Expression of motilin in the hypothalamus and the effect of central erythromycin on gastric motility in diabetic rats.
OBJECTIVE
To investigate the expression of motilin-immunoreactive neurons in the hypothalamus and the effect of central administration of erythromycin (EM) on the regulation of gastric motility in diabetic rats.


METHODS
The motilin immunoreactive neurons in the hypothalamus and the hippocampus were detected by immunohistochemistry with rabbit anti-motilin polyclonal antibody. To measure the gastric motility, force transducers were surgically affixed to the gastric serosa. A microinjection syringe was connected via a plastic tube to an injection cannula, which was connected with a stainless steel guide cannula. The syringe was inserted into the right lateral cerebral ventricle for microinjecting the chemicals.


RESULTS
Diabetic mellitus was successfully induced in cohorts of rats. Motilin-immunoreactive neurons significantly increased in the paraventricular (PVN) and supraoptic nuclei (SON) of the hypothalamus in the diabetic rats. Intracerebroventricular (i.c.v.) administration of EM, a motilin receptor agonist, stimulated the gastric motility of diabetic rats. EM (91.56 nmol, i.c.v.) dose-dependently increased the amplitude by (174.82 +/- 48.62)% (P<0.05), and increased the frequency by (70.43 +/- 27.11)% (P < 0.05) in 5 min. The stimulatory effect lasted more than 15 min to the end of the measurement, and can be blocked partially by the prior treatment of motilin receptor antagonist GM-109.


CONCLUSIONS
Motilin-immunoreactive neurons are increased in the PVN and SON of the hypothalamus in diabetic rats. Centrally administered EM may regulate gastric motility by binding to the central motilin receptors, and central motilin might be involved in regulation of gastric motility in diabetic rats.
Jia
Yun-Dan
YD
Department of Physiology, School of Medicine, Qingdao University, Qingdao 266071, China.
Liu
Chang-Qin
CQ
Tang
Ming
M
Jiang
Zheng-Yao
ZY
D000818:Animals; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004917:Erythromycin / Q000008:administration & dosage / Q000494:pharmacology*; D005765:Gastrointestinal Agents / Q000008:administration & dosage / Q000494:pharmacology*; D005769:Gastrointestinal Motility / Q000187:drug effects / Q000502:physiology*; D006624:Hippocampus / Q000166:cytology / Q000378:metabolism; D007276:Injections, Intraventricular; D008297:Male; D008845:Microinjections; D009037:Motilin / Q000819:agonists / Q000378:metabolism*; D009474:Neurons / Q000166:cytology / Q000378:metabolism; D010286:Paraventricular Hypothalamic Nucleus / Q000166:cytology / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011964:Receptors, Gastrointestinal Hormone / Q000819:agonists; D018013:Receptors, Neuropeptide / Q000819:agonists; D018709:Statistics, Nonparametric; D013495:Supraoptic Nucleus / Q000166:cytology / Q000378:metabolism*
D005765:Gastrointestinal Agents; D011964:Receptors, Gastrointestinal Hormone; D018013:Receptors, Neuropeptide; C050802:motilin receptor; D009037:Motilin; D004917:Erythromycin