Opioid dysregulation in anorexia nervosa: naloxone effects on preprandial and postprandial growth hormone response to growth hormone-releasing hormone.
Previously, we have shown that in the opposite extremes of nutritional status, obesity and anorexia nervosa (AN), growth hormone (GH) response to growth hormone-releasing hormone (GH-RH) is not inhibited by the ingestion of a normal 800-cal meal consumed at lunch time (1 PM), which is at variance with results in normal subjects. However, in obese patients the postprandial increase in GH response to GH-RH is inhibited by an infusion of naloxone (NAL). In this study we have tested anorectic patients, performing the following tests at 1 PM: GH-RH test (50 micrograms IV) or, in a different day session, NAL (1.6 mg/h, starting 30 minutes before GH-RH) + GH-RH test (50 micrograms IV). The tests were performed in the following three different experimental conditions: (1) short-term fasting studies (lasting from breakfast), (2) long-term fasting studies (from midnight of the day before) and (3) postprandial studies (after a standard meal consumed 1 hour before the test). In AN, the GH response to GH-RH was not influenced by NAL infusion at 1 PM, in both short- and long-term fasting studies (short-term fasting: peak values after GH-RH alone, 26.5 +/- 6.5 ng/mL, during NAL, 28.0 +/- 3.3 ng/mL; long-term fasting: peak values after GH-RH alone, 32.2 +/- 6.8 ng/mL, during NAL, 30.6 +/- 4.0 ng/mL). A partial NAL-inhibitory effect was instead observed in postprandial studies, as evidenced by the calculation of areas under the curve ([AUCs] 1,662.1 +/- 90.0 after GH-RH alone v 1,090.5 +/- 245.4 ng/mL/h during NAL).(ABSTRACT TRUNCATED AT 250 WORDS)
De Marinis
L
L
Institute of Endocrinology, Catholic University School of Medicine, Rome, Italy.
Mancini
A
A
Zuppi
P
P
Fiumara
C
C
Fabrizi
M L
ML
Sammartano
L
L
Conte
G
G
Valle
D
D
Daini
S
S
Ferro
F M
FM
D000293:Adolescent; D000328:Adult; D000856:Anorexia Nervosa / Q000503:physiopathology*; D004435:Eating; D004723:Endorphins / Q000502:physiology*; D005215:Fasting; D013006:Growth Hormone / Q000378:metabolism*; D013007:Growth Hormone-Releasing Hormone / Q000494:pharmacology*; D006801:Humans; D009270:Naloxone / Q000494:pharmacology*; D013997:Time Factors
D004723:Endorphins; D009270:Naloxone; D013006:Growth Hormone; D013007:Growth Hormone-Releasing Hormone