Stomach Toxicity Research Articles

Ebselen as Protection Against Ethanol-Induced Toxicity in Rat Stomach

The mucosal protective effect of ebselen was examined in an ethanol-induced rat gastric lesion model. Examination of gastric tissue samples by light microscopy showed that i.g. exposure to 50% ethanol induced gastric injury, which was more prominent in female rats. Ethanol did not effect the gastric acid secretion examined by means of H(+)-K+ATPase, the increment of which might be harmful in the stomach. But ebselen with or without ethanol kept H(+)-K+ATPase below control levels. Gastric alcohol dehydrogenase (ADH) was mainly responsible for oxidation of ethanol in the stomach before it enters the bloodstream. I.g. ethanol exposure inhibited the ADH activity but ebselen eliminated the ethanol-induced inhibition of this enzyme. Therefore, ebselen exhibited a beneficial effect by increasing the gastric ethanol metabolism and by ameliorating the possible tissue toxicity of ethanol. Consistently, we also found that ebselen diminished the blood ethanol level. A gender difference in the blood ethanol levels existed following the same dose of ethanol but there was no difference in ADH activity. Histologically, mucosal injury following ebselen exposure together with ethanol was less severe compared with ethanol treatment alone. We concluded that the decrease in ethanol-induced mucosal injury following ebselen may have contributed to the inhibition of H(+)-K+ATPase and the activation of ADH by ebselen.

Quantitation of an Epithelial S-Phase Response in the Rat Forestomach and Glandular Stomach Following Gavage Dosing with Ethyl Acrylate

Gavage dosing of the irritant, ethyl acrylate (EA), has been found to induce hyperplasia in the rat forestomach, but no signs of toxicity in the glandular stomach or in organs remote from the site of dosing. To quantitatively describe this effect as a background for subsequent modeling studies, pulse measurements of the number of S-phase cells were made following a single gavage dose of EA. The time-course of the S-phase response in the forestomach epithelium following a high dose (200 mg/kg or a 4% solution in corn oil) indicated that the number of S-phase nuclei was decreased relative to control animals immediately following gavage dosing with a minimum at 6 hr, but that the number of S-phase nuclei increased significantly above control values by 20 hr and remained significantly elevated until at least 48 hr following the gavage dose. A single-dose dose-response study with gavage doses of 0, 2, 10, 20, 50, 100, or 200 mg/kg EA and S-phase analysis at 24 hr following gavage dosing indicated that a significant increase in S-phase nuclei was evident at doses of 20 mg/kg or higher. Dosing with EA for 2 weeks at dose levels of 0, 10, 50, or 200 mg/kg caused a prolonged elevation of S-phase nuclei only at the 200 mg/kg dose level during the 24 hr following the last gavage dose. Lower doses did not induce a significant increase in the S-phase nuclei. In contrast to the forestomach, the S-phase response of the glandular stomach was transient following a single 200 mg/kg gavage dose, and only a marginal response was observed following multiple 200 mg/kg doses. No effects were observed at lower doses. Comparison of these results to prior determinations of the effect of EA on the concentration of nonprotein sulfhydryls (primarily glutathione) in the forestomach and glandular stomach indicate a correlation of the stimulation in S-phase activity in the forestomach with the repletion and overshoot of tissue nonprotein sulfhydryl levels

Evaluation of Some Essential Oils as Repellents to the Indian HoneybeeApis Cerana Indica1. Gustatory Repellency and Toxicity

SummaryEssential oils were obtained by water distillation of seeds of ajwan (Trachyspermum ammi (L.)) and leaves of chenopodium (Chenopodium ambrosioides L.), citronella (Cymbopogon nardus (L.)), eucalyptus (Eucalyptus spp.) and lantana (Lantana camara L.). Oils were evaluated in the laboratory for gustatory repellency (CCR50) and stomach toxicity (LD50) to worker honeybees of A. c. indica using benzaldehyde as a reference standard. Oils of ajwan, citronella, chenopodium, lantana and eucalyptus respectively were 6·49, 5·95, 3·20, 1·31 and 0·69 times as repellent and 3·74, 1·15, 2·15, 1·10 and 1·36 times as toxic to bees as benzaldehyde. The order of safety to bees (ratio of LC50 to CCR50) was citronella (11·36) > ajwan (3·81) > chenopodium (3·27) > lantana (2·62) > benzaldehyde (2·19) > eucalyptus (1.11). On the basis of its high gustatory repellency, low toxicity and high margin of safety, citronella appears to be a promising candidate for further repellency tests.

Susceptibility to Acaricides of the Mite Tetranychus cinnabarinus Infesting Cotton in Egypt12

The susceptibility to acaricides of the mite Tetranychus cinnabarinus Boisduval, which infests cotton in Egypt, was determined. Fourteen acaricides, 10 organophosphorus and 4 chlorinated hydrocarbons, were evaluated in the laboratory for their contact or contact plus stomach toxicity on the adult female mites and also for their ovicidal effect. The organophosphorus acaricides were more toxic by contact and contact plus feeding than the chlorinated hydrocarbons. Most of the organophosphates were more toxic by contact plus feeding than by contact alone. By contact carbophenothion was the most effective, followed by Elcatin® ( O,O -dimethyl-5-ethylthioethyl phosphorodithioate), and parathion. Dicofol and Aramite® (2 ( p-tert -butylphenoxy) isopropyl-2-chloroethyl sulfite) were intermediate in their contact effect, but tetradifon and ovex were poor. Most chlorinated hydrocarbons were more toxic than most organophosphates to the eggs. All organophosphates were more toxic to the adult females than to the eggs, while the opposite was true for the chlorinated hydrocarbons except for Aramite. Tetradifon, though poor on adult females, was the most toxic of the 14 acaricides to the mite eggs. To evaluate the combined effect on adults and eggs, a toxicity index was calculated for each acaricide. Carbophenothion had the highest value. The LD50 values for the strain used in this study generally agreed with those of susceptible strains previously tested. Thus the strain could be considered susceptible to most of the acaricides tested.

Time of Feeding in Relation to the Toxicity of a Stomach Poison to the Desert Locust

PEARSON1 first showed that the stomach toxicity of dieldrin to fifth-instar hoppers (nymphs) of the desert locust (Schistocerca gregaria Forsk.) was increased by a period of starvation after treatment and suggested that this was due to variation in the rate of passage of the poison through the gut. We have confirmed and extended his observations and are directing attention to them because there appears to be little published information on the effects of starvation on the toxicity of stomach poisons to insects2 although attention has been given to the effects of the diet fed to insects before they are used for experimental purposes3.