Catecholamine concentrations in venous plasma and cerebrospinal fluid in normal and complicated pregnancy

Regulation of anxiety during the postpartum period

Healthy mother-infant interactions are critical for the physical, cognitive, and psychological development of offspring. Such interactions rely on numerous factors, including a positive maternal emotional state. However, many postpartum women experience emotional dysregulation, often involving elevated anxiety. Neuroendocrine factors contributing to the onset of postpartum anxiety symptoms are mostly unknown, but irregularities in hypothalamic-pituitary-adrenal axis function, reduced prolactin and oxytocin signaling, or parturitional withdrawal of ovarian, placental and neural steroids could contribute to anxiety in susceptible women. Although the causes of initial onset are unclear, postpartum anxiety can be mitigated by recent contact with infants. Numerous neurochemical systems, including oxytocin, prolactin, GABA, and norepinephrine mediate this anxiolytic effect of infant contact. Insight into the etiology of postpartum anxiety disorders, and how contact with infants helps counter existing anxiety dysregulation, will surely facilitate the diagnosis and treatment of postpartum women at risk for, or experiencing, an anxiety disorder.

Physiological stress reactivity in human pregnancy—a review

Prenatal maternal stress has been found to have long-lasting effects on the behavioral and physiological development of the offspring. These programming effects on the fetus would be physiologically mediated through heightened and/or abnormal activity of the maternal sympathetic-adrenal-medullary system (SAM) and especially of her hypothalamic-pituitary-adrenocortical axis (HPA-axis). The abnormalities in maternal physiology could be present in her basal functioning, but also in her physiological reactivity to stressors, which constitutes the topic of this paper. This article reviews studies that have used laboratory challenges to study physiological stress reactivity in pregnant women. It concentrates on stress tests designed to produce pain or discomfort, or cognitive and psychological stress, and that assess changes in blood pressure, heart rate and/or cortisol as reactivity measures. The general conclusion is that physiological stress reactivity appears to be dampened during pregnancy. Nonetheless, the physiological responses to laboratory challenges are clearly present and display enough inter-individual variability to enable the study of links between responsivity patterns, psychosocial variables, fetal behavior, pregnancy outcome and offspring development. This paper also looks into the methodological limitations present in the reviewed studies. Options for sound design of stress test protocols are discussed and recommendations for future studies are presented. These methodological points are general and can therefore also be of use for researchers studying human stress reactivity in other populations and ages.

Changes in cerebrospinal fluid neurochemistry during pregnancy

BACKGROUND

Little is known about changes in brain function that may occur during pregnancy. Studies in rodents and sheep suggest that several brain neurotransmitter and neurohormonal systems known to modulate anxiety may be altered during pregnancy.

METHODS

Cerebrospinal fluid (CSF) and plasma samples were obtained from 21 women (during weeks 38-39 of pregnancy) who were undergoing elective cesarean section and from 22 healthy nonpregnant women.

RESULTS

The CSF levels of g-aminobutyric acid (GABA) and 3-methoxy-4-hydroxyphenylglycolwere reduced in pregnant women. There were no changes in CSF glutamate, 5-hydroxyindoleactic acid, and homovanillic acid. There was a large increase in CSF prolactin in pregnant women and also a trend toward an elevation in CSF oxytocin. Levels of prolactin, but not oxytocin, in CSF and plasma were correlated in pregnant women.

CONCLUSIONS

These results suggest that pregnancy alters regulation of brain GABA, norepinephrine, and prolactin, which may play a role in changes in vulnerability to anxiety and depression during pregnancy and postpartum. Prolactin circulating in the bloodstream seems to be the major source of CSF prolactin during pregnancy.

Effects of magnesium sulphate on the noradrenaline-induced cerebral vasoconstrictor and pressor responses in the goat

OBJECTIVE

To examine the ability of magnesium sulphate to counteract the noradrenaline-induced cerebral vasoconstrictor and pressor responses in goats by using both in vivo and in vitro techniques.

DESIGN

Cerebral blood flow was measured in vivo by means of an electromagnetic flow probe around the internal maxillary artery. Isometric tension was recorded in vitro from rings of goat middle cerebral artery maintained in an organ bath.

RESULTS

1. In vivo. Continuous infusion of noradrenaline (10 micrograms/min) directly into the cerebral arterial supply elicited sustained decrease in cerebral blood flow (61% [SEM 3] of control values) and increase in cerebral vascular resistance (178% [SEM 9] of control values). Magnesium sulphate, injected directly into the cerebral arterial supply (10-300 mg) or infused intravenously (0.3 g and 3 g during 15 min) at the noradrenaline-induced steady state, increased cerebral blood flow by decreasing cerebral vascular resistance in a dose-dependent manner. A similar result was obtained when intravenous magnesium sulphate (3 g/15 min) was tested against the cerebral vasoconstrictor and pressor responses induced by intravenous infusion of noradrenaline (30 micrograms/min). 2. In vitro. When compared with the response obtained in a control medium (1 mmol/L Mg2+), 10 mmol/L Mg2+ significantly inhibited the maximum contraction elicited by noradrenaline (10(-8) to 3 x 10(-3) mol/L) from 45% [SEM 4] to 26% [SEM 4].

CONCLUSIONS

Magnesium sulphate reverses the noradrenaline-induced cerebral vasoconstrictor and pressor responses by a direct inhibitory action of Mg2+ on the actions of noradrenaline in the cerebral and peripheral vascular beds, which leads to a decrease in vascular resistance. These results could explain, at least in part, the beneficial effects of magnesium sulphate in the management of preeclampsia and eclampsia.

Increased concentrations of plasma epinephrine and norepinephrine in patients with eclampsia

We measured plasma catecholamine concentrations on admission (after eclamptic fit) and after 6 days of delivery in 21 eclamptic patients and on admission in 15 normotensive pregnant women in Bangladesh. Plasma epinephrine and norepinephrine concentrations in eclamptic patients were significantly higher on admission than those of normotensive pregnant women (P < 0.0001). Plasma catecholamine concentrations and mean arterial blood pressure had return to be almost normal as normotensive pregnant women after 6 days of delivery, resulting in no correlation between mean arterial blood pressure and plasma catecholamines. On admission (after eclamptic fit) mean arterial blood pressure was positively correlated with plasma epinephrine (r = 0.626, P < 0.002) and norepinephrine (r = 0.553, P < 0.008) concentrations in patients with eclampsia. The amount of proteinuria was also significantly correlated with plasma epinephrine (r = 0.515, P < 0.02) and norepinephrine (r = 0.606, P < 0.003) concentrations. Number of convulsions was significantly correlated with concentrations of plasma epinephrine (r = 0.514, P < 0.02), norepinephrine (r = 0.521, P < 0.01) and mean arterial blood pressure (r = 0.535, P < 0.01). A positive correlation was found between time passed after convulsion with plasma epinephrine (r = 0.515, P < 0.02) and norepinephrine (r = 0.570, P < 0.006) concentrations. These suggested that the increased plasma levels of epinephrine and norepinephrine in eclamptic patients were well correlated with the severity of the clinical features of eclampsia.

Increased concentrations of plasma epinephrine and norepinephrine in patients with eclampsia

We measured plasma catecholamine concentrations on admission (after eclamptic fit) and after 6 days of delivery in 21 eclamptic patients and on admission in 15 normotensive pregnant women in Bangladesh. Plasma epinephrine and norepinephrine concentrations in eclamptic patients were significantly higher on admission than those of normotensive pregnant women (P < 0.0001). Plasma catecholamine concentrations and mean arterial blood pressure had return to be almost normal as normotensive pregnant women after 6 days of delivery, resulting in no correlation between mean arterial blood pressure and plasma catecholamines. On admission (after eclamptic fit) mean arterial blood pressure was positively correlated with plasma epinephrine (r = 0.626, P < 0.002) and norepinephrine (r = 0.553, P < 0.008) concentrations in patients with eclampsia. The amount of proteinuria was also significantly correlated with plasma epinephrine (r = 0.515, P < 0.02) and norepinephrine (r = 0.606, P < 0.003) concentrations. Number of convulsions was significantly correlated with concentrations of plasma epinephrine (r = 0.514, P < 0.02), norepinephrine (r = 0.521, P < 0.01) and mean arterial blood pressure (r = 0.535, P < 0.01). A positive correlation was found between time passed after convulsion with plasma epinephrine (r = 0.515, P < 0.02) and norepinephrine (r = 0.570, P < 0.006) concentrations. These suggested that the increased plasma levels of epinephrine and norepinephrine in eclamptic patients were well correlated with the severity of the clinical features of eclampsia.

The concentration of plasma atrial natriuretic peptide in normotensive and preeclamptic pregnancies

Atrial natriuretic peptide (ANP) is a family of peptides secreted by the heart, affecting the cardiovascular, renal and endocrine systems. This study questions previous research findings regarding elevated ANP levels, despite vasoconstriction and hypovolemia, in preeclamptic patients.

MATERIALS AND METHODS

Seventeen patients with preeclampsia, 5 with superimposed preeclampsia with chronic hypertension and 17 normotensive pregnant women were compared with respect to plasma ANP levels. Seventeen non-pregnant women were taken as the control group. All the women, except the ones with superimposed preeclampsia, were age matched and in their third trimester.

RESULTS

ANP levels in the non-pregnant women (6.9 +/- 0.7 pg/ml) were not different from those in the normotensive pregnant women (6.4 +/- 0.7 pg/ml). ANP levels were significantly higher in women with preeclampsia (10.8 +/- 1.8 pg/ml) or superimposed preeclampsia (9.7 +/- 1.4 pg/ml) than in normotensive pregnant women and normal non-pregnant women (P < 0.05). According to the literature, there is a volume depletion in preeclamptic women. However, this wasn't demonstrated in our study group.

CONCLUSION

ANP levels in preeclamptic women were found to be higher than those in normotensive pregnant women. The etiology still remains obscure.