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A verification study of gastrointestinal motility-stimulating action of guinea-pig motilin using isolated gastrointestinal strips from rabbits and guinea-pigs
- Source :
- General and Comparative Endocrinology. 274:106-112
- Publication Year :
- 2019
- Publisher :
- Elsevier BV, 2019.
-
Abstract
- Motilin (MLN), a 22-amino-acid peptide hormone, is generally present in the mucosa of the upper gastrointestinal (GI) tract, mainly the duodenum of mammals, and it regulates GI motility, especially that related to interdigestive migrating contraction. However, MLN and its receptor are absent in mice and rats, and MLN does not cause any mechanical responses in the rat and mouse GI tracts. The guinea-pig is also a rodent, but expression of the MLN gene in the guinea-pig has been reported. In the present study, two guinea-pig MLNs, FIPIFTYSELRRTQEREQNKGL found in the Ensemble Genome Database (gpMLN-1) and FVPIFTYSELRRTQEREQNKRL reported by Xu et al. (2001) (gpMLN-2), were synthesized, and their biological activities were evaluated in the rabbit duodenum and guinea-pig GI tract in vitro. Both gpMLNs showed contractile activity in longitudinal muscle strips of the rabbit duodenum. The EC50 values of gpMLN-1 and gpMLN-2 were slightly higher than that of human MLN (hMLN), but the maximum contractions were as same as that of hMLN. Treatment with GM109 and hMLN-induced receptor desensitization decreased the contractile activity of both gpMLNs, indicating that the two gpMLN candidates are able to activate the MLN receptor (MLN-R) of the rabbit duodenum. In guinea-pig GI preparations, hMLN and gpMLNs did not show any mechanical responses in circular muscle strips from the gastric antrum or in longitudinal strips of the duodenum, ileum and colon although acetylcholine and 1,1-dimethyl-4-phenylpiperazinium (DMPP) caused definite mechanical responses. The DMPP-induced neural responses in the gastric circular muscle and ileal longitudinal muscles were not modified by gpMLN-1. Even in the gastric and ileal strips with intact mucosa, no mechanical responses were seen with either of the gpMLNs. Furthermore, RT-PCR using various primer sets failed to amplify the gpMLN-2 mRNA. In conclusion, gpMLNs including one that was already reported and the other that was newly found in a database were effective to the rabbit MLN-R, whereas they did not cause any contractions or modification of neural responses in the guinea-pig GI tract, indicating that the MLN system is vestigial and not functional in regulation of GI motility in the guinea-pig as well as in other rodents such as rats and mice.
- Subjects :
- Male
Receptors, Neuropeptide
medicine.medical_specialty
Duodenum
Motilin receptor
Guinea Pigs
Motility
030209 endocrinology & metabolism
Ileum
In Vitro Techniques
Biology
digestive system
Receptors, Gastrointestinal Hormone
Motilin
Guinea pig
03 medical and health sciences
0302 clinical medicine
Endocrinology
Gastrointestinal tract
Internal medicine
parasitic diseases
medicine
Animals
Humans
Receptor
030304 developmental biology
0303 health sciences
Contraction
digestive, oral, and skin physiology
Muscle, Smooth
Guinea-pig
Acetylcholine
medicine.anatomical_structure
Female
Animal Science and Zoology
Rabbits
Gastrointestinal Motility
Muscle Contraction
Subjects
Details
- ISSN :
- 00166480
- Volume :
- 274
- Database :
- OpenAIRE
- Journal :
- General and Comparative Endocrinology
- Accession number :
- edsair.doi.dedup.....5d928882f378d0c422e2d28709a9a0c9