RESUMEN
An impaired nitrergic system and altered redox signaling contribute to gastric dysmotility in diabetics. Our earlier studies show that NF-E2-related factor 2 (NRF2) and phase II antioxidant enzymes play a vital role in gastric neuronal nitric oxide synthase (nNOS) function. This study aims to investigate whether supplementation of sepiapterin (SEP), a precursor for tetrahydrobiopterin (BH4) (a cofactor of NOS) via the salvage pathway, restores altered nitrergic systems and redox balance in spontaneous diabetic (DB) female rats. Twelve-week spontaneous DB and age-matched, non-DB rats, with and without dietary SEP (daily 20 mg/kg body wt for 10 days) treatment, were used in this study. Gastric antrum muscular tissues were excised to investigate the effects of SEP in nitrergic relaxation and the nNOS-nitric oxide (NO)-NRF2 pathway(s). Dietary SEP supplementation significantly ( P < 0.05) reverted diabetes-induced changes in nNOS dimerization and function; nitric oxide (NO) downstream signaling molecules; HSP-90, a key regulator of nNOSα activity and dimerization; miRNA-28 that targets NRF2 messenger RNA (mRNA), and levels of microRNA (miRNA) biogenesis pathway components, such as DGCR8 (DiGeorge Syndrome Critical Region Gene 8) and TRBP (HIV1-1 transactivating response RNA-binding protein). These findings emphasize the importance of the BH4 pathway in regulating gastric motility functions in DB animals by modulating nNOSα dimerization in association with changes in enteric NRF2 and NO downstream signaling. Our results also identify a new pathway, wherein SEP regulates NRF2 mRNA turnover by suppressing elevated miRNA-28, which could be related to alterations in miRNA biogenesis pathway components. NEW & NOTEWORTHY This study is the first to show a causal link between NF-E2-related factor 2 (NRF2) and neuronal nitric oxide synthase (nNOS) in gastric motility function. Our data demonstrate that critical regulators of the miRNA biosynthetic pathway are upregulated in the diabetic (DB) setting; these regulators were rescued by sepiapterin (SEP) treatment. Finally, we show that low dihydrofolate reductase expression may lead to impaired nNOS dimerization/function-reduced nitric oxide downstream signaling and elevate oxidative stress by suppressing the NRF2/phase II pathway through miRNA; SEP treatment restored all of the above in DB gastric muscular tissue. We suggest that tetrahydrobiopterin supplementation may be a useful therapy for patients with diabetes, as well as women with idiopathic gastroparesis.
Asunto(s)
Diabetes Mellitus/tratamiento farmacológico , Motilidad Gastrointestinal , Factor 2 Relacionado con NF-E2/metabolismo , Óxido Nítrico Sintasa de Tipo I/metabolismo , Pterinas/uso terapéutico , Píloro/efectos de los fármacos , Animales , Diabetes Mellitus/fisiopatología , Femenino , Proteínas HSP90 de Choque Térmico/metabolismo , MicroARNs/genética , MicroARNs/metabolismo , Relajación Muscular , Factor 2 Relacionado con NF-E2/genética , Pterinas/farmacología , Píloro/metabolismo , Píloro/fisiopatología , ARN Mensajero/genética , ARN Mensajero/metabolismo , Ratas , Ratas Wistar , Transducción de SeñalRESUMEN
Gestational low-protein (LP) diet causes hyperglycemia and insulin resistance in adult offspring, but the mechanism is not clearly understood. In this study, we explored the role of insulin signaling in gastrocnemius muscles of gestational LP-exposed female offspring. Pregnant rats were fed a control (20% protein) or an isocaloric LP (6%) diet from gestational day 4 until delivery. Normal diet was given to mothers after delivery and to pups after weaning until necropsy. Offspring were euthanized at 4 months, and gastrocnemius muscles were treated with insulin ex vivo for 30 minutes. Messenger RNA and protein levels of molecules involved in insulin signaling were assessed at 4 months. LP females were smaller at birth but showed rapid catchup growth by 4 weeks. Glucose tolerance test in LP offspring at 3 months showed elevated serum glucose levels (P < 0.01; glycemia Δ area under the curve 342 ± 28 in LP vs 155 ± 23 in controls, mmol/L * 120 minutes) without any change in insulin levels. In gastrocnemius muscles, LP rats showed reduced tyrosine phosphorylation of insulin receptor substrate 1 upon insulin stimulation due to the overexpression of tyrosine phosphatase SHP-2, but serine phosphorylation was unaffected. Furthermore, insulin-induced phosphorylation of Akt, glycogen synthase kinase (GSK)-3α, and GSK-3ß was diminished in LP rats, and they displayed an increased basal phosphorylation (inactive form) of glycogen synthase. Our study shows that gestational protein restriction causes peripheral insulin resistance by a series of phosphorylation defects in skeletal muscle in a mechanism involving insulin receptor substrate 1, SHP-2, Akt, GSK-3, and glycogen synthase causing dysfunctional GSK-3 signaling and increased stored glycogen, leading to distorted glucose homeostasis.
Asunto(s)
Dieta con Restricción de Proteínas , Glucosa/metabolismo , Insulina/metabolismo , Fenómenos Fisiologicos Nutricionales Maternos/fisiología , Músculo Esquelético/metabolismo , Animales , Femenino , Glucógeno Sintasa Quinasa 3/metabolismo , Insulina/farmacología , Proteínas Sustrato del Receptor de Insulina/metabolismo , Resistencia a la Insulina/fisiología , Músculo Esquelético/efectos de los fármacos , Fosforilación/genética , Fosforilación/fisiología , Embarazo , Proteínas Proto-Oncogénicas c-akt/metabolismo , Ratas , Transducción de Señal/genética , Transducción de Señal/fisiologíaRESUMEN
Elevated maternal testosterone levels are shown to cause fetal growth restriction, eventually culminating in sex-specific adult-onset hypertension that is more pronounced in males than in females. In this study, we tested whether uteroplacental and fetoplacental disturbances underlie fetal growth restriction and if these changes vary in male and female placentas. Pregnant Sprague-Dawley rats were injected with vehicle (n=16) or testosterone propionate (0.5 mg/kg per day from gestation day 15-19; n=16). On gestation day 20, we quantified uterine artery blood flow using microultrasound, visualized placental arterial network using x-ray microcomputed tomography, determined fetoplacental hypoxia using pimonidazole and hypoxia-inducible factor-1α, and used Affymetrix array to determine changes in placental expression of genes involved in vascular development. Plasma testosterone levels increased 2-fold in testosterone-injected rats. Placental and fetal weights were lower in rats with elevated testosterone. Uterine artery blood flow was lower, and resistance index was higher in the testosterone group. Radial and spiral artery diameter and length, the number of fetoplacental arterial branches, and umbilical artery diameter were reduced in the testosterone group. In addition, markers of hypoxia in the placentas and fetuses were elevated in the testosterone group. The magnitude of changes in placental vasculature and hypoxia was greater in males than in females and was associated with sex-specific alteration of unique sets of genes involved in angiogenesis and blood vessel morphogenesis. The results demonstrate that elevated testosterone during gestation induces a decrease in uterine arterial blood flow and fetal sex-related uteroplacental vascular changes, which may set the stage for subsequent sex differences in adult-onset diseases.
Asunto(s)
Velocidad del Flujo Sanguíneo/fisiología , Retardo del Crecimiento Fetal/metabolismo , Consumo de Oxígeno/fisiología , Placenta/metabolismo , Preñez , Testosterona/sangre , Arteria Uterina/fisiología , Animales , Femenino , Retardo del Crecimiento Fetal/diagnóstico , Retardo del Crecimiento Fetal/fisiopatología , Masculino , Embarazo , Ratas , Ratas Sprague-Dawley , Útero/irrigación sanguínea , Útero/metabolismo , Microtomografía por Rayos XRESUMEN
Prenatal exposure to excess testosterone induces hyperandrogenism in adult females and predisposes them to hypertension. We tested whether androgens induce hypertension through transcriptional regulation and signaling of protein kinase C (PKC) in the mesenteric arteries. Pregnant Sprague-Dawley rats were injected with vehicle or testosterone propionate (0.5 mg/kg per day from gestation days 15 to 19, SC) and their 6-month-old adult female offspring were examined. Plasma testosterone levels (0.84±0.04 versus 0.42±0.09 ng/mL) and blood pressures (111.6±1.3 versus 104.5±2.4 mm Hg) were significantly higher in prenatal testosterone-exposed rats compared with controls. This was accompanied with enhanced expression of PKCδ mRNA (1.5-fold) and protein (1.7-fold) in the mesenteric arteries of prenatal testosterone-exposed rats. In addition, mesenteric artery contractile responses to PKC activator, phorbol-12,13-dibutyrate, was significantly greater in prenatal testosterone-exposed rats. Treatment with androgen receptor antagonist flutamide (10 mg/kg, SC, BID for 10 days) significantly attenuated hypertension, PKCδ expression, and the exaggerated vasoconstriction in prenatal testosterone-exposed rats. In vitro exposure of testosterone to cultured mesenteric artery smooth muscle cells dose dependently upregulated PKCδ expression. Analysis of PKCδ gene revealed a putative androgen responsive element in the promoter upstream to the transcription start site and an enhancer element in intron-1. Chromatin immunoprecipitation assays showed that androgen receptors bind to these elements in response to testosterone stimulation. Furthermore, luciferase reporter assays showed that the enhancer element is highly responsive to androgens and treatment with flutamide reverses reporter activity. Our studies identified a novel androgen-mediated mechanism for the control of PKCδ expression via transcriptional regulation that controls vasoconstriction and blood pressure.
Asunto(s)
Hipertensión/etiología , Hipertensión/fisiopatología , Efectos Tardíos de la Exposición Prenatal/etiología , Proteína Quinasa C-delta/fisiología , Receptores Androgénicos/fisiología , Transducción de Señal/fisiología , Testosterona/efectos adversos , Animales , Presión Sanguínea/efectos de los fármacos , Presión Sanguínea/fisiología , Células Cultivadas , Modelos Animales de Enfermedad , Relación Dosis-Respuesta a Droga , Femenino , Flutamida/farmacología , Hiperandrogenismo/etiología , Arterias Mesentéricas/efectos de los fármacos , Arterias Mesentéricas/patología , Arterias Mesentéricas/fisiopatología , Embarazo , Ratas , Ratas Sprague-Dawley , Transducción de Señal/efectos de los fármacos , Testosterona/farmacología , Vasoconstricción/efectos de los fármacos , Vasoconstricción/fisiologíaRESUMEN
Pre-eclampsia is a life-threatening pregnancy disorder whose pathogenesis remains unclear. Plasma testosterone levels are elevated in pregnant women with pre-eclampsia and polycystic ovary syndrome, who often develop gestational hypertension. We tested the hypothesis that increased gestational testosterone levels induce hypertension via heightened angiotensin II signaling. Pregnant Sprague-Dawley rats were injected with vehicle or testosterone propionate from Gestational Day 15 to 19 to induce a 2-fold increase in plasma testosterone levels, similar to levels observed in clinical conditions like pre-eclampsia. A subset of rats in these two groups was given losartan, an angiotensin II type 1 receptor antagonist by gavage during the course of testosterone exposure. Blood pressure levels were assessed through a carotid arterial catheter and endothelium-independent vascular reactivity through wire myography. Angiotensin II levels in plasma and angiotensin II type 1 receptor expression in mesenteric arteries were also examined. Blood pressure levels were significantly higher on Gestational Day 20 in testosterone-treated dams than in controls. Treatment with losartan during the course of testosterone exposure significantly attenuated testosterone-induced hypertension. Plasma angiotensin II levels were not significantly different between control and testosterone-treated rats; however, elevated testosterone levels significantly increased angiotensin II type 1 receptor protein levels in the mesenteric arteries. In testosterone-treated rats, mesenteric artery contractile responses to angiotensin II were significantly greater, whereas contractile responses to K(+) depolarization and phenylephrine were unaffected. The results demonstrate that elevated testosterone during gestation induces hypertension in pregnant rats via heightened angiotensin II type 1 receptor-mediated signaling, providing a molecular mechanism linking elevated maternal testosterone levels with gestational hypertension.
Asunto(s)
Presión Sanguínea/efectos de los fármacos , Hipertensión Inducida en el Embarazo/inducido químicamente , Losartán/uso terapéutico , Receptor de Angiotensina Tipo 1/metabolismo , Testosterona/farmacología , Angiotensina II/sangre , Animales , Modelos Animales de Enfermedad , Femenino , Hipertensión Inducida en el Embarazo/tratamiento farmacológico , Hipertensión Inducida en el Embarazo/metabolismo , Hipertensión Inducida en el Embarazo/prevención & control , Losartán/farmacología , Arterias Mesentéricas/efectos de los fármacos , Arterias Mesentéricas/metabolismo , Embarazo , Ratas , Ratas Sprague-Dawley , Receptor de Angiotensina Tipo 1/genética , Testosterona/sangreRESUMEN
Type II diabetes originates from various genetic and environmental factors. Recent studies showed that an adverse uterine environment such as that caused by a gestational low-protein (LP) diet can cause insulin resistance in adult offspring. The mechanism of insulin resistance induced by gestational protein restriction is not clearly understood. Our aim was to investigate the role of insulin signaling molecules in gastrocnemius muscles of gestational LP diet-exposed male offspring to understand their role in LP-induced insulin resistance. Pregnant Wistar rats were fed a control (20% protein) or isocaloric LP (6%) diet from gestational day 4 until delivery and a normal diet after weaning. Only male offspring were used in this study. Glucose and insulin responses were assessed after a glucose tolerance test. mRNA and protein levels of molecules involved in insulin signaling were assessed at 4 months in gastrocnemius muscles. Muscles were incubated ex vivo with insulin to evaluate insulin-induced phosphorylation of insulin receptor (IR), Insulin receptor substrate-1, Akt, and AS160. LP diet-fed rats gained less weight than controls during pregnancy. Male pups from LP diet-fed mothers were smaller but exhibited catch-up growth. Plasma glucose and insulin levels were elevated in LP offspring when subjected to a glucose tolerance test; however, fasting levels were comparable. LP offspring showed increased expression of IR and AS160 in gastrocnemius muscles. Ex vivo treatment of muscles with insulin showed increased phosphorylation of IR (Tyr972) in controls, but LP rats showed higher basal phosphorylation. Phosphorylation of Insulin receptor substrate-1 (Tyr608, Tyr895, Ser307, and Ser318) and AS160 (Thr642) were defective in LP offspring. Further, glucose transporter type 4 translocation in LP offspring was also impaired. A gestational LP diet leads to insulin resistance in adult offspring by a mechanism involving inefficient insulin-induced IR, Insulin receptor substrate-1, and AS160 phosphorylation and impaired glucose transporter type 4 translocation.
Asunto(s)
Dieta con Restricción de Proteínas/efectos adversos , Glucosa/metabolismo , Proteínas Sustrato del Receptor de Insulina/metabolismo , Resistencia a la Insulina , Músculo Esquelético/metabolismo , Efectos Tardíos de la Exposición Prenatal , Animales , Femenino , Proteínas Activadoras de GTPasa/metabolismo , Prueba de Tolerancia a la Glucosa , Transportador de Glucosa de Tipo 4/metabolismo , Insulina/sangre , Proteínas Sustrato del Receptor de Insulina/antagonistas & inhibidores , Masculino , Embarazo , Proteínas Proto-Oncogénicas c-akt/metabolismo , Ratas , Ratas Wistar , Receptor de Insulina/metabolismo , Aumento de PesoRESUMEN
Elevated testosterone levels increase maternal blood pressure and decrease uterine blood flow in pregnancy, resulting in abnormal perinatal outcomes. We tested whether elevated testosterone alters uterine artery adaptations during pregnancy, and whether these alterations depend on endothelium-derived factors such as nitric oxide, endothelium-derived hyperpolarizing factor, and prostacyclin, or endothelium-independent mechanisms such as angiotensin II (Ang-II). Pregnant Sprague-Dawley rats were injected with vehicle (n=20) or testosterone propionate (0.5 mg/kg per day from gestation day 15 to 19; n=20). Plasma testosterone levels increased 2-fold in testosterone-injected rats compared with controls. Elevated testosterone significantly decreased placental and pup weights compared with controls. In endothelium-intact uterine arteries, contractile responses to thromboxane, phenylephrine, and Ang-II were greater in testosterone-treated rats compared with controls. In endothelium-denuded arteries, contractile responses to Ang-II (pD2=9.1±0.04 versus 8.7±0.04 in controls; P<0.05), but not thromboxane and phenylephrine, were greater in testosterone-treated rats. Ang-II type 1b receptor expression was increased, whereas Ang-II type 2 receptor was decreased in testosterone-exposed arteries. In endothelium-denuded arteries, relaxations to sodium nitroprusside were unaffected. Endothelium-dependent relaxation to acetylcholine was significantly lower in arteries from testosterone-treated dams (Emax=51.80±6.9% versus 91.98±1.4% in controls; P<0.05). The assessment of endothelial factors showed that nitric oxide-, endothelium-derived hyperpolarizing factor-, and prostacyclin-mediated relaxations were blunted in testosterone-treated dams. Endothelial nitric oxide synthase, small conductance calcium-activated potassium channel-3, and prostacyclin receptor expressions were significantly decreased in arteries from testosterone-treated dams. Hypoxia-inducible factor-1α, Ankrd37, and Egln were significantly increased in testosterone-exposed placentas. These results suggest that elevated maternal testosterone impairs uterine vascular function, which may lead to an increased vascular resistance and a decrease in uterine blood flow.
Asunto(s)
Angiotensina II/farmacología , Endotelio Vascular/metabolismo , Testosterona/sangre , Arteria Uterina/metabolismo , Vasodilatación/fisiología , Acetilcolina/farmacología , Animales , Presión Sanguínea/efectos de los fármacos , Presión Sanguínea/fisiología , Endotelio Vascular/efectos de los fármacos , Femenino , Nitroprusiato/farmacología , Embarazo , Ratas , Ratas Sprague-Dawley , Testosterona/farmacología , Arteria Uterina/efectos de los fármacos , Vasodilatación/efectos de los fármacosRESUMEN
Prenatal testosterone (T) exposure impacts postnatal cardiovascular function, leading to increases in blood pressure with associated decreased endothelium-dependent vascular relaxation in adult females. Endothelial function in males is not known. Furthermore, which of the endothelial pathways contributes to endothelial dysfunction and if there exists sex differences are not known. The objective of this study was to characterize the relative contribution of nitric oxide (NO) and endothelium-derived hyperpolarizing factor (EDHF) to the impaired endothelium-dependent vasodilation in prenatal T-exposed adult males and females. Offspring of pregnant rats treated with T propionate or its vehicle were examined. Telemetric blood pressure levels and endothelium-dependent vascular reactivity were assessed with wire myography. Levels of nitric oxide synthase (NOS3) and Kcnn3 and Kcnn4 channel expression were examined in mesenteric arteries. Mean arterial pressure was significantly higher in T males and females than in controls. Endothelium-dependent acetylcholine relaxation was significantly lower in both T males and females. EDHF-mediated relaxation was specifically blunted in T males (Emax = 48.64% ± 3.73%) compared to that in control males (Emax = 81.71% ± 3.18%); however, NO-mediated relaxation was specifically impaired in T females (Emax = 36.01% ± 4.29%) compared with that in control females (Emax = 54.56% ± 6.37%). Relaxation to sodium nitroprusside and levcromakalim were unaffected with T-treatment. NOS3 protein was decreased in T females but not in T males. Kcnn3 expression was decreased in both T males and females compared to controls. These findings suggest that prenatal T leads to an increase in blood pressure in the adult offspring, associated with blunting of endothelial cell-associated relaxation and that the effects are sex-specific: EDHF-related in males and NO-related in females.
Asunto(s)
Andrógenos/efectos adversos , Endotelio Vascular/efectos de los fármacos , Hipertensión/inducido químicamente , Óxido Nítrico Sintasa de Tipo III/metabolismo , Efectos Tardíos de la Exposición Prenatal , Canales de Potasio de Pequeña Conductancia Activados por el Calcio/metabolismo , Testosterona/efectos adversos , Andrógenos/sangre , Animales , Factores Biológicos/antagonistas & inhibidores , Factores Biológicos/metabolismo , Regulación hacia Abajo/efectos de los fármacos , Endotelio Vascular/metabolismo , Endotelio Vascular/fisiopatología , Femenino , Desarrollo Fetal/efectos de los fármacos , Hipertensión/metabolismo , Hipertensión/fisiopatología , Canales de Potasio de Conductancia Intermedia Activados por el Calcio/genética , Canales de Potasio de Conductancia Intermedia Activados por el Calcio/metabolismo , Masculino , Arterias Mesentéricas/efectos de los fármacos , Arterias Mesentéricas/metabolismo , Arterias Mesentéricas/fisiopatología , Óxido Nítrico/antagonistas & inhibidores , Óxido Nítrico/metabolismo , Óxido Nítrico Sintasa de Tipo III/antagonistas & inhibidores , Embarazo , Ratas , Ratas Sprague-Dawley , Caracteres Sexuales , Canales de Potasio de Pequeña Conductancia Activados por el Calcio/antagonistas & inhibidores , Canales de Potasio de Pequeña Conductancia Activados por el Calcio/genética , Testosterona/sangre , Propionato de Testosterona/administración & dosificación , Vasodilatación/efectos de los fármacosRESUMEN
Sex steroid hormones estradiol and progesterone play an important role in vascular adaptations during pregnancy. However, little is known about the role of androgens. Plasma testosterone (T) levels are elevated in preeclampsia, mothers with polycystic ovary, and pregnant African American women, who have endothelial dysfunction and develop gestational hypertension. We tested whether increased T alters vascular adaptations during pregnancy and whether these alterations depend on endothelium-derived factors, such as prostacyclin, endothelium-derived hyperpolarizing factor, and NO. Pregnant Sprague Dawley rats were injected with vehicle (n=12) or T propionate [0.5 mg/Kg per day from gestation day 15-19; n=12] to increase plasma T levels 2-fold, similar to that observed in preeclampsia. Telemetric blood pressures and endothelium-dependent vascular reactivity were assessed with wire-myograph system. Phospho-endothelial NO synthase and total endothelial NO synthase were examined in mesenteric arteries. Mean arterial pressures were significantly higher starting from gestation day19 until delivery in T-treated dams. Endothelium-dependent relaxation responses to acetylcholine were significantly lower in mesenteric arteries of T-treated dams (pD(2) [-log EC(50)]=7.05±0.06; E(max)=89.4±1.89) compared with controls (pD(2)=7.38±0.04; E(max)=99.9±0.97). Further assessment of endothelial factors showed NO-mediated relaxations were blunted in T-treated mesenteric arteries (E(max)=42.26±5.95) compared with controls (E(max)=76.49±5.06); however, prostacyclin- and endothelium-derived hyperpolarizing factor-mediated relaxations were unaffected. Relaxation to sodium nitroprusside was unaffected with T-treatment. Phosphorylations of endothelial NO synthase at Ser(1177) were decreased and at Thr(495) increased in T-treated mesenteric arteries without changes in total endothelial NO synthase levels. In conclusion, increased maternal T, at concentrations relevant to abnormal clinical conditions, cause hypertension associated with blunting of NO-mediated vasodilation. T may induce the increased vascular resistance associated with pregnancy-induced hypertension.
Asunto(s)
Presión Arterial , Endotelio Vascular/fisiología , Arterias Mesentéricas/fisiología , Óxido Nítrico Sintasa de Tipo III/metabolismo , Óxido Nítrico/fisiología , Testosterona/fisiología , Acetilcolina/farmacología , Adaptación Fisiológica/efectos de los fármacos , Adaptación Fisiológica/fisiología , Animales , Factores Biológicos/farmacología , Endotelio Vascular/efectos de los fármacos , Endotelio Vascular/enzimología , Epoprostenol/farmacología , Femenino , Hipertensión Inducida en el Embarazo/tratamiento farmacológico , Hipertensión Inducida en el Embarazo/enzimología , Hipertensión Inducida en el Embarazo/fisiopatología , Arterias Mesentéricas/efectos de los fármacos , Arterias Mesentéricas/enzimología , Óxido Nítrico Sintasa de Tipo III/análisis , Óxido Nítrico Sintasa de Tipo III/antagonistas & inhibidores , Nitroprusiato/farmacología , Fosforilación , Embarazo , Ratas , Ratas Sprague-Dawley , Serina/metabolismo , Testosterona/sangre , Testosterona/farmacología , Treonina/metabolismo , Vasodilatadores/farmacologíaRESUMEN
OBJECTIVE: Examine temporal alterations in vascular angiotensin II receptors (AT(1)R and AT(2)R) and determine vascular response to angiotensin II in growth-restricted offspring. STUDY DESIGN: Offspring of pregnant rats fed low-protein (6%) and control (20%) diet were compared. RESULTS: Prenatal protein restriction reprogrammed AT(1a)R messenger RNA expression in male rats' mesenteric arteries to cause 1.7- and 2.3-fold increases at 3 and 6 months of age associated with arterial pressure increases of 10 and 33 mm Hg, respectively; however, in female rats, increased AT(1a)R expression (2-fold) and arterial pressure (15 mm Hg) occurred only at 6 months. Prenatal protein restriction did not affect AT(2)R expression. Losartan abolished hypertension, suggesting that AT(1a)R plays a primary role in arterial pressure elevation. Vasoconstriction to angiotensin II was exaggerated in all protein-restricted offspring, with greater potency and efficacy in male rats. CONCLUSION: Prenatal protein restriction increased vascular AT(1)R expression and vasoconstriction to angiotensin II, possibly contributing to programmed hypertension.
Asunto(s)
Dieta con Restricción de Proteínas/efectos adversos , Hipertensión/etiología , Efectos Tardíos de la Exposición Prenatal/etiología , Receptor de Angiotensina Tipo 1/metabolismo , Receptor de Angiotensina Tipo 2/metabolismo , Vasoconstricción/fisiología , Bloqueadores del Receptor Tipo 1 de Angiotensina II/farmacología , Animales , Biomarcadores/metabolismo , Presión Sanguínea/efectos de los fármacos , Femenino , Hipertensión/metabolismo , Hipertensión/fisiopatología , Losartán/farmacología , Masculino , Arterias Mesentéricas/metabolismo , Arterias Mesentéricas/fisiopatología , Embarazo , Efectos Tardíos de la Exposición Prenatal/metabolismo , Efectos Tardíos de la Exposición Prenatal/fisiopatología , Ratas , Ratas Sprague-Dawley , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Factores SexualesRESUMEN
Prenatal testosterone exposure impacts postnatal reproductive and endocrine function, leading to alterations in sex steroid levels. Because gonadal steroids are key regulators of cardiovascular function, it is possible that alteration in sex steroid hormones may contribute to development of hypertension in prenatally testosterone-exposed adults. The objectives of this study were to evaluate whether prenatal testosterone exposure leads to development of hypertension in adult males and females and to assess the influence of gonadal hormones on arterial pressure in these animals. Offspring of pregnant rats treated with testosterone propionate or its vehicle (controls) were examined. Subsets of male and female offspring were gonadectomized at 7 wk of age, and some offspring from age 7 to 24 wk received hormone replacement, while others did not. Testosterone exposure during prenatal life significantly increased arterial pressure in both male and female adult offspring; however, the effect was greater in males. Prenatal androgen-exposed males and females had more circulating testosterone during adult life, with no change in estradiol levels. Gonadectomy prevented hyperandrogenism and also reversed hypertension in these rats. Testosterone replacement in orchiectomized males restored hypertension, while estradiol replacement in ovariectomized females was without effect. Steroidal changes were associated with defective expression of gonadal steroidogenic genes, with Star, Sf1, and Hsd17b1 upregulation in testes. In ovaries, Star and Cyp11a1 genes were upregulated, while Cyp19 was downregulated. This study showed that prenatal testosterone exposure led to development of gonad-dependent hypertension during adult life. Defective steroidogenesis may contribute in part to the observed steroidal changes.
Asunto(s)
Hipertensión/inducido químicamente , Efectos Tardíos de la Exposición Prenatal/fisiopatología , Testosterona/efectos adversos , Animales , Castración , Estradiol/administración & dosificación , Estradiol/biosíntesis , Estradiol/sangre , Femenino , Expresión Génica/efectos de los fármacos , Hipertensión/cirugía , Masculino , Ovario/efectos de los fármacos , Ovario/enzimología , Ovario/cirugía , Embarazo , Efectos Tardíos de la Exposición Prenatal/sangre , Ratas , Factores Sexuales , Testículo/efectos de los fármacos , Testículo/enzimología , Testículo/cirugía , Testosterona/administración & dosificación , Testosterona/biosíntesis , Testosterona/sangreRESUMEN
BACKGROUND: Exposure of pregnant mothers to elevated concentrations of circulating testosterone levels is associated with fetal growth restriction and delivery of small-for-gestational-age babies. We examined whether maternal testosterone crosses the placenta to directly suppress fetal growth or if it modifies placental function to reduce the capacity for transport of nutrients to the fetus. METHODS: Pregnant rats were exposed to testosterone propionate (TP; 0.5 mg/kg) by daily subcutaneous injection from gestational days (GD) 15-19. Maternal and fetal testosterone levels, placental nutrient transport activity and expression of transporters and birth weight of pups and their anogenital distances were determined. RESULTS: This dose of TP doubled maternal testosterone levels but had no effect on fetal testosterone levels. Maternal daily weight gain was significantly lower only on GD 19 in TP treated dams compared to controls. Placental weight and birth weight of pups were significantly reduced, but the anogenital distance of pups were unaffected by TP treatment. Maternal plasma amino acids concentrations were altered following testosterone exposure, with decreases in glutamine, glycine, tyrosine, serine, proline, and hydroxyproline and increases in asparagine, isoleucine, leucine, lysine, histidine and arginine. In the TP dams, placental system A amino acid transport activity was significantly reduced while placental glucose transport capacity was unaffected. Decreased expression of mRNA and protein levels of slc38a2/Snat2, an amino acid transporter, suggests that reduced transporter proteins may be responsible for the decrease in amino acid transport activity. CONCLUSIONS: Taken together, these data suggest that increased maternal testosterone concentrations do not cross the placenta to directly suppress fetal growth but affects amino acid nutrient delivery to the fetus by downregulating specific amino acid transporter activity.