Pharmacological effects of oxytocin on gastric emptying and intestinal transit of a non-nutritive liquid meal in female rats

Abstract

The effects of oxytocin (OT) on gastric emptying, gastrointestinal transit, and plasma levels of cholecystokinin (CCK) were studied in female rats. Gastrointestinal motility was assessed in rats 15 min after intragastric instillation of a test meal containing charcoal and Na(2)(51)CrO(4). Gastric emptying was determined by measuring the amount of radiolabeled chromium contained in the small intestine as a percentage of the initial amount received. Gastrointestinal transit was evaluated by calculating the geometric center of distribution of the radiolabeled marker. Blood samples were collected for CCK radioimmunoassay. After administration of OT (0.2-0.8 mg/kg), gastric emptying and gastrointestinal transit were inhibited, whereas the plasma concentration of CCK was increased in a dose-dependent manner. Atosiban, an oxytocin receptor antagonist, effectively attenuated the OT- induced inhibition of gastric emptying and gastrointestinal transit. However, administration of atosiban alone had no effect on gastric emptying and gastrointestinal transit. The selective CCK(1) receptor antagonists, devazepide and lorglumide, effectively attenuated the OT-induced inhibition of gastric emptying and gastrointestinal transit. L-365, 260, a selective CCK(2) receptor antagonist, did not alter the OT-induced inhibition of gastric emptying and gastrointestinal transit. These results suggest that OT inhibits gastric emptying and gastrointestinal transit in female rats via a mechanism involving CCK stimulation and CCK(1) receptor activation.

Evaluation of the effect of Metformin on the inhibitory effect of oxytocin on Potassium chloride stimulated goat ileum

“…For example, oxytocin accelerates 9,10 and oxytocin receptor antagonists delay gastric emptying in humans, 1 but oxytocin delays gastric emptying in rats. 5 The motility in the stomach, ileum and caecum was inhibited, while the motility in the colon was stimulated, in several animal species.…”

“…4 In contrast, gastric motility is inhibited in dogs and rats. 5 Oxytocin relaxes the ileum and caecum, while it has a contracting effect on colon, both in vitro and in vivo.…”

The Effect of Oxytocin on the Gastric Emptying Rate of Liquids: The Role of Oxytocin and CCK-2 Receptors

“…Sonuç olarak, tokluk hissi, tat duyusu, CCK ve OT arasında karşılıklı bir etkileşim vardır. Bizim sonuçlarımız, OT'ye bağlı sıvı boşalmasının erken dönemde gözlenen gecikmesinin, Wu ve ark'nın (11,12) çalışmalarının aksine CCK-2 reseptörleri aracılı olduğunu göstermiştir. Bu farklılık olasılıkla adı geçen çalışmalarda kullanılan mide boşalma yönteminin farklı olmasından kaynaklanmaktadır.…”

“…Ancak, farklı hayvan türlerinde in vivo yapılan çalışmaların sonuçları OT'nin etkileri konusunda net ve açıklayıcı değil-dir. Bu çalışmaların bazıları OT'nin sıçan, köpek ve kobay üzerinde mide boşalmasını azaltıcı etkisi olduğunu göste-rirken (8)(9)(10)(11)(12)(13), diğer bazı çalışmalar ise OT'nin sıçanlarda mide motilitesini hızlandırıcı bir etkisi olduğunu ortaya koymuşlardır (14). Tavşanlarda yapılan farklı çalışmalarda OT' nin proksimal kolon kasılmasını inhibe ettiği (15), ancak safra kesesinin fazik kasılmaları üzerinde uyarıcı etkiye sahip olduğu gösterilmiştir (16).…”

Human chorionic gonadotropin regulates gastric emptying in ovariectomized rats

“…A SEP-PAK C 18 cartridge (Waters Associates, Milford, MA, USA) was equilibrated with 1 ml 60% acetonitrile in 1% TFA, followed by 3!3 ml 1% TFA, and then the supernatant from the treated plasma sample was applied. After washing with 2!3 ml 1% TFA, the peptide was eluted with 3 ml 60% acetonitrile in 1% TFA, dried down in a Speed Vac concentrator (Salvant Instruments, Farmingdale, NY, USA), the dried samples were stored at K70 8C, and reconstituted with the appropriate assay buffer before CCK measurement (Jin et al 1994, Wu et al 2003. CCK was measured in duplicate using a commercial EIA kit (Phoenix Pharmaceuticals, Belmont, CA, USA); the inter-and intra-assay coefficients of variance were !10%, with a lower detection limit of 0.04 ng/ml.…”