Immunomodulatory effects by oral contraceptives in normal and cholestatic female rats: role of cytokines.

Oral contraceptives (OC) may cause intrahepatic cholestasis or increase a pre-established liver damage. OC effects on hepatic injury biochemical markers remain contradictory and the role of cytokines in those processes is fairly unknown. Two doses, simple or double, of the OC combination ethinylestradiol/norgestrel were administered during 14 or 28 days to normal and cholestatic female rats. Liver damage markers and the cytokines tumor necrosis factor-α (TNF-α), interleukin-10 (IL-10) and transforming growth factor-ß (TGF-ß) were determined in plasma and liver. OC caused ambiguous results on cholestasis indicators, even more in cholestatic rats. Necrosis rose during cholestasis while OC lowered it in normal rats. Fibrosis was induced by cholestasis but OC double dose or intake time diminished that. Cholestasis depleted glycogen while OC did not alter it. Double dose or time of administration of OC significantly elevated the lipid peroxidation. Cholestasis modified plasma and liver cytokines but OC remarkably altered them in normal and cholestatic animals. TNF-α as well as IL-10 were increased in both tissues by OC, such rise was higher in normal rats. TGF-ß was augmented by OC and more in cholestatic rats receiving double dose. Thus, OC modified most liver injury markers in normal rats although more pronouncedly in cholestatic ones, as well as increased hepatic oxidative stress. Liver fibrosis was decreased and corroborated by histological analysis even when TGF-ß is elevated by OC. OC strongly immunomodulate cytokines that mediate liver damage or worsen a prior hepatopathy; those processes are influenced by dose, administration time and OC formulation.

Membrane potential differences and GABAA receptor expression in hepatic tumor and non-tumor stem cells.

The ability to differentiate tumor initiating stem cells (TISCs) from healthy, normal stem cells (NSCs) could have important diagnostic and therapeutic implications for patients with hepatocellular carcinoma (HCC). The aim of this study was to document and compare cell membrane potentials (PDs) and GABAA receptor subunit expression in hepatic TISCs and NSCs. PD values were determined in CD133(+) Huh-7 TISCs and CD133(+) WBF344 NSCs by single channel microelectrode impalement. GABAA receptor subunit expression was documented using immunohistochemistry (IH) in both cell lines as well as surgically resected HCC and healthy liver tissues. TISCs were significantly depolarized compared with NSCs (-4.0 ± 1.8 versus -11.0 ± 2.4 mV, respectively; p < 0.05). GABAA α6 subunit expression was either absent or markedly attenuated, while γ3 subunit expression was abundant in TISCs and HCC compared with NSCs and healthy liver tissues. Exposure to the GABAA receptor agonist muscimol caused hyperpolarization of TISCs (Δ -4.4 ± 1.1) but depolarization of NSCs (Δ + 5.2 ± 2.3) and attenuation of TISC proliferative activity. We conclude that TISCs and NSCs have significantly different cell membrane potentials and these differences are associated with differences in GABAA receptor subunit expression.

Protective effect of N,N'-dialkylated analogs of 4,4'-diaminodiphenylsulfone in a model of intrastriatal quinolinic acid induced-excitotoxicity.

The bacteriostatic agent 4,4'-diaminodiphenylsulfone or dapsone (DDS) and some of its N,N'-dialkylated analogs have shown anticonvulsant and neuroprotective properties in different experimental models. In this study, we tested the ability of five DDS analogs (N,N'-dimethyldapsone, N,N'-diethyldapsone, N,N'-dipropyldapsone, N,N'-dibutyldapsone and N,N'-ditosyldapsone) to attenuate quinolinic acid-induced toxicity in vivo. Male Wistar rats were treated with either DDS or analogs (12.5mg/kg and equimolar doses respectively) 30 min before quinolinic acid intrastriatal stereotaxic injection (240 nmol/µl). Six days after injury, circling behavior was evaluated by counting ipsilateral turns for 1h after apomorphine challenge (1mg/kg, sc). Twenty-four hours later, rats were sacrificed and their corpora striata were dissected out to determine GABA content. Hemotoxicity of the analogs was assessed as the ability to produce methemoglobin (MHb) in vivo. Blood was sampled from tail vein within 18 h after drugs administration. Methemoglobin levels were determined by visible spectrophotometry and mean profiles of MHb-percentage versus time were obtained. All of the analogs tested decreased the number of ipsilateral turns/hour, reducing up to 67% the turns counting (p<0.05) when compared to those induced in animals receiving quinolinic acid with no treatment. N,N'-dimethylated, N,N'-diethylated and N,N'-dibutylated analogs significantly prevented the decrease of intrastriatal GABA content (p<0.05). Methemoglobin produced by the administration of analogs was significantly lower than the levels of the group receiving dapsone (p<0.05). The neuroprotective effect of analogs and their diminished hemotoxicity make them potential candidates for therapeutic applications.

A novel fluorinated stilbene exerts hepatoprotective properties in CCl(4)-induced acute liver damage.

There has been a recently increase in the development of novel stilbene-based compounds with in vitro anti-inflamatory properties. For this study, we synthesized and evaluated the anti-inflammatory properties of 2 fluorinated stilbenes on carbon tetrachloride (CCl4)-induced acute liver damage. To achieve this, CCl4 (4 g·kg(-1), per os) was administered to male Wistar rats, followed by either 2-fluoro-4'-methoxystilbene (FME) or 2,3-difluoro-4'-methoxystilbene (DFME) (10 mg·kg(-1), per os). We found that although both of the latter compounds prevented cholestatic damage (γ-glutamyl transpeptidase activity), only DFME showed partial but consistent results in the prevention of necrosis, as assessed by both alanine aminotransferase activity and histological analysis. Since inflammatory responses are mediated by cytokines, mainly tumour necrosis factor α (TNF-α), we used the Western blot technique to determine the action of FME and DFME on the expression level of this cytokine. The observed increase in the level of TNF-α caused by CCl4 administration was only prevented by treatment with DFME, in agreement with our biochemical findings. This result was confirmed by measuring interleukin-6 (IL-6) levels, since the expression of this protein depends on the level of TNF-α. In this case, DFME completely blocked the CCl4-induced increase of IL-6. Our results suggest that DFME possesses greater anti-inflammatory properties in vivo than FME. DFME constitutes a possible therapeutic agent for liver disease and could serve as a template for structure optimization.

Genomic action of permanently charged tamoxifen derivatives via estrogen receptor-alpha.

Tamoxifen is a selective estrogen receptor modulator widely used in oncology and reproductive endocrinology. In order to decrease its non-desirable effects and elucidate mechanisms of action, permanently charged tamoxifen derivatives (PCTDs) have been reported. Whether PCTDs have genomic effects remains controversial. Since the clinical relevance of tamoxifen, the necessity to have new anticancer drugs, and in order to gain insights into the mechanisms of action of PCTDs, we obtained six quaternary ammonium salts derived from tamoxifen including three new compounds. We characterized them by nuclear magnetic resonance, X-ray diffraction, electron microscopy, and/or high performance liquid chromatography, and detected them in cell lysates by liquid chromatography coupled to mass spectrometry. We evaluated their binding to estrogen receptor-alpha (ERalpha, their effect on the transcriptional activity mediated by ERalpha (gene reporter assays), and the proliferation of cancer cells (MCF-7 and cells from a cervical cancer primary culture). Structural studies demonstrated the expected identity of the molecules. All PCTDs did bind to ERalpha, one of them induced ERalpha-mediated transcription while two others inhibited such genomic action. Accordingly, PCTDs were detected in cell lysates. PCTDs inhibited cell proliferation, noteworthy, two of them displayed higher inhibition than tamoxifen. Structure-activity analysis suggests that PCTDs permanent positive charge and the length of the aliphatic chain might be associated to the biological responses studied. We suggest genomic effects as a mechanism of action of PCTDs. The experimental approaches here used could lead to a better design of new therapeutic molecules and help to elucidate molecular mechanisms of new anticancer drugs.

The thalidomide analog 3-phthalimido-3-(3,4-dimethoxyphenyl)-propanoic acid improves the biliary cirrhosis in the rat.

Chronic cholestasis and cholangitis may lead to the last phase known as biliary cirrhosis, characterized by cellular necrosis, apoptosis, tissue damage, local regeneration, inflammation and fibrosis. Such events are mediated by cytokines. Thalidomide and its analogs have shown to be effective immunomodulatory and hepatoprotective agents. The aim of this work was to evaluate the hepatoprotective properties of a thalidomide analog, the 3-phthalimido-3-(3,4-dimethoxyphenyl)-propanoic acid (PDA), on bile duct obstruction-induced cirrhosis. Vehicle or PDA (67 mg/kg) was orally administered twice a day to sham (Sham) or bile duct-ligated (BDL) male Wistar rats. The animals were sacrificed 28 days after treatments. Alkaline phosphatase (AP), gamma-glutamyl transpeptidase (GGTP) and alanine aminotransferase (ALT) enzyme activities as well as direct and total bilirubins concentration were determined in plasma. Lipid peroxidation (LP), glycogen and collagen were quantified in liver; in addition, histopathology was performed. PDA improved cholestasis, necrosis and fibrosis by significantly diminishing most of liver injury markers (P<0.05). Histopathology also showed remarkable liver damage amelioration. PDA effectiveness may be due to its water-solubility, stability, phosphodiesterase-4 inhibitory and immunomodulatory actions. Thalidomide and its analogs seem to be promising drugs for further treatment of biliary cirrhosis.

Trolox down-regulates transforming growth factor-beta and prevents experimental cirrhosis.

Cirrhosis is a very common disease and its treatment is limited due to lack of effective drugs. Some studies indicate that this disease is associated with oxidative stress. Therefore, we decided to study the effect of trolox, an effective antioxidant, on experimental cirrhosis. Cirrhosis was induced by CCl4 administration (0.4 g/kg, intraperitoneally, three times per week, for 8 weeks) to Wistar male rats. Trolox was administered daily (50 mg/kg, orally). Fibrosis was assessed histologically and by measuring liver hydroxyproline content. Glutathione, lipid peroxidation and glycogen were measured in liver; serum markers of liver damage were also quantified. Transforming growth factor-beta (TGF-beta) was determined by Western blot and quantified densitometrically. Alkaline phosphatase, gamma-glutamyl transpeptidase and alanine aminotransferase increased in the group receiving CCl4; trolox completely or partially prevented these alterations. Glycogen was almost depleted by CCl4 but was partially preserved by trolox. Lipid peroxidation increased while glutathione decreased by CCl4 administration; trolox corrected both effects. Histology showed thick bands of collagen, necrosis and distortion of the hepatic parenchyma in the CCl4 group, such effects were prevented by trolox. Hydroxyproline content increased 5-fold by CCl4, while the group receiving both CCl4 and trolox showed no significant difference compared to the control group. CCl4 increased 3-fold TGF-beta, while trolox completely prevented this increase. We found that trolox effectively prevented cirrhosis induced with CCl4 in the rat. Our results suggest that the beneficial effects of trolox may be associated to its antioxidant properties and to its ability to reduce the profibrogenic cytokine TGF-beta expression.

Synthesis and biological evaluation of (-)- and (+)-debromoflustramine B and its analogues as selective butyrylcholinesterase inhibitors.

A series of pyrrolidinoindolines have been synthesized as debromoflustramine B (4a) analogues for their evaluation as cholinesterase inhibitors. Structure-activity studies of this series revealed the optimum pharmacophoric elements required for activity and resulted in the discovery of selective butyrylcholinesterase inhibitors with micromolar potency. Biological testing demonstrated that (-)-4a was 7500 times more potent than its enantiomer (+)-4b. The most active inhibitor against BChE in the series was demethyldebromoflustramine B (5a), with an IC50 value of 0.26 microM. X-ray crystallography of 15 and docking studies of selected compounds into human BChE (PDB 1POI) are presented. Molecular modeling studies showed that pi-hydrogen bond, classical hydrogen bond, and cation-pi interactions are critical for optimum potency.

Resveratrol and trimethylated resveratrol protect from acute liver damage induced by CCl4 in the rat.

The importance of hydroxyl groups in the antioxidant and hepatoprotective properties of resveratrol was investigated. To achieve this, resveratrol or its trimethylated analog were administered (10 mg kg(-1), p.o.) to male Wistar rats and liver damage was induced by acute administration of CCl4 (4 g kg(-1), p.o.); appropriate controls were performed. The animals were killed 24 h after CCl4 intoxication. The amount of reduced glutathione (GSH) in the liver was not modified by any treatment; interestingly, the GSH/GSSG (oxidized glutathione) ratio decreased in the groups receiving CCl4 and resveratrol associated with an increase in GSSG. In blood GSH and the GSH/GSSG ratio were decreased by CCl4; both effects were completely prevented by any of the compounds tested. Lipid peroxidation and the activity of gamma-glutamyl transpeptidase were increased significantly after CCl4. Resveratrol partially prevented these increases and surprisingly, trimethylated resveratrol completely prevented the increase of these markers. Both compounds partially but significantly prevented the increase in the activity of alanine aminotransferase; this result agrees with observations in the histological analysis. Both tested compounds administered alone produced no effect. The results of the present study suggest that OH groups are important for the antioxidant and hepatoprotective properties of the molecule of resveratrol; nevertheless, these effects can be improved by replacing hydrogen by a methyl in these groups. The differences in the antioxidant and hepatoprotective effects of these compounds could be due to the possibility that the trimethylated resveratrol acts like a prodrug, prolonging, probably, the half-life of the original compound.

Trans-3-phenyl-2-propenoic acid (cinnamic acid) derivatives: structure-activity relationship as hepatoprotective agents.

Among various phenolic compounds, caffeic acid (3,4-dihydroxycinnamic acid) exhibited pharmacological antioxidant, anticancer and antimutagenic activities. The antioxidant properties of phenolic compounds depend on their chemical structure, however, the role of the ethylenic side chain in the radical scavenging activity remains controversial. Thus, the aim of this study consisted to test cinnamic acid and 15 cinnamic acid derivatives in the well known CCl(4)-induced acute liver damage model, which is dependent on oxidative stress mechanisms. Cinnamic acid and 15 cinnamic acid derivatives (50 mg/kg, p.o.) were administered to male Wistar rats intoxicated with CCl(4) (4 g/kg, p.o.). The activities of gamma-glutamyl transpeptidase, alkaline phosphatase and alanine aminotransferase were measured in serum. The lipid peroxidation products were determined in liver. Compounds with a methoxy group at position 3 or 4, or a 3,4-methylenedioxy moiety were the most active ones. Also, we observed that the monosubstituted 3 or 4 hydroxy, or the bulky 3,4 dibenzyloxy substituted compounds showed lower activity. The poorest activity was displayed by disubstituted 3,4-dihydroxy, dimethoxy or diacetyl cinnamic acid derivatives, the ester derived from cinnamic acid with an 8 carbon chain and N-dimethyl substituted compound. Thus, the methoxy substituted group at positions 3 or 4 or the 3,4-methylenedioxy moiety in the caffeic acid derivatives; seem to be the main features required for the hepatoprotection in this model.

Renal angiotensin-II receptors expression changes in a model of preeclampsia.

The blunted response to angiotensin II (Ang II) during pregnancy is lost in patients by preeclampsia. This impaired response has been attributed to a change in one or both of the Ang II receptors, type 1 (AT(1)R) and type 2 (AT(2)R). The ratio of the Ang II receptor types in the kidney has not been studied. We postulated that an imbalance exists between AT(1)R/AT(2)R receptors in the renal cortex from rats subjected to an experimental model of preeclampsia, and that this altered ratio can modify the characteristic blunted pressor response to Ang II during pregnancy. The feto-placental units of Wistar rats were made ischemic by subrenal aortic coarctation, thus creating an experimental model of preeclampsia. We measured the AT(1)R and AT(2)R protein expression and the presence of the heterodimer AT(1)R/AT(2)R in the renal cortex and evaluated the pressor response to Ang II in an isolated kidney preparation from non-pregnant, healthy pregnant, and preeclampsia model rats. Pregnancy increased AT(2)R and AT(1)R/AT(2)R heterodimer expression and decreased the pressor response to Ang II. In contrast, AT(1)R increased, while AT(2)R and AT(1)R/AT(2)R heterodimer decreased in the preeclampsia model group. Thus, Ang II hypersensitivity observed in preeclampsia might be related to an increased expression of AT(1)R over AT(2)R and to a decreased presence of the AT(1)R/AT(2)R heterodimer in renal cortex.

Vasoactive properties of antidepressant N-alkyl derivatives.

Hypotension is a principal side effect of antidepressant therapy. In addition to serotonin and noradrenalin reuptake inhibition, some antidepressants have shown ion channel interactions which are thought to be related to the vascular effects of these agents. Methylation of the pharmacophore has shown to change the pharmacological properties of a variety of compounds. The purpose of this work was to evaluate whether methylation of the amino group of imipramine (TCA's) and fluoxetine (SSRI) could change their vasodilator properties. N-methyl imipramine (NMI), N-methyl fluoxetine and (NMF) N-N dimethyl fluoxetine (NNDF) were synthesized and compared with desipramine (DES), imipramine (IMI) and fluoxetine (F) in their ability to relax rat aortic rings pre-contracted with 80mM KCl using an isolated bath preparation. Drugs were evaluated in thoracic aorta rings with and without endothelium. All compounds displayed a vasorelaxant effect. Endothelium-denuded aortic rings showed an increased relaxant response for IMI and derivatives compared with endothelium-intact vessels, while no endothelium-dependent effect was observed with F and its methyl derivatives. Maximal relaxant potency was displayed by dimethylated derivatives (IMI and NMF), while NMI in the TCA series and NNDF in the SSRI series (both with 3 methyl groups), had the least potency to relax either preparation. Endothelium plays an important role inhibiting the vasodilatation induced by IMI and its derivatives. Vascular relaxation is increased in the compounds tested with 2 methyl groups in their structure, while the presence of 3 methyl groups (positive charge) importantly reduced the relaxant potency.

Chronic bile duct obstruction induces changes in plasma and hepatic levels of cytokines and nitric oxide in the rat.

Chronic bile duct ligation (BDL) is a useful model of cirrhosis. However, its parallel plasma and liver changes in levels of cytokines and nitric oxide (NO), involved in liver damage, remain unknown. The aims of this work were to quantify both the plasma and hepatic levels of five cytokines and NO in cirrhotic rats, 28 days after bile BDL, and to analyze their relationship with liver damage markers. One group of male Wistar rats was bile duct ligated and another group was sham operated, both groups were sacrificed 28 days after BDL. Plasma and liver cytokines, tumor necrosis factor-alpha (TNF-alpha), interleukin-6, -1beta, -10 (IL-6, -1beta, -10) and interferon-gamma (IFN-gamma), were measured by ELISA. Plasma and hepatic NO was determined as NO(2)(-)+NO(3)(-) by an enzymatic method. Alkaline phosphatase, gamma-glutamyl transpeptidase, alanine aminotransferase and bilirubins were determined in plasma. Collagen, lipid peroxidation and glycogen were quantified in liver. Two histopathological staining techniques were performed. BDL-induced cirrhosis was corroborated by the elevated liver damage markers and histopathological analysis. Chronic BDL significantly increased (P<0.05) most of plasma and hepatic cytokine levels and diminished the hepatic IFN-gamma amount. NO was increased in both tissues, but such change was only significant in plasma. Biliary cirrhosis produces interesting changes in plasma and hepatic levels of cytokines and NO. This finding in chronic BDL model in rats has not been previously described in both tissues for such cytokines and NO. Cytokines and NO imbalance favor establishment and perpetuation of cirrhosis.

Effect of pregnancy on the roles of nitric oxide and prostaglandins in 5-hydroxytryptamine-induced contractions in rat isolated thoracic and abdominal aorta.

1. Vascular resistance and sensitivity to circulating pressor and vasoconstrictor substances are blunted during pregnancy. This has been attributed mainly to an increased production of endothelium-derived mediators. The aim of the present study was to determine whether pregnancy changes the relative participation of nitric oxide (NO) and prostaglandins (PG) in the modulation of the contractile response to 5-hydroxytryptamine (5-HT) in two anatomically distint segments of the rat aorta. 2. Full concentration-response curves to 5-HT were obtained in isolated rings from the thoracic and abdominal portion of the aorta from pregnant and non-pregnant rats in the presence and absence of the NO synthase (NOS) inhibitor N(G)-nitro-l-arginine methyl ester (L-NAME; 10 micromol/L) or the PG synthesis inhibitor indomethacin (10 micromol/L). Cyclo-oxygenase (COX)-1, COX-2 and endothelial (e) NOS protein expression were determined in the same tissues by immunoblot. 3. The effects of pregnancy were accentuated in the abdominal compared with the thoracic aorta. In addition, the relative participation of the NO and PG pathways seems to be changed during pregnancy. Although NO seems to be the mediator mainly responsible for the effect of pregnancy in the thoracic aorta, our results suggest a complex interaction between NO and PG in the abdominal aorta. Indomethacin significantly reduced the contractile response of both segments of the aorta, whereas expression of COX-1, COX-2 and eNOS were increased only in the abdominal segment of pregnant animals. 4. These results show that the effect of pregnancy is not homogeneous along the aorta. There seems to be a mutual interaction between PG and NO in the abdominal, but not in the thoracic, aorta from pregnant rats: the role of NO becomes evident in the absence of vasodilatory PG, whereas the participation of the latter increases in the absence of NO working as a compensatory mechanism.

Renal vascular responses in an experimental model of preeclampsia.

In pregnancy there is an attenuated response to vasoconstrictors and pressor agents, including Angiotensin II (Ang II). This effect is reverted in preeclampsia. We evaluated the renal pressor response induced by Ang II in an experimental model of preeclampsia based on the development of feto-placental ischemia produced by a subrenal aortic coarctation (SRAC). Dose-response curves for Ang II were obtained in an isolated perfused kidney preparation comparing groups of SRAC pregnant and non-pregnant rats in the presence and absence of losartan (AT1 antagonist) or PD123319 (AT2 antagonist). Kidneys from the experimental model of pre-eclampsia showed an enhanced response to AngII. In addition, losartan (10 nM) inhibited the vasopressor effect to Ang II in this model but not in the control group. PD 123319 (1 nM), increased the response in both groups, but the effect was more evident in the pre-eclamptic group. This suggests modifications in the relative participation of renal vascular receptors AT1/AT2 induced by an experimental model of pre-eclampsia, with an increased participation of AT1 and a decreased participation of AT2.

Immunomodulatory effects of thalidomide analogs on LPS-induced plasma and hepatic cytokines in the rat.

Thalidomide has shown to inhibit, selectively and mainly the cytokine tumor necrosis factor-alpha (TNF-alpha), thus, thalidomide has inhibitory consequences on other cytokines; this is ascribed as an immunomodulatory effect. Novel thalidomide analogs are reported with immunomodulatory activity. The aim of this work was to synthesize some of these analogs and to assess them as immunomodulatory agents in an acute model of LPS-induced septic challenge in rat. Animal groups received orally twice a day vehicle carboxymethylcellulose (0.9%), or thalidomide in suspension (100mg/kg), or analogs in an equimolar dose. Two hours after last dose, rats were injected with saline (NaCl, 0.9%, i.p.) or LPS (5mg/kg, i.p.). Groups were sacrificed 2h after injection and samples of blood and liver were obtained. TNF-alpha, interleukin-6, -1beta, and -10 (IL-6, IL-1beta, IL-10) were quantified by enzyme linked immunosorbent assay (ELISA) and studied in plasma and liver. After 2h of LPS-induction, different patterns of measured cytokines were observed with thalidomide analogs administration evidencing their immunomodulatory effects. Interestingly, some analogs decreased significantly plasma and hepatic levels of LPS-induced proinflammatory TNF-alpha and others increased plasma concentration of anti-inflammatory IL-10. Thalidomide analogs also showed slight effects on the remaining proinflammatory cytokines. Differences among immunomodulatory effects of analogs can be related to potency, mechanism of action, and half lives. Thalidomide analogs could be used as a pharmacological tool and in therapeutics in the future.

Thalidomide ameliorates carbon tetrachloride induced cirrhosis in the rat.

OBJECTIVE: Thalidomide has anti-inflammatory, anti-tumour necrosis factor-alpha and anti-collagen activities. Cirrhosis is characterized by inflammation and fibrosis. Thus, thalidomide was evaluated in an experimental model of liver cirrhosis. METHODS: Male Wistar rats were used. Group 1 (n = 8) received mineral oil i.p. (control); group 2 (n = 15) received CCl(4) i.p. for 8 weeks to induce cirrhosis; group 3 (n = 15) consisted of rats receiving CCl(4) plus thalidomide (200 mg/kg/12 h); animals in group 4 (n = 8) received thalidomide only. Alanine aminotransferase (ALT), gamma-glutamyl transpeptidase (gamma-GTP) and alkaline phosphatase (ALP) were measured in serum, while collagen (hydroxyproline), glycogen and lipid peroxidation were determined in liver samples. A liver histopathological analysis was performed by using Gomori's trichromic staining. RESULTS: Intoxication with CCl(4) induced 33.3% mortality, while thalidomide co-treatment reduced it to 13.3%. The serum activities of ALT, gamma-GTP and ALP increased 3, 2 and 4-fold by CCl(4) treatment; thalidomide completely prevented elevation of these enzymes. In the liver, lipid peroxidation increased about 20-fold and glycogen was abolished in CCl(4) cirrhotic rats; thalidomide completely prevented the former and partially (P < 0.05) the latter. CCl(4) treated rats revealed a loss of normal architecture and nodules of hepatocytes surrounded by thick bands of collagen. Thalidomide + CCl(4) treated rats showed minor histological alterations and thinner bands of collagen. The anti-fibrotic effect estimated by hydroxyproline was partial but significant (P < 0.05). CONCLUSION: Thalidomide prevented necrosis, cholestasis and fibrosis induced by CCl(4). Its mechanism of action may be related to its anti-inflammatory, anti-tumour necrosis factor-alpha and anti-fibrotic activities reported previously.

Pregnancy influence on the vascular interactions between nitric oxide and other endothelium-derived mediators in rat kidney.

Peripheral vascular resistance and sensitivity to circulating pressor and vasoconstrictor agents are blunted during pregnancy. This has been mainly attributed to an increased production of endothelium-derived mediators. The objective of this work was to evaluate if pregnancy changes the relative participation of nitric oxide (NO) and prostaglandins (PG) in respect to the modulation of the increases in renal perfusion pressure induced by phenylephrine (Phe). Dose-response curves were made with gradually increasing doses of Phe using an isolated kidney preparation in the presence of a NO synthase (NOS) inhibitor (L-NAME, 1 microM), a PG-synthesis inhibitor (indomethacin, 1 microM), both, or neither. Also, renal cyclooxygenase (COX-1 and COX-2) and endothelial NOS (eNOS) expression was determined using PCR. The experiments were done in kidneys from nonpregnant and pregnant rats. Our results showed that the relative participation of renal vasoactive mediators seems to change during pregnancy. We found the presence of a COX-1-dependent vasoconstrictor in the middle of pregnancy that was not found in nonpregnant rats. Our results also suggest that there is increased participation of another renal vasodilator substance, the effect of which is observed when NO or PG synthesis is inhibited during late pregnancy. In addition, an apparent interaction between renal eNOS and COX-1 expression was observed: eNOS expression was diminished, while COX-1 was increased during the 2nd week of pregnancy. In contrast, in kidneys from the 3rd week of pregnancy, the expression of these two enzymes was similar.