Bombesin prevents the atrophy of Peyer's patches and the dysfunction of M cells in rabbits receiving long-term parenteral nutrition.
BACKGROUND
Long-term parenteral nutrition (PN) induces atrophy of the gut-associated lymphoid tissue (GALT). We examined whether bombesin could ameliorate this atrophy of Peyer's patches and the down-regulation of particle transport by M cells, which was also observed in rabbits undergoing PN.


METHODS
Adult female rabbits were randomized into 6 groups to receive chow ad libitum, chow + bombesin, PN, or PN + bombesin (20 microg/kg, subcutaneously every 8 hours) for 2 or 4 weeks. At the end of each nutrition period, a laparotomy was performed under anesthesia and a suspension of 1 x 10(10)/mL of 0.5-microm fluorescent microspheres was injected into the lumen of intestinal segments containing Peyer's patches and incubated for 2 hours. After the incubation, segments were harvested and prepared for light microscopy, immunohistochemistry, fluorescent microscopy, and electron microscopy.


RESULTS
Long-term PN reduced the size of ileal Peyer's patches, the number of microspheres that was taken up into the follicle-associated epithelium of lymphoid nodules, and the area of Peyer's patch surface occupied by M cells. The number of intraepithelial lymphocytes within the follicle-associated epithelium near the perifollicular crypts of Peyer's patches was also reduced by long-term PN. These consequences were dramatically ameliorated by treatment with bombesin. No ultrastructural alteration of the M cells of Peyer's patches was found in the chow, the PN, or the PN + bombesin groups.


CONCLUSIONS
Bombesin prevents PN-induced atrophy of GALT, reduction of M cell numbers, and decrease in particulate transport by M cells during long-term PN. Bombesin may modulate the genesis of and particulate transport by M cells through stimulation of lymphoid cells in Peyer's patch epithelium near perifollicular crypts, where M cells and other constituents of lymphoid follicle epithelium are generated, thereby preserving mucosal immunity.
Fujimura
Yoshinori
Y
Department of Internal Medicine, Center for Gastroenterology and Endoscopy, Kawasaki Hospital, Kawasaki Medical School, Okayama, Japan. fujimura@kawasaki-hp.jp
Haruma
Ken
K
Owen
Robert L
RL
D000818:Animals; D001839:Bombesin / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D018928:Immunity, Mucosal; D007150:Immunohistochemistry; D007279:Injections, Subcutaneous; D007413:Intestinal Mucosa / Q000166:cytology / Q000276:immunology; D018377:Neurotransmitter Agents / Q000494:pharmacology; D010288:Parenteral Nutrition / Q000009:adverse effects*; D010581:Peyer's Patches / Q000166:cytology / Q000187:drug effects* / Q000473:pathology / Q000648:ultrastructure; D011817:Rabbits; D011897:Random Allocation
D018377:Neurotransmitter Agents; D001839:Bombesin