mixed-function oxidase activities in the liver. In males, 7-ethoxyresorufin O-deethylase activity decreased and lauric acid 12-hydroxylase activity increased at all doses. Decreases in aminopyrine N-demethylase activity and testosterone 2α- and 16α-hydroxylase activity were also found at 2.5?mg/kg and above in males. In females, the only significant change was increased lauric acid 12-hydroxylase activity at 12.5?mg/kg. These findings indicate that HDBB would have hepatic peroxisome proliferative activity, and the difference in susceptibility of male and female rats to this effect might lead to marked gender-related differences in HDBB toxicity.     

How do transport and metabolism affect on the biological effects of polycyclic aromatic hydrocarbons?

Polycyclic aromatic hydrocarbons (PAHs), some of which are carcinogenic/mutagenic, are generated by combustion of fossil fuels and also released through tanker or oilfield accident to cause a large scale environmental pollution. PAHs concentration in China is especially high in East Asia because of many kinds of generation sources such as coal heating systems, vehicles and factories without exhaust gas/particulate treatment systems. So, the atmospheric pollution caused by PAHs in China has been seriously concerned from the view point of health effects. Like yellow sand and sulfur oxide, PAHs exhausted in China are also transported to Japan. Additionally, strongly mutagenic nitrated PAHs (NPAHs), estrogenic/antiestrogenic PAH hydroxides (PAHOHs) and reactive oxygen species-producing PAH quinones (PAHQs) are formed from PAHs by the chemical reaction during the transport. Furthermore these PAHOHs and PAHQs are produced by the metabolism in animal body. In the biological activities caused by the above PAH derivatives, the structure-activity relationship was observed. In this review, our recent results on the generation of PAH derivatives by atmospheric transport and metabolism are reported. Also, the existing condition of PAHs as atmospheric pollutants is considered.     

Relationship of metabolism of 2′-, 3′- and 5′-adenine nucleotides to presynaptic inhibition of transmitter release in rat vas deferens

Summary In the isolated rat vas deferens stimulated at 0.2 Hz, a series of 2, 3-, and 5-substituted adenine nucleotides all inhibited the twitch responses, their actions being potentiated by the nucleoside transport inhibitors, HNBTGR, NBMPR and dipyridamole.The metabolism of these nucleotides was examined utilising HPLC analysis of the bathing medium after exposure to 30 M nucleoside or nucleotide for 5 min. 5-AMP, 5-ADP, 5-ATP, and NAD⁺ were all partially hydrolysed to adenosine, the relative extent of this being 5-AMP>5-ADP=5-ATPNAD⁺. However, the other nucleotides examined were not detectably converted to adenosine or to adenosine deamination products.These results indicate that the 2-, 3- and 5-substituted nucleotides studied act at a P₁-purinoceptor in rat vas deferens to inhibit neurotransmission and, with the exception of 5-AMP, 5-ADP, 5-ATP and NAD⁺, all appear to act directly at this receptor. However, the 5-adenine nucleotides (AMP, ADP and ATP) and NAD⁺ all appear to act at least partially indirectly subsequent to their hydrolysis to adenosine.Abbreviations. The following abbreviations are used ADA adenosine deaminase (EC 3.5.4.4) - 5-ADP adenosine 5-diphosphate - 2,5-ADP adenosine 2,5-diphosphate - 3 5-ADP, adenosine 3,5-diphosphate - 2-, 3 or 5-AMP adenosine 2-, 3-, or 5-monophosphate - 5-ATP adenosine 5-triphosphate - cNADP⁺ -nicotinamide dinucleotide 2,3-cyclic monophosphate - CoA coenzyme A - HNBTGR 6-(2-hydroxy-5-nitrobenzyl)-thioguanosine - NAD⁺ -nicotinamide adenine dinucleotide - NADP⁺ -nicotinamide adenine dinucleotide phosphate - NBMPR 6-(4-nitrobenzylthio)-purine riboside     

Effects of clonidine and some α-adrenergic antagonists alone and in combination on schedule-controlled behavior in pigeons and mice

Schedule-controlled responding was maintained under multiple fixed-interval, fixed-ratio schedules in pigeons and single fixed-ratio schedules in mice. In pigeons, clonidine, an ₂-receptor agonist, produced dose-related decreases in responding under both fixed-interval and fixedratio schedules; fixed-interval responding was decreased at a lower dose than fixed-ratio responding. Low to intermediate doses of yohimbine, an ₂-receptor antagonist, increased responding under the fixed-interval schedule without appreciably affecting responding under the fixed-ratio schedule; higher doses decreased responding under both schedules. In mice, both clonidine and yohimbine produced dose-related decreases in responding under fixed-ratio schedules. Decreases in response rates produced by clonidine were antagonized by low to intermediate doses of yohimbine. Decreases in response rates under fixed-ratio schedules produced by yohimbine were antagonized only slightly, if at all, by clonidine. Under the fixed-interval schedule, clonidine potentiated the response-rate increasing effects of intermediate doses of yohimbine and slightly antagonized the rate-decreasing effects. Although some effects of clonidine were antagonized by yohimbine, at no dose combination did performances completely resemble control performances. Prazosin, an ₁-receptor antagonist, was ineffective both when administered alone and as an antagonist of the effects of clonidine. The behavioral effects of clonidine appeared to be mediated by ₂ rather than ₁ receptors. Additionally, yohimbine appears to have significant behavioral effects other than ₂-antagonist actions.     

β-adrenergic receptor density and adenylate cyclase activity in lead-exposed rat brain after cessation of lead exposure

To understanding the reversible or irreversible harm to the -adrenergic system in the brain of lead-exposed rats, this study sets up an animal model to estimate the change in the sympathetic nervous system of brain after lead exposure was withdrawn. We address the following topics in this study: (a) the relationship between withdrawal time of lead exposure and brain -adrenergic receptor, blood lead level, and brain lead level in lead-exposed rats after lead exposure was stopped; and (b) the relationship between lead level and -adrenergic receptor and cyclic AMP (c-AMP) in brain. Wistar rats were chronically fed with 2% lead acetate and water for 2 months. Radioligand binding was assayed by a method that fulfilled strict criteria of -adrenergic receptor using the ligand [¹²⁵I]iodocyanopindolol. The levels of lead were determined by electrothermal atomic absorption spectrometry. The c-AMP level was determined by radioimmunoassay. The results showed a close relationship between decreasing lead levels and increasing numbers of brain -adrenergic receptors and brain adenylate cyclase activity after lead exposure was withdrawn. The effect of lead exposure on the -adrenergic system of the brain is a partly reversible condition.     

Effect of developmental lead exposure on synaptic plasticity and N—methyl—D—aspartate receptor subunit in rat hippocampus

Chronic lead(Pb) exposure is known to be associated with learning and memory,and cognitive dysfunction in children.Previous studies have demonstrated that Pb exposure may impair neuronal process underlying synaptic plasticity via a direct interaction with N-methyl-D-aspartate (NMDA) receptors(NMDARs).The studies described here were carried out to investigate effect of developmental Pb exposure on long-term potentiation(LTP),long-tern depression(LTD) and NMDAs subunits in rat hippocampus.The results are listed as follows:(1)low-level Pb exposture can impair the induction and maintenance of LTP in vivo and in vitro;(2)the Pb-induced impairment of LTD magnitude was an age-related decline in area CA1 of rat hippocampus;(3)chronic Pb exposure affected two components,voltage-gated calcium channel-dependent LTD and NMDARs-dependent LTD,of LTD induction in area CA1 of rat hippocampus;(4)different effects of developmental Pb exposure on NMDA receptor NR1,NR2A,NR2B,NR2C,NR2D and NR3A subunits in area CA1,CA2,CA3 and CA4 of rat hippocampus were observed;(5)the α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptors enriched in area CA1,CA3 and dentate gyrus and kainite receptors enriched in area CA1 and dentate gyrus of rat hippocampus were impaired by Pb exposure.     

Effect of corilagin on cholesterol metabolism in macrophages and its mechanism北大核心CSCD

Aim To elucidate the effect of corilagin (Cor) on cholesterol metabolism in macrophages and the underlying mechanism. Methods Molecular docking was applied to predict the protein target of Cor on cellular cholesterol metabolism. The RAW264.7 macrophage foam model induced by 80 mg • L-1 oxidized low density lipoprotein (ox-LDL) was established to evaluate the activity of Cor on lowering-cholesterol. The expression of genes and proteins related with cholesterol metabolism were detected by q-PCR and Western blotting,respectively. Then the activity of Cor on lipid metabolism was validated in ApoE mice fed with high-fat-diet. Results Cor and Class A Scavenger receptor (SRA), CD36, peroxisome proliferator-activated receptor γ (PPAR-γ), ATP binding cassette transporter Gl(ABCGl), which associated with cholesterol metabolism, could form hydrogen bonds and hydrophobic interactions. Cell experiments showed that Cor (60,120 and 240 μmol • L-1) significantly decreased TC content in macrophages, Cor could down-regulate SRA and CD36 gene expression, SRA protein expression, up-regulate the expression of ABCA1 and ABCG1 genes. Animal experiments demonstrated that Cor (15,30 and 60 mg • k g - 1 ) could decrease the serum TMAO content, the plaque area and formation of foam cells in the aortic root,the expression levels of CD36 and SRA fluorescent proteins in aortic root plaques. Conclusions Cor could inhibit the formation of macrophage foam cells through the regulation of cholesterol metabolism mediated by CD36,SRA, ABCA1 and ABCG1 to cure the AS. © 2023 Publication Centre of Anhui Medical University. All rights reserved.