Detection of salicylate and its hydroxylated adduct 2,3-dihydroxybenzoic acid in glutamate neurotoxicity and the effects of verapamil and ryanodine in rats.

It has been suggested that salicylate hydroxylation can be used to detect hydroxyl radical formation in vivo. In the present study we investigated the effects of verapamil and or ryanodine on salicylate (SA) and its hydroxylated adduct; 2,3-dihydroxybenzoic acid (2,3-DHBA) levels in glutamate induced neurotoxicity of whole rat brains. To detect SA and 2,3-DHBA, an HPLC-EC/UV method was used. Retention time was found to be 3.9 min for 2,3-DHBA and 12.0 min for SA. Verapamil at 10(-5) and 10(-7) and ryanodine at 10(-5) M concentrations were found to have a significant decreasing effect on this degradation induced by glutamate. This was the highest dose for ryanodine tested. As an L-type voltage dependent calcium channel blocker, verapamil was found ineffective at 10(-4), 10(-6) and 10(-8) M concentrations. Surprisingly, none of the combined application groups (verapamil + ryanodine) was found effective on SA hydroxylation. As a result, ryanodine was effective only at the highest dose, while verapamil exerts its effect in a dose dependent fashion as reported before in the literature.

Nimodipine improves kainic acid induced neurotoxicity in cerebellar granular cell culture: a double-blind dose-response study.

The neuroprotective role of nimodipine was tested in kainic acid (50 and 100 microM) induced neurotoxicity in cerebellar granular cell cultures of 4 to 7 day-old rat pups. Nimodipine was applied in 50, 100 and 200 microM concentrations. Kainate, in either dose, induced cerebellar granular cell death in respect to controls and the results were statistically significant (P = 0.000 for both doses). However, kainic acid in 100 microM concentration led to higher rates of cell death than 50 microM (P = 0.017). The neuroprotective role of nimodipine in kainate induced neurotoxicity was dose dependent. Kainate toxicity in 50 microM concentration was blocked by 50 and 100 microM nimodipine concentrations (P = 0.006 and P = 0.002, respectively) while 200 microM nimodipine was found ineffective. The most effective nimodipine dose for 100 microM kainic acid neurotoxicity was 200 microM (P = 0.000) while 50 and 100 microM concentrations of nimodipine were found ineffective. In this study, we have proven the dose-dependent neuroprotective role of nimodipine in kainate induced neurotoxicity in cerebellar granular cell cultures of rat pups.

Effects of norepinephrine on NMDA-induced neurotoxicity in cerebellar granular cell culture of rat pups.

In this study, norepinephrine was tested in 0.1, 1, 10, 25 and 50 microM doses in 100 microM NMDA toxicity on cerebellar granular cell culture of rats. NMDA in 100 microM concentration induced cell death significantly with respect to controls. Death cell population was 1.08 +/- 0.44% in control and 22.15 +/- 2.46% in 100 microM NMDA (P < 0.0001). None of the norepinephrine concentrations administrated 15 min prior to NMDA was able to reduce death cell scores to control levels. Results were 8.75 +/- 0.83% in 0.1 microM, 7.0 +/- 1.01% in 1 microM, 17.25 +/- 1.31% in 10 microM, 35.5 +/- 1.38% in 25 microM and 17.9 +/- 1.72% in 50 microM norepinephrine plus 100 microM NMDA administrated groups (P < 0.0001 for all with respect to control). Labetalol, as an alpha and beta blocker in 0.5 microM concentration which was given 15 min prior to norepinephrine was able to block the effects of it. In comparison with 100 microM NMDA administered group, only low doses of norepinephrine reduced the death cell scores significantly (for 0.1 and 1 microM norepinephrine plus NMDA groups; P < 0.0001). For 10 and 50 microM norepinephrine plus NMDA groups, death cell scores were found statistically insignificant from the NMDA-administered group (P > 0.05 for both) while for the 25 microM norepinephrine plus NMDA group, the death cell score was found to be statistically increased (P < 0.0001).

Sister chromatid exchange analysis in patients exposed to low dose of iodine-131 for thyroid scintigraphy.

To determine the genotoxic risk associated with diagnostic exposure to low doses of iodine 131 (131I), sister chromatid exchange (SCE) analysis was performed in lymphocytes of 18 non-smoking women who received 370 kBq (10 microCi) intravenous 131I sodium iodide as an adjuvant for scintigraphy for diagnosing thyroid nodularity. SCE frequencies were measured before and after 131I administration. SCE results in the pre-treated phase were regarded as control. Although SCE values 24 h after 131I administration did not show a significant increment (p > 0.05), there was a significant increase 72 h after treatment (p < 0.05). These results indicate that genetic damage might be induced by low dose of 131I.

Antiinflammatory effect of the aqueous extract from Rumex patientia L. roots.

Pharmacological studies were conducted with the aqueous extract of roots of Rumex patientia L. (Polygonaceae) on experimental animals. For evaluating the antiinflammatory activity, carrageenan, histamine, dextrane, serotonine formaldehyde-induced oedema tests, cotton-pellet granuloma, and Kabak tests in rats were used. The extract was found to possess antiinflammatory activity. Acute toxicity studies revealed that the extract up to a dose of 3 mg/kg orally was nontoxic.

Protective role of intramuscularly administered vitamin E on the levels of lipid peroxidation and the activities of antioxidant enzymes in the lens of rats made cataractous with gamma-irradiation.

PURPOSE: To determine the antioxidant role of vitamin E (VE) (10 mg/kg/day) against radiation-induced cataract in lens after total-cranium irradiation of rats with a single dose of 5 Gy. METHODS: Sprague-Dawley rats were divided into three groups. Group 1 did not receive VE or irradiation but received both 0.1 ml physiologic saline intraperitoneally and sham irradiation (control group). Group 2 received to total cranium 5 Gy of gamma irradiation as a single dose (RT group) plus 0.1 ml physiologic saline intraperitoneally. Group 3 received irradiation to total cranium plus 10 mg/kg/day VE (RT+VE group). The rats were irradiated using a cobalt-60 teletherapy unit. Chylack's cataract classification (1) was used in this study. At the end of 10 days, the rats were killed and their eyes were enucleated to measure the antioxidant enzymes (the activity of superoxide dismutase [SOD], glutathione peroxidase [GSH-Px]) and lipid peroxidation level (malondialdehyde [MDA]). RESULTS: While grade 1 cataract development was detectable in seven rats in the RT group, it was detectable only in two rats in the RT+VE group, whereas none of the rats in the control group exhibited any biomicroscopic change in their lenses. MDA level and GSH-Px activity in the rat lens in the RT group was significantly higher than in the control group. SOD activity in the RT group was lower than in the control group. The activity of SOD and GSH-Px enzymes was higher in the RT+VE group, but MDA level was lower in the RT+VE group when compared with the RT group. CONCLUSIONS: Vitamin E has a protective effect on radiation-induced cataract by decreasing oxidative stress.

Effect of the aqueous extract of Rumex patientia on xylol and hyaluronidase induced capillary permeability compared to indomethacin.

In this study, the effect of an aqueous extract of Rumex patientia L. (Polygonaceae) (D-1) on capillary permeability which was induced by xylol and hyaluronidase was investigated. Experiments were conducted on rabbits according to Monakova and Matusis methods. The effects of D-1 were compared to those of indomethacin, which was used as a control throughout the experiment. Both D-1 (100 mg/kg) and indomethacin (10 mg/kg) were administered orally. As a result, D-1 inhibited capillary permeability, which was induced by xylol and hyaluronidase, and it was found that it was as effective as indomethacin.

Effects of Leontice smirnowii tuber monodesmosides and crude extract in carrageenan- and histamine-induced acute inflammation model of rats.

Leontice smirnowii is a member of the Berberidaceae family. We have recently reported the 1,1-diphenyl-2-picryl-hydrazyl radical scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging, reducing power and metal chelating activities of L. smirnowii products. In the current study we investigated the possible effects of the crude extracts of L. smirnowii (CELS) and the monodesmoside's purified extract (MPE) of L. smirnowii in the carrageenan- and histamine-induced acute inflammation models in rats. The experiment revealed that CELS and MPE have anti-inflammatory effects, dose dependently in carrageenan-induced acute inflammation. On the other hand, their proinflammatory effects were surprisingly observed, especially in low doses, in the histamine-induced acute inflammation model. Summarizing these data, we may state that CELS and MPE exert their anti-inflammatory effects via non-histaminergic pathways.

Screening of antiradical and antioxidant activity of monodesmosides and crude extract from Leontice smirnowii tuber.

Leontice smirnowii is a member of the Berberidaceae family. In the current study we investigated the possible antiradical and antioxidant activity of the monodesmosides (MLS) and crude extract (CELS) of Leontice smirnowii using different antioxidant tests: 1,1-diphenyl-2-picryl-hydrazyl (DPPH) free radical scavenging, scavenging of superoxide anion radical-generated non-enzymatic system, ferric thiocyanate (FTC) method, reducing power, hydrogen peroxide scavenging and metal chelating activities. Experiment revealed that MLS and CELS have an antioxidant effect concentration-dependently. Total antioxidant activity was performed according to FTC method. At the 30mug/ml concentration, the inhibition effects of MLS and CELS on peroxidation of linoleic acid emulsion were found to be 95.3% and 95.6%, respectively. On the other hand, percentage inhibition of butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), alpha-tocopherol and trolox were found to be 98.2%, 98.5%, 84.0% and 87.9% inhibition of peroxidation of linoleic acid emulsion, respectively, at the same concentration. In addition, MLS and CELS had effective DPPH radical scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging, reducing power and metal chelating activities. Also, these various antioxidant activities were compared with BHA, BHT, alpha-tocopherol and trolox which were accepted as references antioxidants.

Is growth hormone a radioprotective agent?

There is currently substantial clinical interest in growth hormone (GH) as a protective agent against radiation-related normal tissue injury. To further assess the potential radiation injury-preventive effects of GH, these effects were studied in rats by using a radiation-induced skin injury model. Group 1 received neither GH nor irradiation (control group). Group 2 received 30 Gy of gamma irradiation as a single dose to the right hind legs of the rats (radiation group). Group 3 and 4 received the same irradiation plus either 0.01 U/kg/day GH (RT + 0.01 GH group) or 0.02 U/kg/day GH (RT + 0.02 GH group) subcutaneously. Clinically and histopathologically, acute skin reactions were assessed by two independent experts in radiation oncology and pathology, respectively. Irradiation increased dermatitis in rats when compared with the control group. The severity of radiodermatitis in the rats in the RT + 0.01 GH and RT + 0.02 GH groups was significantly lower than that in the RT group; radiodermatitis developed earlier in the RT group than in the other groups. GH was efficacious in preventing epidermal atrophy, dermal degeneration such as oedema and collagen fibre loss, and hair follicle atrophy, but not better than in the control group. These results are preliminary to studies that will be performed with higher doses of GH in radiation-treated cancer patients, with the aim of reducing radiation-induced toxicity.

Acute anti-inflammatory activity of four saponins isolated from ivy: alpha-hederin, hederasaponin-C, hederacolchiside-E and hederacolchiside-F in carrageenan-induced rat paw edema.

The anti-inflammatory potential of alpha-hederin (monodesmoside) and hederasaponin-C from Hedera helix, and hederacolchisides-E and -F (bidesmosides) from H. colchica was investigated in carrageenan-induced acute paw edema in rats. Saponins and indomethacin were given orally in concentrations of 0.02 and 20mg/kg body wt. For the first phase of acute inflammation, indomethacin was found as the most potent drug. Alpha-hederin and hederasaponin-C were found ineffective, while hederacolchisides-E and -F showed slight anti-inflammatory effects on the first phase. For the second phase of acute inflammation, indomethacin and hederacolchiside-F were determined as very potent compounds. alpha-hederin was found ineffective for the second phase, either. Despite hederasaponin-C and -E were found effective in the second phase of inflammation, they were not found as effective as indomethacin and hederacolchiside-F. As a conclusion, hederasaponin-C, -E and -F, may exert their anti-inflammatory effects by blocking bradykinin or other inflammation mediators. The latter affect may occur via affecting prostaglandin pathways. Regarding the structure activity relationship, it is likely that sugars at C3 position and Rha7-Glcl-6Glc moiety at C28 position are essential for the acute anti-inflammatory effect.

A simple tremor model induced by pentobarbitone in guinea pig.

We have recently reported that a combined application of chlorpromazine and pentobarbitone induced intermittently occurring tremor bursts in guinea pigs (Tan et al., in press). This was a chance discovery. It will be shown in the present work that chlorpromazine is not essential for this postural tremor; only pentobarbitone in low dosages produced intermittent tremor bursts in guinea pigs lying in a supine position. Chlorpromazine alone was not effective in producing tremor. The pentobarbitone-induced tremors were attenuated by the i.v. application of biperiden or lioresal. These results indicate that these tremors would be produced by the basal ganglia as in Parkinsonism.

Intermittent tremor-bursts induced by chlorpromazine and pentobarbitone in guinea pigs: a new tremor model.

It was discovered by serendipity that a combined application of chlorpromazine (3.5 mg/kg) and pentobarbitone (20.0 mg/kg) induced intermittent tremor-bursts in four extremities of guinea pigs. This tremor with a prominent extensor activity disappeared after spinalization, indicating a supraspinal process. Biperiden reduced the frequency and amplitude of the tremor, which was further diminished by amantadine. Baclofen was found to be most potent drug in suppressing tremor. It was suggested that the cortico-striato-pallido-thalamo-cortical feedback loop may be impaired by a combined action of chlorpromazine and pentobarbitone. This new animal model for drug-induced tremor would be of considerable importance with regard to physiological, biochemical, pharmacological and pathological aspects of motor control.

Parkinsonian-like tremor induced by a combined application of chlorpromazine and pentobarbitone in cats with left-paw preference.

A Parkinsonian-like tremor can be induced by a combined application of chlorpromazine and pentobarbitone in cats. Interestingly enough, only cats with left-paw preference were found to have a predisposition to this drug-induced tremor. The cats with ambidexterity and right-preference in paw use did not show any visible tremorogenic action of these drugs. Especially the proximal muscles of all four extremities showed oscillations with a frequency of about 12 per second in all animals tested, which completely disappeared after i.v. application of lioresal, atropine and biperiden. It was suggested that this new drug-induced tremor model may reflect an impairment within the cortico-striato-pallido-thalamo-cortical feedback loop. It was also concluded that left-handers may have an increased predisposition to centrally acting drugs than nonleft-handers.

Acute and chronic antiinflammatory profile of the ivy plant, Hedera helix, in rats.

Hedera helix is a plant well-known as ivy or English ivy, and a member of the Araliaceae family. In the present study, we tested the possible antiinflammatory effects of a crude saponin extract (CSE) and a saponin's purified extracts (SPE) of Hedera helix in carrageenan- and cotton-pellet-induced acute and chronic inflammation models in rats. Both the CSE and SPE of Hedera helix were found to have antiinflammatory effects. The most potent drug screened was indomethacin (89.2% acute antiinflammatory effect), while the most potent extract screened was the CSE of Hedera helix at 100 and 200 mg/kg body wt. doses with 77% acute antiinflammatory effects. For testing chronic antiinflammatory (antiproliferative) effects, the cotton-pellet-granuloma test was conducted. Indomethacin was found to be the most potent drug in the chronic phase of inflammation, with 66% effect. The SPE of Hedera helix was more potent than the CSE in its chronic antiinflammatory effect (60% and 49%, respectively).

Effects of salicylic acid in glutamate- and kainic acid-induced neurotoxicity in cerebellar granular cell culture of rats.

Glutamate (10(-7)m) and one of its non-NMDA receptor agonists, kainic acid (10(-4)m), were administered to rat cerebellar granular cell cultures, and the neuroprotective role of salicylic acid was examined. Glutamate induced 38.58 +/- 1.45% neuronal cell death while kainic acid induced only 21.4 +/- 2.01% despite being 1000 times more concentrated. The most effective dose for the neuroprotective effect of salicylate in glutamate-induced neurotoxicity was 10(-5)m and it had no protective effect at 10(-7)m. With kainic acid-induced toxicity, 10(-6)m salicylate had no protective effect but 10(-5)m and. 10(-4)m salicylic acid were very effective against kainic acid-induced toxicity. As an OH-trapping agent, salicylate had a protective role in NMDA and non-NMDA receptor-activated neuronal cell death. The present study gives some important clues about oxygen free radical generation having an important role in glutamate- and kainic acid-induced neurotoxicity. On the other hand, the neuroprotective effects of salicylic acid in the present study may depend on the pH alterations in salicylic acid solutions.

The effects of melatonin in glutamate-induced neurotoxicity of rat cerebellar granular cell culture.

In the present study, melatonin was tested in subsequent doses in glutamate induced neurotoxicity in cerebellar granular cell culture of rat pups. Glutamate at 10(-7) M was found to induce neuronal cell death. The dead cell score was 2.75+/-0.7 in the control, while it was found to be 35.12+/-1.8 in the glutamate-administered group (P<0.0001). Melatonin very potently blocked glutamate neurotoxicity at all doses tested, with 10(-3) M, the highest dose tested, being the most effective. Glutamate may exert a neuroprotective effect by blocking one or more steps of the oxidation cascade in neurons and this effect may be blocked by melatonin.

Response to nimodipine in caffeine-induced neurotoxicity in cerebellar granular cell culture of rat pups.

Methylxanthines (theophylline, theobromine and caffeine) are widely used as central nervous system stimulants and caffeine is used in the treatment of apnea in newborns. Plasma therapeutic concentration of caffeine is around 110 microM. Caffeine diffuses the blood brain barrier easily, increasing oxygen consumption in neurones and leading to cell death. In the present study, 4-7-day-old rats were used to obtain cerebellar granular cell cultures. Caffeine was used 50, 150, 250 and 350 microM concentrations and the most toxic dose for it was found to be 350 microM. Death cell scores were 0.9+/-0.63 for control, 1.1+/-0.63 for 50 microM, 0.89+/-0.47 for 150 microM (P>0.05 for both), 3.84+/-0.8 for 250 microM (P=0.024) and 6.2+/-0. 86 for 350 microM (P=0.001) caffeine concentrations. The role of voltage-dependent calcium channels in caffeine-induced neurotoxicity was tested with the doses of 100 and 200 microM nimodipine 45 min before or after the 350 microM caffeine. Both doses of nimodipine after caffeine administration were found to be ineffective in blocking neurotoxicity. Doses administered 45 min prior to caffeine, reduced death cell score to 0.89+/-0.23 (P=0.000) for 100 microM nimodipine and 2.35+/-0.96 (P=0.000) for 200 microM nimodipine administration into the cultures. A dose-dependent manner of nimodipine in ischemic states is well-known. In the light of these results, nimodipine may be used in the treatment of newborn apneas together with caffeine to prevent neurotoxic side effects of high or repeated doses of it.

The effects of dantrolene alone or in combination with nimodipine in glutamate-induced neurotoxicity in cerebellar granular cell cultures of rat pups.

Despite the existence of some positive and negative reports on dantrolene in ischemic states, combined application of an endoplasmic reticulum Ca2+ release inhibitor and a calcium channel blocker has not yet been elucidated. In the present study, we have investigated the role of dantrolene in subsequent doses alone or in coexistence with the dihydropyridine calcium antagonist nimodipine (10(-4) M concentration) in glutamate-induced (10(-7) M) neurotoxicity in cerebellar granular cell cultures of rat pups. Glutamate induced neuronal cell death at a concentration of 10(-7) M. Despite the fact that none of the groups tested were able to reverse cell death to control values, dantrolene was found to be effective in preventing glutamate toxicity in cerebellar cultures of rat pups. The protective effect of dantrolene potentialized in combination with nimodipine at all doses tested. The most effective dose of dantrolene was found to be 10(-4)M in combination with nimodipine. As a result, both extracellular and internal calcium stores play important roles in the genesis of neuronal cell death induced by glutamate.

Antiulcerogenic effect of Hippophae rhamnoides L.

The antiulcerogenic effect of a hexane extract (HRe-1) from Hippophae rhamnoides (Eleagnaceae) was tested on indomethacin- and stress-induced ulcer models. As a result HRe-1 was found to be active in preventing gastric injury.