Some biochemical and hormonal aspects of experimental ovine pregnancy toxaemia

Abstract

1. Some of the effects of stress, fasting and ACTH injections in pregnant ewes were investigated.2. A 6-day fast produced a relatively mild hypoglycaemia and hyperketonaemia without inducing pregnancy toxaemia.3. Stress of transport produced an immediate slight rise in plasma cortisol; 4 hr. later the plasma cortisol had returned to the pre-stress levels.4. A combination of stress and fasting produced severe hypoglycaemia, hyperketonaemia and subacute pregnancy toxaemia, but there was no increase in plasma cortisol levels.5. Daily injections of ACTH resulted in a fourfold increase in plasma cortisol and prevented the development of hypoglycaemia, severe hyperketonaemia, and pregnancy toxaemia in pregnant ewes subjected to stress and fasting.6. Changes in plasma concentrations of NEFA, urea, proteins, catecholamines and insulin were also investigated.

Daily changes in foetal urine and relationships with amniotic and allantoic fluid and maternal plasma during the last two months of pregnancy in conscious, unstressed ewes with chronically implanted catheters

“…It seems possible therefore that the elevated corticosteroid concentrations of maternal plasma during the first 2-4 days after operation decreased the permeability of the placenta to glucose. The results of Saba, Burns, Cunningham, Hebert & Patterson (1966) are consistent with this. They fasted three groups of pregnant (near term) ewes for 6 days.…”

Daily changes in amniotic and allantoic fluid during the last three months of pregnancy in conscious, unstressed ewes, with catheters in their foetal fluid sacs

“…The placenta is relatively impermeable to both maternal and foetal corticosteroids Comline et al 1970) and to other hormones (Alexander, Britton, Cohen, Nixon & Parker, 1968;Bassett, Thorburn &Wallace, 1970;Comline, Nathanielsz & Silver, 1970;Alexander et al 1971 a, b) which suggests that the stimulus is indirect through maternal metabolites. The normal response of pregnant and non pregnant ewes to fasting, particularly if the environment is changed during the fast, is the development of hypoglycaemia, hyperketonaemia, and an increased plasma [FFA] (Reid, 1960b;Reid & Hinks, 1962 b;Saba, Burns, Cunningham, Hebert & Patterson, 1966;D. J. Mellor & J. S. Slater, unpublished data).…”

“…These facts indicate that during maternal hypoglycaemia the foetal adrenal glands may be stimulated to secrete additional corticosteroid by a reduction in foetal plasma glucose, and that a subsequent increase in maternal plasma glucose concentration would tend to reverse these effects. The elevated concentrations of corticosteroid in maternal plasma during the first 3-4 days after operation would act to increase maternal plasma glucose levels (Bassett, Mills & Reid, 1966;Saba et al 1966). In pregnant ewes plasma glucose concentrations usually increased the day after operation (D. J.…”

“…Data on plasma concentrations of aldosterone under these circumstances are not available. However, plasma cortisol concentrations during fasting and refeeding (Lindner, 1959;Reid, 1960b;Saba et at. 1966) and cortisol and corticosterone concentrations of maternal plasma between 110 days gestational age and term have been measured and do not change significantly.…”

Avaliação do perfil hormonal de garrotes submetidos à carência energética prolongada

“…Isto foi observado por Saba et al (1966) trabalhando com ovelhas prenhes submetidas ao jejum prolongado e ao estresse de transporte para induzir toxemia da prenhez nos animais. …”