Administration of opiate receptor antagonist inhibits mucosal atrophy of the gut in fasting rats.
OBJECTIVE
The objective of this study was to determine whether the opiate mu receptor antagonist naloxone would prevent atrophy of the gut in 24-h-fasted rats.


METHODS
Male Sprague-Dawley rats (n = 76, body weight 200-225 g) were catheterized in the jugular vein on Day 0. The rats were fed standard rat chow for 4 days. On Day 4, the diet was changed to the standard liquid diet, and the rats were allowed free access to the liquid diet. On Day 7, the rats were randomized into five groups: (1) free fed, (2) free fed plus naloxone, (3) pair fed, (4) fasting, (5) free fed plus morphine, (6) fasting plus naloxone. Either naloxone (0.16 mg/kg/h) or morphine (0. 21 mg/kg/h) was continuously infused via venous catheter for 24 h. On Day 8, 24 h after fasting or free feeding, the animals were sacrificed.


RESULTS
Twenty-four hours of fasting caused atrophy of the jejunum and elevated morphine levels in the brain (free fed, 931. 3 +/- 122.3 fmol/g, vs fasting, 1419.0 +/- 150.0, P < 0.05). Morphine infusion reduced villus height, mucosal weight, and protein content in jejunum as compared with the free fed rats receiving saline. Administration of naloxone caused an increase in villus height (fasting, 587.0 +/- 25.8 microm, vs fasting plus naloxone, 670.0 +/- 17.4, P < 0.05), mucosal weight (fasting, 17.4 +/- 1.8 mg/cm, vs fasting plus naloxone, 22.6 +/- 1.9, P < 0.05), and protein content (fasting, 13.5 +/- 0.7 microg/cm, vs fasting plus naloxone, 16.7 +/- 0.6, P < 0.05) in jejunum.


CONCLUSIONS
Mucosal atrophy of the jejunum is caused by endogenous opioid in fasting rats.
Yoshida
S
S
Department of Surgery, School of Medicine, Kurume University, 67 Asahi-machi, Kurume, Fukuoka, 830-0011, Japan. shogo@med.kurume-u.ac.jp
Tajiri
T
T
Yahara
T
T
Yoshizumi
T
T
Tanaka
K
K
Muraoka
T
T
Yamasaki
K
K
Shirouzu
K
K
D000818:Animals; D001284:Atrophy; D001835:Body Weight / Q000187:drug effects; D003345:Corticosterone / Q000097:blood; D005215:Fasting; D007413:Intestinal Mucosa / Q000187:drug effects* / Q000473:pathology; D007583:Jejunum / Q000187:drug effects / Q000473:pathology; D007930:Leucine / Q000097:blood; D008297:Male; D009020:Morphine / Q000097:blood / Q000494:pharmacology; D009270:Naloxone / Q000494:pharmacology*; D009292:Narcotic Antagonists / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017450:Receptors, Opioid, mu / Q000502:physiology
D009292:Narcotic Antagonists; D017450:Receptors, Opioid, mu; D009270:Naloxone; D009020:Morphine; D007930:Leucine; D003345:Corticosterone