Polyethylene glycol: its adverse gastric effects in rats

Multiscale Spectral Analysis on Lysozyme Aqueous Solutions in the Presence of PolyEthyleneGlycol

Infrared spectroscopy measurements were performed on Lysozyme aqueous solutions also in the presence of PolyEthylene Glycol (PEG 400) as a function of an increasing temperature from T = 27 °C to 90 °C, and, successively in sequence, by decreasing temperatures from T = 90 °C to 27 °C. Data were analyzed by evaluating the spectral difference with respect to the initial spectrum collected at 27 °C. This procedure allows to quantitatively evaluate the thermal restraint related to the thermal scan from T = 27 °C to 90 °C, as well as to introduce a spectral resilience concerning the entire increasing and decreasing thermal paths which allow to highlight the bioprotectant effectiveness of low molecular weight PEG. In particular, the main purpose of the present work is to highlight the effects of a thermal treatment on a mixture of Lysozyme/water and of Lysozyme/water/PEG 400 during an increasing temperature scan, and then after a successive decreasing temperature scan, in order to highlight the bioprotectant role of PEG 400. On that score, an evaluation of the spectral distances of the registered spectra as a function of increasing and decreasing temperatures has been performed and analyzed.

Adrenalectomy-induced cell death in the dentate gyrus: further characterisation using TUNEL and effects of the Ginkgo biloba extract, EGb 761, and ginkgolide B

This study investigated the potential neuroprotective effects of the Ginkgo biloba extract, EGb-761, and ginkgolide B, on adrenalectomy (ADX)-induced cell death in the dentate gyrus (DG). Adrenalectomised, sham surgery-treated, and naive controls received either EGb-761 (25, 50, or 100 mg/kg), 0.9% saline vehicle control, ginkgolide B (10 or 25 mg/kg), or a polyethylene glycol vehicle control, i.p, daily for 6 days postsurgery. Cell death in the DG was determined by in situ labelling of DNA fragments, using the TUNEL method; sections were counterstained with hematoxylin. Radioimmunoassay was used to confirm a decrease in plasma corticosterone (CORT) after ADX. TUNEL-positive granule cells were observed in the DG at 1 week, but not at 24 h, post-ADX. The rate of granule cell death at this time was highest in the suprapyramidal blade and increased in a crest tip and a rostrotemporal gradient. Whereas CORT replacement completely prevented the occurrence of TUNEL-positive granule cells, EGb-761 and ginkgolide B did not, at any of the doses used. These results suggest that these drugs may not have substantial neuroprotective effects in the ADX model of neurodegeneration.

Gastric acid secretion in L-histidine decarboxylase-deficient mice

BACKGROUND & AIMS

Histamine, gastrin, and acetylcholine are known to be the primary secretagogues of gastric acid secretion, but how the roles are shared among these secretagogues remains to be fully clarified. To evaluate the cooperation between histamine and the other secretagogues, acid secretion responses induced by each secretagogue were measured in L-histidine decarboxylase (HDC)-deficient mice.

METHODS

Acid secretion was measured by the titration of acid under anesthesia. The expression of selected genes involved in acid secretion was determined by Northern blot and/or immunoblot analysis. Histamine-2 (H(2)) receptor binding in the gastric mucosa was investigated using [(3)H]tiotidine.

RESULTS

HDC-deficient mice showed low basal and high exogenous histamine-stimulated acid secretion. The mutant mice showed hypergastrinemia and did not undergo acid secretion upon treatment with exogenous gastrin. However, carbachol stimulated weak and transient acid secretion in the mutants. The Bmax values for H(2) and the expression of Gs alpha in gastric mucosal membranes were higher in the mutants than in the wild-type mice.

CONCLUSIONS

This study confirms the concept that histamine production is essential for gastric acid secretion induced by gastrin, but not for that induced by carbachol. HDC-deficient mice should be a suitable model for further functional analyses of the correlation between histamine and the other acid secretagogues.

Effects of polyethylene glycol 400 (PEG 400) following 13 weeks of gavage treatment in Fischer-344 rats

Fischer-344 rats (10/group/sex) were administered polyethylene glycol 400 (PEG 400) by gavage at 1.0, 2.5 or 5.0 ml/kg (1.1, 2.8 and 5.6 g/kg, respectively) body weight/day 5 days/wk for 13 wk. Animals in the control group received water by gavage (5.0 ml/kg body weight/treatment day). An additional 10 rats/sex/group were assigned to the control and high-dose groups for a 6-wk recovery period. Evaluation of potential renal toxicity was identified as a primary objective. There was no mortality or changes in haematology or clinical chemistry measurements attributed to PEG 400 toxicity. Loose faeces in the mid- and/or high-dose group of both sexes were attributed to bulk cathartic effects of PEG 400. Slight decreases in food consumption and body weights in the mid- and/or high-dose group of male rats and female rats were attributed to the physical presence of PEG 400 in the intestinal tract. However, a direct effect of PEG 400 on the intestinal tract was not ruled out. Increased water consumption was attributed to a possible increase in serum osmolality due to the absorption of the PEG 400 or a reflection of the water dosing received by the control animals. Increased urinary concentration and decreased urinary pH were at least partially attributed to absorption, possible metabolism, and urinary excretion of PEG 400. Small increases in absolute and/or relative kidney weights observed in many dose groups, were attributed to the osmotic effect of the test substance and/or metabolites in the urine. The significance of a slight increase in relative kidney weights in female rats following the recovery period was unknown. Although no microscopic changes were observed in the kidneys or urinary bladder, a slight, reversible renal toxicity may have resulted in male rats treated by gavage with 2.5 ml/kg/day and rats of both sexes treated by gavage with 5.0 ml PEG 400 kg/day. This was based on the increased concentration of protein and bilirubin, urinary vascular cell findings and N-acetyl-beta-D-glucosaminidase activity.