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Encoding meal in integrated vagal afferent discharge

100%

Krolczyk G., Zurowski D., Sobocki J., Laskiewicz J., Thor P. J.

Journal of Physiology and Pharmacology

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2004

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tom 55

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nr 1,1

Vagal afferents are integral part of the negative feedback loop induced by constitution and size of food stomach and jejunum. Aim of this study was to assess vagal discharge in response to food and gastric distension in rats. Electrophysiological recordings of vagal afferents in fasted (n=32), fed rats (n=20) and during gastric balloon distension (n=12) were performed. After 60 minutes of fasted nerve recording tube feeding was done. Fasted rats also underwent gastric distension via oesophagus. Vagal afferents discharges were analysed with dual time-amplitude window discriminator. Total vagal afferent discharge in fasted and fed rats revealed 0.3 ± 0.12 vs 0.56 ± 0.22 Hz (p<0.05). We observed two distinct discharge patterns: high amplitude low frequency (HALF) and low amplitude high frequency (LAHF). HALF spikes were observed more frequent in fasted than in fed rats (0.05 ± 0.02 vs. 0.03 ± 0.016 Hz (p<0.05). Conversely LAHF spikes in fed rats predominated over their occurrence in fasted rats: 0.52 ± 0.2 vs. 0.25 ± 0.12 Hz (p<0.05). Left vagal afferents discharge rises with gastric distension of 6, 8 and 10 ml and were: 0.46 ± 0.22 Hz, 0.65 ± 0.31 Hz, 0.86 ± 0.33 Hz (p<0.05) respectively. Similar discharge showed right vagal afferents: 0.41 ± 0.08 Hz, 0.51 ± 0.13 Hz and 0.77 ± 0.27 Hz (p<0.05) for 6, 8 and 10 ml of distension, respectively. We conclude that interdigestive information from gastrointestinal tract is encoded in high amplitude low frequency of spikes pattern in the vagus nerves.

2

Reduced mechanosensitivity of duodenal vagal afferent neurons after an acute switch from milk-based to plant-based diets in anaesthetized pigs

63%

Bligny D., Blat S., Chauvin A., Guerin S., Malbert C.-H.

Journal of Physiology and Pharmacology. Supplement

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2005

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tom 56

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nr 3

89-100

Acute changes in diet composition and/or origin alter gastric emptying and gastro-intestinal motility. One of the hypotheses explaining these alterations involves changes in the sensitivity of duodenal vagal sensory neurons. The aim of this study was to evaluate the characteristics of multimodal duodenal vagal sensory neurons in 20 pigs feed either with milk-based or plant-based diets of identical caloric content. Twenty duodenal vagal afferents were recorded in anesthetized animal from the cervical vagus using the single fiber method. 10 pigs were fed with a milk-based diet (MD) for one month while the diet of the 10 other pigs was changed for plant-based diet (PD) the day preceding the recording session. The behavior of the receptors was tested in basal resting conditions and after challenges with duodenal intralipid and close intra-arterial injection of CCK, 5-HT or capsaicin with and without isovolumetric duodenal distensions at 20, 40 and 60 mmHg. All receptors were slowly adapting C type fiber with a receptor field located 6-7 cm distal to the pylorus. The rate of discharge during distension (20, 40 and 60 mmHg) combined with duodenal intralipid was significantly larger for MD compared with PD. Similarly, the rate of discharge observed during distensions performed with CCK and with 5-HT were greater for MD compared with PD while CCK and 5-HT without distension were equally stimulating for MD and PD. No significant difference was found between groups during capsaicin infusion irrespective of the stimulating pressure. In conclusion, a switch to plant-based diet, when compared to a milk-based diet, results in an overall decrease in mechanical sensitivity of duodenal neurons during lipid, 5HT and CCK challenges, but not in basal conditions or after capsaicin. This reduced sensitivity to distension may explain the diet-induced alteration of gastric emptying that is controlled primarily through a vago-vagal reflex.

3

Effects of vagal neuromodulation and vagotomy on control of food intake and body weight in rats

63%

Laskiewicz J., Krolczyk G., Zurowski D., Sobocki J., Matyja A., Thor P. J.

Journal of Physiology and Pharmacology

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2003

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tom 54

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nr 4

Food induced neurohumoral signals are conduced to data processing brain centers mainly as vagal afferent discharge resulting in food intake regulation. The aim of this study was to evaluate effects of vagal nerve neuromodulation in control of food intake with fed-pattern microchip (MC) pacing. Experiments were performed on 60 rats divided on 5 groups: I group 0,05Hz left vagal pacing, II - pacing of both vagal nerves with MC 0,05Hz, III- left vagal MC 0,1Hz pacing, IV - pacing of both vagal nerves with MC 0,1 Hz was performed. In group V left vagal pacing was combined with right side abdominal vagotomy. Body weight and total food intake decreased by 12% and 14% (I), 26% and 30%(II), 8% and 21%(III), 14% and 30%(IV), 38% and 41%(IV), respectively (p<0.05). Effects of both vagal nerves stimulation on final body weight and food intake was significantly more effective than only single nerve MC pacing however most effective was stimulation with 0,1Hz combined with right vagotomy. We conclude that vagal stimulation reduce food intake and body weight by increasing vagal afferent signals. Our results suggest that information in vagal afferents can be modulated resulting in changes of feeding behaviour and body weight.

4

Effects of central hypervolemia on respiratory function

51%

Aleksandrova N. P., Donina Z. A., Danilova G. A.

Journal of Physiology and Pharmacology. Supplement

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2007

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tom 58

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nr 5

Ograniczanie wyników

2 Journal of Physiology and Pharmacology

2 Journal of Physiology and Pharmacology. Supplement

2 Krolczyk G.

2 Laskiewicz J.

2 Sobocki J.

2 Thor P. J.

2 Zurowski D.

1 Aleksandrova N. P.

1 Blat S.

1 Bligny D.

1 Chauvin A.

1 Danilova G. A.

1 Donina Z. A.

1 Guerin S.

1 Malbert C.-H.

1 Matyja A.

1 2007

1 2005

1 2004

1 2003

Encoding meal in integrated vagal afferent discharge

Reduced mechanosensitivity of duodenal vagal afferent neurons after an acute switch from milk-based to plant-based diets in anaesthetized pigs

Effects of vagal neuromodulation and vagotomy on control of food intake and body weight in rats

Effects of central hypervolemia on respiratory function