Female rats show an increased sensibility to the forced swim test depressive-like stimulus in the hippocampus and frontal cortex 5-HT1A receptors

Affective disorders are more common in women. The forced swim test acts like a depressive stimulus. Hippocampus and frontal cortex 5-HT1A receptors of female and male Wistar rats subjected to the forced swim test were compared with a sham group. The forced swim test diminishes (P<0.05) the hippocampus 3H-8OH-DPAT bound in the female rats (184+/-16 fmol/mg protein) with respect to the male rats (309+/-41 fmol/mg protein) and to the female sham rats (255+/-20 fmol/mg protein). The forced swim test increases the frontal cortex 5-HT1A receptors in the female rats with respect to the female sham group (40.4+/-5 versus 24.7+/-4 fmol/mg protein, P<0.05). An increased sensibility of the 5-HT1A receptors to depressive-stimulus may be one mechanism underlying the higher prevalence of depression in female.

Alzheimer's disease: relationship between muscarinic cholinergic receptors, beta-amyloid and tau proteins

Senile dementia is one of the most important health problems in developed countries. The main disease causing dementia is Alzheimer's disease that is characterized by the progressive deterioration of the cholinergic system, beta-amyloid production and deposition, and neurofibrillary tangle formation. Most of the reviewed data, along with data from experiments performed in our laboratory, suggest that there are no changes in the number of muscarinic receptors between Alzheimer and control brains, although the receptors expressed in Alzheimer's disease brains can be anomalous in their function. The muscarinic receptor-G-protein interaction also seems to be impaired in Alzheimer's disease compared with control brains, as well as the G-protein system, with an important decrease in the function of the Gq/11, the most important G-protein stimulating phosphoinositide hydrolysis in human brain; in addition, the second messenger system is also impaired, with a decrease in the synthesis of phosphoinositides and in the number of IP3 receptors. Muscarinic cholinergic receptors are also linked to beta-amyloid production, stimulation of the M1 subtype with agonists results in the processing of the beta-amyloid precursor protein to non-amyloidogenic products and administration of a fraction of the beta-amyloid (beta-amyloid 25-35) to rats, results in a decrease in the number of muscarinic receptors in brain. M1 agonists also decrease the phosphorylation of tau proteins, playing again a modulatory role in the pathogenesis of Alzheimer's disease. The existence of a link between beta-amyloid and tau proteins also has been reported; treatment of hippocampal neurones with beta-amyloid, or the 25-35 residue fragment, resulted in an increase in tau protein phosphorylation. The particular contribution of muscarinic receptors, beta-amyloid and tau proteins in the pathogenesis of Alzheimer's disease remains still unclear. Probably Alzheimer's disease could be due to a progressive degeneration in the relationship between the three components covered in this review.

Effects of S-adenosyl-L-methionine on hepatic and renal oxidative stress in an experimental model of acute biliary obstruction in rats

We used an animal model of extrahepatic biliary obstruction of 7 days' duration to study the production of thiobarbituric acid reactive substances (TBARS), total glutathione (TG), reduced glutathione (GSH), and oxidized glutathione (GSSG), and the enzymatic activities of GSH-peroxidase, GSSG-reductase, and GSH-transferase. Four groups of six rats each were treated with saline, drug solvent, S-adenosyl-L-methionine (SAM) 5 mg/kg/d, subcutaneously, or SAM 10 mg/kg/d, subcutaneously. Extrahepatic biliary obstruction increased TBARS. SAM had the dose-dependent effects of inhibiting TBARS production and increasing TG content, mainly as a result of the increase in GSH. The activity of GSH-peroxidase and GSH-transferase was also significantly increased. In renal tissue these effects were statistically significant only in animals given the higher dose of SAM. In liver we found a reduction in biochemical values indicative of liver damage. We conclude that effect of SAM on hepatorenal function is strongly influenced by the drug's ability to reestablish equilibrium after oxidative tissue stress.

Pharmacological characterization and distribution of muscarinic receptors in human placental syncytiotrophoblast brush-border and basal plasma membranes

Based on the existence of choline acetyltransferase and acetylcholine in human placenta, we have investigated the presence of muscarinic acetylcholine receptors in brush-border and basal plasma membranes from human term placenta. Radioligand binding assay, using [3H]N-methyl-scopolamine as tracer, showed the existence of acetylcholine muscarinic receptors in brush-border (Kd 0.28 +/- 0.04 nM; Bmax 9.4 +/- 1.6 fmol/mg protein) and basal plasma membranes (Kd 0.24 +/- 0.05 nM; Bmax 34.3 +/- 6.3 fmol/mg protein). In order to perform a pharmacological characterization of these receptors, competition binding experiments were carried out using the muscarinic receptor antagonists pirenzepine, (11(2-diethyl-amino)methyl)-1-piperidinylacetyl-5-11-dihydro-6H-py rido(14) benzodiazepine (AF-DX 116), himbacine, 4-diphenylacetoxy-N-methylpiperidine methiodide (4-DAMP), dicyclomine and hexahydro-sila-difenidol (HHSD). The results obtained showed that the muscarinic receptors in brush-border and basal plasma membranes belong to different subtypes. In brush-border membranes, the receptor found match in terms of affinity for the antagonists with the muscarinic M1 receptor subtype (Ki pirenzepine, 13.6 +/- 8.2 nM; Ki AF-DX 116, 1680 +/- 271 nM; Ki himbacine, 212 +/- 6.5 nM; Ki 4-DAMP. 1.5 +/- 0.4 nM; Ki dicyclomine, 5.1 +/- 0.8 nM; Ki HHSD, 34.3 +/- 7.3 nM), whereas the receptor in basal plasma membrane seems to be of the muscarinic M2 receptor subtype (Ki pirenzepine, 202 +/- 48 nM; Ki AF-DX 116, 124 +/- 60 nM; Ki himbacine, 20.6 +/- 4.8 nM; Ki 4-DAMP, 4.5 +/- 1.2 nM; Ki dicyclomine, 54.6 +/- 22 nM; Ki HHSD, 89.2 +/- 15.8 nM). The results obtained show the existence of muscarinic acetylcholine receptors in brush-border and basal plasma membranes from human term placenta with a different distribution pattern in terms of number of receptors and distribution of different subtypes. The functional significance of these findings is as yet unknown, but these receptors probably mediate different functions as they belong to different subtypes and are coupled to different second messengers.

Oral fenoterol versus sustained release theophylline in adult asthmatics

AIM

The question regarding the minimal effective oral dose of fenoterol remains unanswered. The present study was undertaken to compare the therapeutic effects of sustained release theophylline and a conventional low dose oral fenoterol in patients with asthma.

PATIENTS AND METHODS

A double-blind, double-dummy, randomized, 2-phase, cross-over comparison between sustained-release theophylline (SR-T) and oral fenoterol 2.5 mg 3 times daily in 21 patients with stable bronchial asthma (mean age 51 years) was conducted. Each drug was administered for a 2-week period. All patients qualified with a > or = 15% reversibility in forced expiratory volume in 1 second (FEV1) following 200 micrograms of inhaled salbutamol. Spirometric tests and body plethysmography were done at baseline and at the end of each treatment period. Blood was drawn for routine laboratory analysis and serum theophylline concentration. During each treatment period the patient kept a diary of symptoms and the concurrent use of inhaled salbutamol was recorded.

RESULTS

During SR-T administration trough serum concentrations were 12.9 (1.5) mg/l mean (+/- SEM). SR-theophylline produced greater maximal changes in all parameters measured: FEV1, forced vital capacity, and specific airway resistance from the pretreatment and fenoterol phase, while fenoterol caused significant changes in none of the test variables. Patients showed an overall preference for SR-T over fenoterol (p < 0.05).

CONCLUSIONS

Thus, 2.5 mg of fenoterol at 8-hour intervals did not prove to be an effective alternative to sustained release theophylline for management of patients with asthma. An appropriate dosing schedule for fenoterol needs to be redefined.

Flavonoid inhibition of enzymic and nonenzymic lipid peroxidation in rat liver differs from its influence on the glutathione-related enzymes

Eight flavonoids were tested for their antiperoxidative activities against lipid peroxidation induced in liver cell membranes either by nonenzymic way (ascorbic acid-Fe2+ system, FeAs) or by enzymic way (arachidonic acid, AA). When lipid peroxidation is induced by FeAs, the order in the inhibitory potency for the different flavonoids assayed is: (-)-epicatechin approximately luteolin > quercetin approximately (+)-catechin > delphinidin > kaempferol >> apigenin > naringenin. However, when lipid peroxidation is induced by AA, the potency order is markedly modified: delphinidin > (-)-epicatechin > (+)-catechin > kaempferol > quercetin > luteolin > naringenin > apigenin. These flavonoids were also tested for their influence on glutathione-related enzymes, which constitute one of the aim physiological antioxidant systems. It is concluded that the antiperoxidative effect shown by most of the flavonoids is exerted without modifying these enzymes.

Atropine and glycopyrronium show similar binding patterns to M2 (cardiac) and M3 (submandibular gland) muscarinic receptor subtypes in the rat

Atropine and glycopyrronium are frequently used for premedication to reduce oral and respiratory secretions and prevent bradycardia. Glycopyrronium is said to have similar antisialagogue effects, but is less likely to cause significant tachycardia than atropine. Different antimuscarinic receptor selectivity patterns could explain the differences. The aim of this investigation was to determine the possible selectivity of glycopyrronium for M2 and M3 muscarinic receptor subtypes. Muscarinic receptor subtypes in Wistar rat ventricle and submandibular gland homogenates were characterized with [3H]-N-methylscopolamine ([3H]-NMS) by ligand binding studies. Inhibition of [3H]-NMS binding by non-labelled compounds showed the following order: in rat ventricle: glycopyrronium > atropine >> otenzepad > hexahydrosiladiphenidol (HHSiD) > pirenzepine; in rat submandibular gland: glycopyrronium > atropine >> HHSiD >> pirenzepine > otenzepad. These were similar to the expected order of frequency of M2 and M3 subtypes, respectively. Glycopyrronium showed similarly high affinities for both M2 (Ki = 1.889 (SEM 0.049) nmol litre-1) and M3 (Ki = 1.686 (0.184) nmol litre-1) subtypes. Glycopyrronium bound to a homogeneous population of binding sites in both tissues and showed no selectivity for M2 or M3 muscarinic receptor subtypes.

Aminoglycoside-associated nephrotoxicity in extrahepatic obstructive jaundice

Experimental data demonstrate that biliary obstruction increases renal sensitivity to gentamicin. In the present study the incidence of and risk factors for aminoglycoside nephrotoxicity were prospectively studied in patients with extrahepatic obstructive jaundice. Two hundred and thirty-seven hospitalized adult patients were classified into three groups. Group I consisted of 84 patients with extrahepatic obstructive jaundice, who received aminoglycoside (gentamicin or tobramycin). Group II consisted of 81 patients with extrahepatic obstructive jaundice, who received either antibiotics other than aminoglycoside or no antimicrobial therapy. Group III consisted of 72 noncholestatic patients receiving aminoglycosides for different disorders. Nephrotoxicity developed in 27 patients (32%) in group I vs 9 patients (11%) in group II and 4 patients (5.6%) in group III (p < 0.00001). In group I, a comparison of patients with and without nephrotoxicity revealed significantly higher values in the former for mean serum bilirubin concentration, initial steady-state trough aminoglycoside concentration and estimated half-life. Stepwise multivariate analysis with nephrotoxicity status as the dependent variable determined that the most significant variable for predicting nephrotoxicity was serum total bilirubin level. In extrahepatic cholestasis a high serum bilirubin level is a distinct factor predisposing to aminoglycoside nephrotoxicity.

Oral administration of quercitrin modifies intestinal oxidative status in rats

1. Oral administration of quercitrin to rats for 3 days increases the mucosal glutathione contents in ileum and colon as well as inhibits non-enzymatic lipid peroxidation induced in membrane fractions from jejunal and colonic mucosa. 2. After 7 days of treatment with quercitrin, rat intestinal oxidative status trends to normalize to control rats.

Antiplatelet effect of pentoxifylline in human whole blood

1. Pentoxifylline inhibits platelet aggregation in whole blood more than in platelet-rich plasma. 2. An inhibition of the erythrocyte uptake of adenosine contributes to the antiaggregatory effect of pentoxifylline.

Muscarinic receptor subtypes in human and rat colon smooth muscle

Muscarinic receptor subtypes in human and rat colon smooth muscle homogenates were characterized with [3H]N-methylscopolamine ([3H]NMS) by ligand binding studies. [3H]NMS saturation experiments show the existence of a homogeneous population of non-interacting binding sites with similar affinity (KD values of 1.38 +/- 0.20 nM in human colon smooth muscle and 1.48 +/- 0.47 nM in rat colon smooth muscle) and with Hill slopes close to unity in both samples of tissue. However, a significant (P less than 0.01) increase in muscarinic receptor density (Bmax) is found in human colon (29.9 +/- 2.9 fmol/mg protein) compared with rat colon (17.2 +/- 1.5 fmol/mg protein). Inhibition of [3H]NMS binding by non-labelled compounds shows the following order in human colon: atropine greater than AF-DX 116 greater than pirenzepine. Whereas in rat colon the rank order obtained is atropine greater than pirenzepine greater than AF-DX 116. Atropine and pirenzepine bind to a homogeneous population of binding sites, although pirenzepine shows higher affinity to bind to the sites present in rat colon (Ki = 1.08 +/- 0.08 microM) than those in human colon (Ki = 1.74 +/- 0.02 microM) (P less than 0.05). Similarly, IC50 values obtained in AF-DX 116 competition experiments were significantly different (P less than 0.01) in human colon (IC50 = 1.69 +/- 0.37 microM) than in rat colon (IC50 = 3.78 +/- 0.75 microM). Unlike atropine and pirenzepine, the inhibition of [3H]NMS binding by AF-DX 116 did not yield a simple mass-action binding curve (nH less than 1, P less than 0.01) suggesting the presence of more than one subtype of muscarinic receptor in both species. Computer analysis of these curves with a two binding site model suggests the presence of two populations of receptor. The apparent Ki1 value for the high affinity binding site is 0.49 +/- 0.07 microM for human colon smooth muscle and 0.33 +/- 0.05 microM for rat colon smooth muscle. The apparent Ki2 for the low affinity binding site is 8.01 +/- 1.0 microM for human samples and 6.07 +/- 1.1 microM for rat samples. These values are close enough to suggest that the first subtype of muscarinic receptor may be considered cardiac (M2) and the second subtype glandular (M3). The relative densities of the receptor subtypes are significantly different for both species. Human colon samples show the major densities of subtype M2, 22.62 +/- 1.11 fmol/mg protein, this represents 75.66 +/- 3.73% of the total receptors.(ABSTRACT TRUNCATED AT 400 WORDS)

Inhibition of ferrous-induced lipid peroxidation by pyrimido-pyrimidine derivatives in human liver membranes

The effects of pyrimido-pyrimidine derivatives (dipyridamole, RA-642, and RA-233) on lipid peroxidation, using d-alpha-tocopherol as standard, were studied in enriched membrane fractions from human and rat hepatocytes. Equimolar concentrations of ferrous sulfate and ascorbic acid were used to induce lipid peroxidation. The amount of peroxidized lipids observed in membrane fractions from human liver was smaller than in those from rat liver. In both species, however, pyrimido-pyrimidine derivatives, except for RA-233 in rat liver, inhibited lipid peroxidation dose-dependently in the following sequence: RA-642 greater than dipyridamole greater than d-alpha-tocopherol RA-233.

Triflusal vs aspirin on the inhibition of human platelet and vascular cyclooxygenase

1. Triflusal is a salicylic derivative that inhibits platelet aggregation in human whole blood with a minimal inhibition of prostacyclin production. 2. Aspirin inhibits platelet aggregation at concentrations that reduce vascular prostacyclin production.

Dipyridamole and RA-642 inhibit the production of superoxide anion and free radical damage to rat lens

We studied the effects of dipyridamole and RA-642 on the production of superoxide anions and on oxygen radicals-induced lipid peroxidation in lens tissue homogenates from normal rats and rats given dipyridamole or RA-642 intraperitoneally. Superoxide production was evaluated by phenazine methosulphate (PMS)-induced nitroblue tetrazolium (NBT) reduction and lipid peroxidation by ferrous sulfate and ascorbic acid (FeAs)-induced malondialdehyde (MDA) production. Dipyridamole and RA-642 showed an inhibitory effect on both assays in the experiments with lens tissue homogenates from untreated or treated rats. The extent of inhibition, however, was significantly higher in pyrimidopyrimidinic-treated rats (range of inhibition at different times of incubation was 18% versus 23-57% for dipyridamole and 14% versus 73-80% for RA-642 in the assay of MDA production, and 10% versus 33-37% for dipyridamole and 2.5% versus 11-32% for RA-642 in the assay of NBT reduction). Concentrations of dipyridamole and RA-642 in lens tissue from treated animals could not be determined (less than 0.001 micrograms/mg of tissue). Although both compounds inhibited lipid peroxidation induced by oxygen free radicals, the mechanism of action might include the role of adenosine as a mediator.

Does the association dipyridamole-aspirin only act by a functional synergism?

1. Some of the antiplatelet effects of the dipyridamole-aspirin association may be explained by a functional (additive) synergism, but other effects by a potentiation synergism. 2. Platelet adhesivity and aggregation induced by ADP, adrenaline and collagen, and malondialdehyde production, are tests in which dipyridamole and aspirin shows a potentiation synergism.

Effects of dipyridamole on the short-term evolution of glomerulonephritis

The aim of the present study is to evaluate the effect of dipyridamole (300 mg/day) versus placebo in a double-blind randomized trial on membranous glomerulonephritis (M-GMN), mesangial IgA glomerulonephritis (IgA-GMN), and segmentary and focal hyalinosis glomerulonephritis (SFH-GMN) during the first 3 months of treatment. In the case of M-GMN, proteinuria dropped by 60% of the basal value in patients treated with dipyridamole; in the case of IgA-GMN it dropped by 65-70%; and in the case of SFH-GMN it dropped by 40% of the basal value. Inhibition of proteinuria in M-GMN was correlated to platelet response, and above all, to the ADP-induced platelet aggregation in whole blood.

Effect of antiplatelet drug therapy on the retinal vascular pattern in experimental diabetes mellitus

We performed a study to evaluate the effect of acetylsalicylic acid (ASA) plus dipyridamole on the retinal vascular pattern over 3 months in rats with experimental diabetes mellitus. Rats treated with ASA alone showed a continuous vascular bed and less tortuous vessels than untreated diabetic rats. Rats treated with ASA plus dipyridamole showed a continuous vascular bed, scarce tortuous vessels and vascular diameters similar to those in nondiabetic control rats. The findings were related to aortic prostacyclin production: treatment with ASA alone produced a reduction in prostacyclin production, whereas treatment with ASA plus dipyridamole resulted in normal prostacyclin production. ASA alone or with dipyridamole inhibited collagen-induced aggregation in whole blood by 57% compared with the untreated diabetic rats.

Enhanced gentamicin nephrotoxicity after experimental biliary obstruction in rats

To explore whether bile duct ligation increased the risk for gentamicin nephrotoxicity, male Wistar rats were subjected to bile duct ligation or sham surgery and given either gentamicin 20 mg/kg or saline twice daily intraperitoneally for 8 days. Bile duct ligated and gentamicin injected rats elicited a decline in renal function and tubular cell necrosis after 8 days of treatment whereas equal dosage regimen in sham operated rats exhibited no evidence of renal dysfunction. In addition, though serum and kidney gentamicin levels were higher in bile duct ligated rats (1.84 +/- 0.11 micrograms/ml versus 0.20 +/- 0.03 microgram/ml, and 1453 +/- 164 micrograms/g versus 698 +/- 138 micrograms/g of cortex, respectively, P less than 0.05). The data indicate that complete biliary obstruction enhances renal sensitivity to gentamicin.

Diltiazem enhances gentamicin nephrotoxicity in rats

The effect of the calcium antagonist, diltiazem, was examined in gentamicin-induced nephrotoxicity states in rats. Animals were injected for 5 days with diltiazem intraperitoneally (40 mg/kg/day), or gentamicin subcutaneously (100 mg/kg/day) or simultaneously with both preparations using the same doses. At the time of sacrifice, the urea and creatinine clearances, as well as urine osmolality were determined and the renal tissues were processed for examination by light microscopy. Gentamicin-injected rats demonstrated the typical pattern of aminoglycoside nephrotoxicity characterized by poliuric renal failure and necrosis of the proximal tubular epithelium. Rats injected with diltiazem revealed only mild depression of urine osmolality. There was no elevation of blood urea nitrogen and serum creatinine or depression of urea and creatinine clearances, and no focal tubular cell necrosis was detected. However, concomitant administration of both compounds considerably increased nephrotoxicity by according both histological indications and renal function measurements. Thus, we conclude that the combination of diltiazem and gentamicin must be used carefully in human clinical practice.

Effects of triflusal and acetylsalicylic acid on platelet aggregation in whole blood of diabetic patients

A study was made on the inhibitory effect of triflusal (600 mg/d X 15) and acetylsalicylic acid (ASA, 400 mg/d X 15) on platelet aggregation in whole blood (WB) and platelet-rich plasma (PRP) induced by ADP (2.5 mumol/l), adrenaline (50 mumol/l), collagen (1 microgram/ml) and arachidonic acid (0.8 mmol/l), in 30 insulin-dependent diabetic patients without vascular complications. Determination was also made of the serum levels of thromboxane B2 (TxB2) and of the plasma levels of 6-keto-PGF1-alpha and of beta-thromboglobulin (B-TG). Both drugs exhibited higher inhibitory effects in WB than in PRP. In WB, a significant difference between triflusal and ASA was observed against ADP-induced aggregation (67% and 46% inhibition respectively, p less than 0.01). Both drugs strongly inhibit the formation of TxB2 in serum (85% and 99%, respectively). Triflusal does not significantly change the plasma levels of 6-keto-PGF1-alpha; ASA, by contrast, causes reduction of over 95% in those plasma levels. The plasma levels of B-TG were not modified by either of the drugs.

Bronchodilator effect and serum theophylline level after combined treatment with fenoterol and theophylline in reversible chronic airflow obstruction

Sustained-release theophylline 10.1 mg/kg b.d. was given with placebo of fenoterol 2.5 mg t.d.s. to 12 patients with chronic airway obstruction. Fenoterol did not significantly affect the steady state serum theophylline trough level (11.84 micrograms/ml for fenoterol vs 11.10 micrograms/ml for placebo). Addition of fenoterol produced no further increase in spirometric function nor in clinical status.

Platelet aggregation in human whole blood after chronic administration of aspirin

We have used the impedance aggregometer to study the "ex vivo" effect of acetylsalicylic acid (ASA) in whole blood (WB) versus platelet-rich plasma (PRP) in 35 male healthy volunteers after 10 days of treatment with 25, 50, 125, 250, and 500 mg/day of ASA. Percent of inhibition of platelet aggregation was determinated at the end of treatment. A greater inhibition of platelet aggregation was observed in WB than in PRP when ASA was administrated at almost all doses. Maximal differences were at 25, 50, and 125 mg/day of ASA on adrenaline, collagen and arachidonic acid induced aggregation, and with 250 and 500 mg/day of ASA when ADP was used as aggregating agent. In the "in vitro" trials, IC-50 values of ASA on ADP and collagen induced aggregation were determined in platelet aggregation by the impedance method in both WB and PRP. ASA shows a lower IC-50 in WB than in PRP. When leucocytes were incubated in PRP samples, it effect was similar to the percent of inhibition in WB.

Effects of acetylsalicylic acid on platelet aggregation in male and female whole blood: an in vitro study

We have used the impedance aggregometer to study the in vitro effect of acetylsalicylic acid (ASA) in whole blood (WB) versus platelet-rich plasma (PRP) using blood samples from 24 male and 24 female healthy volunteers. IC50 was calculated from dose-response curves of ADP-, adrenaline-, collagen- and arachidonic acid-induced aggregation. ASA inhibited platelet aggregation in WB with a lower IC50 than PRP in male and female samples; the greater differences between WB and PRP inhibitory effect of ASA were in collagen- and archidonic acid-induced aggregation. A higher ASA concentration was needed in order to produce half maximal inhibition of platelet aggregation in female than in male samples with both WB and PRP method, except when ADP was used as the aggregating agent in PRP.

Characterization of muscarinic receptors in human submandibular salivary glands

We studied the binding of the muscarinic antagonist [3H]N-methyl-scopolamine [( 3H]NMS) in order to characterize muscarinic receptors located in human submandibular salivary glands obtained from intrasurgical biopsy. [3H]NMS bound with a Kd value of 1.56 nM to a single class of muscarinic receptors (Bmax 37.3 fmol/mg protein) since pirenzepine exhibited a homogeneous binding profile.