European Journal of Pharmacology (v.398, #1)

In this study, we examined the effect of clozapine, olanzapine, risperidone and haloperidol on the neuropathology (i.e. neuronal vacuolization) and the expression of Fos-like protein and c-fos mRNA in the retrosplenial cortex of female Sprague–Dawley rats induced by the NMDA receptor antagonist dizocilpine. Pretreatment (15 min) with clozapine or olanzapine, but not risperidone or haloperidol, blocked the neuronal vacuolization produced by dizocilpine (0.5 mg/kg, s.c.) in the rat retrosplenial cortex in a dose-dependent manner. Furthermore, pretreatment (15 min) with clozapine or olanzapine, but not risperidone or haloperidol, significantly attenuated the expression of Fos-like protein in the retrosplenial cortex induced by dizocilpine (0.5 mg/kg, s.c.) in a dose-dependent manner. The marked expression of c-fos mRNA in the rat retrosplenial cortex induced by the administration of dizocilpine (0.5 mg/kg, s.c.) was significantly attenuated by pretreatment (15 min) with clozapine (10 mg/kg) or olanzapine (10 mg/kg), but not risperidone (10 mg/kg) or haloperidol (10 mg/kg). The present results suggest that pharmacologically relevant doses of clozapine or olanzapine, but not risperidone or haloperidol, block the neuropathological changes and the expression of Fos-like protein and c-fos mRNA in the rat retrosplenial cortex elicited by the administration of dizocilpine. It is possible that the blockade of dizocilpine-induced neuropathological changes by clozapine and olanzapine may be related to the unique antipsychotic actions of these drugs in schizophrenic patients, although this remains to be verified.
Keywords: Dizocilpine ((+)-MK-801); NMDA receptor antagonist; Neurotoxicity; Retrosplenial cortex; Clozapine; Olanzapine; Immediate early gene;

Metabolic mapping of discrete brain regions using cytochrome oxidase histochemistry was used as a marker for alterations in mitochondrial function and cytochrome oxidase enzymatic activity in response to high doses of amphetamine derivatives. The activity of cytochrome oxidase, complex IV of the electron transport chain, was determined at three different time-points following administration of high doses of methamphetamine or 3,4-methylenedioxymethamphetamine (MDMA) (four injections of 10–15 mg/kg administered over 8 h). There was a rapid decrease in cytochrome oxidase staining in the striatum (23–29%), nucleus accumbens (29–30%) and substantia nigra (31–43%), 2 h following administration of either methamphetamine and MDMA. This decrease in cytochrome oxidase activity was transient and returned to control levels within 24 h. Since the methamphetamine and MDMA-induced decrease in cytochrome oxidase activity was localized to dopamine-rich regions, increased extracellular concentrations of dopamine may contribute to the inhibition of metabolic function via its metabolism to form quinones or other reactive oxygen species. These results support previous studies demonstrating that psychostimulants induce a rapid and transient decrease in striatal ATP stores and provide further evidence that these drugs of abuse can disrupt mitochondrial function.
Keywords: Neurotoxicity; Cytochrome oxidase; Amphetamine; Histochemistry; Energy metabolism;

Dissociation between the Ca2+ signal and tube formation induced by vascular endothelial growth factor in bovine aortic endothelial cells by Junya Kawasaki; Katsuya Hirano; Mayumi Hirano; Junji Nishimura; Akio Nakatsuka; Masatoshi Fujishima; Hideo Kanaide (19-29).
The correlation between the intracellular Ca2+ signal and the tube formation in collagen gels induced by vascular endothelial cell growth factor (VEGF) was investigated using cultured bovine aortic endothelial cells. The VEGF-induced sustained elevation of cytosolic Ca2+ concentration ([Ca2+]i) was similarly inhibited by 10 μM 1-{β-[3-(4-methoxyphenyl)propyl]-4-methoxyphenethyl}-1H-imidazole hydrochloride (SKF 96365) and 10 μM troglitazone. However, 10 μM diltiazem had no effect. The basal tube formation obtained with 1% serum was augmented twofold by 100 ng/ml VEGF. SKF 96365 (0.1–10 μM) inhibited the VEGF-induced and basal tube formation, while 10 μM troglitazone or 10 μM diltiazem had no effect. The proliferation of endothelial cells was markedly inhibited by SKF 96365 but only slightly by troglitazone and diltiazem. The inhibition of tube formation by three Ca2+ entry blockers thus correlated with the inhibition of cell proliferation. The [Ca2+]i elevation is thus not a prerequisite for VEGF to induce tube formation.
Keywords: Endothelial cell; Angiogenesis; Ca2+ influx; Proliferation;

Further characterization of an adenosine transport system in the mitochondrial fraction of rat testis by Andrés Jiménez; David Pubill; Mercè Pallàs; Antonio Camins; Sı́lvia Lladó; Jorge Camarasa; Elena Escubedo (31-39).
Previous work from our laboratory has demonstrated the presence of high-affinity binding sites for [3H]nitrobenzylthioinosine ([3H]NBTI), a marker of adenosine uptake systems, in the mitochondrial fraction of rat testis. Here, we characterize this system functionally through [3H]adenosine uptake assays. This system (K m=2±1.3 μM; V max=86.2±15.5 pmol/mg protein/min) was found to be saturable, non sodium-dependent and sensitive to temperature, pH and osmolarity. [3H]Adenosine incorporation was potently inhibited by hydroxynitrobenzylthioguanosine (HNBTG, IC50=3 nM) although NBTI inhibited this uptake weakly (IC50=72.7±37.1 μM). Dilazep>dipyridamole≥hexobendine inhibited [3H]adenosine incorporation at low micromolar concentrations. The nucleosides inosine and uridine were weak inhibitors of this system. The adenosine receptor ligands N6-phenylisopropyladenosine (PIA) and 2-chloroadenosine inhibited the uptake only at micromolar concentrations. Neither 5′-(N-ethylcarboxamido)-adenosine (NECA) nor theophylline inhibited adenosine uptake by more than 60% but the mitochodrial benzodiazepine receptor ligands 4′-chloro-diazepam (Ro 5-4864) and 1-(2-chlorophenyl)-N-methyl-N-(1-methyl-propyl) isoquinoline carboxamide (PK 11195) were able to inhibit it. The lack of inhibition by the blockers of the mitochondrial adenine-nucleotide carrier, atractyloside and α,β-methylene-ATP, indicates that [3H]adenosine uptake occurs via a transporter other than this carrier. All these results support the existence of an equilibrative adenosine transport system, which might mediate the passage of adenosine formed in the mitochondria to the cytoplasm.
Keywords: [3H]Adenosine; Adenosine uptake; Mitochondrion; Testis; Benzodiazepine receptor ligand;

Effects of buspirone on brain indoleamines and catecholamines in wild-type mice and Lurcher mutants by Tomás A Reader; Ariel R Ase; Nathalie Le Marec; Robert Lalonde (41-51).
The effects of a chronic serotoninergic stimulation on brain monoamine levels and metabolism were studied in wild-type (+/+) mice and Lurcher (Lc/+) mutants. Endogenous serotonin, dopamine, noradrenaline and some of their major metabolites were measured in the frontal cortex, neostriatum, thalamus, brainstem, cerebellum and spinal cord. In +/+ mice, buspirone (1 mg/kg; i.p.) treatment during 40 days increased indoleamines, albeit with moderate changes in the ratios between tissue serotonin metabolites and endogenous serotonin, augmented noradrenaline contents in the spinal cord, and caused elevations of dopamine metabolites in most regions. In Lc/+ mutants, the effects of buspirone were attenuated, but higher l-tryptophan and indoleamine levels, suggest a storage of serotonin in a non-releasable compartment. In the hypoplastic Lc/+ cerebellum, indoleamine content was accrued, but with a decreased [serotonin metabolites]/[serotonin] ratio, indicating that the reorganized nerve terminals in Lc/+ mutants although they can synthesize and accumulate serotonin, may not utilize it efficiently in synaptic transmission.
Keywords: 5-HT (5-hydroxytryptamine, serotonin); 5-HIAA (5-hydroxyindole-3-acetic acid); 5-Hydroxytryptophol; Dopamine; Noradrenaline; Ataxia;

A microdialysis study on the mechanism of action of gabapentin by Wia Timmerman; Marielle Bouma; Jan B De Vries; Michael Davis; Ben H.C Westerink (53-57).
To gain insight into the mechanism of action of the anti-epileptic, gabapentin, the effects of gabapentin on the in vivo extracellular γ-aminobutyric acid (GABA) levels in the rat substantia nigra reticulata were studied using microdialysis. In order to investigate possible interference with different GABA-ergic compartments in the substantia nigra reticulata, we studied the effects of gabapentin under basal, K+-, nipecotic acid- and glutamate-stimulated conditions. Intraperitoneally (i.p.) administered gabapentin, at a dose of 100 mg/kg, did not significantly affect extracellular GABA levels under any condition. Thus, our data do not support the involvement of nigral GABA release in the mechanism of action of the anti-epileptic gabapentin.
Keywords: Gabapentin; Substantia nigra reticulata; γ-Aminobutyric acid; Microdialysis;

Non-dopaminergic therapies are of potential interest in the treatment of Parkinson's disease given the complications associated with current dopamine-replacement therapies. In this study we demonstrate that SB 206553 (5-methyl-1-(3-pyridylcarbamoyl)-1,2,3,5-tetrahydropyrrol[2,3-f]indole) (20 mg/kg) enhanced the actions of the dopamine D1 receptor agonist, SKF 82958 ((+)-6-chloro-7,8-dihydroxy-3-allyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine hydrobromide) (1 mg/kg), in eliciting locomotion in the 6-hydroxydopamine-lesioned rat model of Parkinson's disease. This action was only seen following prior priming with l-DOPA (l-3,4-dihydroxyphenylalanine). SB 206553 had no effect on rotational behaviour when given alone. 5-HT2C receptor antagonists may have potential as a means of reducing reliance on dopamine replacement in the treatment of Parkinson's disease.
Keywords: Parkinson's disease; 6-Hydroxydopamine-lesioned rat; 5-HT2C receptor; SKF 82958;

The effects of (−)-huperzine A, a promising therapeutic agent for Alzheimer's disease, on learning behavior and on alterations of the cholinergic system, the oxygen free radicals and energy metabolites induced by permanent bilateral ligation of the common carotid arteries were investigated in rats. Daily oral administration of huperzine A produced a significant improvement of the deficit in the learning of the water maze task, beginning 28 days after ischemia, correlating to about 33–40% inhibition of acetylcholinesterase activity in cortex and hippocampus. Huperzine A significantly restored the decrease in choline acetyltransferase activity in hippocampus and significantly reduced the increases in superoxide dismutase, lipid peroxide, lactate and glucose to their normal levels. The present findings demonstrate that the improvement by huperzine A of the cognitive dysfunction in the late phase in chronically hypoperfused rats is due to its effects, not only on the cholinergic system, but also on the oxygen free radical system and energy metabolism. Our results strongly suggest that huperzine A has therapeutic potential for the treatment of dementia caused by cholinergic dysfunction and/or decrease of cerebral blood flow.
Keywords: (−)-Huperzine A; Acetylcholinesterase; Cholinesterase inhibitor; Cerebral ischemia; Morris water maze; Learning; Memory; Free radical; Alzheimer's disease;

The anti-migraine drug, eletriptan [(R)-3-(1-methyl-2-pyrrolidinylmethyl)-5-[2-(phenylsulphonyl)ethyl]-1H-indole; UK-116,044], is a novel 5-HT1B/1D receptor agonist. In this paper, the regional vasoconstrictor profile of eletriptan, in comparison with sumatriptan, was examined in the anaesthetised dog. The inhibitory actions of eletriptan on neurogenic inflammation in rat dura mater were also assessed. In the anaesthetised dog, eletriptan (1–1000 μg kg−1 i.v.) produced a dose-dependent reduction of carotid arterial blood flow with a similar potency and maximum effect to sumatriptan (ED50 values: eletriptan and sumatriptan, 12 and 9 μg kg−1, i.v., respectively). However, eletriptan exhibited a significantly lower potency than sumatriptan in reducing coronary artery diameter (ED50 values: 63 and 19 μg kg−1, i.v., respectively, P<0.05). In the femoral circulation, sumatriptan caused a significant reduction in arterial blood flow (ED50 35 μg kg−1 i.v.) whereas eletriptan (1–1000 μg kg−1 i.v.) had no significant effect upon femoral arterial blood flow when compared to vehicle-treated animals. In rats, eletriptan (30–300 μg kg−1 i.v.) administered prior to electrical stimulation of the trigeminal ganglion produced a dose-related and complete inhibition of plasma protein extravasation in the dura mater (mean extravasation ratio: control 1.9; eletriptan 1.0, minimum effective dose 100 μg kg−1, P<0.05). The potency and maximum effect of eletriptan was identical to that of sumatriptan in this model. When administered during a period of continual stimulation of the trigeminal nerve, eletriptan (100 μg kg−1 i.v.) produced a complete inhibition of plasma protein extravasation. The ability to reduce canine carotid arterial blood flow and inhibit neurogenic inflammation in rat dura mater suggests that vascular and neurogenic mechanisms may contribute to eletriptan's clinical efficacy in migraine patients. In addition, eletriptan exhibits some selectivity for reducing carotid arterial blood flow when compared with femoral arterial blood flow and coronary artery diameter, in the anaesthetised dog.
Keywords: Eletriptan; Sumatriptan; Carotid artery blood flow; Femoral artery blood flow; Neurogenic inflammation; Coronary artery diameter;

Diltiazem has cardioprotective properties following myocardial ischemic injury. However, there are controversial results regarding the beneficial effects of diltiazem on regional myocardial flow after ischemia. Therefore, we investigated the effect of diltiazem on changes in regional myocardial flow due to ischemia for different periods. Non-radioactive colored microspheres were used for this measurement in isolated rat heart. After 20 or 40 min of global ischemia and 40 min of reperfusion, regional myocardial flow was decreased, especially in the endocardial layer. The endocardial/epicardial ratio was also decreased. The decreases in endocardial flow and the endocardial/epicardial ratio were more remarkable after 40 min of ischemia than after 20 min of ischemia. Diltiazem (10−6 M), which was administered 15 min before ischemia, prevented only the decrease in endocardial flow and endocardial/epicardial ratio after 20 min of ischemia, whereas it did not prevent that after 40 min of ischemia. Nifedipine (2×10−6 M) did not exert a cardioprotective effect. These findings suggested that the effect of ischemia is marked in the endocardium and, also, that the protective effect of diltiazem is seen only during a decrease in endocardial flow following short-term and reversible ischemia.
Keywords: Diltiazem; Coronary flow; Heart; Ischemia; Microsphere; Reperfusion;

Effects of vitamin E and sodium selenate on neurogenic and endothelial relaxation of corpus cavernosum in the diabetic mouse by Cemil Göçmen; Ata Seçilmiş; Eda Karabal Kumcu; Peyman Uçar Ertuğ; Serpil Önder; Atilla Dikmen; Firuz Baysal (93-98).
We studied the effect of vitamin E and sodium selenate treatment on the neurogenic and endothelium-dependent relaxation of isolated corpus cavernosum obtained from streptozotocin-induced diabetic mice. Relaxant responses of corpus cavernosum precontracted by phenylephrine to electrical field stimulation and to acetylcholine were significantly decreased in diabetic mice. There was no significant difference between diabetic and non-diabetic groups for the relaxant response of corpus cavernosum to sodium nitroprusside and papaverine. Treatment with sodium selenate, but not vitamin E, partially prevented the impairment of the neurogenic relaxation, whereas both had a significant, partial restorative action on endothelial dysfunction in corpus cavernosum obtained from diabetic groups. Neither agent exhibited a significant action on the relaxant responses of corpus cavernosum obtained from non-diabetic mice. A decrease in the sensitivity of the neurogenic impairment to antioxidant action may develop more rapidly than that of endothelial dysfunction in streptozotocin-induced diabetic mice.
Keywords: Streptozotocin-induced diabetic mouse; Corpus cavernosum; Nitric oxide (NO); Antioxidant; Vitamin E; Sodium selenate; Oxidative stress;

Enalapril and valsartan improve cyclosporine A-induced vascular dysfunction in spontaneously hypertensive rats by Markus Lassila; Piet Finckenberg; Anna-Kaisa Pere; Heikki Vapaatalo; Marja-Leena Nurminen (99-106).
Cyclosporine A causes hypertension and nephrotoxicity in spontaneously hypertensive rats (SHR). In the present study, arterial function was investigated using in vitro vascular preparations after long-term treatment with cyclosporine A. SHR received cyclosporine A (5 mg kg−1 day−1 s.c.) and high-Na+ diet for 6 weeks during the developmental phase of hypertension. Part of the rats were treated concomitantly either with the angiotensin converting enzyme inhibitor enalapril (30 mg kg−1 day−1 p.o.) or with an angiotensin AT1 receptor antagonist valsartan (3 or 30 mg kg−1 day−1 p.o.). In renal arteries, contractile responses to noradrenaline and angiotensin II, as well as relaxation responses to acetylcholine (endothelium-dependent) and to sodium nitroprusside (endothelium-independent), were severely impaired by cyclosporine A-treatment. There was also a trend for the dysfunction of the mesenteric arteries, but the impairment did not reach statistical difference. Enalapril and valsartan improved the impaired renal arterial functions. Cyclosporine A-induced hypertension and nephrotoxicity seem to be associated with renal arterial dysfunction in SHR on high-Na+ diet. Antagonism of the renin–angiotensin system protects from vascular toxicity of cyclosporine A.
Keywords: Cyclosporine A; Na+; Enalapril; Valsartan; Angiotensin II; Vascular response;

Antiarrhythmic and cardiohemodynamic effects of a novel Ca2+ channel blocker, AH-1058, assessed in canine arrhythmia models by Akira Takahara; Atsushi Sugiyama; Hideki Dohmoto; Ryota Yoshimoto; Keitaro Hashimoto (107-112).
The antiarrhythmic profile and cardiohemodynamic effect of a novel Ca2+ channel blocker, 4-(5H-Dibenzo[a,d]cyclohepten-5-ylidene)-1-[(E)-3-(3-methoxy-2-nitro)phenyl-2-propenyl]piperidine hydrochloride (AH-1058), were analyzed using the epinephrine-, digitalis- and two-stage coronary ligation-induced canine ventricular arrhythmia models. Intravenous administration of AH-1058 (100 μg/kg) effectively suppressed each of the ventricular arrhythmias accompanied by weak hypotensive effects. The results contrast well with those of a typical Ca2+ channel blocker, verapamil, which suppresses only the epinephrine-induced ventricular arrhythmia with severe hypotension. These results indicate that AH-1058 may possess a more selective inhibitory action on Ca2+ channels in the heart than on those in the vessels. Furthermore, the antiarrhythmic actions of AH-1058 were slower in onset and longer-lasting, than those in our previous studies using other antiarrhythmic drugs, including Na+ and Ca2+ channel blockers. The antiarrhythmic effects of AH-1058 did not correlate with its plasma concentrations when administered either intravenously or orally. These results suggest that AH-1058 can become a long-acting Ca2+ channel blocker with unique antiarrhythmic properties, and that AH-1058 may be used in certain pathological processes, for which selective inhibition of the cardiac Ca2+ channels is essential.
Keywords: AH-1058; Ca2+ channel blocker; Ventricular arrhythmia;

Protein kinase Cδ and α are involved in the development of vasospasm after subarachnoid hemorrhage by Shigeru Nishizawa; Kazuo Obara; Koichi Nakayama; Masayo Koide; Tetsuo Yokoyama; Naoki Yokota; Seiji Ohta (113-119).
We have previously shown the enhanced activity of protein kinase C in the membrane fraction of the canine vasospastic artery after subarachnoid hemorrhage, which increased with progression of angiographic vasospasm. This study examined identification of protein kinase C isoforms in the canine basilar artery, and the changes in expression and/or translocation of each isoform during the development of vasospasm. Vasospasm was produced by using the “two-hemorrhage” canine model in the basilar artery, and angiographic progression of vasospasm was assessed consecutively. Two isoforms, protein kinase Cα and δ were identified in basilar arteries by Western blotting. Densitometric analysis showed that the expression of protein kinase Cδ in the membrane fraction was significantly increased in the earlier stage, and protein kinase Cα was increased later as vasospasm progressed. These results indicate that protein kinase Cδ and α isoforms may play a significant role in the development and maintenance of vasospasm.
Keywords: Protein kinase C isoform; Subarachnoid hemorrhage; Cerebral vasospasm;

Acute dependence on and tolerance to heroin and morphine were assessed in rhesus monkeys using measures of respiration. Respiratory frequency (f) and minute volume (V e) were measured in monkeys breathing air or 5% CO2 in air using a pressure-displacement plethysmograph. Cumulative doses of naltrexone (0.0001–1.0 mg/kg, i.m) did not alter these parameters in untreated monkeys. Twenty-four hours after a cumulative dose of heroin (1 mg/kg, i.m.), naltrexone produced an increase in both f and V e when monkeys were breathing air or 5% CO2. Following 1 to 3 days of treatment with heroin (0.5 mg/kg/day, i.m.) or morphine (16 mg/kg/day, i.m.), naltrexone produced an increase in f and V e that was related to the dose of naltrexone and the number of days of agonist administration. Two days following termination of heroin administration, naltrexone-induced respiratory stimulation declined and had disappeared completely by the fifth day. In tolerance studies, heroin (0.032–0.5 mg/kg, i.m.) and morphine (1–16 mg/kg, i.m.) were injected cumulatively each day for three consecutive days. These drugs suppressed f and V e to nearly the same extent on day 3 as they had on day 1 of administration. These results suggest that dependence to morphine and heroin can be measured under conditions of acute 1 to 3 day administration conditions in primates using f and V e as reliable and quantitative indicators of opioid withdrawal. Under these conditions, tolerance does not occur.
Keywords: Respiration; Opioid; Tolerance; Dependence; (Rhesus monkey);

Hoe 140 and pseudo-irreversible antagonism in the rat vas deferens in vitro by Aziz U.R. Asghar; Alan Wheeldon; Robert A. Coleman; Chas Bountra; Daniel S. McQueen (131-138).
The effects of bradykinin and the bradykinin B2 receptor antagonists d-Arg-[Hyp3,Thi5,8,d-Phe7]-bradykinin (NPC 349) and d-Arg-[Hyp3,Thi5,d-Tic7,Oic8]-bradykinin (Hoe 140) were examined in the electrically-stimulated rat vas deferens. Cumulative additions of bradykinin (1–3000 nM) produced two distinct responses: an enhancement in the magnitude of the basal electrically-induced twitch response (neurogenic response) and an increase in the baseline tension (musculotropic response). NPC 349 (10–100 μM) produced concentration-dependent surmountable rightward shifts of both the bradykinin neurogenic and musculotropic response curves. In contrast, while Hoe 140 (10–100 nM) caused an apparently surmountable antagonism of the bradykinin neurogenic response, it caused an apparent insurmountable antagonism of the bradykinin musculotropic response. Interestingly, co-incubation of Hoe 140 (30 nM) with NPC 349 (30 and 100 μM) resulted in a concentration-related upwards displacement of the Hoe 140-suppressed bradykinin musculotropic response curve. Thus, Hoe 140 can be described as a pseudo-irreversible antagonist against the bradykinin musculotropic response. No time-dependent changes were observed in the maximum bradykinin musculotropic response attainable when NPC 349 (100 μM) additions were made for the final 2 or 18 min of the Hoe 140 incubation (20 min). These findings indicate that slow reversibility of Hoe 140 from the bradykinin B2 receptor is unlikely to be the mechanism responsible for the pseudo-irreversible antagonism of the bradykinin-induced musculotropic response. Instead, we propose an alternative explanation involving a third, unstable and inactive form of the bradykinin B2 receptor.
Keywords: Vas deferens; Bradykinin; Bradykinin receptor; Hoe 140; Antagonism;

This study was designed to (1) evaluate retinal lipid peroxidation in early diabetes by the method specific for free malondialdehyde and 4-hydroxyalkenals, (2) identify impaired antioxidative defense mechanisms and (3) assess if enhanced retinal oxidative stress in diabetes is prevented by the potent antioxidant, dl-α-lipoic acid. The groups included control and streptozotocin-diabetic rats treated with or without dl-α-lipoic acid (100 mg kg−1 day−1, i.p., for 6 weeks). All parameters were measured in individual retinae. 4-Hydroxyalkenal concentration was increased in diabetic rats (2.63±0.60 vs. 1.44±0.30 nmol/mg soluble protein in controls, P<0.01), and this increase was prevented by dl-α-lipoic acid (1.20±0.88, P<0.01 vs. untreated diabetic group). Malondialdehyde, reduced glutathione (GSH) and oxidized glutathione (GSSG) concentrations were similar among the groups. Superoxide dismutase, glutathione peroxidase (GSHPx), glutathione reductase (GSSGRed) and glutathione transferase (GSHTrans) activities were decreased in diabetic rats vs. controls. Quinone reductase was upregulated in diabetic rats, whereas catalase and cytoplasmic NADH oxidase activities were unchanged. dl-α-Lipoic acid prevented changes in superoxide dismutase and quinone reductase activities induced by diabetes without affecting the enzymes of glutathione metabolism. In conclusion, accumulation of 4-hydroxyalkenals is an early marker of oxidative stress in the diabetic retina. Increased lipid peroxidation occurs in the absence of GSH depletion, and is prevented by dl-α-lipoic acid.
Keywords: Antioxidant; Diabetic retinopathy; Glutathione; Lipid peroxidation; Superoxide dismutase;

Role of gastric acid secretion in progression of acute gastric erosions induced by ischemia–reperfusion into gastric ulcers by Tomasz Brzozowski; Peter Ch Konturek; Stanislaw J Konturek; Danuta Drozdowicz; Slawomir Kwiecieñ; Robert Pajdo; Wladyslaw Bielanski; Eckhart G Hahn (147-158).
Ischemia followed by reperfusion is known to produce gastric lesions due to oxidative stress, but the role of gastric H+ secretion in the formation of this mucosal injury remains unknown. We studied alterations in gastric acid secretion and gastric histamine content, as well as the expression of histidine-decarboxylase and interleukin-1β during the mucosal recovery from ischemia–reperfusion erosions. Gastric secretion was studied in rats (series A) with gastric fistula before, during and after the ischemia induced by clamping of celiac artery for 0.5 h followed by reperfusion in animals pretreated with vehicle (saline), omeprazole, a proton pump inhibitor, or ranitidine, a histamine (H2) receptor antagonist. In series B, the animals were submitted to 0.5 h of ischemia followed by 1 h of reperfusion and then anesthetized at 0, 3, 12 and 24 h or 3, 5, 10 or 15 days after the end of ischemia–reperfusion to determine gastric blood flow by H2-gas clearance technique, area of gastric lesions, plasma gastrin and interleukin-1β levels, histamine content by radioimmunoassay (RIA) and expression of histidine-decarboxylase and interleukin-1β mRNA by reverse transcription polymerase chain reaction. Clamping of celiac artery caused cessation of gastric blood flow and almost complete suppression of basal gastric acid secretion (series A) that returned gradually to the control value at day 3 after ischemia–reperfusion, accompanied by the rise in plasma gastrin levels, pronounced expression of histidine-decarboxylase mRNA and increased mucosal histamine content. Ischemia, followed by 1 h of reperfusion, produced gastric erosions (series B) that reached maximum at 12 h, but then declined at 24 h. These erosions progressed at day 3 into deeper ulcers whose area declined progressively within the next 5–15 days. The gastric blood ceased to flow (series B) during 30 min of clamping and was reduced throughout the period of healing of acute erosions, being accompanied by a gradual rise in mucosal interleukin-1β mRNA content and in plasma interleukin-1β levels. Treatment with omeprazole or ranitidine, which completely suppressed gastric acid secretion and significantly raised plasma gastrin level, greatly reduced the formation of erosive lesions preventing the progression of these lesions to chronic gastric ulcers, and this was accompanied by the rise in gastric blood flow and plasma gastrin levels and the significant attenuation of plasma interleukin-1β levels. The ranitidine and omeprazole-induced suppression of ischemia–reperfusion erosions were abolished by the instillation of exogenous 0.2 N HCl into the stomach of these rats. The histidine-decarboxylase was faintly expressed in the intact gastric mucosa, but strongly upregulated during mucosal recovery from the damage induced by ischemia–reperfusion. We conclude that following ischemia–reperfusion: (1) gastric acid secretion, gastric microcirculation and histamine production markedly decline, while interleukin-1β release significantly increases, probably playing an important role in the progression of acute lesions into chronic gastric ulcerations; (2) the suppression of gastric acid secretion by omeprazole and ranitidine, that induces hypergastrinemia, prevents the progression of gastric erosions into ulcers; and (3) the addition of exogenous acid restores the progression of the acute lesions into gastric ulcers, indicating that gastric acid plays a key role in ulcerogenesis induced by ischemia–reperfusion.
Keywords: Ischemia–reperfusion; Gastric secretion; Omeprazole; Ranitidine; Ulcer healing; Gastric blood flow; Interleukin-1β; Gastrin; Somatostatin;

Epidermal growth factor accelerates pancreatic recovery after caerulein-induced pancreatitis by Artur Dembiński; Zygmunt Warzecha; Peter Ch Konturek; Piotr Ceranowicz; Jerzy Stachura; Romana Tomaszewska; Stanisław J Konturek (159-168).
We examined the influence of endogenous and exogenous epidermal growth factor (EGF) on pancreatic repair after acute pancreatitis. Caerulein-induced pancreatitis was evoked in rats with intact or removed salivary glands and EGF (10 μg/kg) was administered starting 24 h after cessation of caerulein infusion. The dose of EGF 10 μg/kg was chosen because it was the most effective in preliminary experiments when 1, 10 or 50 μg/kg of EGF was used. Caerulein administration caused acute edematous pancreatitis with biochemical and histological manifestation of pancreatic damage, followed by spontaneous regeneration. The effect of salivectomy on the course of acute pancreatitis was slight, resulting in additional reduction in pancreatic blood flow, DNA synthesis and in an increase in plasma interleukin 1β level. Treatment with EGF accelerated the healing of pancreatic damage, causing an increase in pancreatic blood flow and DNA synthesis. EGF caused faster normalization of plasma amylase and lipase activity and plasma interleukin 1β concentration, as well as, this peptide accelerated the restoration of pancreatic amylase activity. On histological examination, EGF caused reduction of pancreatic damage and acceleration of tissue repair. We conclude that EGF reduces the severity of pancreatic damage evoked by caerulein-induced pancreatitis-related pancreatic damage and accelerates tissue repair. The beneficial effects of EGF appear to depend, at least in part, on the improvement of pancreatic blood flow, as well as on an increase of pancreatic cell growth and limitation of the activation cytokine release.
Keywords: Pancreatitis; EGF (epidermal growth factor); Pancreatic regeneration; Interleukin 1β;

Effects of low-dose VOSO4 on age-related changes in glucose homeostasis in rats by Vincenzo De Tata; Ettore Bergamini; Maria Bombara; Roberto Lupi; Michela Novelli; Pellegrino Masiello (169-175).
The effects of low doses of vanadyl sulfate (0.2 mg/ml in the drinking water) on the age-related impairment of glucose homeostasis in Sprague–Dawley rats were investigated. VOSO4 administration was initiated in 5-month-old animals and lasted 3 months. Thus, in 8-month-old rats, we investigated glucose metabolism in vivo and insulin secretory function in vitro. Results showed that VOSO4 allowed the disposal of an oral glucose load at lower insulin levels than in age-matched controls. No significant changes were found in muscle glucose transporter (GLUT-4) levels or in glycogen content upon VOSO4 treatment. Islets isolated from VOSO4-treated rats released less insulin than control islets, but showed a better preserved sensitivity to secretagogues, in terms of incremental release over basal release, secretory efficiency, and maintenance of the priming effect of glucose. In conclusion, chronic low-dose VOSO4 treatment facilitates insulin action by a mechanism independent of muscle GLUT-4 levels and helps preserve the appropriate sensitivity of β cells to stimuli, thereby preventing age-dependent functional alterations.
Keywords: Aging; Vanadyl sulfate; Insulin action; Insulin release; Islet;