Tianeptine, olanzapine and fluoxetine show similar restoring effects on stress induced molecular changes in mice brain: An FT-IR study

Chronic stress which can cause a variety of disorders and illness ranging from metabolic and cardiovascular to mental leads to alterations in content, structure and dynamics of biomolecules in brain. The determination of stress-induced changes along with the effects of antidepressant treatment on these parameters might bring about more effective therapeutic strategies. In the present study, we investigated unpredictable chronic mild stress (UCMS)-induced changes in biomolecules in mouse brain and the restoring effects of tianeptine (TIA), olanzapine (OLZ) and fluoxetine (FLX) on these variations, by Fourier transform infrared (FT-IR) spectroscopy. The results revealed that chronic stress causes different membrane packing and an increase in lipid peroxidation, membrane fluidity. A significant increment for lipid/protein, C=O/lipid, CH3/lipid, CH2/lipid, PO(-)2/lipid, COO(-)/lipid and RNA/protein ratios but a significant decrease for lipid/protein ratios were also obtained. Additionally, altered protein secondary structure components were estimated, such as increment in random coils and beta structures. The administration of TIA, OLZ and FLX drugs restored these stress-induced variations except for alterations in protein structure and RNA/protein ratio. This may suggest that these drugs have similar restoring effects on the consequences of stress activity in brain, in spite of the differences in their action mechanisms. All findings might have importance in understanding molecular mechanisms underlying chronic stress and contribute to studies aimed for drug development.

Effects of ziprasidone, SCH23390 and SB277011 on spatial memory in the Morris water maze test in naive and MK-801 treated mice

Introduction: Patients with schizophrenia have cognitive dysfunctions; positive psychotic symptoms are the primary purposes for schizophrenia treatment. Improvements in cognitive function should be a characteristic of all newly developed drugs for the treatment of schizophreniawith dementia. Thus,we investigated the effects of the second-generation antipsychotic ziprasidone, dopamine D1 antagonist SCH-23390 and dopamine D3 antagonist SB-277011 on spatial learning and memory. Materials and methods: Male inbred mice were used. The effects of ziprasidone, SCH-23390 and SB-277011 were investigated using the Morris water maze test. Results: Ziprasidone (0.5 and 1mg/kg), SCH-23390 (0.05 and 0.1 mg/kg) and SB-277011 (10 and 20 mg/kg) had no effect on the time spent in the target quadrant in naive mice.MK-801 (0.1mg/kg) significantly decreased the time spent in the target quadrant. The time spent in the target quadrant was significantly prolonged by Ziprasidone (0.5 and 1 mg/kg) and SCH-23390 (0.1 mg/kg), but not with SB-277011 (20 mg/kg) in MK-801-treated mice. Ziprasidone (0.5 and 1mg/kg), SCH-23390 (0.05 and 0.1 mg/kg) and SB-277011 (10 and 20 mg/kg) had no effect on themean distance to the platformin naivemice.MK-801 significantly increased themean distance to the platform. Ziprasidone (1 mg/kg) and SCH-23390 (0.1 mg/kg) significantly decreased the mean distance to the platform in MK-801-treated mice, but SB-277011 (20 mg/kg) didn't. MK-801 significantly increased the total distance moved. Ziprasidone (0.5 and 1 mg/kg), SCH-23390 (0.05 and 0.1 mg/kg) and SB-277011 (10 and 20 mg/kg) had no effect on the total distance moved in naive mice. Ziprasidone (1 mg/kg) and SCH-23390 (0.1 mg/kg) significantly decreased the total distance moved in MK-801-treated mice, but SB-277011 (20 mg/kg) didn't. Conclusions: The second-generation antipsychotic drug ziprasidone and D1 antagonist SCH23390, but not the D3 antagonist SB277011, might be clinically useful for the treatment of cognitive impairments in patients with schizophrenia.

Effects of rolipram and zaprinast on learning and memory in the Morris water maze and radial arm maze tests in naive mice

Inhibition of phosphodiesterase 5 (PDE) improved recognition memory and counteracted spatial learning impairment induced by nitric oxide synthase (NOS) inhibition in recent studies. Aim of this study was to investigate effects of rolipram, a PDE4 inhibitor and zaprinast, a PDE5 inhibitor, on learning and memory in Morris water maze (MWM) and radial arm maze (RAM) tests in naive mice. Male Balb-c mice were treated subchronically with zaprinast (3 and 10 mg/kg) and rolipram (0.05 and 0.1 mg/kg) for 6 days in the MWM test and acutely before the retention trial of radial arm maze test. Rolipram (0.05 and 0.1 mg/kg) significantly decreased escape latency between 2(nd) and 5(th) sessions, while zaprinast (10 mg/kg) significantly decreased escape latency only in 2(nd) session. Rolipram (0.05 and 0.1 mg/kg) and zaprinast (10 mg/kg) significantly increased time spent in escape platform's quadrant in probe trial of MWM test; only rolipram decreased mean distance to platform, while zaprinast had no effect on mean distance to platform. Zaprinast (3 and 10 mg/kg) significantly decreased number of errors compared to control group, while rolipram (0.05 and 0.1mg/kg) had no effect on number of errors in retention trial of RAM test. Rolipram (0.05 and 0.1 mg/kg) and zaprinast (10 mg/kg) significantly decreased time spent to complete retention trial (latency) compared to control group. Our study revealed that both zaprinast and rolipram enhanced spatial memory in MWM, while zaprinast seems to have more memory enhancing effects compared to rolipram in radial arm maze test.

Involvement of serotonin receptor subtypes in the antidepressant-like effect of beta receptor agonist Amibegron (SR 58611A): an experimental study

New therapeutic strategies against depression, with less side effects and thus greater efficacy in larger proportion of depressed patients, are needed. Amibegron (SR58611A) is the first selective β3 adrenergic agent that has been shown to possess a profile of antidepressant activity in rodents. To investigate the involvement of serotonin receptors in the effects of amibegron, we used the serotonin 5HT1A receptor antagonist WAY-100635 (WAY) or serotonin 5HT2A-2C receptor antagonist ketanserin or serotonin 5HT3 receptor antagonist ondansetron in mice forced swimming test (FST). The locomotor activity was evaluated by measuring the total distance moved in the apparatus and the speed of the animals in the open field test. Imipramine (30mg/kg) significantly reduced immobility time compared to vehicle-treated group while amibegron (5 and 10mg/kg) dose dependently reduced immobility time in the FST. WAY(0.1mg/kg), ondansetron (1mg/kg), ketanserin(5mg/kg) had no effect on immobility time in naive mice while all of the drugs partially and significantly reversed amibegron (10mg/kg) induced decreasement in the immobility time in FST. None of the drugs alter locomotor activity in the open field test. The antidepressant-like effect of amibegron in the FST seems to be mediated by an interaction with serotonin 5-HT1A, serotonin 5-HT2A-2C and serotonin 5-HT3 receptors.

Effects of olanzapine, sertindole and clozapine on MK-801 induced visual memory deficits in mice

We investigated the effects of the second generation antipsychotics olanzapine, sertindole and clozapine on visual recognition memory using the novel object recognition (NOR) test in naive and MK-801-treated animals. The effects of drug treatment on locomotion and anxiety were also determined using the open field test. Male Balb-c mice were treated with olanzapine (0.2, 0.4 and 0.6 mg/kg; i.p.), sertindole (0.63, 1.3 and 2.5mg/kg; s.c.) or clozapine (0.5 and 1mg/kg; i.p.), and cognitive deficits were induced by MK-801 (0.2mg/kg; i.p.) administration. Olanzapine treatment decreased the ratio index in the NOR test, whereas sertindole and clozapine had no effect in naive mice. MK-801-induced cognitive impairment was reversed by treatment with olanzapine, sertindole or clozapine. While olanzapine, sertindole and clozapine had no effect on the anxiety of naive mice as determined by the open field test, MK-801 significantly increased the total distance traveled, time spent in the center zone and the velocity of the animals. MK-801-induced effects on locomotion and anxiety in the open field test were reversed by olanzapine, sertindole or clozapine treatment. The results of the present study demonstrated that olanzapine, sertindole and clozapine improved cognition in MK-801 treated mice, and indicate that these drugs have a potential to improve cognition in schizophrenia.

Beneficial effects of resveratrol on scopolamine but not mecamylamine induced memory impairment in the passive avoidance and Morris water maze tests in rats

Resveratrol (3,5,4-trihydroxy-trans-stilbene), which is found in grapes and red wine has been shown to protect neuronal cells with its antioxidant activity, improve memory function in dementia and reverse acetylcholine esterase (AChE) activity. The aim of this study was to investigate the effect of resveratrol on emotional and spatial memory in naive rats, as well as on scopolamine- and mecamylamine-induced memory impairment in the passive avoidance and Morris water maze (MWM) tests. Resveratrol (12.5, 25 and 50 mg/kg), scopolamine (0.6 mg/kg) and mecamylamine (10mg/kg) were administered to male Wistar rats. In the passive avoidance test, there was no significant difference in the first day latency between all groups, whereas scopolamine and mecamylamine significantly shortened the second day latency compared to the control group. Resveratrol reversed the effect of scopolamine at all doses used, but it had no effect on mecamylamine-induced memory impairment in the passive avoidance test. Both scopolamine and mecamylamine significantly decreased the time spent in the escape platform quadrant during the probe trial of the MWM test compared to the control group. Resveratrol reversed the effect of scopolamine at all doses, but did not change the effect of mecamylamine in the MWM test. There were no significant differences in the locomotor activities of any of the groups. In conclusion, we suggested that resveratrol had improving effects on learning and memory by acting on muscarinic cholinergic receptors and at least in part, may reverse AChE activity.

Effects of diabetes and elevated glucose on nitrergic relaxations in the isolated duodenum of the rat

Nitrergic relaxations of the isolated duodenum, induced by streptozotocin, were investigated in the experimental 8-week diabetes rat model. The effects of elevated glucose were also examined in the incubated duodenal muscles (in Krebs-Henseleit solution containing 44 mM glucose for 6 h) taken from nondiabetic rats. The relaxations induced by electrical field stimulation (EFS) and nicotine were significantly reduced in diabetic rats compared with control rats. Incubating of duodenal tissues in medium containing elevated glucose revealed significantly impaired relaxations to EFS and nicotine compared to responses obtained after normal glucose incubation. However, the relaxant responses to sodium nitroprusside and papaverine were similar in all groups. Incubating in hyperosmolar solutions containing sucrose, the relaxant responses were not affected. In conclusion, impairment of NO-mediated relaxations in diabetes may be related to hyperglycemia. The alterations caused by elevated glucose are not due to a hyperosmotic effect because the same concentration of sucrose had no effect on the relaxations.

Effect of dextromethorphan on reference memory assessed in rats by a three-panel runway task

The effects of dextromethorphan (DM, CAS 6700-34-1), a common over-the-counter cough suppressant, on the reference memory have been investigated by a three-panel runway setup in rats. This study was designed by using a repeated acquisition procedure such as a radialarm maze task or a water maze task. DM (20-40 mg/kg i.p.) produced a significant decrease in the number of errors (pushes made on the two incorrect panels of the three panel gates at four choice points) and latency. Systemically administered scopolamine (CAS 114-49-8) (1 mg/kg i.p.) impaired the performance on both parameters. DM (40 mg/kg i.p.) was effective in reversing the reference memory deficit induced by administration of scopolamine. DM acts as a noncompetitive antagonist of the N-methyl-D-aspartate (NMDA) receptors. Our results suggest that inhibition of NMDA receptors by DM supports its potential positive properties. This finding might present an oppurtunity for the evaluation of this old antitussive drug.

Secondhand tobacco smoke impairs neurogenic and endothelium-dependent relaxation of rabbit corpus cavernosum smooth muscle: improvement with chronic oral administration of L-arginine

The first goal of this study was to examine the effect of secondhand smoking on neurogenic, endothelium- and cGMP-dependent relaxant responses of rabbit corpus cavernosum smooth muscle. Our second goal was to determine whether such an effect can be prevented by oral administration of L-arginine. Male New Zealand rabbits were divided into control, chronic passive cigarette smoking and L-arginine treatment groups. Relaxant or contractile responses in isolated corpus cavernosum smooth muscle strips were determined by using in vitro muscle technique. There was no significant difference in the relaxant response of the strips to papaverine, sodium nitroprusside and contractile response to KCl among the groups. Relaxant responses to acetylcholine and electrical field stimulation and contractile response to phenylephrine were significantly decreased in the strips of the smoking group than that of the control group. The impaired relaxations of strips were markedly improved by treatment of L-arginine, but the contractile responses to phenylephrine were not affected. These data indicate that secondhand smoking may impair both neurogenic and endothelium-dependent relaxation of corpus cavernosum smooth muscle, and may contribute to the etiology of impotence. Chronic dietary supplementation with L-arginine offsets the impairment of neurogenic and endothelial relaxation. Therefore, we suggest that secondhand smoking exposure to cigarette produces selective impairment of neurogenic and endothelium-dependent relaxation of corpus cavernosum smooth muscle via a mechanism related to the decreased production and/or availability of nitric oxide.

Esophagitis impairs esophageal smooth muscle reactivity in the rat model: an in vitro study

The present study investigated how reflux-induced esophagitis affects the smooth muscle reactivity of the esophageal body. Two different esophagitis models were used: acid gastric and mixed duodenogastric reflux. All test animals apart from the controls developed gross and histologic evidence of esophagitis. Contractile (carbachol and KCI) and relaxant (isoproterenol) esophageal smooth muscle responses were significantly decreased in the presence of acid- and mixed reflux-induced esophagitis. Similar relaxant responses to serotonin and papaverine were found in the three groups. Our study demonstrated impaired esophageal smooth muscle reactivity when esophagitis was induced by acid or mixed reflux. These changes may correspond to the functional motor abnormalities of the esophagus seen in patients with reflux esophagitis.

Age-related smooth muscle reactivity changes in the rat bladder: an in vitro study

An experimental study was conducted to investigate developmental changes of the rat detrusor smooth muscle (DSM) reactivity from newborn to adult period. Urinary bladders were obtained from adult (4 months old), 1-month-old and newborn (4-7 days old) male Sprague-Dawley rats. DSM reactivity of the three groups was evaluated in organ chambers. The newborn DSM strips revealed markedly increased purinoceptor- and cholinoceptor-mediated contractions (ATP, carbachol) with increased maximum response (2.98- and 8.96-fold increase for ATP, 2.90- and 4.22-fold increase for carbachol, when the newborn bladder compared with 1-month-old and adult groups, respectively) and sensitivity (1.65- and 1.29-fold increase for ATP when the newborn bladder compared with the 1-month-old and adult groups, respectively). Additionally the maximum contractile response to KCl in the bladder from the newborn was 1.65- and 8.96-fold increased compared to bladders of the 1-month-old and adult groups, respectively. However, no significant changes in the adrenoceptor-mediated relaxation (isoproterenol) of the rat DSM were observed among the groups. These results indicate that development alters the in vitro responsiveness of rat DSM. The newborn rat bladder gains some of the adult bladder properties within 1 month. These changes are likely to reflect the changing role of parasympathetic regulation in the DSM reactivity during development of the rat bladder.

Impaired esophageal reactivity in adriamycin-induced rat esophageal atresia: an in vitro study

PURPOSE

The aim of this study was to investigate the reactivity of lower esophageal smooth muscle in the Adriamycin-induced esophageal atresia (EA) rat model.

METHODS

The fetuses were divided into 3 groups. The control group was exposed to saline. The second group comprised fetuses that were exposed to Adriamycin but in whom EA did not develop. The third group comprised of fetuses that were exposed to Adriamycin and EA was observed. The reactivity of distal esophageal strips was studied in organ chambers.

RESULTS

The tension was similar in all groups precontracted with carbachol for the study of relaxation to serotonin. Relaxation of lower esophageal strips to serotonin was comparably unaffected in the control and Adriamycin-no EA groups, whereas it was significantly inhibited in the EA group with decreased E(max) and pD(2) values. Contractile responses of esophageal smooth muscle to carbachol or 80 mmol/L KCl and relaxant responses to papaverine were similar in all groups. No change in agonist potency was observed among the groups.

CONCLUSIONS

Our study showed impairment of serotonin-receptor-mediated relaxation; but not of cholinoceptor-mediated contraction of the lower esophageal smooth muscle in the EA. Thus, impaired relaxant responses may be, at least in part, a contributing factor in the esophageal dismotility seen in EA.

Impaired neurogenic and endothelium-dependent relaxant responses of corpus cavernosum smooth muscle from hyperthyroid rabbits

We investigated the effect of hyperthyroidism on the responsiveness of the rabbit corpus cavernosum smooth muscle. In male albino rabbits, hyperthyroidism was established by oral feeding of L-thyroxine at increasing dosages (150-450 microg/kg) over an 8-week period. This treatment produced a stable hyperthyroid state as indicated by the increased serum T4 levels. The reactivity of corpus cavernosum tissue from hyperthyroid animals and euthyroid control animals was studied in organ chambers. Hyperthyroidism caused impaired neurogenic and endothelium-dependent relaxant responses with decreased Emax and pD2 values. However, hyperthyroidism had no effect on both phenylephrine- and KCl-induced contractile responses and sodium nitroprusside- and papaverine-induced endothelium-independent relaxant responses, and there was no change in agonist potency. These data indicate that hyperthyroidism may impair both neurogenic and endothelium-dependent relaxation of corporal smooth muscle, and may contribute to the etiology of impotence.

Chronic ethanol consumption impairs adrenoceptor- and purinoceptor-mediated relaxations of isolated rat detrusor smooth muscle

OBJECTIVE

To investigate the effects of chronic ethanol consumption on the reactivity of detrusor smooth muscle.

MATERIALS AND METHODS

Eight male rats received ethanol (7.2% v/v) in a modified liquid diet for 4 weeks. Two control groups were assessed; eight rats in one group were fed sucrose and received a liquid diet, and 12 rats in the second group received standard rat chow and water for 4 weeks. The reactivity of detrusor smooth muscle strips from ethanol-fed animals and control animals was evaluated in organ chambers.

RESULTS

The relaxation response elicited by isoprenaline or adenosine was unaffected in the both control groups while it was significantly inhibited, with decreased maximum responses and pD2 values, in the ethanol-fed group. Contractile responses of detrusor smooth muscle to carbachol or 80 mmol/L KCl and relaxant responses to papaverine were similar in the control groups and the ethanol-fed group. There was no change in agonist potency among the groups.

CONCLUSION

Chronic ethanol consumption impairs beta-adrenoceptor- and purinoceptor-mediated relaxation but not cholinoceptor-mediated contraction of the rat detrusor smooth muscle. Thus, it appears that different regulatory mechanisms are involved in ethanol-induced alterations in beta-adrenergic, purinergic and muscarinic receptors in detrusor strip.

Blood pressure and vascular reactivity to endothelin-1, phenylephrine, serotonin, KCl and acetylcholine following chronic alcohol consumption in vitro

Ethanol has been reported to cause hypertension, the mechanism of which is unknown. Therefore, the effect of chronic ethanol consumption on vascular responsiveness and blood pressure was investigated. Systolic blood pressure was recorded weekly by tail-cuff method. Aortic rings from rats fed chow ad libitum or pair-fed liquid diets containing either ethanol (7.2% v/v) or isocaloric carbohydrate for 4 weeks were placed in organ chambers for isometric tension measurement. There was a mild but significant elevation of the systolic blood pressure in the alcohol-fed rats by week 1 compared to baseline measurements and this remained higher. No significant changes in reactivity of rat isolated aortas to phenylephrine, serotonin, endothelin-1 (ET-1) and KCl were seen in chronic ethanol consumption. In addition, the sensitivity (i.e. pD2) of alcohol-fed aortic rings to the vasoconstrictors was also unchanged compared to controls. Chronic ethanol consumption, however, increased relaxation to acetylcholine with increased pD2 values, but did not alter relaxation to sodium nitroprusside, a cyclic guanosine monophosphate (cGMP)-dependent direct smooth muscle dilator. The results indicate that chronic ethanol consumption significantly potentiates endothelium-dependent relaxations in aortic rings, probably through interference with the production and/or the release of nitric oxide (NO) or adaptive alterations in muscarinic receptors on the endothelial cells, and that increased vascular responsiveness to several vasoconstrictors is not a mechanism responsible for the blood pressure elevation in the chronic alcohol consumption in rats.

Antidepressant, anxiogenic, and antinociceptive properties of levofloxacin in rats and mice

Levofloxacin, an optically active isomer of ofloxacin, is a fluorinated quinolone with a broad spectrum of antibacterial activity. Fluoroquinolones have been used for the treatment of bacterial infections for many years. Although they were considered as relatively safe drugs, various adverse effects have recently been reported along with increase in the usage of new-generation fluoroquinolones. In the present study, some of the central nervous system (CNS)-related side effects of levofloxacin were clarified in animals. Our results suggested that: levofloxacin (10-20-40 mg/kg i.p.) had no depression-like effect in the forced swimming test (FST) in rats; exerted anxiety-like effect in the elevated plus maze test in rats; did not alter the locomotor activity in rats; had no apparent effect on sleep latency but shortened the sleeping time on pentobarbital sleeping time in mice; and showed analgesic activity in acetic acid writhing and hot plate test in mice.

Investigation on the mechanism involved in the effects of agmatine on ethanol-induced gastric mucosal injury in rats

Effects of agmatine, an endogenous metabolite formed by decarboxylation of L-arginine, on ethanol-induced gastric mucosal injury were investigated in rats. Agmatine at 1 and 10 mg/kg i.p doses significantly increased ethanol-induced gastric mucosal injury. This effect of agmatine was abolished completely by pretreatment with idazoxan, an imidazoline receptor-antagonist and alpha2 receptor- antagonist, (0.5 mg/kg i.p), partly by yohimbine, an alpha2 receptor- antagonist, (1 mg/kg i.p) but not by L-arginine, a precursor of nitric oxide, (500 mg/kg i.p). Our results suggest that agmatine had a potent ulcerogenic effect mediated, at least in part, by both alpha2-adrenoceptors and imidazoline receptors.

Antidepressant-like effect of 7-nitroindazole in the forced swimming test in rats

RATIONALE

There is some strong evidence about the role of nitric oxide (NO) as an intercellular messenger in central physiological mechanisms. NO is synthesized from L-arginine by nitric oxide synthase (NOS), as a response to activation of N-methyl-D-aspartate (NMDA) receptors by excitatory amino acids. NMDA receptor antagonists also produce antidepressant-like actions in preclinical models.

OBJECTIVE

In the present study, the involvement of NO in the mechanism of depression was investigated. 7-Nitroindazole (7-NI) (15, 30, 60, 90 mg/kg IP), a selective inhibitor of neuronal NOS was examined.

METHODS

The Porsolt forced swimming test (FST) has been used as a test for screening new antidepressant agents.

RESULTS

7-NI dose-dependently decreased the immobility time in FST, but produced no significant change in locomotor activity in naive rats. Neither L-arginine, nor D-arginine (100 mg/kg) affected the immobility time in the FST or revealed any effect on locomotion. L-Arginine but not D-arginine, given 10 min before 7-NI, reversed the 7-NI-induced effect on immobility time.

CONCLUSIONS

Our findings suggest that NO might be an important modulator of depression in rats.

Anxiolytic-like effects of 7-nitroindazole in the rat plus-maze test

It is considered that nitric oxide (NO) is one of the most interesting research subjects. Because the actual role of NO in the mechanism of anxiety is still unclear, in this study, the involvement of NO in the mechanism of anxiety was investigated, using the plus-maze test. 7-Nitroindazole (7-NI) (15, 30, 60, 90, and 120 mg/kg), a new nitric oxide synthase (NOS) inhibitor was studied. The time spent on open arms and open-arm visits was evaluated. 7-NI, at 15-120 mg/kg doses potently increased the time spent on open arms and open-arm visits. However, at 120 mg/kg it attenuated the time spent on the open arms, compared to at 90 mg/kg. This effect was attributed to decreased locomotor activity in the higher dose group. Neither L-arginine, nor D-arginine (100 mg/kg) significantly affected any of the behavioral parameters measured in the rat elevated plus-maze test. Neither drugs revealed any effect on locomotion. L-Arginine but not D-arginine given 10 min before 7-NI, reversed the 7-NI induced anxiolytic-like effects. These data support an involvement of NO in the process of anxiety, and further suggest that the anxiolytic-like effect of 7-NI may be attributable to the inhibition of NO synthesis.

Dextromethorphan attenuates ethanol withdrawal syndrome in rats

The effects of dextromethorphan (DM), a noncompetitive antagonist of the N-methyl-D-aspartate (NMDA) receptors, have been investigated on ethanol withdrawal signs in rats. Ethanol (7.2% v/v) was given to rats in a liquid diet for 16 days. DM (10, 20, and 40 mg/kg) and saline were injected intraperitoneally at the third hour of ethanol withdrawal. DM (40 mg/kg) and ethanol dependent saline were also administered to ethanol naive rats. DM (40 mg/kg) did not produce any significant change in locomotor activity in ethanol naive rats. The effects of DM on locomotor activity and total ethanol withdrawal score were evaluated at the fourth and sixth hours of ethanol withdrawal. DM inhibited locomotor hyperactivity at these periods. DM also reduced total ethanol withdrawal score from the fourth hour to the sixth hour, and it significantly decreased audiogenic seizures. Seizure susceptibility after chronic ethanol exposure may be dependent upon sensitization or upregulation of NMDA processes and NMDA receptors. Our results suggest that inhibition of NMDA receptors by DM alleviates signs of ethanol withdrawal.

The effect of isradipine on maximal electroshock seizures in mice

1. The aim of this study was to investigate the possible anticonvulsant effect of a dihydropyridine calcium antagonist, isradipine, which easily crosses the blood-brain barrier displaying high affinity and specificity for the brain L-type voltage-sensitive calcium channel, on maximal electroshock seizures in mice. 2. Isradipine at i.p. doses of 2.5 mg/kg and 5.0 mg/kg was found to cause a statistically significant increase in the convulsion threshold of maximal electroshock seizures in a dose-dependent manner (P = 0.047 and P = 0.022, respectively). 3. It was concluded that the mode of action of the anticonvulsant effect of isradipine is related to blockade of the intraneuronal calcium currents, which play an important role in epileptic activity.

Is arachis oil a solvent only, or does it also have an effect on the central nervous system?

Peanut (Archis hypogaea L.) seed, an important oil crop (arachis oil) throughout the world, is grown in large quantities in Africa, India and China. The oil is used in many edible products, including shortenings, margarines and mayonnaise, as a cooking and frying oil and as a salad oil. Arachis oil contains fatty acids and antioxidants. It has been shown to be unexpectedly atherogenic in the diets of experimental animals (Chow 1992).

Antinociception induced by verapamil and chloramphenicol in mice

The analgesic effects of verapamil, a calcium channel blocker, and chloramphenicol, a phenicolated antibiotic, were compared using the test of acetic-acid-induced writhing and the hot-plate test in mice. The results suggest that both drugs have antinociceptive properties comparable to salicylate analgesia. No significant difference was found between verapamil- and chloramphenicol-induced analgesia (p < 0.05).

The effect of 7-nitro indazole on pentobarbital-induced sleep in mice

The sleep-wakefulness continuity is sensitive to a wide range of agents with pharmacological activity. There is some strong evidence about the role of nitric oxide (NO) as an intercellular messenger in the central physiological mechanisms. The effects of 7-nitro indazole (7-NI 15, 30, 60 mg kg-1; intraperitoneal, i.p.), a selective inhibitor of neuronal nitric oxide synthase (NOS) and L-arginine (500, 1000 mg kg-1, i.p.), a NO precursor, on pentobarbital (35 mg kg-1, i.p.) sleep were examined in mice. Loss of the righting reflex was used to determine the start of sleep. Sleep latency and sleeping time were evaluated in each experiment. 7-Nitro indazole (7-NI 30 mg kg-1; i.p.), had no apparent effect on sleep latency but significantly increased sleeping time (P < 0.02) on pentobarbital sleep in mice. L-Arginine had no effect on both parameters. These findings suggest that NO might be an important modulator of sleep regulation and implicate that inhibition of release and/or synthesis of NO might lead to changes in the maintenance of sleep.

Omeprazole, nitrendipine, famotidine and stress-induced ulcers

BACKGROUND

Omeprazole inhibits gastric acid secretion by blocking the proton pump of the gastric parietal cell. Nitrendipine is a derivative of the dihydropyridine group of calcium channel blockers and administrated for angina and hypertension. Famotidine is one of the newer histamine H2-receptor antagonists and heals gastric and duodenal ulcers by reducing gastric acid output.

OBJECTIVES

The healing effects of omeprazole, nitrendipine and famotidine on stress-induced gastric ulcers were investigated in rats.

METHODS

Forty male Wistar-albino rats were separated into five groups (n = 8), a control (non-stress) and four experimental (stress) groups. Experimental rats were treated with omeprazole, nitrendipine, famotidine or a placebo after the stresses of starvation and cold-restraint.

RESULT

Macroscopically, the mean area of the affected lesional mucosa was 1/4 of the total gastric mucosa in the famotidine treated group and 1/5 of the total gastric mucosa in the nitrendipine treated group. A considerably decrease was observed in the omeprazole treated group in which the mean area of the lesional mucosa was only in 1/8 of the total gastric mucosa. On microscopic examination, congestive vessels and chronic inflammatory cell infiltrates were significantly reduced in the omeprazole treated group. Tissue regeneration was more prominent in the omeprazole group than the other groups.

CONCLUSION

Omeprazole was found to be superior in terms of the effect on the healing process to nitrendipine and famotidine. Although therapeutic effects of nitrendipine and famotidine were observed, those were less than omeprazole.

Protective effect of fish oil against stress-induced gastric injury in rats

The effect of fish oil and olive oil on the gastric mucosal damage induced by cold-restraint stress was investigated in rats. The oils were dietary supplemented for 3 weeks. The results demonstrate that a diet containing fish oil, when ingested for 3 weeks before exposure to stress, protected from gastric ulceration significantly (p < 0.01) and led to a statistically significant increase both in mucus and phospholipid content of the gastric mucosal barrier (p < 0.02 and p <0.001, resp.) in cold-restraint stress-induced gastric injury in rats. However, further studies are required to determine the role of dietary fish oils in the prophylaxis and treatment of peptic ulcer.

Effect of fish oil on indometacin-induced gastric lesions in rats

The effect of fish oil in promoting the healing of indomethacin-induced gastric lesions was investigated in Wistar albino rats. After indomethacin treatment (30 mg/kg, s.c.), animals were given fish oil, olive oil, or normal diet for 48 h. The ulcer index was found to be decreased to 2.1 +/- 1.8 mm with fish oil, 13.7 +/1 5.4 mm with olive oil, and 14.6 +/- 2.4 mm with normal diet. Fish oil showed a potent healing-promoting effect on acute gastric erosions and ulcers induced by indomethacin and significantly enhanced the mucus content of the mucosa (p < 0.05).

Effect of oral pyridoxine hydrochloride supplementation on in vitro platelet sensitivity to different agonists

Effect of vitamin B6 (pyridoxine-HCl, CAS 58-56-0) on platelet aggregation, plasma lipids and serum zinc level was investigated. The trial comprised 24 healthy male volunteers, aged between 19-24 years. The subjects were randomized in two groups of 12 and treated for 4 weeks by a single daily oral dose of 5 mg/kg vitamin B6 or placebo. Pyridoxine inhibited ADP- or epinephrine-induced aggregation by 48% and 41% (p < 0.001), respectively, whereas there was no change in control group. No significant effect on either, bleeding time, coagulation time or on platelet count was demonstrated in subjects given placebo. Pyridoxine prolonged both bleeding and coagulation time but not over the physiological limits. It had no effect on platelet count. These observations strongly suggest that vitamin B6, with no effect on platelet count, not only inhibits platelet aggregation but also prolongs clotting time. Pyridoxine significantly reduced total plasma lipid and cholesterol levels, whereas it enhanced HDL-cholesterol level. Serum zinc level was also significantly increased by pyridoxine (p < 0.001). These findings suggest that oral vitamin B6 inhibits platelet aggregation in normal subjects.

Effects of vasoactive intestinal polypeptide on isolated rat urinary bladder smooth muscle

The effect of vasoactive intestinal polypeptide (VIP) on the contractile activity of the urinary bladder was investigated in the rat. VIP caused a weak contraction and a small potentiation of carbachol- and acetylcholine-induced contractions. The present results may provide the evidence that VIP could be a modulator in the urinary bladder.

[The effects of ciprofloxacin and ofloxacin on the cellular and humoral immune response in mice]

The effects of a 7 days chemotherapy with ciprofloxacin or ofloxacin on the cellular and humoral immune responses in albino mice were studied. The non-toxic doses of the drugs (10 or 30 mg/kg/day) were used. The delayed-type hypersensitivity reaction to sheep blood cells and skin biopsy were evaluated for cellular immune response. The complement fixation method was applied for the determination of the humoral immune response. Both drugs increased the cellular and humoral immune responses.

The effect of ofloxacin on pentobarbital-induced sleep in mice

There have been several reports that insomnia occurs in some patients who receive ofloxacin. Since almost no experimental data on ofloxacin-induced insomnia were available, this study was conducted for the evaluation of ofloxacin effects on sleep parameters in mice. In Experiment 1, mice were pretreated with ofloxacin (20 or 40 mg/kg IP) or saline 15 minutes before sodium pentobarbital (35 mg/kg IP). Experiment 2 was carried out in two days. On the first day mice were treated twice, in the morning and in the evening, with ofloxacin (20 or 80 mg/kg IP) or saline. On the second morning, mice were pretreated with the same doses of ofloxacin or saline 15 minutes before sodium pentobarbital (35 mg/kg IP). Sleep latency and sleeping time were recorded in each experiment. Results showed that ofloxacin had no apparent effect on sleep latency, but caused a shortening in sleeping time. However, this effect was significant only in the 40 and 80 mg/kg ofloxacin-treated groups.

Gastroprotective effect of nitrendipine on stress-induced gastric lesions in rats

The effects of nitrendipine on stress-induced acute gastric lesions were investigated in rats. Intraperitoneally injected nitrendipine (8, 16, or 32 mg/kg) given 30 min before stress, dose-dependently prevented gastric glandular ulceration. The anti-ulcer effects of nitrendipine were not reversible by indometacin or dexamethasone. These results suggest that calcium is important in gastric pathophysiology and that the proof of gastroprotective effects of calcium channel blockers is of great value in the development of new and improved therapies for treatment and prevention of gastric ulcers in humans.