Plasma Corticosteroid Concentrations Research Articles

Impact of CYP3A5 Polymorphisms on Pediatric Asthma Outcomes.

Genetic variation among inhaled corticosteroid (ICS)-metabolizing enzymes may affect asthma control, but evidence is limited. This study tested the hypothesis that single-nucleotide polymorphisms (SNPs) in Cytochrome P450 3A5 (CYP3A5) would affect asthma outcomes. Patients aged 2-18 years with persistent asthma were recruited to use the electronic AsthmaTracker (e-AT), a self-monitoring tool that records weekly asthma control, medication use, and asthma outcomes. A subset of patients provided saliva samples for SNP analysis and participated in a pharmacokinetic study. Multivariable regression analysis adjusted for age, sex, race, and ethnicity was used to evaluate the impact of CYP3A5 SNPs on asthma outcomes, including asthma control (measured using the asthma symptom tracker, a modified version of the asthma control test or ACT), exacerbations, and hospital admissions. Plasma corticosteroid and cortisol concentrations post-ICS dosing were also assayed using liquid chromatography-tandem mass spectrometry. Of the 751 patients using the e-AT, 166 (22.1%) provided saliva samples and 16 completed the PK study. The e-AT cohort was 65.1% male, and 89.6% White, 6.0% Native Hawaiian, 1.2% Black, 1.2% Native American, 1.8% of unknown race, and 15.7% Hispanic/Latino; the median age was 8.35 (IQR: 5.51-11.3) years. CYP3A5*3/*3 frequency was 75.8% in White subjects, 50% in Native Hawaiians and 76.9% in Hispanic/Latino subjects. Compared with CYP3A5*3/*3, the CYP3A5*1/*x genotype was associated with reduced weekly asthma control (OR: 0.98; 95% CI: 0.97-0.98; p < 0.001), increased exacerbations (OR: 6.43; 95% CI: 4.56-9.07; p < 0.001), and increased asthma hospitalizations (OR: 1.66; 95% CI: 1.43-1.93; p < 0.001); analysis of 3/*3, *1/*1 and *1/*3 separately showed an allelic copy effect. Finally, PK analysis post-ICS dosing suggested muted changes in cortisol concentrations for patients with the CYP3A5*3/*3 genotype, as opposed to an effect on ICS PK. Detection of CYP3A5*3/3, CYPA35*1/*3, and CYP3A5*1/*1 could impact inhaled steroid treatment strategies for asthma in the future.

Prolonged joint residency of triamcinolone acetonide after an intra-articular injection of FX006, a sustained release formulation for the treatment of osteoarthritis

Purpose: Although available intra-articular (IA) corticosteroids are well established in the treatment of painful osteoarthritis (OA), limitations include short duration of pain relief (1-4 weeks), an effect consistent with the transient residency of these compounds in the joint and high plasma corticosteroid concentrations immediately following injection. FX006 is a novel IA sustained-release injectable formulation of 25% triamcinolone acetonide (TCA) in poly(lactic-co-glycolic acid) microspheres intended to prolong therapeutic concentrations of TCA in the joint and limit systemic exposure. In a previously described 6-week long clinical study, FX006 at 40 mg demonstrated maintenance of synovial concentrations of TCA consistent with pharmacologic activity for a period of at least 6 weeks, when levels of TCA produced by an equivalent dose of TCA IR were below the limit of quantitation. The current study extended these data on joint residency by measuring synovial fluid levels of TCA at later time points. Methods: In this multi-center, open-label study, patients with OA of the knee received a single IA injection of FX006 containing 10 or 40 mg TCA, or 40 mg of a standard, immediate-release suspension of TCA (TCA IR). A total of 50 patients were enrolled (FX006 10 mg: 10 patients, FX006 40 mg: 30 patients, TCA IR: 10 patients). Synovial fluid and plasma samples were obtained at baseline (pre-dose) and at the planned Final Visit at either Week 12, 16, or 20, depending on cohort assignment and availability of fluid in the knee. Concentrations of TCA were measured in plasma or in filtered synovial fluid samples using High Performance Liquid Chromatographic methods with Tandem Mass Spectrometry Detection and Automated Extraction, validated for the determination of TCA in human plasma and synovial fluid respectively. The quantitation limits of both assays were 50 to 50000 pg/mL. Results: In the FX006 10 mg group, 8 patients had synovial fluid available for analysis at Week 12. In the FX006 40 mg group, 6 patients had synovial fluid available for analysis at Week 12, 8 patients at Week 16 and 11 patients at Week 20. In the TCA IR group, 5 patients had synovial fluid available for analysis at Week 12. The concentrations of TCA achieved by 40 mg FX006 in the synovial fluid at Week 12 were 924 pg/mL, at Week 16, the IA concentrations of TCA were 224 pg/mL and by Week 20 they were below the lower limit of quantitation (Figure; geometric means from the earlier 6-week study and the current study are merged). The IA concentration of TCA in patients receiving 40 mg of TCA IR at Week 12 was below the lower limit of quantitation. FX006 maintained a gradient between synovial and systemic plasma concentrations of TCA for 16 weeks. Conclusions: A single IA administration of 40 mg of FX006 maintained pharmacologically active synovial fluid concentrations of TCA for at least 12 weeks, while TCA IR produced levels that are below the lower limit of quantitation by 6 weeks. These data underpin the differentiation of FX006 from TCA IR and provide pharmacokinetic basis for previously demonstrated prolongation and amplification of pain relief compared to TCA IR in OA patients following a single IA injection. FX006 also has the potential for an improved systemic safety profile as evidenced by peak plasma concentrations that are 40-fold lower than TCA IR at the same dose, seen in the aggregate of clinical studies with FX006 to date.

Assessment of the accuracy and reproducibility of adrenal volume measurements using MRI and its relationship with corticosteroid phenotype: a normal volunteer pilot study

The significant role of corticosteroids in hypertension and cardiovascular disease highlights the importance of the adrenal gland in these disorders. The ability to correlate corticosteroid production with adrenal volume offers a novel research tool and intermediate phenotype in cardiovascular disease. The aim of this study was to develop and validate the use of magnetic resonance imaging (MRI) in adrenal volume assessment and investigate whether this associates with corticosteroid production. Twenty normotensive men underwent noncontrast 1·5T MRI scanning of adrenals, measurement of blood pressure and plasma corticosteroids. Left adrenal volume was calculated twice using standard segmentation software by four independent observers with differing levels of clinical expertise and segmentation experience. To optimize this process, adrenal 'phantoms' with known fixed volumes underwent MRI scanning and analysis by two observers. Intra-observer coefficients of repeatability (CoRs) in phantoms ranged from 0·23 to 0·43ml (interobserver CoR 0·48ml). In the subject group, mean adrenal volumes were 3·99-5·82ml with intra-observer CoRs 0·27-1·94ml. Interobserver variability was 2·73ml. Segmentation expertise was the main factor affecting variability, with experienced observers having the lowest CoRs; clinical knowledge was a factor when combined with segmentation experience. Mean adrenal volume correlated with plasma glucocorticoids (r=0·523, P<0·05) and aldosterone (r=0·515, P<0·05) for the most experienced observer only. Measurement of adrenal volume using MRI is challenging; most accurate volumes are achieved using a single observer with both segmentation experience and anatomical knowledge. The data also provide novel preliminary evidence that adrenal gland volume may be associated with plasma corticosteroid concentrations supporting further study of adrenal volume and steroid production across a range of blood pressures.

The effect of long-acting ACTH on plasma corticosteroids, testosterone, and LH levels in the male pig.

Intramuscular injection of long-acting ACTH (10 micrograms/kg body weight) into male pigs, fitted with permanently indwelling jugular catheters, resulted in a significant rise of plasma corticosteroid concentrations for a period of between 0.5 and 20 hours after injection. Plasma testosterone levels were significantly increased between 60 and 120 min after ACTH administration. Between 6 and 12 hours after ACTH application, however, they were significantly depressed, evidencing a two phase effect of ACTH on testosterone levels. Plasma LH concentrations showed a slight but progressive decrease which was significant between 2.5 and 12 hours p.i. From these results it has been concluded that long-acting ACTH stimulates testosterone release. Because LH levels were depressed, they cannot have been responsible for the increase in plasma testosterone. The increase of plasma testosterone concentrations was not accompanied by a change of plasma prolactin levels.

Lack of Pharmacokinetic Interaction Between St. John's Wort and Prednisone

St. John's wort (SJW) is a popular dietary supplement involved in numerous dietary supplement-drug interactions with prescription and non-prescription drugs. The supplement has been shown to affect the metabolism of various CYP3A4 substrates. The CYP3A4 pathway mediates the metabolism of a large number of drug entities, including the corticosteroids prednisone and prednisolone. To examine the effects of long-term SJW administration on the pharmacokinetics of prednisone and its reversible metabolite prednisolone in male subjects. Eight male subjects participated in this single-dose study. The pharmacokinetics of prednisone and prednisolone were evaluated before and after 28 days of SJW administration. Plasma corticosteroid concentrations were determined using a normal phase high-performance liquid chromatography assay. Model-independent methods were used to evaluate corticosteroid pharmacokinetics. Twenty-eight days of SJW treatment resulted in no significant alterations in the pharmacokinetic parameters for prednisone or prednisolone. Oral administration of prednisone resulted in prednisone mean +/- SD area under the curves (AUCs) of 115.89 +/- 39.52 microg x h/L prior to SJW treatment and 128.76 +/- 32.71 microg x h/L after 28 days of treatment. Prednisolone mean AUCs were 714.19 +/- 153.29 microg x h/L before SJW administration and 700.74 +/- 89.68 microg x h/L after treatment. Concurrent administration of SJW had no significant effect on the single-dose pharmacokinetics of prednisone or metabolic prednisolone in male subjects.

Plasma and Urine Levels of Electrolytes, Urea and Steroid Hormones Involved in Osmoregulation of Cetaceans

Cetaceans are well adapted to their hyperosmotic environment by properly developed osmoregulatory ability. A question here is how they regulate water and mineral balances in marine habitats. In the present study, we determined blood and urine levels of various chemicals involved in osmoregulation, compared them with those in artiodactyls, and characterized the values in the whales. Blood and urine samples obtained from baleen whales of common minke (Balaenoptera acutorostrata), sei (B. borealis), and Bryde's whales (B. brydei), and toothed whales of sperm whales (Physeter macrocephalus) were analyzed for osmolality, major electrolytes, urea, steroid hormones and glucose. The urine osmolality and Na(+) concentrations in the cetaceans were much higher than those in the cattle. Furthermore, the cetaceans had 5 to 11-fold urea in plasma than the cattle, and 2 to 4-fold urea in urine. There were no significant difference in the plasma concentrations of corticosteroids between the cetaceans and the cattle. The present results indicate that the osmoregulatory parameters seem to be not affected by the reproductive stage and sex steroid hormones. The concentrations of urea in plasma and urine of the baleen whales were higher than those of the sperm whales, indicating a possibility that their osmoregulatory mechanisms may be correlated to their feeding habits. The present results suggest that cetaceans have unique osmoregulatory mechanisms by which they excrete strongly hypertonic urine to maintain fluid homeostasis in marine habitats.

Chronic alterations in ovine maternal corticosteroid levels influence uterine blood flow and placental and fetal growth.

Previous work from this laboratory demonstrated that the elevation of maternal plasma corticosteroid concentrations during pregnancy is important for the support of fetal development. Reducing ovine maternal plasma cortisol concentrations to nonpregnant levels stimulates homeostatic responses that defend fetal blood volume. The present study was designed to test the hypothesis that chronic decreases or increases in maternal plasma cortisol concentration alter uterine and placental blood flow and morphology. Three groups of pregnant ewes and their fetuses were chronically catheterized and studied: ewes infused with cortisol (1 mg.kg(-1).day(-1); high cortisol), ewes adrenalectomized and underreplaced with cortisol (0.5 mg.kg(-1).day(-1); low cortisol), and control ewes. The normal increment in uterine blood flow between 120 and 130 days was eliminated in the low-cortisol ewes; conversely, uterine blood flow was increased in the high-cortisol group compared with the control group. Fetal arterial blood pressure was increased in the high-cortisol group compared with controls, but there was no increase in fetal arterial pressure from 120 to 130 days of gestation in the low-cortisol group. The fetuses of both low-cortisol and high-cortisol groups had altered placental morphology, with increased proportions of type B placentomes, and overall reduced fetal placental blood flow. The rate of fetal somatic growth was impaired in both low-cortisol and high-cortisol groups compared with the fetuses in the intact group. The results of this study demonstrate that maternal plasma cortisol during pregnancy is an important contributor to the maternal environment supporting optimal conditions for fetal homeostasis and somatic growth.

Behavioural and physiological consequences of home advantage resource holding in male guinea pigs

This study tested the physiological and behavioural effects of a resource asymmetry between guinea pig males. Asymmetry was defined via cohabitation with a female in a home area during a 5-day period. An experimental setup was designed in which the same male alternated between being in this home area (and monopolizing a female therein) and playing the role of an intruder. The confrontation phase between the resource holder and the intruder lasted 5 days. Behavioural data were collected for 0.5 h at the start of the confrontation and again for 0.5 h at 3, 24, 72, and 120 h after the onset of confrontation. Blood samples were taken before the test started and after 3, 72, and 120 h. Body mass was registered before and after the confrontation phase. The results indicate that resource holders were more highly motivated than intruders in displaying aggressiveness. They exhibited more chasing behaviour and won more confrontations. Both male groups performed almost identical frequencies of threat displays and courtship behaviour. Physiologically, the resource holders lost less body mass and showed increased plasma testosterone concentrations after 120 h. Resource holders also exhibited steady plasma corticosteroid concentrations, whereas the intruders showed elevated corticosteroid levels at 72 and 120 h. The results show that when acting as a resource holder, males react according to the resident-always-wins hypothesis, and when acting as an intruder, lose most confrontations. We conclude that the behavioural and physiological reaction of males during confrontations is determined to a greater extent by environmental asymmetries than by experiences or physical conditions before the conflict.

Hormonal interactions within the hypothalamus and pituitary with respect to stress and reproduction in sheep

Endocrine systems may be used as indicators of stress in two ways. The primary role of a hormone may be as part of the homeostatic response to a stimulus (e.g., adrenaline, corticosteroids). The amplitude of hormone response may correlate with the severity of the stimulus and any change indicate that the body is responding. Alternatively, a hormone may have a key role in normal body function (e.g., reproduction) and stress may deleteriously alter the hormone signal prevent normal function. This demonstrates that the stimulus was sufficiently severe that homeostatic mechanisms were unable to maintain normal function. Stress may effect reproduction by reducing both LH pulse amplitude and frequency. The LH surge may also be delayed. Several mechanisms may account for these effects both at the hypothalamus and pituitary. Corticosteroids have a broad, yet fundamental, role in homeostasis and have been used as primary indicators of stress for many years. Excess corticosteroid can be detrimental so the concentration is controlled via the hypothalamus–pituitary–adrenal (HPA) axis by multi-level feedback mechanisms. Under field and experimental conditions, after an initial large response prolonged stimulation leads to a gradually reducing plasma corticosteroid concentrations. This has been interpreted as a reduction in perceived stimulus severity or habituation to the stimulus and the animal deemed “less stressed” and its welfare “better.” However, this reduction may be due to the intrinsic control mechanisms designed to prevent prolonged increases in corticosteroid concentrations. The stress signal at higher brain levels may still be present and the animal may still be experiencing the stimulus as aversive. Thus, the welfare interpretation of a corticosteroid concentration may differ during the time course of a stress response. A greater understanding of the mechanisms controlling corticosteroid secretion at each level of the HPA is required to determine what is the correct interpretation at any time point. To address these issues, we have used mathematical modelling to produce representations of possible control mechanisms at each level of the HPA. The starting point was to measure AVP and CRH concentrations in hypophysial portal blood and ACTH and cortisol concentrations in jugular blood in conscious sheep during 2 h road transport (a cognitive stimulus). Modelling identified the signal inputs that were most likely to explain the secretion rate of each hormone. Modelling suggested that the reduction in AVP and CRH secretion observed during transport was most likely due to a reduction in stimulus input, with a significant contribution from cortisol negative feedback only on AVP secretion. At the pituitary level, ACTH secretion was stimulated more by AVP than by CRH (ratio 2.3:1) and there was also a stimulatory effect related to cortisol concentration at the time of sampling. However, the responses to both stimuli were curtailed by cortisol negative feedback and an inhibitory effect of prior CRH concentration. These are complex effects, but the modelling does suggest that while “stress” inputs may reduce over time hormone negative feedback is a major factor reducing hormone responses. When interpreting hormone data for animal welfare purposes, it is important not to interpret a reduction in hormone concentration due to intrinsic hormone control mechanisms as a reduction due to a decrease in the stress stimulus.

Some Possibilities for Influence on the Stress Level and the Boar Taint in Pigs by Estrogens

ABSTRACTImmature female pigs from the Danube white breed at the age of 2.5 months, were treated only once intramuscularly with 17, β-estradiol or diethylstilbestrol dipropionate—100 μg kg−1 body weight. The corticosteroid concentration in the blood plasma has been determined fluorimetrically. At the third hour after the estrogen administration the level of the plasma corticosteroids increased by 33–35% and at the 24th hour it showed values equal to those obtained before the hormonal treatment. The possibility for the estrogens to participate in the raising of the adaptive potentialities of the pigs to different stress factors is assumed. Male non-castrated pigs from the same breed, fattened to 110 kg were treated for 5 days before the slaughter intramuscularly daily with diethylstilbestrol dipropionate—50 μg kg−1 body weight. The individual levels of indoles have been determined fluorimetrically in protein-free extracts of blood plasma. The values in the treated animals are lower than in the control. The possibility of the estrogens to lessen the specific unpleasant odour of boar meat due to indoles to a great extent is supposed.

Porcine Fetal and Maternal Adrenocorticotropic Hormone and Corticosteroid Concentrations during Gestation and their Relation to Fetal Size1

A study was conducted to characterize fetal plasma ACTH and corticosteroid concentrations during porcine gestation and to relate plasma corticosteroids to fetal size. Samples were taken in white crossbred pigs at 50, 75, and 100 days of gestation and in Chinese Meishan pigs at Day 75. Fetuses developed in either "crowded" or "roomy" uterine environments after maternal uterine ligation, and all fluid samples were obtained during surgery. Fetal arterial cortisol decreased by 30% between Days 50 and 75 and then increased by 101% between 75 and 100 days. Concomitantly, fetal arterial ACTH increased 4-fold between 50 and 75 days of gestation and 45% between 75 and 100 days. Fetal venous cortisol and ACTH (measured only on Days 75 and 100) concentrations were lower than arterial concentrations. Both amniotic and allantoic fluid cortisol concentrations paralleled those of arterial cortisol but were at least 4-fold less. The percentage of free cortisol on Days 75 and 100 was a constant 24%, whereas cortisol bound to corticosteroid-binding globulin was a constant 60% and albumin-bound cortisol was 16%. White crossbred fetal arterial cortisone concentrations were always lower than cortisol concentrations, did not differ between arterial and venous plasma, decreased 50% between 50 and 75 days, and did not change thereafter. Plasma cortisol concentrations in Chinese Meishan fetuses were 30% greater than in white crossbred fetuses of the same age, but plasma ACTH and cortisone did not differ between breeds. Analysis of covariance indicated a negative regression of fetal weight and fetal length on arterial cortisol in white crossbred fetuses only at Day 100, and at Day 75 in Meishan fetuses. Under the specific conditions of this experimental model, these data demonstrate prenatal developmental changes in plasma ACTH and corticosteroids, indicate breed differences in such development, and suggest that a negative relationship exists between endogenous cortisol concentrations and fetal size at specific gestational ages.

Stress-induced analgesia. The role of hormones produced by the hypophyseal-adrenocortical system.

Experimental studies on the effects of stress on blood corticosteroid levels and the appearance of analgesia were carried out on rats anesthetized with Nembutai (4 mg/100 g). Stress, consisting of stimulation of the hind footpad with a current at 0.7 mA, produced parallel changes in plasma corticosteroid concentrations and the threshold of a pain response. Functional blockade of the hypophyseal-adrenocortical system, produced by systemic administration of hydrocortisone (15 mg/100 g) or by implantation of dexamethasone (200 micrograms) above the paraventricular nucleus of the hypothalamus, resulted in reductions in stress-induced analgesia. Dosage with naloxone (1 and 10 mg/kg) had no effect on the level of analgesia or corticosteroid concentrations. It is concluded that stress-induced analgesia not mediated by opioids is corticosteroid-dependent.

Changes in corticosteroid sensitivity of peripheral blood lymphocytes after strenuous exercise in humans.

Although plasma corticosteroid concentrations can be measured accurately, the biological effect on the target tissue is uncertain. The availability of an accurate measure of corticosteroid sensitivity would potentially clarify the putative roles of endogenous glucocorticoids in illnesses such as inflammatory disease and obesity and allow evaluation of an additional regulatory level of glucocorticoid action. To measure corticosteroid sensitivity, we developed an assay based on the inhibition by dexamethasone (Dex) of lipopolysaccharide (LPS)-induced Interleukin-6 (IL-6) production and release in whole unseparated blood in vitro. LPS induced a dose-dependent increase in IL-6 concentrations up to 34 +/- 6.6 ng/mL, reaching plateau levels after 8 h, whereas Dex dose dependently inhibited LPS-induced IL-6 production. Involvement of the glucocorticoid receptor in this response was supported by abrogation of Dex (10(-7) mol/L) inhibition of IL-6 production by the glucocorticoid receptor antagonist RU 38486. To determine whether corticosteroid sensitivity is a dynamic phenomenon, we subjected healthy males to a graded quantifiable exercise associated with increases in plasma ACTH and cortisol. Before exercise, 3 x 10(-8) mol/L Dex inhibited LPS-induced IL-6 production in vitro; after exercise, 3 x 10(-8) and 10(-7) mol/L Dex were unable to inhibit IL-6 production. We conclude that Dex suppression of LPS-induced IL-6 production is an effective means of determining corticosteroid sensitivity, and that corticosteroid sensitivity in human subjects is a dynamic, rather than a static, phenomenon.

Chronic dexamethasone treatment suppresses hypertension development in the transgenic rat TGR(mREN2)27.

The transgenic rat TGR(mREN2)27 is a monogenetic rat model in hypertension research. Integration of mouse Ren-2 gene into the rat genome led to fulminant hypertension despite suppressed plasma and kidney renin concentrations. Renin is highly expressed in extrarenal tissues, especially throughout the adrenal cortex. Because plasma and urinary corticosteroid concentrations are elevated during the development of hypertension in these rats, we investigated the effect of dexamethasone on blood pressure, adrenal renin and steroid metabolism. A daily injection of 100 micrograms/kg dexamethasone for 8 weeks was capable of suppressing the development of hypertension in the transgenic rats. The same regimen did not alter blood pressure in Sprague-Dawley control rats. Plasma concentrations of adrenocorticotrophic hormone (ACTH)-dependent steroids (corticosterone and 18-hydroxydeoxycorticosterone) decreased markedly in both strains treated with dexamethasone, but more pronouncedly in transgenic rats. Surprisingly, plasma aldosterone concentrations increased exclusively in the transgenic rats, and not in control rats, treated with dexamethasone. The decrease in corticosterone and 18-hydroxydeoxycorticosterone production was accompanied by a decrease in the abundance of the messenger RNA (mRNA) encoding the rate-limiting enzyme in steroidogenesis (P450scc cholesterol side-chain cleavage) and a decrease in the mRNA encoding P450c11 beta (11 beta-hydroxylase). The increase in aldosterone was accompanied by a massive increase in the abundance of the mRNA encoding zona glomerulosa-specific P450c11AS (aldosterone synthase), which was not increased in control rats. We conclude that ACTH-dependent steroids other than the mineralocorticoid aldosterone are responsible for the development of hypertension in the transgenic rat.

ATP “potential” of nutrients may regulated plasma corticosteroid concentration: a hypothesis

Using the cold stressed, fasted animal model, a unified hypothesis is proposed to explain how the ATP “potential” of nutrients may regulate plasma corticosteroid concentration (PCC) by influencing the energy metabolism of the cells, the cellular purine release, and the pituitary-adrenal axis. The nutrient ATP potential is defined as the net number of moles of ATP generated from a mole of nutrient per number of tricarboxylic acid (TCA) cycles used for its metabolism.

Rodent models for studying steroids and hypertension: From fetal development to cells in culture

We have used several different approaches to study the role of steroids in hypertension, including rodent in vivo models, transgenic animals, and cell culture systems. Using the developing rodent fetus as a model for the ontogeny of regulation of glucocorticoid and mineralocorticoid synthesis, we found that in the developing rodent fetus, expression of both P450scc (cholesterol side chain cleavage) and P450c11β (11β-hydroxylase) mRNAs occur early, before there is complete organization of the fetal adrenal. Even after the zones of the adrenal are evident, the fetal adrenal still does not express the glomerulosa-specific P450c11AS (aldosterone synthase) mRNA. Stimulating maternal adrenal mineralocorticoid or glucocorticoid synthesis does not affect accumulation of fetal adrenal steroidogenic mRNAs, suggesting that the rodent fetal adrenal may be somewhat transcriptionally quiescent in vivo. We also used two different transgenic rodent systems to study the roles of steroids in hypertension. Using promoter-directed tumorigenesis in transgenic mice, we created transgenic mice that expressed SV40 T antigen under control of the P450scc promoter. Massive adrenal tumors, but not gonadal tumors, developed in all transgenic mice, and cells from these tumors were easily cultured. Using a novel selection tactic, we obtained several adrenocortical cell lines which have distinct characteristics, suggesting they were locked into various stages of differentiation; both expression of steroidogenic mRNAs and the steroids synthesized differ among the lines. Regulation of steroid synthesis and mRNA abundance also varies among cell lines. Several cell lines also express mouse renin, and its synthesis, secretion, and mRNA abundance is also hormonally regulated. In a second transgenic model, we used a transgenic rat (TGR) that expresses an additional renin-2 gene primarily in the adrenal to study the role of adrenal renin in regulating adrenal steroidogenesis in vivo. Since plasma and urinary corticosteroid concentrations are elevated throughout the development of hypertension in these animals, we studied the effect of ACTH and Dexamethasone (DEX) on blood pressure and steroidogenesis. Daily injections of Dex suppressed the development of hypertension in TGR, but did not alter blood pressure in Sprague-Dawley (SD) control rats. This reduction in blood pressure was associated with reductions in plasma concentrations of corticosterone and 18-OH-DOC and of P450scc and P450c11β mRNAs. Surprisingly, plasma aldosterone concentrations and P450c11AS mRNA increased in TGR but not SD treated with Dex. Although Dex resulted in differences in the regulation of P450scc, P450c11β, and P450c11AS mRNAs between TGR and SD rats, regulation of these mRNAs by ACTH was similar in both strains of rats. These data provide evidence for the important role of adrenal renin and corticosteroids in the development of hypertension in TGR. Taken together, these model systems will continue to allow us to study the varied roles that steroid hormones play in hypertension.

Peripheral blood concentrations of plasma steroids and a metabolite of prostaglandin F 2α in pregnant cows vaccinated against foot and mouth disease

Blood samples were collected from 82 pregnant cows at 6-h intervals to determine the effects of vaccination against foot and mouth disease (FMD) on plasma concentrations of progesterone, total unconjugated oestrogens, total corticosteroids and 13,14-dihydro-15-keto-prostaglandin F2 alpha (PGFM). Twenty-two (26.8%) cows showed a strong post-vaccinal reaction in the form of a significant (P < 0.05) elevation in rectal temperature, accompanied by significant (P < 0.01) increases in plasma progesterone and corticosteroid concentrations for 36-42 h after vaccination. Seven (8.5%) cows returned to oestrus within 5-6 days when vaccinated during the first month of pregnancy and nine (10.9%) gave birth prematurely within 72-80 h when vaccinated during the last month of gestation. The importance of post-vaccinal reactions on embryonic mortality and premature birth is emphasized. It is suggested that cows in early and late pregnancy are most susceptible to adverse effects of vaccination against FMD.

Effect of nutrients on plasma corticosteroid concentration in cold-stressed rats.

Little is known about the mechanisms as to how nutrients affect plasma corticosteroids in cold-stressed and starved animals. Therefore, cold-stressed rats (maintained at 7 degrees C) were fasted (control) or fed a balanced diet (casein 20 wt%, fat 5 wt%, starch 70 wt% and vitamin-mineral premix 5 wt%) or the following dietary nutrients for 72 h: casein, lard, starch, glycerol, stearic acid, leucine or glutamic acid. The animals were then killed and plasma corticosteroid concentrations (PCC) were determined. PCC were significantly reduced (p < 0.05) in cold-stressed animals fed a balanced diet (16.95 micrograms/100 ml plasma) compared to the fasted cold-stressed controls (FCSC) (24.16 micrograms/100 ml plasma). Additionally, corticosteroid concentrations (micrograms/100 ml plasma) of animals fed the following specific nutrients were also significantly lower than the FCSC values: starch (15.53), lard (12.01), stearic acid (12.74), glycerol (13.32) and leucine (16.03). Casein and glutamic acid did not significantly alter plasma corticosteroid levels relative to the FCSC concentration. It is concluded that certain specific building blocks of nutrient classes, i.e. stearic acid or glycerol, can alter PCC to the same extent as the parent compound (lard), however the individual components of casein, a complex nutrient, i.e. leucine, a ketogenic amino acid, versus glutamic acid, a glycogenic amino acid, may elicit a different PCC effect.

Comparative Stress Dynamics of Brood Stock Striped Bass Morone saxatilis Associated with Two Capture Techniques

AbstractMature striped bass (Morone saxatilis) were collected from the spawning reaches of the Choptank River, Maryland for the purpose of evaluating stress effects associated with capture. Two commonly used capture devices were evaluated—gillnetting and electrofishing. Results indicated that stress, as measured by changes in plasma corticosteroid and chloride concentrations, was significantly lower and recovery time quicker in those fish captured by electrofishing compared to gillnetting. By the end of the study period (48 h), those fish captured by electrofishing had recovered from the initial capture shock as evidenced by corticosteroid levels returning to near baseline levels. Conversely, at 48 h post‐capture, those fish captured by gillnetting exhibited severe hypochloremia and elevated corticosteroid levels approaching that of the initial stress associated with capture.

Influence of reproductive state on pituitary-adrenal activity in the ewe

Plasma corticosteroid concentrations are altered in pregnancy, during the reproductive cycle and by ovariectomy in many species. This study was designed to examine basal ACTH and cortisol in ewes of four different reproductive statuses: ovariectomized, nonpregnant cycling, nonpregnant noncycling, and pregnant. Blood samples were drawn every 4 hr for 48 hr from ewes during quiet, undisturbed conditions and analyzed for plasma ACTH, cortisol and progesterone concentrations. There were no significant changes in ACTH, cortisol or progesterone over time. Mean progesterone concentrations were significantly greater in the pregnant ewes than in all other ewes, and were greater in cycling ewes than noncycling or ovariectomized ewes. Mean ACTH was significantly greater in pregnant ewes than noncycling ewes, and mean cortisol was significantly greater in cycling ewes than in nonpregnant cycling or noncycling ewes. Ovariectomized ewes also had significantly greater mean cortisol concentrations than cycling ewes. The results demonstrate that there is an increase in basal ACTH and cortisol in ovine pregnancy.