Plasma insulin and growth hormone concentrations in pregnant sheep I: diurnal variations in mid- and late pregnancy.
Two or three foetal lambs regularly result in a varying degree of carbohydrate shortage in mother ewes in late pregnancy. We have investigated the correlation between plasma insulin, growth hormone and energy substrate concentrations in ewes 8 and 1 weeks before lambing. Plasma growth hormone was fairly constant (2-3 ng/ml) throughout the 24-h cycle 8 weeks before parturition. Seven weeks later higher average levels and increased diurnal fluctuations were observed in 3 out of 4 multiparous ewes. The average post-absorptive insulin levels were reduced by 50 per cent during the same interval. Simultaneously decreased post-absorptive sugar and increased acetoacetate levels were observed. It is concluded that the hormonal adaptations to the increasing carbohydrate deficit in late pregnancy, especially among multiparous ewes, include: a) reduced post-absorptive plasma insulin levels, b) reduced insulin responses to feeding, and c) increased levels of growth hormone in the plasma.
D000090:Acetoacetates / Q000097:blood; D000821:Animal Feed; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D002940:Circadian Rhythm; D005260:Female; D013006:Growth Hormone / Q000097:blood*; D007328:Insulin / Q000097:blood*; D011247:Pregnancy; D011270:Pregnancy, Animal; D012756:Sheep / Q000502:physiology*
D000090:Acetoacetates; D001786:Blood Glucose; D007328:Insulin; D013006:Growth Hormone