Alteration of gastroduodenal acetylcholine metabolism induced by 2-deoxy-D-glucose in rats

Glucose enrichment impair neurotransmission and induce Aβ oligomerization that cannot be reversed by manipulating O-β-GlcNAcylation in the C. elegans model of Alzheimer's disease

Amyloid beta (Aβ) plaques formation and impaired neurotransmission and neuronal behaviors are primary hallmarks of Alzheimer's disease (AD) that are further associated with impaired glucose metabolism in elderly AD's patients. However, the exact role of glucose metabolism on disease progression has not been elucidated yet. In this study, the effect of glucose on Aβ-mediated toxicity, neurotransmission and neuronal behaviors has been investigated using a C. elegans model system expressing human Aβ. In addition to regular diet, worms expressing Aβ were supplemented with different concentrations of glucose and glycerol and 5 mM 2-deoxyglucose to draw any conclusions. Addition of glucose to the growth medium delayed Aβ-associated paralysis, promoted abnormal body shapes and movement, unable to restore impaired acetylcholine neurotransmission, inhibited egg laying and hatching in pre-existing Aβ-mediated pathology. The harmful effects of glucose may associate with an increase in toxic Aβ oligomers and impaired neurotransmission. O-β-GlcNAcylation (O-GlcNAc), a well-known post-translational modification is directly associated with glucose metabolism and has been found to ameliorates the Aβ- toxicity. We reasoned that glucose addition might induce O-GlcNAc, thereby protect against Aβ. Contrary to our expectations, induced glucose levels were not protective. Increasing O-GlcNAc, either with Thiamet-G (TMG) or by suppressing the O-GlcNAcase (oga-1) gene does interfere with and, therefore, reduce Aβ- toxicity but not in the presence of high glucose. The effects of glucose cannot be effectively managed by manipulating O-GlcNAc in AD models of C. elegans. Our observations suggest that glucose enrichment is unlikely to be an appropriate therapy to minimize AD progression.

Effect of 2-deoxy-D-glucose on acetylcholine and histamine levels in gastric juice of pylorus-ligated rats anesthetized with urethane

Acetylcholine (ACh) in gastric juice was detected and measured by pretreatment of acetylcholinesterase inhibitor, 1 mM eserine (1 ml/rat, p.o.), in pylorus-ligated rats, by liquid chromatography with electrochemical detection. In order to elucidate whether or not the ACh level in gastric juice reflects the activity of cholinergic neurons, the effect of 2-deoxy-D-glucose (2-DG), a vagus stimulant, on the levels of ACh, histamine and gastric acid in gastric juice was investigated in pylorus-ligated rats anesthetized with urethane (1.25 g/kg, i.p.). Under the non-anesthetic condition, ACh, histamine and gastric acid levels were 100+/-25 pmol/h, 120+/-10 ng/h, and 240+/-32 microequiv./h, respectively. These levels were completely inhibited by urethane anesthesia. Under the anesthetized condition, 2-DG (50-200 mg/kg, i.v.) significantly increased ACh and histamine levels in gastric juice, as well as acid secretion. The 2-DG (200 mg/kg, i.v.)-induced increases in these levels were completely inhibited by vagotomy. These results suggest that ACh level measured in gastric juice reflects the activity of cholinergic transmission. Furthermore, these results also support the conclusion that vagus stimulation facilitates not only cholinergic transmission but also histaminergic transmission related to gastric acid secretion.

Dyspepsia in general practice: history and symptoms in relation to Helicobacter pylori serum antibodies

BACKGROUND

This study was designed to explore the relationships between serologic Helicobacter pylori positivity and demographic, behavioural, and symptomatologic factors in patients consulting for dyspeptic symptoms in general practice.

METHODS

H. pylori enzyme-linked immunosorbent assay results and checklist data were collected by general practitioners at three community health centers in southern Sweden from consecutive patients aged 18-65 years with upper abdominal pain or discomfort (dyspepsia).

RESULTS

Of the 130 available patients with dyspepsia, 127 agreed to participate, 45 (mean age, 41.2 years) being classified as H. pylori-positive and 82 (mean age, 33.5 years) as H. pylori-negative. Manual workers were diagnosed as H. pylori-positive significantly more often than were non-manual workers (p < 0.05). Of those patients examined earlier by gastroscopy or roentgenography, H. pylori-positives reported stomach or duodenal ulcer significantly more often than did H. pylori-negatives (p < 0.01). H. pylori-positives reported stomach/duodenal ulcer in their parents/siblings to a significantly greater extent than did H. pylori-negatives (45.2% versus 10.1%, p < 0.001). H. pylori-negatives reported stress-generated symptoms significantly more often than did H. pylori-positives (82.9% versus 61.5%, p < 0.01). Hierarchical regression analyses showed that, when age and sex were controlled for, the ability of each of these measures to predict the serologic results remained significant.

CONCLUSIONS

Higher levels of H. pylori antibodies in dyspeptic patients appear to be associated with a relatively low self-perception of stress, with manual work, with being older, and with the occurrence, both in the patients themselves and in their close relatives, of stomach/duodenal ulcer.