Different impacts on brain function depending on the mode of delivery

Impact of Cesarean Delivery on Reward Behavior and Neurodevelopment in Adult Prairie Vole Offspring

Accumulating clinical evidence has shown that birth by Cesarean section (CS) is associated with a higher incidence of disorders involving the dysregulation of dopamine (DA), such as attention deficit-hyperactivity disorder, autism spectrum disorder, and obesity, compared to vaginal delivery (VD). The mesolimbic (ML) system encompasses DAergic neurons that modulate reward processes underlying learning, motivation, and food intake. Previous research has shown that there are lower levels of DA in the prefrontal cortex and higher in the nucleus accumbens (NAc) of CS offspring. Alterations in the ML-DA system as a consequence of birth via CS may impact behavioral response to rewarding stimuli, such as food. Thus, we aimed to ascertain the behavioral and neurodevelopmental outcomes relevant to food reward in CS prairie vole offspring. This study utilized conditioned place preference (CPP) testing to assess learning using context-dependent conditioning, operant conditioning to assess acquisition of a conditioned response and motivation to receive a reinforcer, and immunohistochemistry (IHC) to stain for tyrosine hydroxylase (TH) in the NAc. Behavioral results showed no difference in preference for the conditioned chamber during CPP testing between CS offspring and their VD counterparts. CS prairie vole offspring had a lower average break point during progressive-ratio testing compared to VD offspring, but no difference in response during fixed-ratio 1 or 3 testing. IHC results showed CS offspring had lower levels of TH-immunoreactivity in the NAc core and shell. These findings further support that delivery by CS has long-term neurodevelopmental effects, specifically in the brain's reward system, and that CS offspring have decreased motivation toward food reward independent of deficits in learning.

Impact of cesarean section on metabolic syndrome components in offspring rats

INTRODUCTION

Epidemiological evidence suggests an association between CS and offspring metabolic syndrome (MetS), but whether a causal relationship exists is unknown.

METHODS

In this study, timed-mated Wistar rat dams were randomly assigned to cesarean section (CS), vaginal delivery (VD), and surrogate groups. The offspring from both CS and VD groups were reared by surrogate dams until weaning, and weaned male offspring from both groups were randomly assigned to receive normal diet (ND) or high-fat/high-fructose diet (HFF) ad libitum for 39 weeks.

RESULTS

By the end of study, CS-ND offspring gained 17.8% more weight than VD-ND offspring, while CS-HFF offspring gained 36.4% more weight than VD-HFF offspring. Compared with VD-ND offspring, CS-ND offspring tended to have increased triglycerides (0.27 mmol/l, 95% CI, 0.05 to 0.50), total cholesterol (0.30 mmol/l, -0.08 to 0.68), and fasting plasma glucose (FPG) (0.30 mmol/l, -0.01 to 0.60); more pronounced differences were observed between CS-HFF and VD-HFF offspring in these indicators (triglyceride, 0.66 mmol/l, 0.35 to 0.97; total cholesterol, 0.46 mmol/l, 0.13 to 0.79; and FPG, 0.55 mmol/l, 0.13 to 0.98).

CONCLUSIONS

CS offspring were more prone to adverse metabolic profile and HFF might exacerbate this condition, indicating the association between CS and MetS is likely to be causal.

IMPACT

Whether the observed associations between CS and MetS in non-randomized human studies are causally relevant remains undetermined. Compared with vaginally born offspring rats, CS born offspring gained more body weight and tended to have compromised lipid profiles and abnormal insulin sensitivity, suggesting a causal relationship between CS and MetS that may be further amplified by a high-fat/high-fructose diet. Due to the high prevalence of CS births globally, greater clinical consideration must be given to the potential adverse effects of CS, and whether these risks should be made known to patients in clinical practice merits evaluation.

Preterm Birth by Cesarean Section: The Gut-Brain Axis, a Key Regulator of Brain Development

Understanding the long-term functional implications of gut microbial communities during the perinatal period is a bourgeoning area of research. Numerous studies have revealed the existence of a "gut-brain axis" and the impact of an alteration of gut microbiota composition in brain diseases. Recent research has highlighted how gut microbiota could affect brain development and behavior. Many factors in early life such as the mode of delivery or preterm birth could lead to disturbance in the assembly and maturation of gut microbiota. Notably, global rates of cesarean sections (C-sections) have increased in recent decades and remain important when considering premature delivery. Both preterm birth and C-sections are associated with an increased risk of neurodevelopmental disorders such as autism spectrum disorders, with neuroinflammation a major risk factor. In this review, we explore links between preterm birth by C-sections, gut microbiota alteration, and neuroinflammation. We also highlight C-sections as a risk factor for developmental disorders due to alterations in the microbiome.

Animal Models for Assessing Impact of C-Section Delivery on Biological Systems

There has been a significant increase in Caesarean section (C-section) births worldwide over the past two decades and although it is can be a life-saving procedure, the enduring effects on host physiology are now undergoing further scrutiny. Indeed, epidemiological data have linked C-section birth with multiple immune, metabolic and neuropsychiatric diseases. Birth by C-section is known to alter the colonisation of the neonatal gut microbiota (with C-section delivered infants lacking vaginal microbiota associated with passing along the birth canal), which in turn can impact the development and maintenance of many important biological systems. Appropriate animal models are key to disentangling the role of missing microbes in brain health and disease in C-section births. In this review of preclinical studies, we interrogate the effects of C-section birth on the development (and maintenance) of several biological systems and we discuss the involvement of the gut microbiome on C-section-related alterations.

Brain Volumes in Mice are Smaller at Birth After Term or Preterm Cesarean Section Delivery

The rate of cesarean section (CS) delivery has steadily increased over the past decades despite epidemiological studies reporting higher risks of neonatal morbidity and neurodevelopmental disorders. Yet, little is known about the immediate impact of CS birth on the brain, hence the need of experimental studies to evaluate brain parameters following this mode of delivery. Using the solvent clearing method iDISCO and 3D imaging technique, we report that on the day of birth, whole-brain, hippocampus, and striatum volumes are reduced in CS-delivered as compared to vaginally-born mice, with a stronger effect observed in preterm CS pups. These results stress the impact of CS delivery, at term or preterm, during parturition and at birth. In contrast, cellular activity and apoptosis are reduced in mice born by CS preterm but not term, suggesting that these early-life processes are only impacted by the combination of preterm birth and CS delivery.

Decreased content of ascorbic acid (vitamin C) in the brain of knockout mouse models of Na+,K+-ATPase-related neurologic disorders

Na⁺,K⁺-ATPase is a crucial protein responsible for maintaining the electrochemical gradients across the cell membrane. The Na⁺,K⁺-ATPase is comprised of catalytic α, β, and γ subunits. In adult brains, the α3 subunit, encoded by ATP1A3, is predominantly expressed in neurons, whereas the α2 subunit, encoded by ATP1A2, is expressed in glial cells. In foetal brains, the α2 is expressed in neurons as well. Mutations in α subunits cause a variety of neurologic disorders. Notably, the onset of symptoms in ATP1A2- and ATP1A3-related neurologic disorders is usually triggered by physiological or psychological stressors. To gain insight into the distinct roles of the α2 and α3 subunits in the developing foetal brain, whose developmental dysfunction may be a predisposing factor of neurologic disorders, we compared the phenotypes of mouse foetuses with double homozygous knockout of Atp1a2 and Atp1a3 (α2α3-dKO) to those with single knockout. The brain haemorrhage phenotype of α2α3-dKO was similar to that of homozygous knockout of the gene encoding ascorbic acid (ASC or vitamin C) transporter, SVCT2. The α2α3-dKO brain showed significantly decreased level of ASC compared with the wild-type (WT) and single knockout. We found that the ASC content in the basal ganglia and cerebellum was significantly lower in the adult Atp1a3 heterozygous knockout mouse (α3-HT) than in the WT. Interestingly, we observed a significant decrease in the ASC level in the basal ganglia and cerebellum of α3-HT in the peripartum period, during which mice are under physiological stress. These observations indicate that the α2 and α3 subunits independently contribute to the ASC level in the foetal brain and that the α3 subunit contributes to ASC transport in the adult basal ganglia and cerebellum. We propose that decreases in ASC levels may affect neural network development and are linked to the pathophysiology of ATP1A2- and ATP1A3-related neurologic disorders.

Birth elicits a conserved neuroendocrine response with implications for perinatal osmoregulation and neuronal cell death

Long-standing clinical findings report a dramatic surge of vasopressin in umbilical cord blood of the human neonate, but the neural underpinnings and function(s) of this phenomenon remain obscure. We studied neural activation in perinatal mice and rats, and found that birth triggers activation of the suprachiasmatic, supraoptic, and paraventricular nuclei of the hypothalamus. This was seen whether mice were born vaginally or via Cesarean section (C-section), and when birth timing was experimentally manipulated. Neuronal phenotyping showed that the activated neurons were predominantly vasopressinergic, and vasopressin mRNA increased fivefold in the hypothalamus during the 2–3 days before birth. Copeptin, a surrogate marker of vasopressin, was elevated 30-to 50-fold in plasma of perinatal mice, with higher levels after a vaginal than a C-section birth. We also found an acute decrease in plasma osmolality after a vaginal, but not C-section birth, suggesting that the difference in vasopressin release between birth modes is functionally meaningful. When vasopressin was administered centrally to newborns, we found an ~ 50% reduction in neuronal cell death in specific brain areas. Collectively, our results identify a conserved neuroendocrine response to birth that is sensitive to birth mode, and influences peripheral physiology and neurodevelopment.

Birth signalling hormones and the developmental consequences of caesarean delivery

Rates of delivery by caesarean section (CS) are increasing around the globe and, although several epidemiological associations have already been observed between CS and health outcomes in later life, more are sure to be discovered as this practice continues to gain popularity. The components of vaginal delivery that protect offspring from the negative consequences of CS delivery in later life are currently unknown, although much attention to date has focused on differences in microbial colonisation. Here, we present the case that differing hormonal experiences at birth may also contribute to the neurodevelopmental consequences of CS delivery. Levels of each of the 'birth signalling hormones' (oxytocin, arginine vasopressin, epinephrine, norepinephrine and the glucocorticoids) are lower following CS compared to vaginal delivery, and there is substantial evidence for each that manipulations in early life results in long-term neurodevelopmental consequences. We draw from the research traditions of neuroendocrinology and developmental psychobiology to suggest that the perinatal period is a sensitive period, during which hormones achieve organisational effects. Furthermore, there is much to be learned from research on developmental programming by early-life stress that may inform research on CS, as a result of shared neuroendocrine mechanisms at work. We compare and contrast the effects of early-life stress with those of CS delivery and propose new avenues of research based on the links between the two bodies of literature. The research conducted to date suggests that the differences in hormone signalling seen in CS neonates may produce long-term neurodevelopmental consequences.

Delivery Modality Affect Neonatal Levels of Inflammation, Stress, and Growth Factors

Introduction: As part of the study CODIBINE, Correlations and Diagnoses for Biomarkers in New-borns, the main objective of the study was to explore neonatal inflammation, stress, neurodevelopment, and growth factors after in-labor and pre-labor cesarean section compared to vaginal delivery. Increasing evidence has shown that birth delivery mode has an impact on imminent and long-term child health. However, the effect of the timing of cesarean section is insufficiently elucidated. The main objective of the study was to explore the effect of different delivery modes, vaginal delivery compared to cesarean section with or without initiation of labor, on the infants. Methods: We designed a retrospective cohort study, including dried blood spot samples from mature (gestational age ≥ 37) newborns delivered in the years 2009-2011. The newborns were divided into three groups after delivery mode: (1) pre-labor cesarean section (n = 714), i.e., cesarean delivery without initiation of labor, (2) in-labor cesarean section (n = 655), i.e., cesarean section after initiation of labor, and (3) vaginal delivery (n = 5,897). We measured infant levels of inflammatory (IL-18, MCP-1, CRP, sTNF RI), stress (HSP-70), growth (EGF, VEGF-A), and neurotrophic factors (BDNF, NT-3, S100B) 2-4 days after birth. Results: The neonatal levels of inflammatory and stress markers were significantly lower, while the levels of growth factors were higher after pre-labor cesarean section compared to vaginal delivery. The biomarker levels were similar after in-labor cesarean section and vaginal delivery. Removing cases with pre-labor rupture of membranes and artificial rupture of membranes in the calculations did not change the results. The levels of neurotrophic factors were unaffected by delivery form. Males had generally higher levels of inflammation and lower levels of growth and neurotrophic factors. Overall, the levels of inflammatory markers increased, and the growth factors decreased with increasing gestational age. Conclusion: The present study of the biomarker levels after birth suggests that the labor process has an important effect on the fetal immune system and level of stress, regardless if the delivery ends with cesarean section or vaginal birth.

A Novel Cerclage Insertion: Modified Laparoscopic Transabdominal Cervical Cerclage with Transvaginal Removing (MLTCC-TR)

STUDY OBJECTIVE

To report on our center's experience of a novel modified approach for laparoscopic cervical cerclage and to evaluate its safety and efficacy preliminarily.

DESIGN

Retrospective descriptive study.

SETTING

Single academic institution.

PATIENTS

Pregnant and nonpregnant women who underwent the modified laparoscopic transabdominal cervical cerclage with transvaginal removing (MLTCC-TR) from June 2016 to April 2019. Eligible participants had multiple adverse obstetric histories or the short cervix and were not suitable for a second transvaginal cerclage.

INTERVENTIONS

Preconceptional or postconceptional MLTCC-TR.

MEASUREMENTS AND MAIN RESULTS

A total of 24 participants (including 3 first-trimester singleton pregnant women) underwent the MLTCC-TR, giving birth to 27 infants. Among 21 women who underwent preconceptional cerclage, 26 cases of postoperational pregnancies were noted, and the incidence of term labor was 73.07%, which was significantly higher than that in the precerclage group (p <.001). Their mean gestational age at delivery was 37.21 ± 5.05 weeks. Among 3 cases of postconceptional cerclage, the mean gestational age at cerclage was 10.90 ± 2.61 weeks, and all of them had term delivery. The overall neonatal survival rate was 100% (27/27), of which 81.48% (22/27) were term infants. There were no severe perioperative complications directly related to the insertion of cerclage.

CONCLUSION

Our new approach of MLTCC-TR may be a relatively effective, feasible, and safe treatment for cervical insufficiency. It may be considered as an acceptable alternative to the traditional laparoscopic cervical cerclage with its superiority of transvaginal removing.