Effect of intracerebroventricular injection of IGF-I on circulating growth hormone concentrations in the sheep.
The effect of intracerebroventricular administration of IGF-1 on circulating growth hormone (GH) concentrations has been studied in sheep. Twenty sheep were fitted with jugular vein catheters and with indwelling cerebroventricular cannulae. IGF-I was injected into a lateral cerebral ventricle and changes in the circulating concentrations of GH were measured in jugular vein blood samples. Administration of saline had no effect on circulating GH concentrations over a 3-hr period, and administration of IGF-I (at 1, 3 and 10 micrograms/sheep) also had no significant effect on circulating GH concentrations. From these data we surmise that centrally administered IGF-I does not influence GH secretion and it seems probable that cerebrospinal fluid concentrations of IGF-I do not have a role in regulating GH release in sheep.
Spencer
G S
GS
Ruakura Agricultural Centre, Private Bag, Hamilton, New Zealand.
Bass
J J
JJ
Hodgkinson
S C
SC
Edgley
W H
WH
Moore
L G
LG
D000818:Animals; D013006:Growth Hormone / Q000097:blood* / Q000187:drug effects; D007276:Injections, Intraventricular / Q000662:veterinary; D007334:Insulin-Like Growth Factor I / Q000008:administration & dosage / Q000134:cerebrospinal fluid / Q000494:pharmacology*; D011863:Radioimmunoassay; D012756:Sheep / Q000097:blood*
D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone