In utero exposure to the endocrine disruptor di-(2-ethylhexyl) phthalate induces long-term changes in gene expression in the adult male adrenal gland

The plasticizer di-(2-ethylhexyl) phthalate (DEHP) is used to add flexibility to polyvinylchloride polymers and as a component of numerous consumer and medical products. DEHP and its metabolites have been detected in amniotic fluid and umbilical cord blood, suggesting fetal exposure. In the present study, we used an in utero exposure model in which pregnant rat dams were exposed to 1- to 300-mg DEHP/kg·d from gestational day 14 until birth. We previously reported that this window of exposure to environmentally relevant doses of DEHP resulted in reduced levels of serum testosterone and aldosterone in adult male offspring and that the effects on aldosterone were sustained in elderly rats and resulted in decreased blood pressure. Here, we characterized the long-term effects of in utero DEHP exposure by performing global gene expression analysis of prepubertal (postnatal d 21) and adult (postnatal d 60) adrenal glands. We found that the peroxisome proliferator-activated receptor and lipid metabolism pathways were affected by DEHP exposure. Expression of 2 other DEHP targets, hormone-sensitive lipase and phosphoenolpyruvate carboxykinase 1 (Pck1), correlated with reduced aldosterone levels and may account for the inhibitory effect of DEHP on adrenal steroid formation. The angiotensin II and potassium pathways were up-regulated in response to DEHP. In addition, the potassium intermediate/small conductance calcium-activated channel Kcnn2 and 2-pore-domain potassium channel Knck5 were identified as DEHP targets. Based on this gene expression analysis, we measured fatty acid-binding protein 4 and phosphoenolpyruvate carboxykinase 1 in sera from control and DEHP-exposed rats and identified both proteins as putative serum biomarkers of in utero DEHP exposure. These results shed light on molecular targets that mediate DEHP long-term effects and, in doing so, provide means by which to assess past DEHP exposure.

Consequences of postnatally elevated insulin-like growth factor-II in transgenic mice: endocrine changes and effects on body and organ growth

Insulin-like growth factor-II (IGF-II) is an important regulator of embryonic growth and differentiation, but its function in postnatal life is unclear. To address this point, we generated transgenic mice harboring fusion genes in which a human IGF-II complementary DNA is placed under the transcriptional control of the rat phosphoenolpyruvate carboxykinase promoter. Transgene-specific messenger RNA was detected in liver, kidney, and several parts of the gut. Serum IGF-II levels in transgenic mice were 2-3 times higher than those in controls and increased after starvation. Circulating IGF-I correlated negatively and IGF-binding protein-2 (IGFBP-2) positively with IGF-II levels, suggesting that IGF-I is displaced from IGFBPs by IGF-II and that IGF-II is a major regulator of IGFBP-2. Serum levels of IGFBP-3 and IGFBP-4 tended to be higher in phosphoenolpyruvate carboxykinase-IGF-II transgenic mice than in controls, as evaluated by ligand blot analysis. Starvation reduced serum IGF-I, but increased IGFBP-2 in transgenic mice more markedly than in controls. Fasting insulin levels were significantly reduced in transgenic mice, whereas glucose levels were not influenced by elevated IGF-II. The body growth of 4- and 12-week-old mice was not significantly influenced by elevated IGF-II, but transgenic mice displayed increased kidney and testis weight at the age of 4 weeks, and increased adrenal weight at the age of 12 weeks. Our results demonstrate that elevated IGF-II in postnatal life has multiple endocrine consequences and subtle time-specific effects on organ growth.

Serum activity of the key gluconeogenic enzymes in carbon-tetrachloride-induced experimental hepatotoxicity

Serum activity has been measured in three of the key enzymes in the gluconeogenic pathway in rats subjected to experimental hepatotoxicity after intraperitoneal administration of carbon tetrachloride. The levels of phosphoenolpyruvate carboxykinase (PEPCK) and fructose-1,6-biphosphatase (FBPase) showed a similar behavior to the transaminase (AST and ALT), increasing markedly with respect to the controls at 12 h after administration of the poison, reaching their maximum peak of activity at between 24 and 36 h, and returning to normal values at 96 h. The activity of glucose-6-phosphatase was not significantly modified throughout the treatment. These results seem to demonstrate that the determination of the serum activity of PEPCK and FBPase could be a sensitive and specific marker of hepatic cytolysis.

Altered growth, hypoglycemia, hypoalaninemia, and ketonemia in the young rat: postnatal consequences of intrauterine growth retardation

We characterized some of the consequences of intrauterine growth retardation in rat pups growth retarded [small for gestational age (SGA)] due to bilateral maternal uterine artery ligation. Pups of sham and nonoperated (normal) mothers served as controls. SGA pups had significantly reduced body and carcass mass throughout the study while body mass did not differ between sham and normal pups after 4 days. Brain mass was similar in the three groups at any age, while at 21 days and later, SGA liver weight as % body mass exceeded that of sham or normals. At 21 days, a 48-h fast reduced plasma glucose significantly in SGA compared to sham and normal pups; SGA plasma insulin was decreased and glucagon increased. Hepatic phosphoenolpyruvate carboxykinase activity and glycogen content were similar among groups. SGA pups did have significantly reduced plasma alanine and elevated betahydroxybutyrate levels. No differences in the responses to fasting occurred at 28 or 35 days. These data indicate that intrauterine growth retardation has profound effects on postnatal growth and metabolism.

The development of glucose metabolism in infants of diabetic mothers

The concentrations of plasma glucose, lactate and phosphoenolpyruvate carboxykinase (PEPCK) (EC 4.1.1.32) were studied in caesarian-delivered newborn rats of diabetic mothers (IDM) and normal mothers, at time-intervals up to 6 hr after delivery. Glucose concentrations in plasma of cord blood of IDM were significantly higher than those in normal newborn rats. The glucose concentration of normal newborn rats decreased markedly during 1 hr after delivery and thereafter increased gradually. However, the glucose concentration of IDM decreased to a minimum at 4 hr after delivery and thereafter increased. Lactate concentration in plasma of cord blood was high at delivery. Plasma lactate concentration of normal newborn rats decreased rapidly during 2 hr after delivery. However, plasma lactate concentration of IDM increased during 1 hr after delivery and thereafter decreased markedly over the next 5 hr. Hepatic soluble PEPCK activity in caesarian delivered rats was low at birth. The activity of normal infants increased after a lag of 2 hr whereas the activity of IDM increased after a lag of 4 hr. The concentrations of plasma glucose and hepatic PEPCK activity were measured as a function of time after the administration of glucose (5 g/kg body weight) to caesarian-delivered newborn rats. The glucose concentration increased to a maximum at 2 hr after administration and decreased markedly over the next 2 hr. The development of enzyme activity was delayed in administered rats. The glucose concentration and hepatic PEPCK activity were measured as a function of time after the intraperitoneal injection of insulin (250 mU/rat) into caesarian-delivered rats from diabetic pregnant rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Pyruvate carboxylase and phosphoenolpyruvate carboxykinase activity in leukocytes and fibroblasts from a patient with pyruvate carboxylase deficiency

Normal values are given for the activities of pyruvate carboxylase (E.C.6.4.1.1), mitochondrial phosphoenolpyruvate carboxykinase (E.C. 4.1.1.32, PEPCK), and citrate synthase (E.C. 4.1.3.7) in fibroblasts, lymphocytes, and leukocytes. Also given are values for these enzymes in the leukocytes and fibroblasts from a severely mentally and developmentally retarded patient with proximal renal tubular acidosis and hepatic, cerebral, and renal cortical pyruvate carboxylase deficiency. In normals, virtually all of the mitochondrial PEPCK and pyruvate carboxylase activity was present in the mononuclear leukocyte fraction of whole venous blood. Cellular fractionation studies with human lymphocytes and fibroblasts demonstrated that all of the PEPCK activity in these cells is mitochondrial. Normal values for pyruvate carboxylase in leukocytes were 0.092 (0.070--0.208) mU/mg protein (n=5), in lymphocytes 0.154 (0.092--0.262) mU/mg protein (n=5), and in fibroblasts 1.36 (0.778--2.19) mU/mg protein (n=5). The patient with hepatic, renal, and cerebral pyruvate carboxylase deficiency had no detectable activity (less than 0.009 mU/mg protein) in his leukocytes and 0.018 mU/mg protein in his fibroblasts. Data from an assay for pyruvate carboxylase activity in the patient's fibroblasts show that the activity observed is significant but very close to the lower limits of the assay. Values for PEPCK in normal lymphocytes were 1.42 (0.824--1.88) mU/mg protein (n=5), in leukocytes 1.68 (1.64--1.72) mU/mg protein (n=2), and in fibroblasts 5.49 (3.94--6.33) mU/mg protein (n=6).