bluuebunny/crossref_metadata_2025 huggingface dataset:
Tissue Changes in Glutathione Metabolism and Lipid Peroxidation Induced by Swimming are Partially Prevented by Melatonin
Authors: Mara Masayuki , Abe Mitsushi , Suzuki Takuro , Reiter Russel J.
Published: March 2009

Abstract: The present study used male Sprague‐Dawley rats to investigate changes in glutathione [reduced (GSH) and oxidized GSH (GSSG)], lipid peroxidation (as indicated by tissue levels of malonaldehyde and 4‐hydroxyalkenals), and the activity of the antioxidant enzyme glutathione peroxidase after a bout of swimming (30 min.) with or without melatonin (N‐acetyl‐5‐methoxytryptamine) treatment. In muscle, the concentration of GSH and the GSH/GSSG ratio were decreased following 30 min. of swimming; these changes are indicative of enhanced oxidative stress. Pretreatment with melatonin prevented these effects. In liver, swimming increased significantly both GSH and GSSG, and decreased the GSH/GSSG ratio. When animals were treated with melatonin, concentrations of GSH and GSSG were also increased after swimming; however, the reduction in the GSH/GSSG ratio was prevented by melatonin. Brain GSH/GSSG ratio was not affected by exercise or by melatonin. Swimming enhanced the levels of lipid peroxidation products is muscle; this was prevented in animals treated with melatonin. Glutathione peroxidase activity was significantly elevated after swimming in both liver and brain with the change not being influenced by concurrent melatonin treatment. It is concluded that swimming imposes an oxidative stress on liver and skeletal muscle and the results show that melatonin confers partial protection against oxidative toxicity, especially in muscle.
Effect of Picrotoxin on Antinociception in the Formalin Test
Authors: Heidari M. R. , Khalili F. , Ghazi‐khansari M. , Hashemi B. , Zarrindast M. R.
Published: March 2009

Abstract: Subcutaneous injection of diluted formalin (0.25 μl of 0.5%) caused a biphasic pain response in mice. The first phase of pain was observed during the first 5 min., while the second phase occurred 10‐30 min. after formalin administration. With the formalin test, it was found that the antinociception produced by the GABA‐A antagonist, picrotoxin, and the GABA‐B antagonist, phaclofen, was abolished when employed in combination. The opioid antagonist naloxone and antimuscarinic atropine also decreased the picrotoxin response. However, sulpiride, SCH 23390, phenoxybenzamine and propranolol did not alter the picrotoxin response. Administration of naloxone, sulpiride and propranolol showed a pain response. The data indicate that dopaminergic and adrenergic mechanisms may not be involved in the picrotoxin antino‐ciceptive effect. However, postsynaptic GABA‐A and GABA‐B may be involved in the drug effect, and involvement of opioid or cholinergic systems can not be excluded.
The Influence of Ammonium Persulfate on Guinea Pig Tracheal Muscle Tone: Release of Nitric Oxide
Authors: Mensing Thomas , Marck Wolfgang , Baur Xaver
Published: March 2009

Abstract: Clinical studies have shown that oxidizing substances like hydrogen peroxide (H2O2) and ammonium persulfate used in the hair cosmetic industry may cause airway diseases. In in vitro experiments with isolated guinea pig tracheae ammonium persulfate solutions induced an initial transient relaxation of smooth muscles. This relaxation could be measured by a decrease in isometric pressure in the cannulated trachea instilled with ammonium persulfate at a hydrostatic pressure of 2.5 kPa. In control experiments, saline caused an initial pressure decrease of less than 10% within one minute. In contrast, instillation of different ammonium persulfate solutions (9.10−5 to 9.10−2 M) effectively dilated tracheae and resulted in a concentration‐dependent drop in intratracheal pressure to 1.53±0.62 kPa (61% of the instillation pressure). The effect of ammonium persulfate on smooth muscles is obviously mediated by nitric oxide because the relaxation could be blocked by inhibitors of nitric oxide synthase (L‐NMMA 40 μM and L‐NAME 200 μM). The precursor of nitric oxide, L‐arginine (1 mM), the D‐isomers of the inhibitors and a mixture of L‐arginine and L‐NAME did not affect the ammonium persulfate‐induced initial intratracheal pressure decrease. The results allow us to conclude that acutely elicited tracheal muscle dilatation by ammonium persulfate is mediated by nitric oxide. However, it is possible that a continuous use of oxidizing substances may lead to epithelial damage and, therefore, reduce the production of nitric oxide, thus facilitating constrictory responses.
Effects on Behaviour and EEG of Single Chain Phospholipases A2 from Snake and Bee Venoms Injected into Rat Brain: Search for a Functional Antagonism
Authors: Gandolfo Gabriel , Lambeau Gerard , Lazdunski Michel , Gottesmann Claude
Published: March 2009

Abstract: Three phospholipase A2 (PLA2s), OS1 and OS1 purified from the taipan snake venom Oxyuranus scutellatus scutellatus and bee venom PLA2 were injected to rats by the intracerebroventricular route. OS1 showed no sign of neurotoxicity at doses at which OS2 and bee venom PLA2 produced multiform dose‐dependent behavioural effects including motor disturbances (stereotyped movements), compulsive scratching, convulsions and breathing difficulties. EEG recordings showed at the very time when the animal was motionless the induction of several episodes of a low frequency hippocampal theta rhythm, index of long‐term changes in synaptic neuroplasticity. Spike‐wave discharges were also produced but the occurrence was not systematic. These seizures were often accompanied with behavioural convulsions. Blockers of NMDA receptors and drugs modifying the GABAergic transmission could not abolish the neurotoxic effects of PLA2s except for diazepam (10 mg/kg intraperitoneally) that prevented only OS2‐induced disturbances. Blockers of L‐type Ca2+ channels and K+ channel openers were also without effect. The toxicity of OS2 and bee venom PLA2 is probably due to their initial specific binding to their neuronal receptor sites.
Neurochemical Mediators of Anxiety have Inconsistent Effects on Hypothalamic Self‐Stimulation in Rats
Authors: Borisenko Sergey A. , Meng Quing He , Rauhala Pekka , Männistö Pekka T.
Published: March 2009

Abstract: We studied effects of anxiogenic and anxiolytic compounds on the electric self‐stimulation of the medial forebrain bundle in male rats to find out if there is a link between reward and anxiety‐related behaviours. The cholecystokinin agonist, caerulein (25‐100 μg/kg) and the 5‐HT agonist 1‐(3‐chlorophenyl)piperazine (0.2‐1 mg/kg) dose‐dependently inhibited the electric self‐stimulation. The 5‐HT2A antagonist, ketanserin, at 2.5 mg/kg, increased the self‐stimulation at high currents but not at threshold current. The 5‐HT3 antagonist ondansetron (10 and 100 μg/kg). The α1‐adrenergic antagonist, prazosin (0.125 and 0.5 mg/kg), the β‐adrenergic antagonist, propranolol (5 and 10 mg/kg) and the α2‐adrenoreceptor antagonist, atipamezole (4 mg/kg), did not affect the self‐stimulation. Nor did the benzodiazepine agonist, di‐azepam (5‐15 mg/kg), a benzodiazepine receptor antagonist flumazenil (at 10 and 25 mg/kg) or the inverse agonist of benzodiazepine receptors, N‐methyl‐β‐carboline‐3‐carboxamide (10 and 20 mg/kg), cause any substantial changes of the self‐stimulation. We conclude that only two anxiolytic drugs (caerulein and l‐(3‐chlorophenyl)piperazine) suppress the electric self‐stimulation. These findings indicate that anxiogenicity as such is not able to weaken the hypothalamic electric self‐stimulation. Anxiety and reward are apparently mediated through separate neural pathways.
No Effect of Diclofenac on the Pharmacokinetics of Cloxacillin
Authors: Nergelius Görel , Vinge Ellen , Bengtsson Hans‐Inge , Björkman Roland , Grubb Anders
Published: March 2009

Abstract:We studied the influence of diclofenac on the pharmacokinetics of cloxacillin in healthy volunteers, 60 years or older, as well as the possible effect of cloxacillin and diclofenac on urinary protein excretion. In a randomized, double‐blind, cross‐over study 15 subjects were given 1 g cloxacillin, and placebo or 75 mg diclofenac, as single intravenous doses. Plasma concentrations of cloxacillin were followed over 10.5 hr, and urine excretion of cloxacillin over 24 hr. The effect of the drugs on urinary excretion of protein indicators of glomerular (albumin, IgG) and tubular (protein HC) function was also studied. Total plasma clearance of cloxacillin was with placebo 219+51 (mean + S.D), and with diclofenac 212+39 ml/min./1.73 m2(ns); renal clearance was 97+21 and 96+24 ml/min./1.73 m2, respectively (ns). The terminal t1/2of cloxacillin was 1.03+0.42 hr with placebo, and 1.12+0.37 with diclofenac (ns). The mean ratio of AUC0‐∞'s (cloxacillin plus diclofenac/cloxacillin plus placebo) was 1.03 (90% CI: 0.99, 1.08). Urinary excretion of the proteins was low and was not increased by cloxacillin or diclofenac. In healthy volunteers, 60 years or older, diclofenac does not alter cloxacillin pharmacokinetics, and neither cloxacillin nor diclofenac in single intravenous doses cause renal dysfunction.
Effect of Time Interval between Food and Drug Ingestion on the Absorption of Oxybutynin from a Controlled‐Release Tablet
Authors: Lukkari Eeva , Aranko Kari , Juhakoski Auni , Hakonen Tiina , Neuvonen Pertti J.
Published: March 2009

Abstract: The effect of time interval between food and drug ingestion on the bioavailability of oxybutynin was investigated in a randomized, three‐phase cross‐over study in 31 healthy volunteers. The serum concentrations of oxybutynin and the metabolite, N‐desethyloxybutynin were measured up to 48 hr after ingestion of a controlled‐release 10 mg oxybutynin tablet either in fasting state, 2 hr after breakfast or 1 hr before. The Cmax of both oxybutynin (P<0.0001) and N‐desethyloxybutynin (P<0.0001) and the AUC0‐t of N‐desethyloxybutynin (P<0.05) were significantly larger when oxybutynin was ingested 2 hr after breakfast, than during the fasting, but the AUC0‐t of oxybutynin remained unchanged. Breakfast ingested 1 hr after oxybutynin did not affect the pharmacokinetic parameters of oxybutynin or N‐desethyloxybutynin. The saliva secretion rate decreased slightly more (P<0.05), when oxybutynin was administered 2 hr after breakfast than during fasting. The effect of food ingestion on the serum concentrations of oxybutynin and N‐desethyloxybutynin is expected to have minor clinical significance only. However, ingestion of the controlled‐release tablet 1 hr before meal increases the likelihood of obtaining constant drug levels with lower peak concentrations during the dosage interval, and thus ingestion of the controlled‐release tablet 0.5–1 hr before food may well improve tolerability and compliance in patients who suffer from adverse reactions.
Comparison andin vivoRelevance of Two Differentin vitroHead Space Metabolic Systems: Liver S9 and Liver Slices
Authors: Mortensen Bjarte , Løkken Torbjørn , Zahlsen Kolbjørn , Nilsen Odd G.
Published: March 2009

Abstract:In vitrosystems of high biological organization, e.g. containing intact hepatocytes, have been considered as more reliable for metabolic studies andin vivopredictions of toxicokinetics than subcellular systems. For this reason, the kinetics and metabolism of low‐molecular‐weight volatile chemicals, i.e. head space elimination of substrate and formation of metabolites, were compared in liver S9 and in liver slices. Two substrates, toluene andn‐hexane, were used as they represent differences in metabolic pathways and physical‐chemical properties. The two systems responded similarly to diethyldithiocarbamate inhibition and acetone inhibition/induction of cytochrome P‐450 mediated metabolism. In contrast to liver S9, liver slices did not respond adequately to phenobarbital induction raising the question of substrate availability for P‐450 enzymes in liver slices. Liver slices appeared to be superior to liver S9 when specific metabolic pathways involving phase II enzymes were investigated. However, liver S9 seemed to be at least as good as liver slices for estimation of total metabolic rate constants (Km, Vmax) as a basis forin vivopredictions. As the head space liver S9 system is faster and easier to operate than liver slices, it is a promising screening tool for the metabolism of volatile compounds and metabolic interactions.
Increase of Bone Mass and Mechanical Strength in Rats after Treatment with a Novel Bisphosphonate, YM175, for Two Years
Authors: Motoie Hiroyuki , Okazaki Atsushi , Kanoh Hiroyuki , Shikama Hisataka , Fujikura Takashi
Published: March 2009

Abstract:We have evaluated the relationship between bone mass and mechanical properties of bone from male and female rats treated with YM175, a novel bisphosphonate, for 104 weeks. YM175 [disodium (cycloheptylamino) methylenediphosphonate monohydrate] was given via the drinking water at a concentration of 0, 0.005, 0.015, 0.05, or 0.15%. Since the mortality in the male 0.15% group exceeded the exclusion criteria (75%) at week 88, this group was omitted from the study. Mean daily intake of YM175 was 2.2‐22.1 mg/kg for males and 3.6‐104 mg/kg for females. After the treatment, mechanical properties and ash weight of the humerus were determined. In males, 0.015 and 0.05% of YM175 (6.6–22.1 mg/kg) significantly increased failure load of the midshaft. In females, failure load and stiffness of the midshaft tended to be increased by YM175 (up to 104 mg/kg). Furthermore, ultimate compressive load at the humeral metaphysis treated with the highest dose of YM175 was 2‐ or 3.5‐fold greater than that of untreated male or female control. Ash weight of the humerus was increased dose‐dependently and was positively correlated with failure load of the midshaft. These findings indicate that treatment for 2 years with YM175 increased bone mass and mechanical strength without blocking bone mineralization.
Gene Activation, Apolipoprotein A‐I/High Density Lipoprotein, Atherosclerosis Prevention and Longevity
Authors: Luoma Pauli V.
Published: March 2009

Abstract:Recent studies in man and human apolipoprotein A‐I transgenic animals emphasize the significance of apolipoprotein A‐I and high density lipoprotein in antiatherogenesis. Several drugs and other compounds, e.g. phenobarbital, gemfibrozil, fenofibrate, prednisone, estrogen and alcohol, induce apolipoprotein A‐I synthesis. They commonly produce serum lipoprotein patterns typical of a low risk of coronary heart disease, and many of them have been found to prevent atherogenesis, reduce coronary heart disease mortality and increase survival. These compounds act against atherosclerosis by using one or several mechanisms that include overexpression of the apolipoprotein A‐I gene with an increase in serum apolipoprotein A‐I and high density lipoprotein and promotion of reverse cholesterol transport, upregulation of the low density lipoprotein receptor gene with a decrease in serum apolipoprotein B and low density lipoprotein, maintenance of endothelial cell function and protection against thrombosis. They have been found to raise high density lipoprotein cholesterol and apolipoprotein A‐I together with a decrease in cholesterol ester transfer protein activity, and to induce hepatic cholesterol 7α‐hydroxylase and cholesterol and bile acid elimination from the body. By raising the activities of apolipoprotein A‐I/ high density lipoprotein‐associated paraoxonase and other antioxidative enzymes, the inducers have the capacity to prevent atherogenesis in arterial walls through inhibition of the oxidative modification of low density lipoprotein. Other antiatherogenic vascular actions of high density lipoprotein include interference with low density lipoprotein aggregation and uptake by endothelial cells, and competition with low density lipoprotein for endothelial‐localized low density lipoprotein receptors. Apolipoprotein A‐I/high density lipoprotein beneficially enhances fibrinolysis, decreases platelet aggregation, increases prostacyclin production and stabilization and prevents atherogenic immune and inflammatory responses. This gene activation or microsomal induction can prevent atherosclerosis and is a basis for tailoring effective new agents and optimal non‐invasive therapy against atherosclerotic vascular disease, to promote health and enhance longevity.
Hexamethylene Diisocyanate (HDI)‐Induced Lung Impairment: Studies in Isolated Perfused and Ventilated Guinea Pig Lungs
Authors: Låstbom Lena , Skarping Gunnar , Moldéus Peter , Ryrfeldt Åke
Published: March 2009

Abstract:Isolated, perfused and ventilated guinea pig lungs were exposed to hexamethylene diisocyanate via the air passages. Two air concentrations of hexamethylene diisocyanate were studied (3.5 and 11 mg/m3). There was a statistically significant (P<0.05 − 0.001) dose‐related reduction in both conductance and compliance but no effects were noted on the pulmonary circulation. With 3.5 mg/m3hexamethylene diisocyanate the conductance capacity was reduced with 38% and compliance with 30% after 60 min. exposure. Eleven mg/m3hexamethylene diisocyanate reduced the conductance and compliance capacity with 86 and 69 %, respectively, on an average. The reduction in lung function (with 11 mg/m3) was abolished when 100 μM diclofenac, a cyclooxygenase inhibitor, was added to the perfusate (P<0.01). The thromboxane A2antagonist L‐670,596 (20 μM) exerted a partial protective effect. The capacity of conductance and compliance decreased with 46 and 32% respectively, on an average, after preperfusion with L‐670,596 and a following exposure of 11 mg/m3hexamethylene diisocyanate for 60 min. Statistically significant protection (P<0.05) was obtained on compliance and the P‐value was<0.1 for conductance. Thus, these data indicate that hexamethylene diisocyanate‐induced bronchoconstriction is mediated via arachidonic acid release and thromboxane formation, in isolated, perfused and ventilated guinea pig lungs.
Mechanical Restitution in Atrial Muscle from Human and Rat Hearts: Effects of Agents that Modify Sarcoplasmic Reticulum Function
Authors: Ravens Ursula , Gath Jennifer , Hussaini Maryam Al , Himmel Herbert
Published: March 2009

Abstract: Force of contraction (Fc) of isolated human and rat atrial myocardium shows characteristic patterns of mechanical restitution when single test intervals are interposed in regular stimulation. With several pharmacological agents that modify the function of the sarcoplasmic reticulum we have investigated the role of the sarcoplasmic reticulum in mechanical restitution in these two species. Caffeine, thapsigargin and 2,5‐di‐(tert‐butyl)‐l,4‐benzohydroquinone (BHQ) were used to reduce Ca2+ uptake, ryanodine to open Ca2+ release channels, and forskolin to stimulate Ca2+ uptake. Under control conditions, Fc recovered rapidly with test intervals shorter than steady‐state, and was potentiated with longer than steady‐state intervals. In human atrial tissue the maximum potentiation factor was 1.26+0.03 after a mean test interval of 9.70+1.55 s (n=43) as compared to 3.07+0.45 after 30 sec. in rat atria (n=48). Caffeine (3 mM) did not significantly affect steady‐state Fc but abolished post‐rest potentiation in human and rat preparations. Forskolin (1 μM) enhanced and accentuated the mechanical restitution curve in particular for short test intervals. In the presence of thapsigargin (10 μM), steady‐state Fc and mechanical restitution could not be distinguished from time‐matched controls exposed to solvent only, indicating that this agent is ineffective in human and rat atrial tissue. In contrast, the putative Ca2+ uptake inhibitor BHQ (100 μM) strongly reduced steady‐state Fc and decreased potentiation at all intervals in human muscle, but shifted the mechanical restitution curve in parallel to lower values in rat atria. Ryanodine (10 nM) induced post‐rest decay in human and depressed both steady‐state Fc and post‐rest potentiation in rat atrial muscle. From these results it is concluded that human and rat atrial muscle differ in the Ca2+ handling by the sarcoplasmic reticulum during mechanical restitution.
Molecular Characteristics of Mammalian Dopamine Receptors
Authors: Lachowicz Jean E. , Sibley David R.
Published: March 2009

Abstract:Abstract: Dopamine receptors belong to a large super‐gene family of receptors which are linked to their signal transduction pathways through heterotrimeric G proteins. A variety of signalling events are known to be regulated by dopamine receptors including adenylate cyclase and phospholipase activities and various ion channels. Prior to the advent of molecular cloning technology, dopamine receptors were believed to belong to two subtypes, D1and D2. This distinction was based on both pharmacological and functional criteria. We now know that at least five different dopamine receptors exist although they can still be described as to belonging within “D1” and “D2” subfamilies. The D1subfamily consists of two receptors—the D1and D5, whereas the D2, D3and D4receptors comprise the D2subfamily. The cloning and molecular characteristics of these five receptors are described in this review.
Undernutrition During Suckling Changes the Sensitivity to Haloperidol and Chlorpromazine in Two Behavioural Measures in Weaning Rats
Authors: Rocha Joao B. T. , Santos Jose E. T. , Rocha Luis K. , Kleinpaul Elcio R.
Published: March 2009

Abstract: Undernutrition during critical periods of development may cause changes in the behavioural responses of rats to centrally acting drugs. In the present study, the effects of undernutrition during suckling on the behavioural responses of 21‐days‐old rats to chlorpromazine (0, 2.5, 5, 10 and 20 mg/kg) or haloperidol (0, 0.125, 0.25, 0.5, 1 or 2 mg/kg) were examined. Locomotion was assessed at 1 hr 30 min., 4 hr 30 min., 7 hr 30 min. and 10 hr 30 min., and catalepsy was scored at 3 hr, 6 hr and 9 hr after drug administration. Drug was injected on two consecutive days. On day 1, salinetreated undernourished rats showed significantly greater locomotion activity than did normal rats. The neuroleptic‐induced inhibition of locomotor activity in undernourished rats was significantly less than that observed in normal rats from 4 hr 30 min. to 10 hr 30 min. (chlorpromazine) or from 7 hr 30 min. to 10 hr 30 min. (haloperidol). On day 2, a similar trend was observed but only in rats injected with 5 mg/kg chlorpromazine or 0.5, 1, and 2 mg/kg haloperidol. On day 1, the catalepsy scores at 3 hr revealed no significant difference between nutritional groups, but at 6 hr undernourished rats responded significantly less to chlorpromazine or haloperidol. On day 2, undernourished rats were less responsive to neuroleptics than normal rats, but the effect was not so evident as observed on day 1. The present results suggest that the behavioural effects of chlorpromazine and haloperidol are less persistent in undernourished rats, possibly due to differences in drug distribution and elimination, when compared to well‐nourished rats.
On the Mechanism(s) of Cholecystokinin (CCK): Receptor Stimulation Attenuates Morphine Dependence in Mice
Authors: Rezayat Mehdi , Azizi Nasrin , Zarrindast Mohammad‐Reza
Published: March 2009

Abstract:In the present study, effect of cholecystokinin (CCK) agonists and on dependence to morphine in mice has been investigated. The influence of dopaminergic, adrenergic, cholinergic and serotonergic on attenuation of naloxone‐induced jumping in morphine‐dependent mice by CCK agonists were also considered. Mice were treated subcutaneously with morphine (50, 50 and 75 mg/kg) three times daily (10 a.m. 1 p.m. and 4 p.m.) for 3 days, and a last dose of morphine (50 mg/kg) was administered on the 4th day. Withdrawal syndrome (jumping) was precipitated by naloxone (5 mg/kg) which was administered intraperitoneally 2 hr after the last dose of morphine. To study effects of CCK receptor agonists, 10 injection of morphine (3 administrations each day) for dependence and a dose of 5 mg/kg of naloxone for withdrawal induction were employed. The CCK agonists CCK‐8 (0.001‐ 0.1 mg/kg), unsulfated CCK‐8 (CCK‐8U; 0.001‐0.1 mg/kg) and caerulein (0.00001‐0.01 mg/kg) were able to prevent withdrawal signs precipitated by naloxone (5 mg/kg). Sulpiride and pimozide increased response induced by CCK‐8 agonists. The dopamine antagonists also attenuates jumping by themselves. SCH 23390 did not alter the CCK‐8 effect, but decreased the jumping by itself. Phenoxybenzamine, propranolol, methysergide and atropine did not change the caerulein effect significantly. However, single administration of atropine increased and methysergide decreased jumping. It is concluded that CCK mechanism(s) may be involved in morphine dependence, and dopaminergic mechanism(s) may interact with CCK in attenuation of naloxone‐induced jumping.
L‐Methionine Induces Stage‐Dependent Changes of Differentiation and Oxidative Activity in Sea Urchin Embryogenesis
Authors: Pagano Giovanni , Bonassi Stefano , Biase Antonella De , Degan Paolo , Deeva Irina B. , Doronin Yuri K. , Iaccarino Mario , Oral Rahime , Warnau Michel , Korkina Ludmila G.
Published: March 2009

Abstract: This study was to investigate developmental toxicity of some selected low molecular weight antioxidants, by utilising sea urchin embryos and gametes as model system. Sea urchin embryos or sperm were exposed at different developmental stages to L‐methionine or some selected low molecular weight antioxidants: a) N‐acetylcysteine; b) L‐carnosine; c) L‐homocarnosine, and d) L‐anserine. L‐methionine displayed developmental toxicity at levels ≥10−5 M, whereas the other agents tested were mostly active at levels ≥10−4 M. When embryos were exposed to 10−4 M L‐methionine or N‐acetylcysteine at different developmental stages, the most severe effects were exerted by early exposures (0 to 2 hr after fertilisation), whereas later exposures turned to lesser or no effects. Cytogenetic analysis of L‐methionine‐exposed embryos showed a significant mitogenic effect and increase of mitotic aberrations. Fertilisation success was decreased by L‐methionine (10−6 M to 10−3 M) added at the moment of fertilisation, with increasing developmental and cytogenetic abnormalities in the offspring. The formation of reactive oxygen species in embryos and gametes was determined by: a) analysing the DNA oxidative product, 8‐hydroxy‐2′‐deoxyguanosine (8‐OHdG), and b) luminol‐dependent chemiluminescence. The results showed that: 1) 8‐OHdG levels were increased during embryogenesis; 2) fertilisation was associated with a double‐wave luminol‐dependent chemiluminescence emission; 3) luminol‐dependent chemiluminescence was maximal in cleavage, declining down to zero in plutei, and 4) an embryotoxic L‐methionine or N‐acetylcysteine level (10−4 M) turned to a decrease in reactive oxygen species formation. The data suggest that L‐methionine‐ or N‐acetylcysteine‐induced developmental toxicity is confined to early stages. A role for oxidative activity is suggested in modulating cell differentiation and embryogenesis, consistent with antioxidant‐induced damage to early life stages.
Involvement of Cholinergic and Opioid Receptor Mechanisms in Nicotine‐Induced Antinociception
Authors: Zarrindast Mohammed‐Reza , Pazouki Marjan , Nassiri‐Rad Shadi
Published: March 2009

Abstract:In this work we have studied the influences of nicotinic agents on the antinociception of morphine in formalin test. Nicotine (0.001‐0.1 mg/kg) induced antinociception in mice in a dose‐dependent manner in the early phase of formalin test, and also potentiated the morphine effect. The nicotinic receptor antagonist, mecamylamine (0.5 mg/kg), but not hexamethonium decreased the antinociception induced by nicotine (0.1 mg/kg) in both phases. The muscarinic receptor antagonist atropine (5 and 10 mg/kg) also decreased the response of nicotine. Mecamylamine, hexamethonium or atropine did not alter morphine antinociceptive response, while naloxone decreased responses induced by nicotine or morphine. The antagonists by themselves did not elicit any response in formalin test, however, high doses of mecamylamine tend to increase pain response. It is concluded that central cholinergic and opioid receptor mechanisms may be involved in nicotine‐induced antinociception.
Forskolin Potentiates Isoprenaline‐Induced Glycerol Output and Local Blood Flow in Human Adipose Tissuein vivo
Authors: Enoksson Staffan , Blaak Ellen , Arner Peter
Published: March 2009

Abstract:The synergistic action of forskolin on β‐adrenoceptor‐mediated glycerol output and changes in local blood flow were investigatedin situ, in human adipose tissue of healthy subjects, by the use of microdialysis. The addition of isoprenaline 0.1‐1.0 μM or forskolin 10‐100 μM to the perfusion solvent caused a concentration‐dependent, marked and sustained increase in the levels of glycerol in the dialysate (lipolysis index) as compared to the solvent alone. On a molar basis, isoprenaline was almost one thousand times more potent than forskolin. Isoprenaline caused a rapid and concentration‐dependent decrease in the ethanol clearance ratio (index of local blood flow, i.e. a decrease in ethanol ratio implies an increase in blood flow). Forskolin had no effect on the ethanol ratio at either 1.0 μM or 10 μM, while forskolin at 100 μM induced a significant decrease in the ethanol ratio. When adipose tissue was pre‐treated with forskolin, the subsequent addition of isoprenaline to the microdialysate resulted in a significantly higher glycerol output and a significantly more prominent decrease in the ethanol ratio than with isoprenaline alone. In conclusion, the data demonstrate that forskolin and the (β‐adrenoceptor‐agonist both stimulate lipolysis and local blood flow in human adipose tissuein vivo. Furthermore, forskolin, at concentrations that are ineffective alone, potentiates the actions of isoprenaline on lipolysis and blood flow.
Comparison of Key Steps in 1‐Methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP) Neurotoxicity in Rodents
Authors: Sundström Erik , Samuelsson Eva‐Britt
Published: March 2009

Abstract:Three steps in 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP) neurotoxicity were compared with the neurodegenerative effects of the toxin in mice and rats. Firstly, we compared the neurotoxicity of MPTP, mediated by monoamine oxidase (MAO)‐B, to that of 1‐methyl‐4‐(2′‐methylphenyl)‐1,2,3,6‐tetrahydropyridine (2′‐CH3‐MPTP), an analogue oxidized by MAO‐A and MAO‐B. Both toxins caused degeneration of dopamine terminals in mice but not in rats. In NMRI mice noradrenaline terminals were also affected by both toxins. Pretreatment with deprenyl to prevent MAO‐B‐mediated oxidation in the capillary endothelium enhanced dopamine toxicity to 2′‐CH3‐MPTP in nucleus accumbens but no potentiation was seen in striatum and the olfactory tubercle. Secondly, synaptosomal uptake of the 1‐methyl‐4‐phenylpyridinium ion (MPP+) was studied. Uptake in rats was not significantly different from that in the two mice strains. Thirdly, no significant differences were found in MPP+‐induced lactate production in striatal slices or synaptosomes. We conclude that the lack of effect of MPTP in rats is not due to mechanisms specific for MPTP but probably to the ability of rat catecholamine neurons to cope with, and survive, impaired energy metabolism.
Evaluation of Three Novel Cholecystokinin‐B/Gastrin Receptor Antagonists: A Study of their Effects on Rat Stomach Enterochromaffin‐Like Cell Activity
Authors: Ding Xi‐Qin , Lindström Erik , Håkanson Rolf
Published: March 2009

Abstract:Gastrin stimulates rat stomach enterochromaffin‐like (ECL) cells via activation of cholecystokinin‐B/gastrin receptors. The stimulation is manifested in the activation of the histamine‐forming enzyme histidine decarboxylase and in the secretion of histamine and pancreastatin, a chromogranin A‐derived peptide. We have examined the short‐term effects of three novel cholecystokinin‐B/gastrin receptor antagonists (YF476, JB93182 and AG041R) on the ECL cells in intact fasted rats. The drugs and/or gastrin were infused intravenously for 3 hr and the oxyntic mucosal histidine decarboxylase activity and the serum pancreastatin concentration were measured. We also studied the effects of the three drugs on gastric emptying in mice, a cholecystokinin‐A receptor‐mediated response. YF476, JB93182 and AG041R antagonized the gastrin‐evoked histidine decarboxylase activation in a dose‐dependent manner. YF476, JB93182 and AG041R induced maximal inhibition at 0.03, 0.1 and 0.1 μmol kg−1hr−1, respectively; the corresponding ID50values were 0.002, 0.008, and 0.01 μmol kg−1hr−1. YF476 was selected for further analysis. It produced a rightward shift of the gastrin dose‐response curve, consistent with competitive inhibition. Moreover, it antagonized the omeprazole‐evoked histidine decarboxylase activation and the gastrin‐ and omeprazole‐induced rise in the circulating pancreastatin concentration. None of the three drugs tested inhibited gastric emptying or prevented the cholecystokinin‐8s‐induced inhibition of gastric emptying at the doses tested. The results show that YF476, JB93182 and AG041R are potent and selective cholecystokinin‐B/ gastrin receptor antagonists, and that YF476 is 4‐5 times more potent than JB93182 and AG041R.
The Effects of Glyceryl Trinitrate and Nicotinic Acid Ointments during Cold Exposure
Authors: Lapatto Outi , Kivistö Kari T. , Salorinne Yrjö
Published: March 2009

Abstract: The aim of the present experimental study was to examine the effects of local application of glyceryl trinitrate and nicotinic acid on the cold‐provoked haemodynamic responses, pain and hand dexterity. Ten young healthy volunteers participated in this randomized, cross‐over study with three phases at least two days apart. Five cm of 2% glyceryl trinitrate ointment, 10% nicotinic acid ointment or placebo ointment was applied on the back of each subject's both hands 15 min. before the 7 min. cold exposure. Blood pressure and heart rate were measured prior to, during and after the cold exposure. In addition, the effect of cold on hand dexterity was evaluated by the Purdue pegboard test and the subjects assessed the pain in their hands during the cold exposure. Pretreatment with glyceryl trinitrate ointment counteracted the cold‐induced haemodynamic response, as evidenced by a significantly (P<0.05) smaller mean increase in the systolic blood pressure from the baseline compared with placebo. In contrast, the cold‐induced increase in the systolic blood pressure observed after pretreatment with nicotinic acid ointment did not differ from placebo. Both glyceryl trinitrate and nicotinic acid alleviated the cold‐induced pain, but neither of them prevented the deterioration of hand dexterity. In conclusion, the haemodynamic response provoked by a brief cold exposure could to some extent be counteracted by pretreatment with glyceryl trinitrate ointment, but not with nicotinic acid ointment, compared with placebo.
Opposite Influences of Different Adrenoceptors on Baclofen‐Induced Antinociception in Mice
Authors: Sabetkasai M. , Doost‐Mohammady R. , Zarrindast M. R.
Published: March 2009

Abstract:In the present study, the effects of adrenoceptor agonists and antagonists on baclofen‐induced antinociception was investigated. Intraperitoneal administration of different doses of baclofen (2.5, 5 and 10 mg/kg) induced antinociception in the tail‐flick test. The response was dose‐dependent. The α2‐adrenoceptor agonist, clonidine, increased, while the α1‐adrenoceptor agonist, phenylephrine, decreased the baclofen response. In reserpine‐treated animals, α2‐adrenoceptor, clonidine, induced antinociception and increased that of baclofen. Yohambine and propranolol but not prazosin decreased the baclofen effect. Although phenoxybenzamine itself induced antinociception it did not alter the baclofen response significantly. Reserpine treatment decreased the response induced by single administration of baclofen or phenoxybenzamine and that induced by a combination of baclofen with either phenoxybenzamine or prazosin. It may be concluded that α2‐adrenoceptor stimulation increases, while α1‐adrenoceptor activation decreases the baclofen‐induced antinociception, and aminergic mechanism(s) may have a positive influence on baclofen response.
Effects of Aluminium on the Mineral Metabolism of Rats in Relation to Age
Authors: Sánchez Domènec J. , Gómez Mercedes , Llobet Juan M. , Corbella Jacint , Domingo José L.
Published: March 2009

Abstract: The present study was conducted to assess in rats the effects of chronic aluminium (Al) exposure on calcium (Ca), magnesium (Mg), manganese (Mn), copper (Cu), zinc (Zn) and iron (Fe) accumulation and urinary excretion in relation to the age of the animals. Male young (21 day old), adult (8 months), and old (16 months) rats were orally exposed to 0, 50, or 100 mg Al/kg/day for a period of 6.5 months. Urinary levels of essential elements were determined after 3 and 6.5 months of exposure, whereas tissue Ca, Mg, Mn, Cu, Zn and Fe concentrations were examined after 6.5 months of Al administration. A number of age‐related changes in tissue accumulation and urinary excretion of essential elements following chronic exposure to Al were found. Concentrations of essential elements in most tissues of young Al‐exposed rats were generally lower than those of adult and old rats. The highest levels of essential elements were found in old animals. Liver, testes and spleen were the tissues that showed the most remarkable increases in relation to the levels found in those tissues of young rats. Adult rats showed a pattern comparable to that of old animals for mineral metabolism in brain, whereas in bone and testes the pattern of accumulation was closer to that of young rats. While the urinary levels of Ca were generally reduced in the Al‐exposed groups, no Al‐associated changes were noted for Mg, Mn, Cu and Zn. In turn, after 6.5 months of Al administration Fe excretion was increased in Al‐treated adult and old rats. The results of this study suggest that early stages of life cycle should be of special concern for Al‐induced changes in the metabolism of essential elements.
Prejunctional Modulation by Prostaglandin E2of Noradrenaline Release from Sympathetic Neurones in Rabbit Aorta
Authors: Jensen Tenna Juul , Nedergaard Ove A.
Published: March 2009

Abstract:The modulating effect of prostaglandin E2(PGE2) on the electrically‐evoked3H‐overflow from rabbit isolated aorta preloaded with3H‐noradrenaline was examined. PGE2(3x10‐9‐3x10‐7M) inhibited the stimulation‐evoked3H‐overflow (maximum inhibition: 81%; pIC50: 8.1). The inhibition was reversible and inversely related to stimulation frequency (1‐30 Hz). Cocaine (3x10‐5M) and corticosterone (4x10‐5M) did not alter the inhibitory effect of PGE2(3x10‐9‐10‐7M). Rauwolscine (10‐6M) enhanced the reduction caused by PGE2(3x10‐9‐10‐7M). Rauwolscine (10‐6M) alone enhanced the3H‐overflow by 360%. Indomethacin (3x10‐6M) and suprofen (4x10‐5M) did not alter the PGE2(3x10‐9‐10‐7M)‐induced reduction of the3H‐overflow. Indomethacin (3x10‐6M) and suprofen (4x10‐5M) alone had no effect. We conclude that in the rabbit aorta (1) PGE2modulates noradrenaline release from sympathetic neurones through a prejunctional inhibitory receptor mechanism; (2) that there is an interaction between α2‐adrenoceptors and EP‐receptors; (3) that uptake inhibition does not affect the effect of PGE2; and (4) that the influence of endogenous prostaglandins on the noradrenaline release can be excluded.
Drugs that Influence Tubulin Polymerization Modulate Thyrotropin‐Releasing Hormone Receptor Number in AtT‐20 Cells
Authors: Ravindra R. , McIlroy P. J. , Patel S. A.
Published: March 2009

Abstract: In order to examine the role of cytoskeleton in modulating the cell surface receptors, AtT‐20 cells (stably expressing thyrotropin‐releasing hormone receptors) were incubated with drugs that are known to modify the tubulin‐microtubule system. The binding of [3H]methyl thyrotropin‐releasing hormone ([3H]mTRH) to intact cells increased as a function of time, and was linear from 1.25x106 to 6.25x106 cells/ml. Cells incubated with colchicine, vinblastine, and taxol for 16 hr were harvested and the cell concentration was determined using a haemocytometer. Because the drugs inhibited the cell proliferation at 100 nM, it was decided to examine the effect of 100 nM of each of the three drugs on the ability of [3H]mTRH to bind cell surface receptors. Cells were incubated with the drugs for 16 hr at 37°. After the incubation, cells (5x106 cells/ml) from each group were assayed for [3H]mTRH binding. Colchicine, vinblastine, and taxol stimulated [3H]mTRH binding by up to 27, 27, and 21%, respectively, without altering the Ka of the ligand to the receptor. These results suggest that perturbation of cytosolic microtubules leads to a reorganization of the spatial location of hormone receptors.
Proliferation and Differentiation of Cultured Human Keratinocytes is Modulated by 1,25(OH)2D3 and Synthetic Vitamin D3 Analogues in a Cell Density‐, Calcium‐ and Serum‐Dependent Manner*
Authors: Svendsen Morten L. , Daneels Guy , Geysen Johan , Binderup Lise , Kragballe Knud
Published: March 2009

Abstract: The natural form of vitamin D3, 1,25‐dihydroxyvitamin D3 (1,25(OH)2D3) decreases proliferation and promotes terminal differentiation of cultured human epidermal keratinocytes. The purpose of this study was to find out to what extent the culture conditions determine the sensitivety of keratinocytes to 1,25(OH)2D3 and synthetic vitamin D analogues. Human keratinocytes were grown in microplates. Cell proliferation (MTT‐assay) and differentiation (quantity of transglutaminase type I) were measured consecutively in the same monolayer. When vitamin D3 analogues were added to 50–60% confluent keratinocytes grown in serum‐free keratinocyte growth medium with 0.09 mM Ca2+, stimulation of the proliferation was either minimal or non‐existent, while differentiation was unaffected or slightly inhibited. There was no difference in the sensitivity to 1,25(OH)2D3 and the vitamin D3 analogues. When 1,25(OH)2D3 was added to less confluent keratinocytes (30%) a marked antiproliferative effect was observed. Addition of 3% charcoal stripped foetal calf serum further enhanced the antiproliferative effect of 1,25(OH)2D3, and a difference in the sensitivity of the vitamin D3 analogues was noted. If, finally, the Ca2+ concentration was raised to 0.3 mM, 1,25(OH)2D3 and the vitamin D3 analogues stimulated differentiation. Also, a biphasic effect on proliferation occurred: stimulation at low vitamin D concentrations and inhibition at higher concentrations. Furthermore, keratinocytes became more sensitive to the synthetic vitamin D3 analogues than to 1,25(OH)2D3: KH1060>EB1089>GS1500≥EB1213>calcipotriol>1,25(OH)2D3. For all compounds tested differentiation occurred at concentrations 10 to 30 times lower than for proliferation. These results indicate that the sensitivity to vitamin D3 analogues as well as the direction of the response to vitamin D3 analogues is dependent on the keratinocyte density, the availability of serum and Ca2+ concentrations.
Inhibition by 5‐N‐(4‐Chlorobenzyl)‐2′,4′‐dimethylbenzamil of Na+/Ca2+Exchange and L‐type Ca2+Channels in Isolated Cardiomyocytes
Authors: Sharikabad Mohammad Nouri , Cragoe Jr. Edward. J. , Brørs Odd
Published: March 2009

Abstract:The inhibitory effect of the amiloride derivative 5‐N‐(4‐chlorobenzyl)‐2′,4′‐dimethylbenzamil (CBDMB) on calcium (Ca2+) uptake via sarcolemmal sodium‐calcium (Na+/Ca2+) exchange and L‐type Ca2+channels was investigated in isolated adult rat ventricular cardiomyocytes under depolarizing conditions in cells preincubated with 1 mM ouabain or 137 mM lithium (Li+), respectively. Fifteen or 120 min. preincubation with CBDMB inhibited Ca2+uptake via Na+/Ca2+exchange in Na+‐loaded depolarized cells completely at 100 μM with an IC50of 21 μM. After 120 min. preincubation, CBDMB inhibited Ca2+uptake via L‐type Ca2+channels by 75.1±8.1% (mean and S.E.M.) and IC50of 4 μM, whereas no significant inhibition was observed after 15 min. preincubation. (+)‐Isradipine (10 μM) inhibited high potassium (K+) induced Ca2+uptake via L‐type Ca2+channels by 35% after 15 min. and by 70% after 120 min. preincubation. Inhibition by CBDMB of specific (+)‐[3H]isradipine binding to L‐type Ca2+channels showed similar concentration dependency as inhibition of Ca2+uptake via L‐type Ca2+channels. In conclusion, CBDMB inhibits sarcolemmal Na+/Ca2+exchange in rat ventricular cardiomyocytes rapidly. However, after longer preincubation periods, L‐type Ca2+channels are inhibited as well and with higher potency than Na+/Ca2+exchange.
Contribution of Lysosomal Trapping to the Total Tissue Uptake of Psychotropic Drugs
Authors: Daniel Wladyslawa Anna , Wöjcikowski Jacek
Published: March 2009

Abstract:The present study was aimed at assessing individual contributions of the phospholipid binding and lysosomal trapping to the total tissue uptake of psychotropic drugs with different chemical structures, such as promazine, imipramine, amitriptyline, fluoxetine, sertraline (basic lipophilic drugs) and carbamazepine (lipophilic, but not basic). We also tried to find out whether lysosomal trapping may be involved in the pharmacokinetic interactions in clinical combinations of psychotropics. Uptake experiments were carried out on slices of various rat tissues as a system with intact lysosomes. Initial concentration of each drug was 5 μM. The results were compared with those obtained in the presence of the "lysosomal inhibitors", ammonium chloride or monensin. The basic lipophilic psychotropics showed high uptake in tissues known for the abundance of lysosomes, mainly the lungs. The highest drug accumulation was found for promazine and amitriptyline. "Lysosomal inhibitors" significantly decreased the uptake of the basic lipophilic drugs, particularly in the lungs and liver. The most potent effect was observed for amitriptyline, imipramine and promazine. The brain showed moderate accumulation of basic lipophilic psychotropics and the effect of the "lysosomal inhibitors" was significant only in the case of amitriptyline, imipramine and sertraline. The only exception to the above regularity were imipramine and sertraline which were taken up more extensively by the adipose tissue than by lysosome‐rich tissues such as the lungs or liver. Carbamazepine did not show lysosomotropism. Amitriptyline and promazine mutually decreased their uptake by lung slices when the drugs were incubated jointly. In the presence of ammonium chloride the interaction did not occur. In conclusion, the obtained results show that (1) the lysosomal trapping is an important factor determining the distribution of the basic lipophilic psychotropics; however (2) their tissue uptake depends more on the phospholipid binding than on the lysosomal trapping; (3) the lysosomal trapping may be involved in the pharmacokinetic interactions between psychotropics.
Glucuronidation of SN‐38, the Active Metabolite of Irinotecan, by Human Hepatic Microsomes
Authors: Haaz Marie‐Christine , Rivory Laurent , Jantet Sophie , Ratanasavanh Damrong , Robert Jacques
Published: March 2009

Abstract:We have investigated the glucuronidation in vitro of SN‐38, the active metabolite of irinotecan, a semi‐synthetic anticancer drug derived from 20(S)camptothecin. Preparations of human hepatic microsomes (final concentration: 1 mg prot./ml), were incubated for 1 hr in 0.1 M Tris buffer, pH 7.4, containing 10 mM MgCl2, in the presence of UDP‐glucuronic acid (4 mM), saccharolactone (4 mM), and a detergent. Microsomes from five livers were studied individually or as a pooled preparation. SN‐38, either in its lactone or its carboxylate form, was added at a range of concentrations. The SN‐38 β‐glucuronide formed was measured by HPLC with fluorometric detection. The glucuronidation reaction appeared linear over 1 hr in these conditions and Brij 35 at 0.5 mg/mg prot. was the best activator. The apparent parameters of the reaction were independent of the molecular form of the substrate. The half‐saturation constant was 17‐20 μM and Vmax was 60‐75 pmol/min./mg prot. The interindividual variation of SN‐38 glucuronidation was relatively low (ratio of 1.8 between extreme values). In addition, the effect of twelve drugs currently associated with irinotecan in clinics was evaluated in this system (drug concentration: 100 μM; SN‐38 concentration: 5 μM). These produced little if any interference with SN‐38 glucuronidation. Therefore, major interferences of this transformation by comedications are unlikely to occurin vivo.