Search

Placental 11[beta]-hydroxysteroid dehydrogenase-2 (ll[beta]HSD2) limits fetal glucocorticoid exposure and is associated with physiological stability in the premature newborn infant. Antenatal betamethasone alters 11[beta]HSD2 activity and confers sex-specific advantages in neonatal outcome. We investigated the influence of betamethasone and sex on 11[beta]HSD2 activity, neonatal adrenal function and clinical course in 24- to 36-wk gestation neonates from birth to day 5 of life. Univariate analyses demonstrated an interaction between timing of betamethasone exposure and sex for 11[beta]HSD2 activity rate (P = 0.02) and umbilical arterial cortisol (P = 0.01). For infants born < 72 h following antenatal betamethasone, females had higher 11[beta]HSD2 activity (P < 0.01) and umbilical arterial cortisol (P = 0.01) than males. Females born < 72 h of betamethasone exposure had higher day 1 urinary cortisol, if exposed to perinatal stress, than males (P < 0.01). For infants born < 72 h after betamethasone exposure, 11[beta]HSD2 activity was negatively correlated with Clinical Illness Severity Score score (r = -0.79 P = 0.01) and positively correlated with mean arterial blood pressure (r = 0.8 P = 0.01) only in females. Sex-specific placental 11BHSD2 autoregulation following antenatal betamethasone exposure may limit adrenal suppression in females influencing physiological stability following preterm birth. A lack of adjustment in 11 [beta]HSD2 and adrenal response may contribute to the increased incidence of poor outcome observed in preterm males. placenta; fetal sex

Urocortin: a mechanism for the sustained activation of the HPA axis in the late-gestation ovine fetus? Am J Physiol Endocrinol Metab 283: E165-E171, 2002. First published March 19, 2002; 10.1152/ajpendo.00497.2001.--We hypothesized that urocortin might be produced in the pituitary of the late-gestation ovine fetus in a manner that could contribute to the regulation of ACTH output. We used in situ hybridization and immunohistochemistry to identify urocortin mRNA and protein in late-gestation fetal pituitary tissue. Levels of urocortin mRNA rose during late gestation and were associated temporally with rising concentrations of pituitary proopiomelanocortin (POMC) mRNA. Urocortin was localized both to cells expressing ACTH and to non-ACTH cells by use of dual immunofluorescence histochemistry. Transfection of pituitary cultures with urocortin antisense probe reduced ACTH output, whereas added urocortin stimulated ACTH output from cultured pituitary cells. Cortisol infusion for 96 h in chronically catheterized late-gestation fetal sheep significantly stimulated levels of pituitary urocortin mRNA. We conclude that urocortin is expressed in the ovine fetal pituitary and localizes with, and can stimulate output of, ACTH. Regulation of urocortin by cortisol suggests a mechanism to override negative feedback and sustain feed-forward of fetal hypothalamic-pituitary-adrenal function, leading to birth. urocortin; adrenocorticotropic hormone; parturition; hypothalamic-pituitary-adrenal axis

Perinatal exposures are associated with altered risks of childhood allergy. Human studies and our previous work suggest that restricted growth in utero (IUGR) is protective against allergic disease. The mechanisms are not clearly defined, but reduced fetal abundance and altered metabolism of methyl donors are hypothesized as possible underlying mechanisms. Therefore, we examined whether late-gestation maternal dietary methyl donor and cofactor supplementation of the placentally restricted (PR) sheep pregnancy would reverse allergic protection in progeny. Allergic outcomes were compared between progeny from control pregnancies (CON; n = 49), from PR pregnancies without intervention (PR; n = 28), and from PR pregnancies where the dam was fed a methyl donor plus cofactor supplement from day 120 of pregnancy until delivery (PR + Methyl; n = 25). Both PR and PR + Methyl progeny were smaller than CON; supplementation did not alter birth size. PR was protective against cutaneous hypersensitivity responses to ovalbumin (OVA; P < 0.01 in singletons). Cutaneous hypersensitivity responses to OVA in PR + Methyl progeny were intermediate to and not different from the responses of CON and PR sheep. Cutaneous hypersensitivity responses to house dust mites did not differ between treatments. In singleton progeny, upper dermal mast cell density was greater in PR + Methyl than in PR or CON (each P < 0.05). The differences in the cutaneous allergic response were not explained by treatment effects on circulating immune cells or antibodies. Our results suggest that mechanisms underlying in utero programming of allergic susceptibility by IUGR and methyl donor availability may differ and imply that late-gestation methyl donor supplementation may increase allergy risk.

Prenatal and early childhood exposures are implicated as causes of allergy, but the effects of intrauterine growth restriction on immune function and allergy are poorly defined. We therefore evaluated effects of experimental restriction of fetal growth on immune function and allergic sensitization in adolescent sheep. Immune function (circulating total red and white blood cells, neutrophils, lymphocytes, monocytes, eosinophils, and basophils, and the antibody response to Clostridial vaccination) and responses to house dust mite (HDM) allergen and ovalbumin (OVA) antigen sensitization (specific total Ig, IgG1, and IgE antibodies, and cutaneous hypersensitivity) were investigated in adolescent sheep from placentally restricted (PR, n = 23) and control (n = 40) pregnancies. Increases in circulating HDM-specific IgE (P = 0.007) and OVA-specific IgE (P = 0.038) were greater in PR than control progeny. PR did not alter total Ig, IgG1, or IgM responses to either antigen. PR increased OVA-specific but not HDM-specific IgA responses in females only (P = 0.023). Multiple birth increased Ig responses to OVA in a sex-specific manner. PR decreased the proportion of positive cutaneous hypersensitivity responders to OVA at 24 h (P = 0.030) but had no effect on cutaneous responses to HDM. Acute wheal responses to intradermal histamine correlated positively with birth weight in singletons (P = 0.023). Intrauterine growth restriction may suppress inflammatory responses in skin downstream of IgE induction, without impairment in antibody responses to a nonpolysaccharide vaccine. Discord between cutaneous and IgE responses following sensitization suggests new mechanisms for prenatal allergy programming.

Placental 11beta-hydroxysteroid dehydrogenase-2 (11betaHSD2) limits fetal glucocorticoid exposure and is associated with physiological stability in the premature newborn infant. Antenatal betamethasone alters 11betaHSD2 activity and confers sex-specific advantages in neonatal outcome. We investigated the influence of betamethasone and sex on 11betaHSD2 activity, neonatal adrenal function and clinical course in 24- to 36-wk gestation neonates from birth to day 5 of life. Univariate analyses demonstrated an interaction between timing of betamethasone exposure and sex for 11betaHSD2 activity rate (P = 0.02) and umbilical arterial cortisol (P = 0.01). For infants born < 72 h following antenatal betamethasone, females had higher 11betaHSD2 activity (P < 0.01) and umbilical arterial cortisol (P = 0.01) than males. Females born < 72 h of betamethasone exposure had higher day 1 urinary cortisol, if exposed to perinatal stress, than males (P < 0.01). For infants born < 72 h after betamethasone exposure, 11betaHSD2 activity was negatively correlated with Clinical Illness Severity Score score (r = -0.79 P = 0.01) and positively correlated with mean arterial blood pressure (r = 0.8 P = 0.01) only in females. Sex-specific placental 11BHSD2 autoregulation following antenatal betamethasone exposure may limit adrenal suppression in females influencing physiological stability following preterm birth. A lack of adjustment in 11betaHSD2 and adrenal response may contribute to the increased incidence of poor outcome observed in preterm males.