Fetal endocrine and metabolic adaptations to hypoxia: the role of the hypothalamic-pituitary-adrenal axis.

In utero, hypoxia is a significant yet common stress that perturbs homeostasis and can occur due to preeclampsia, preterm labor, maternal smoking, heart or lung disease, obesity, and high altitude. The fetus has the extraordinary capacity to respond to stress during development. This is mediated in part by the hypothalamic-pituitary-adrenal (HPA) axis and more recently explored changes in perirenal adipose tissue (PAT) in response to hypoxia. Obvious ethical considerations limit studies of the human fetus, and fetal studies in the rodent model are limited due to size considerations and major differences in developmental landmarks. The sheep is a common model that has been used extensively to study the effects of both acute and chronic hypoxia on fetal development. In response to high-altitude-induced, moderate long-term hypoxia (LTH), both the HPA axis and PAT adapt to preserve normal fetal growth and development while allowing for responses to acute stress. Although these adaptations appear beneficial during fetal development, they may become deleterious postnatally and into adulthood. The goal of this review is to examine the role of the HPA axis in the convergence of endocrine and metabolic adaptive responses to hypoxia in the fetus.

Adrenocorticotropic Hormone and PI3K/Akt Inhibition Reduce eNOS Phosphorylation and Increase Cortisol Biosynthesis in Long-Term Hypoxic Ovine Fetal Adrenal Cortical Cells.

This study was designed to determine the role of the MEK/ERK1/2 and PI3K/Akt pathways in cortisol production and endothelial nitric oxide synthase (eNOS) phosphorylation (peNOS) in the ovine fetal adrenal in response to long-term hypoxia (LTH). Pregnant ewes were maintained at high altitude (3820 m) for the last 100 days of gestation (dGa). At 138 to 142 dGa, fetal adrenal cortical cells (FACs) were collected from LTH and age-matched normoxic fetuses. Cortisol production and peNOS were measured in response to pretreatment with the MEK/ERK1/2 pathway inhibitor UO126 (UO) and adrenocorticotropic hormone (ACTH) stimulation. UO126 reduced ACTH-stimulated cortisol in both normoxic and LTH FACs. UO126 alone or in combination with ACTH reduced peNOS in the normoxic group, while ACTH alone or ACTH + UO inhibited peNOS in LTH FACs. Additionally, cortisol was measured in response to pretreatment with UO and treatment with 22R-hydroxycholesterol (22R-OHC) or water-soluble cholesterol (WSC) with and without ACTH stimulation. UO126 had no effect on 22R-OHC-treated cells, but reduced cortisol in cells treated with WSC and/or ACTH. Cortisol and peNOS were also measured in response to pretreatment with PI3K/Akt pathway inhibitor Wortmannin (WT) and ACTH stimulation. Wortmannin further increased cortisol under ACTH-stimulated conditions and, like ACTH, reduced peNOS in LTH but not normoxic FACs. Together, these data suggest that in LTH FACs MEK/ERK1/2 does not regulate peNOS but that UO acts downstream from eNOS, possibly at cholesterol transport, to affect cortisol production in LTH FACs, while the PI3K/Akt pathway, along with ACTH, regulates peNOS and plays a role in the fetal adaptation to LTH in FACs.

Natural history of paediatric inflammatory bowel diseases over a 5-year follow-up: a retrospective review of data from the register of paediatric inflammatory bowel diseases.

OBJECTIVES: The natural history of paediatric inflammatory bowel diseases (IBDs) is poorly understood. We aim to describe the disease course in this cohort and generate prognostic information for patients and clinicians. MATERIALS AND METHODS: Patient records from 6 tertiary paediatric gastroenterology centres were reviewed to generate data concerning original diagnosis, change in diagnosis, family history, surgical interventions, growth, and presence of extragastrointestinal manifestations. RESULTS: Data were collected on 116 children with Crohn disease (CD), 74 with ulcerative colitis (UC), and 20 with indeterminate colitis (IC), followed for a mean period of 3.42, 3.3, and 2.9 years from date of diagnosis, respectively. A male predominance is demonstrated in CD. Revision of diagnosis in patients with IC is mainly to UC, with most children receiving a definitive diagnosis within 2 years of initial presentation. Of the children with UC, 17.6% underwent 1 or more major operations with a median time to surgery of 1.92 years. Of children with CD, 11.6% underwent 1 or more major intraabdominal procedures with a median time to surgery of 1.83 years. We recorded a positive family history in 2.7%, 8.2%, and 10% of cases for CD, UC, and IC, respectively. For both boys and girls with CD, but only for boys with UC, height standard deviation score became more negative over time. CONCLUSIONS: This retrospective study quantifies certain distinctions between IBDs diagnosed in paediatric and adult populations. We document a trend toward male predominance in children with CD. We also note impaired linear growth in children with CD, whereas it appears maintained in girls with UC. We also have recorded a low incidence of IBDs in the families of this cohort and suggest that environmental influences may be of greater importance. We document that major intraabdominal surgery may be required in about 15% of patients with either UC or CD within 2 years of diagnosis, and that the majority of those diagnosed initially with IC will be reclassified as either UC or CD within 2 years.