Influence of nutritional status on growth hormone-dependent circulating somatomedin-C activity in mature sheep.
The effect of daily administration of ovine GH for a period of 4 weeks on somatomedin-C biological activity in plasma was investigated in mature Merino sheep fed a maintenance energy intake (low plane; LP) or 1.6 times this amount (high plane; HP). The GH treatment resulted in a significant (P less than 0.05) increase in plasma GH levels in blood samples collected 23.5 h after each daily injection in both LP and HP groups. Plasma concentrations of somatomedin-C activity and insulin were significantly stimulated to a maximum level by the third GH injection and remained at this level for 7 days. Subsequently, circulating levels of both hormones fell to 40-50% of the peak response to GH and returned to basal levels within 48 h of the cessation of GH injections. In the HP group the response of plasma insulin and somatomedin-C activity to GH injection was greater than in the LP group.
Department of Animal Science, Sydney University, Camden, New South Wales, Australia.
P C
PC
Wynn
M C
MC
Stuart
A L
AL
Wallace
A C
AC
Kirby
E F
EF
Annison
D000818:Animals; D002149:Energy Intake / Q000502:physiology*; D005260:Female; D013006:Growth Hormone / Q000494:pharmacology / Q000502:physiology*; D007328:Insulin / Q000097:blood; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D009752:Nutritional Status / Q000502:physiology*; D012756:Sheep / Q000097:blood / Q000502:physiology*; D013268:Stimulation, Chemical
D007328:Insulin; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone