Effect of the GH secretagogue L-163,255 and restricted feeding time on GH pulsatility in the rat

• Published in: European journal of endocrinology Vol. 147; no. 1; pp. 143 - 148
• Main Authors: MOULAS, Anargyros N, KRIEG, Richard J, VELDHUIS, Johannes D, CHAN, James C. M
• Format: Journal Article
• Language: English
• Published: Colchester Portland Press 01-07-2002
• Subjects: Administration, Oral; Animals; Biological and medical sciences; Eating - drug effects; Growth Hormone - blood; Growth Hormone - metabolism; Hormones. Endocrine system; Male; Medical sciences; Pharmacology. Drug treatments; Piperidines - pharmacology; Pituitary Gland, Anterior - drug effects; Pituitary Gland, Anterior - metabolism; Pulsatile Flow; Rats; Rats, Sprague-Dawley; Spiro Compounds - pharmacology; Rat; Ligand; Postprandial; Somatotropin releasing factor; Rodentia; Meal; Somatotropin hormone; Administration schedule; Experimental study; Nutrient starvation; Vertebrata; Mammalia; Treatment; Secretion curve; Analog; Animal; Fast; Release
• ISSN: 0804-4643; 1479-683X
• DOI: 10.1530/eje.0.1470143

To determine the effect of repeated treatments with the growth hormone secretagogue (GHS) L-163,255 on the pulsatile release of GH when administered in meal-fed rats before and after feeding.
The first group of rats (AL, n=6) had food available ad libitum. The second (restricted, R, n=6), third (GHSB, n=6), and fourth (GHSA, n=6) groups were fed from 1100 to 1400 h. Groups GHSB and GHSA were given GHS by gavage, 3.0 mg/kg L-163,255, at 1000 h (before feeding, B) and at 1500 h (after feeding, A) respectively. Three weeks after the initiation of the treatment, blood samples were collected at 10-min intervals over 6 h, and GH levels were determined.
In group R, the concentrations of GH were higher before feeding (17.6+/-2.4 ng/ml) than during feeding (11.2+/-1.2 ng/ml), P<0.05. The average concentrations of the peak in response to GHS were higher when GHS was administered before (121.70+/-33.68 ng/ml) than after (49.67+/-17.87 ng/ml) feeding. The mass of GH, as calculated by deconvolution analysis was also higher in the GHSB group than in the GHSA group (251.6+/-64.1 ng/ml per min vs 85.3+/-22.9 ng/ml per min respectively, P<0.05).
L-163,255 is effective in inducing GH release after repeated oral administration in rats. The effectiveness is greater when GHS is administered before rather than after feeding in meal-fed animals.