Effects of acute haemorrhagic hypotension during pregnancy and lactation in conscious goats

Olsson, Kerstin; Andén, Nils‐Erik; Johansson, Kjell; Thornström, Ulla

doi:10.1111/j.1365-201x.1987.tb10621.x

Cited by 15 publications

(13 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The last-mentioned result is somewhat surprising since labour involves intense muscular work, and exercise can induce the release of vasopressin in a dose-related fashion in humans (Wade 1984). High vasopressin levels during labour could also be explained by increased plasma osmolality (Landgraf et al 1983) and haemorrhage (Larsson et al 1978, Olsson et al 1987. The increases in vasopressin during expulsion in both goats and heifers may therefore be secondary to several causes.…”

Section: Figurementioning

confidence: 99%

Hormonal changes during parturition in heifers and goats are related to the phases and severity of labour

Hydbring¹,

Madej²,

MacDonald³

et al. 1999

Journal of Endocrinology

View full text Add to dashboard Cite

Parturition is a natural event that involves stress and pain for the mother. We thus hypothesized that levels of stress hormones measured during parturition could reflect levels reached in response to severe discomfort and pain of other kinds as well. The aim of this study was therefore to determine whether plasma concentrations of cortisol, adrenaline, noradrenaline, -endorphin, met-enkephalin, vasopressin and oxytocin vary depending on the phase and severity of labour in dairy heifers (ten) and dairy goats (six), and how these hormones interact with each other. Blood samples were taken once a day for 3 days before labour and for 3 days afterwards and at predetermined phases during labour. All heifers delivered one calf and five of them needed obstetrical assistance. Two of the goats delivered one kid, and four had twins; all kidded without help. The cortisol concentration peaked when the calf and the first kid were born. In the heifers, plasma adrenaline increased after delivery, while the noradrenaline concentration did not change significantly in heifers that needed assistance, but increased during expulsion in heifers calving without help. In the goats, adrenaline and noradrenaline concentrations increased in association with expulsion of the first kid. The -endorphin concentration increased during labour in goats. In heifers that needed assistance, -endorphin concentration increased 1 h after labour but there was no change in heifers that did not need assistance. The met-enkephalin concentration was elevated during expulsion in heifers and fluctuated in the goats. Both oxytocin and vasopressin increased during expulsion in both groups of heifers, but vasopressin increased four times more in heifers needing assistance. In the goats, oxytocin reached its highest levels just as the feet of the first kid became visible, and vasopressin peaked as the head emerged. Parturition took longer in heifers that needed assistance than in those that did not. It is concluded that, even though the pattern of change differed between hormones during labour, the changes were related to the phases of labour. A longer labour therefore meant that the hormone concentrations stayed elevated for longer. Vasopressin reached high levels in goats and was the only hormone for which plasma concentrations were higher in heifers that needed assistance than in those that did not, indicating that this hormone is released in order to deal with the painrelated stress associated with labour.

show abstract

Section: Figurementioning

confidence: 99%

Hormonal changes during parturition in heifers and goats are related to the phases and severity of labour

Hydbring¹,

Madej²,

MacDonald³

et al. 1999

Journal of Endocrinology

View full text Add to dashboard Cite

show abstract

“…This change was first noted by Humphreys and Joels (97,98) in an extensive series of studies in anesthetized pregnant rabbits, in which reductions in carotid sinus pressure failed to elicit normal increases in arterial pressure and peripheral vascular resistance. Since then, arterial baroreflex impairment has been documented in several species studied in the conscious state, including dogs (23), rats (24,124), rabbits (21,97,162), goats (152), sheep (104,123), and humans (16,79,122,164,175,193). Reflex responses to atrial stretch are also blunted (51,94,95,103), which may contribute to retention of the expanded blood volume.…”

mentioning

confidence: 99%

“…Pregnant women are prone to orthostatic hypotension, due to blunted reflex activation of the sympathetic nervous system and inadequate peripheral vasoconstriction (56,122,132). Moreover, in many species, pregnancy interferes with the normal ability to maintain arterial pressure during hemorrhage (26,36,99,152,186). Hemodynamic studies have revealed that in pregnant animals, arterial pressure falls with less blood loss due to both a failure to maintain cardiac output and also inadequate peripheral vasoconstriction (22,36).…”

mentioning

confidence: 99%

Pregnancy and the endocrine regulation of the baroreceptor reflex

Brooks

Dampney

Heesch

2010

American Journal of Physiology-Regulatory, Integrative and Comp

View full text Add to dashboard Cite

-The purpose of this review is to delineate the general features of endocrine regulation of the baroreceptor reflex, as well as specific contributions during pregnancy. In contrast to the programmed changes in baroreflex function that occur in situations initiated by central command (e.g., exercise or stress), the complex endocrine milieu often associated with physiological and pathophysiological states can influence the central baroreflex neuronal circuitry via multiple sites and mechanisms, thereby producing varied changes in baroreflex function. During pregnancy, baroreflex gain is markedly attenuated, and at least two hormonal mechanisms contribute, each at different brain sites: increased levels of the neurosteroid 3␣-hydroxydihydroprogesterone (3␣-OH-DHP), acting in the rostral ventrolateral medulla (RVLM), and reduced actions of insulin in the forebrain. 3␣-OH-DHP appears to potentiate baroreflex-independent GABAergic inhibition of premotor neurons in the RVLM, which decreases the range of sympathetic nerve activity that can be elicited by changes in arterial pressure. In contrast, reductions in the levels or actions of insulin in the brain blunt baroreflex efferent responses to increments or decrements in arterial pressure. Although plasma levels of angiotensin II are increased in pregnancy, this is not responsible for the reduction in baroreflex gain, although it may contribute to the increased level of sympathetic nerve activity in this condition. How these different hormonal effects are integrated within the brain, as well as possible interactions with additional potential neuromodulators that influence baroreflex function during pregnancy and other physiological and pathophysiological states, remains to be clearly delineated.3␣-hydroxy-dihydroprogesterone; angiotensin II; insulin; paraventricular nucleus of the hypothalamus NORMAL PREGNANCY is characterized by profound changes in fluid and electrolyte balance and blood pressure regulation. Blood volume and cardiac output increase by 30 -50%, but arterial pressure falls due to even greater decreases in systemic vascular resistance (120,138,189). These hemodynamic alterations are evident early in pregnancy, precede the increases in uterine blood flow, and are sustained until parturition (127,138,189). Considerable data implicate increases in relaxin and nitric oxide (NO) in the systemic vasodilation induced by pregnancy (20,127,128,177,196). In addition, peripheral vascular sensitivity to circulating vasoconstrictors including vasopressin, angiotensin II (ANG II), and norepinephrine (NE) is decreased (50,71,154).Unlike the hemodynamic changes, which likely subserve adequate fetal development, an adverse consequence of normal pregnancy is a marked impairment of the arterial baroreceptor reflex. This change was first noted by Humphreys and Joels (97,98) in an extensive series of studies in anesthetized pregnant rabbits, in which reductions in carotid sinus pressure failed to elicit normal increases in arterial pressure and peripheral vascular resistanc...

show abstract

“…Several studies have documented that pregnant animals are less able to maintain arterial pressure during haemorrhage (Humphreys & Joels 1985;Tabsh et al 1986;Olsson et al 1987;Brooks & Keil 1994a). This change in cardiovascular homeostasis is highlighted in Fig.…”

Section: Pregnancy Alters Haemodynamic Responses To Haemorrhagementioning

confidence: 93%

“…1, bottom), it appears that with a roughly equivalent absolute volume loss, the pregnant animals still experienced greater hypotension, ruling out this argument. An inability to regulate arterial pressure during haemorrhage has also been described in other species including goats, sheep and rabbits (Humphreys & Joels 1985;Tabsh et al 1986;Olsson et al 1987). Moreover, pregnant women are known to be more susceptible to orthostatic hypotension (Metcalfe et al 1986).…”

Section: Pregnancy Alters Haemodynamic Responses To Haemorrhagementioning

confidence: 97%

Pregnancy Attenuates Activity of the Baroreceptor Reflex

Brooks

Quesnell

Cumbee

et al. 1995

Clin Exp Pharma Physio

View full text Add to dashboard Cite

1. Pregnancy-induced changes in acute blood pressure regulation are reviewed. 2. Pregnant animals are less able to maintain arterial pressure during haemorrhage than non-pregnant animals. 3. Baroreceptor reflex-mediated increases in heart rate, renal sympathetic activity, vasopressin, ACTH and cortisol are reduced during pregnancy. Therefore, one explanation for the subnormal ability of pregnant animals to regulate arterial pressure during haemorrhage is that the baroreceptor reflex is not as effective. 4. Chronic increases in oestrogen levels in non-pregnant rabbits do not reduce the gain of baroreflex control of renal sympathetic activity. This and other findings suggest that oestrogen alone does not mediate the blunted baroreflex activity observed during pregnancy.

show abstract

Effects of acute haemorrhagic hypotension during pregnancy and lactation in conscious goats

Cited by 15 publications

References 23 publications

Hormonal changes during parturition in heifers and goats are related to the phases and severity of labour

Hormonal changes during parturition in heifers and goats are related to the phases and severity of labour

Pregnancy and the endocrine regulation of the baroreceptor reflex

Pregnancy Attenuates Activity of the Baroreceptor Reflex

Contact Info

Product

Resources

About