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


METHODS
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.


RESULTS
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).


CONCLUSIONS
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.
Moulas
Anargyros N
AN
Department of Animal Production, Technological Education Institute (T.E.I.) of Larissa, GR 41110 Larissa, Greece. moulas@teilar.gr
Krieg
Richard J
RJ
Veldhuis
Johannes D
JD
Chan
James C M
JC
D000284:Administration, Oral; D000818:Animals; D004435:Eating / Q000187:drug effects*; D013006:Growth Hormone / Q000097:blood* / Q000378:metabolism*; D008297:Male; D010880:Piperidines / Q000494:pharmacology*; D010903:Pituitary Gland, Anterior / Q000187:drug effects / Q000378:metabolism; D011673:Pulsatile Flow; D051381:Rats; D017207:Rats, Sprague-Dawley; D013141:Spiro Compounds / Q000494:pharmacology*
D010880:Piperidines; D013141:Spiro Compounds; C102119:L 163255; D013006:Growth Hormone