RSUME inhibits VHL and regulates its tumor suppressor function

Somatic mutations or loss of von Hippel-Lindau (pVHL) happen in the majority of VHL disease tumors, which present a constitutively active Hypoxia Inducible Factor (HIF), essential for tumor growth. Recently described mechanisms for pVHL modulation shed light on the open question of the HIF/pVHL pathway regulation. The aim of the present study was to determine the molecular mechanism by which RSUME stabilizes HIFs, by studying RSUME effect on pVHL function and to determine the role of RSUME on pVHL-related tumor progression. We determined that RSUME sumoylates and physically interacts with pVHL and negatively regulates the assembly of the complex between pVHL, Elongins and Cullins (ECV), inhibiting HIF-1 and 2α ubiquitination and degradation. We found that RSUME is expressed in human VHL tumors (renal clear-cell carcinoma (RCC), pheochromocytoma and hemangioblastoma) and by overexpressing or silencing RSUME in a pVHL-HIF-oxygen-dependent degradation stability reporter assay, we determined that RSUME is necessary for the loss of function of type 2 pVHL mutants. The functional RSUME/pVHL interaction in VHL-related tumor progression was further confirmed using a xenograft assay in nude mice. RCC clones, in which RSUME was knocked down and express either pVHL wt or type 2 mutation, have an impaired tumor growth, as well as HIF-2α, vascular endothelial growth factor A and tumor vascularization diminution. This work shows a novel mechanism for VHL tumor progression and presents a new mechanism and factor for targeting tumor-related pathologies with pVHL/HIF altered function.

Age-related changes in sympathetic activity: biochemical measurements and target organ responses

The aim of this study was to evaluate using several parameters the effect of aging on sympathetic nervous system activity. We measured heart rate, skin conductance level and free and total plasma catecholamines in 60 normal subjects aged 20-80 years, divided into three age groups, in basal supine conditions and in response to standing and to hyperventilation. Basal heart rate was similar in all subjects and failed to correlate with age. Skin conductance level decreased with increasing age and correlated negatively and significantly with age. In response to standing and to hyperventilation, heart rate and skin conductance level increased in all groups but the values attained became lower in older subjects. Basal free and total norepinephrine (NE) and total epinephrine (E) correlated positively and significantly with age. In response to standing, free NE determined at the peak heart rate response, increased significantly only in young subjects. In response to hyperventilation free and total NE increased in all subjects. In conclusion, our study supports and extends previous findings that sympathetic nervous system activity is altered in aging. Moreover, these data also show that biochemical measurements of sympathetic nerve activity do not reflect the same alterations as those involving target organ responses.

Low sodium intake induces an increase in renal monoamine oxidase activity in the rat. Involvement of an angiotensin II dependent mechanism

AIMS

The interplay between natriuretic dopamine and antinatriuretic angiotensin II represents an important mechanism for the regulation of renal sodium and water excretion. Monoamine oxidase is the main metabolizing pathway for dopamine in the renal cortex. In this study, we have analysed the effect of low sodium feeding and AT1 receptor blockade on renal dopamine metabolism by monoamine oxidase.

METHODS

Four groups of rats were studied: 1, normal salt diet (NS); 2, low salt diet (LS); 3, NS receiving Losartan (Los, specific AT1 receptor antagonist, 20 mg kg(-1) bwt day(-1), NS + Los); 4, LS receiving Los (LS + Los).

RESULTS

Urinary dopamine excretion was lower in LS than in NS rats (543 +/- 32 vs. 680 +/- 34 ng day(-1) 100 g(-1) bwt, P < 0.05). When treated with Los, DOPAC excretion and urinary DOPAC/dopamine ratio fell significantly in the LS + Los group as compared with the LS group (1199 +/- 328 vs. 3081 +/- 681 ng day(-1) 100 g(-1) bwt and 1.90 +/- 0.5 vs. 5.7 +/- 1.2, respectively, both P < 0.02). Losartan increased hydroelectrolyte excretion in the LS group. No changes were found in the NS + Los group. Aromatic L-amino acid decarboxylase activity in cortex was similar in NS and LS rats. Instead, monoamine oxidase activity was higher in cortical homogenates from LS rats (in nmol mg tissue(-1) h(-1): NS 7.66 +/- 0.52; LS 9.82 +/- 0.59, P < 0.05) and this difference was abolished in LS + Los rats (7.34 +/- 0.49 nmol mg tissue(-1) h(-1), P < 0.01, vs. LS).

CONCLUSIONS

We have concluded that low levels of dopamine in the urine of LS rats are because of an increase in the activity of renal monoamine oxidase and that angiotensin II mediates this increase through stimulation of AT1 receptors.

Plasma met-enkephalin levels: its relationship with age and type of headache

The aim of the present study was to assess the peripheral proenkephalin-A system in order to determine if it is related in any way to age and/or the type of headache. Our results show no significant change in plasma met-enkephalin (ME) and neutrophil met-enkephalin-containing peptide (NMECP) with aging in controls. Plasma ME levels and NMECP in patients suffering from migraine without aura and tension-type headaches were found to be similar in both groups, younger and older than 60 years old. When ME plasma levels were compared among the three groups of subjects in the two age-groups, only chronic tension-type headache patients differed ( [Formula: see text] ) from both controls and migraine without aura subjects.

Atenolol improves ventricular function without changing plasma noradrenaline but decreasing plasma atrial natriuretic factor in chronic heart failure

1 There is good evidence that beta-blockers improve ventricular function, disease progression and survival in patients with left ventricular systolic dysfunction. The aim of this study was to determine the effects of atenolol therapy on the sympathetic nervous system at rest and after ergometric exercise, on left ventricular function and on baseline plasma atrial natriuretic factor (ANF) in ambulatory patients with chronic heart failure (CHF). 2 Twenty-two patients [left ventricular ejection fraction (LVEF) <36%; New York Heart Association II-III] were studied before atenolol treatment. Because of cardiac events (new Hospital admission or death) only 13 patients completed 1 year of treatment. Baseline noradrenaline (NE) concentrations were similar in patients and controls while ANF was higher in patients than in controls (328 +/- 35 pg ml(-1) vs. 37 +/- 3 pg ml(-1); P<0.01). 3 Patients with events showed higher NE (540 +/- 87 pg ml(-1) vs. 303 +/- 44 pg ml(-1); P<0.01) and ANF (460 +/- 70 pg ml(-1) vs. 291 +/- 44 pg ml(-1); P<0.03) at rest; and greater NE response to exercise (2.003 +/- 525 pg ml(-1) vs. 694 +/- 121 pg ml(-1); P<0.005). Atenolol treatment improved LVEF (19.5 +/- 1.9% vs. 33 +/- 3.9%; P<0.001), increased exercise tolerance (9 +/- 3.2 min vs. 17 +/- 4.8 min; P<0.001) and decreased plasma ANF (292 +/- 42 pg ml(-1) vs. 133 +/- 35 pg ml(-1); P<0.01). 4 Reduced basal dihydroxyphenylglycol (DHPG)/NE ratio (3.4 +/- 0.46 vs. 4.3 +/- 0.35; P<0.01) was observed in patients compared with healthy volunteers. Atenolol increased DHPG plasma levels (1.398 +/- 129 pg ml(-1) vs. 913 +/- 86 pg ml(-1); P<0.005) but the DHPG/NE ratio during exercise was not modified after treatment, suggesting that re-uptake of released NE is not changed by beta-blocker treatment. 5 In conclusion, the fact that atenolol treatment improves ventricular dysfunction and clinical status without changing plasma NE levels in CHF patients, suggests that plasma NE is a poor surrogate measurement for cardiac sympathetic activity in this pathology. In addition, decrease in plasma ANF produced by atenolol treatment may reflect the improvement of ventricular function.

Decreased tubular uptake of L-3,4-dihydroxyphenylalanine in streptozotocin-induced diabetic rats

BACKGROUND/AIMS

This study determined alterations in renal dopamine production in streptozotocin-treated rats and explored the mechanisms underlying this alteration.

METHODS

Streptozotocin (65 mg/kg) or vehicle was administered to 3-month-old male Wistar rats. Treated animals had hyperglycemia, glycosuria and increased diuresis, natriuresis and excretion of L-dopa. Urinary dopamine and dihydroxyphenylacetic acid were similar to those in control animals. The production of dopamine by renal cortex slices from treated rats was significantly less than that from control animals. The addition of glucose (8.4-18.4 mM) to the incubation medium decreased about 40% the uptake of L-dopa by isolated proximal tubular cells. Scatchard analysis of the saturation curves obtained in this condition showed a decrease in the V(max) without changes in the K(m).

RESULTS

Our results confirm previous studies suggesting a renal dopaminergic deficiency in insulin-dependent diabetes and provide evidence strongly suggesting that a decrease in the number of tubular L-dopa transport sites is the underlying defect of this deficiency.

CONCLUSION

These results highlight the role of the uptake of dopa as an important modulator of renal dopamine synthesis.

Mechanisms of hypothalamic-pituitary-gonadal disruption in polycystic ovarian syndrome

Although the pathogenesis of polycystic ovarian syndrome (PCOS) is still controversial, a series of investigations has demonstrated an array of neuroendocrine abnormalities as a major component of the syndrome. From a neuroendocrine perspective, patients with PCOS exhibit an accelerated frequency and/or higher amplitude of LH pulses, augmentation of LH secretory burst mass, and a more disorderly LH release. Elevated in vitro LH bioactivity and a preponderance of basic LH isoforms, which correlate positively with elevated serum 17-hydroxyprogesterone, androstenedione, and testosterone concentrations, also characterize adolescents with PCOS. Heightened GnRH drive of gonadotropin secretion and a steroid-permissive milieu appear to jointly promote elevated secretion of basic LH isoforms. Positive feedback is implied, because hypersecretion of highly bioactive LH in PCOS probably contributes to inordinate androgen output. However, the precise nature of feedback disruption remains uncertain. Indeed, recent data suggest that PCOS is marked by anomalies of both feedforward and feedback signaling between GnRH/LH and ovarian androgens. From a single hormone perspective, the individual patterns of LH and androstenedione release are consistently more irregular in patients with PCOS. Bihormonal analysis has disclosed concomitant uncoupling of the pairwise synchrony of LH and testosterone, LH and androstenedione, and testosterone and androstenedione secretion. The foregoing ensemble of findings points to deterioration of both orderly uniglandular and coordinate bihormonal output in PCOS. Additional studies are needed to establish the primary pathophysiologic mechanisms underlying this disorder.

Correlation of increased grooming behavior and motor activity with alterations in nigrostriatal and mesolimbic catecholamines after alpha-melanotropin and neuropeptide glutamine-isoleucine injection in the rat ventral tegmental area

1. We wished to further study the behavioral effects of alpha-melanotropin (alpha-MSH), melanin-concentrating hormone (MCH), and neuropeptide glutamine-isoleucine (NEI). 2. To this effect we administered alpha-MSH, MCH, and NEI in the ventral tegmental area of the rat, a structure where these neuropeptides are highly concentrated. To further elucidate the biochemical mechanisms of the behavioral effect of these neuropeptides, we determined the degree of grooming behavior and the levels of catecholamines. after neuropeptide administration. 3. We preselected those animals responding to the central injection of alpha-MSH with excessive grooming behavior. We administered the neuropeptides at the dose of 1 microg/0.5 microL, in each side of the ventral tegmental area, bilaterally. We studied grooming behavior, locomotor activity, and total behavior scores, 30 and 65 min after administration of the peptides. 4. Three groups of animals were decapitated immediately after the injection of the neuropeptides, and 30 or 65 min after injection. We measured dopamine (DA), noradrenaline (NA), and the dopac/dopamine ratio (DOPAC/DA) to determine steady state levels of catecholamines and an indirect measure of DA release and metabolism, respectively. 5. Injections of alpha-MSH produced significant elevations in grooming behavior, locomotor activity, and total behavior scores, both 30 and 65 min after peptide administration. This was correlated with significant decreases in DA content, increases in DOPAC content, and increases in the DOPAC/DA ratio. In the caudate putamen, changes in catecholamines occurred both at 30 and 65 min after injection. In the nucleus accumbens, changes were present at 65 min after injection. Conversely, there were no alterations in NA content, either in the caudate putamen or in the nucleus accumbens, at any time after the injection. 6. Injections of NEI resulted in significant elevations in grooming behavior, locomotor activity, and total behavior scores, both 30 and 65 min after peptide administration. This was correlated with increased DOPAC/DA ratio in the nucleus caudatus but not in the nucleus accumbens. Conversely, NEI produced increased NA concentrations in the nucleus accumbens, but not in the nucleus caudatus. 7. Injections of MCH did not produce significant changes in behavior or significant changes in nucleus caudatus or nucleus accumbens catecholamines. 8. Our results indicate (a) There is a correlation with alterations in behavior as induced for the neuropeptides injected here, and changes in extrapyramidal catecholamines. (b) There is a correlation between alterations in behavior and increases in DOPAC/DA ratio in the nucleus caudatus. (c) There is a correlation between alterations in behavior and alterations in catecholamines in the nucleus accumbens. In the nucleus accumbens, DOPAC/DA ratio is changed after alpha-MSH, and NA ratio is changed after NEI injection. (d) Absence of alterations in extrapyramidal catecholamines, and in particular in catecholamines in the nucleus accumbens, correlates with absence of behavioral alterations after neuropeptide administration to the ventral tegmental area. 9. In conclusion, the behavioral effect of exogenous administration of neuropeptides in the ventral tegmental area is peptide-specific, and is probably associated with alterations in catecholamine metabolism and release in the nucleus caudatus and the nucleus accumbens. Both alpha-MSH and NEI seem to stimulate the nigrostriatal DA system. While alpha-MSH appears to stimulate the mesolimbic DA system as well, NEI may exert its actions not through the DA, but through the NA mesolimbic system. The precise contribution of DA and NA, and the relative role of the nucleus caudatus and nucleus accumbens in these behaviors remain to be elucidated.

Peripheral administration of an angiotensin II AT(1) receptor antagonist decreases the hypothalamic-pituitary-adrenal response to isolation Stress

Angiotensin II, which stimulates AT(1) receptors, is a brain and peripheral stress hormone. We pretreated rats with the AT(1) receptor antagonist candesartan for 13 d via sc-implanted osmotic minipumps, followed by 24-h isolation in individual metabolic cages. We measured angiotensin II receptor-type binding and mRNAs and tyrosine hydroxylase mRNA by quantitative autoradiography and in situ hybridization, catecholamines by HPLC, and hormones by RIA. Isolation increased AT(1) receptor binding in hypothalamic paraventricular nucleus as well as anterior pituitary ACTH, and decreased posterior pituitary AVP. Isolation stress also increased AT(1) receptor binding and AT(1B) mRNA in zona glomerulosa and AT(2) binding in adrenal medulla, adrenal catecholamines, tyrosine hydroxylase mRNA, aldosterone, and corticosterone. Candesartan blocked AT(1) binding in paraventricular nucleus and adrenal gland; prevented the isolation-induced alterations in pituitary ACTH and AVP and in adrenal corticosterone, aldosterone, and catecholamines; abolished the increase in AT(2) binding in adrenal medulla; and substantially decreased urinary AVP, corticosterone, aldosterone, and catecholamines during isolation. Peripheral pretreatment with an AT(1) receptor antagonist blocks brain and peripheral AT(1) receptors and inhibits the hypothalamic-pituitary-adrenal response to stress, suggesting a physiological role for peripheral and brain AT(1) receptors during stress and a possible beneficial effect of AT(1) antagonism in stress-related disorders.

Disruption of the synchronous secretion of leptin, LH, and ovarian androgens in nonobese adolescents with the polycystic ovarian syndrome

The present study probes putative disruption of hypothalamic control of multihormone outflow in polycystic ovarian syndrome by quantitating the joint synchrony of leptin and LH release in adolescents with this syndrome and eumenorrheic controls. To this end, hyperandrogenemic oligo- or anovulatory patients with polycystic ovarian syndrome (n = 11) and healthy girls (n = 9) underwent overnight blood sampling every 20 min for 12 h to monitor simultaneous secretion of leptin (immuno-radiometric assay), LH (immunofluorometry), and androstenedione and T (RIA). Synchronicity of paired leptin-LH, leptin-androstenedione, and leptin-T profiles was appraised by two independent bivariate statistics; viz., lag-specific cross-correlation analysis and pattern-sensitive cross-approximate entropy. The study groups were comparable in chronological and postmenarchal age, body mass index, fasting plasma insulin/glucose ratios, and serum E2 concentrations. Overnight mean (+/- SEM) serum leptin concentrations were not distinguishable in the two study groups at 30 +/- 4.8 (polycystic ovarian syndrome) and 32 +/- 7.4 microg/liter (control). Serum LH concentrations were elevated at 9.5 +/- 1.4 in girls with polycystic ovarian syndrome vs. 2.8 +/- 0.36 IU/liter in healthy subjects (P = 0.0015), androstenedione at 2.8 +/- 0.30 (polycystic ovarian syndrome) vs. 1.2 +/- 0.11 ng/ml (control) (P = 0.0002), and T at 1.56 +/- 0.29 (polycystic ovarian syndrome) vs. 0.42 +/- 0.06 ng/ml (P < 0.0001). Cross-correlation analysis shows that healthy adolescents maintained a positive relationship between leptin and LH release, wherein the latter lagged by 20 min (P < 0.01). No such association emerged in girls with polycystic ovarian syndrome. In eumenorrheic volunteers, leptin and androstenedione concentrations also covaried in a lag-specific manner (0.0001 < P < 0.01), but this linkage was disrupted in patients with polycystic ovarian syndrome. Anovulatory adolescents further failed to sustain normal time-lagged coupling between leptin and T (P < 0.01). Approximate entropy calculations revealed erosion of orderly patterns of leptin release in polycystic ovarian syndrome (P = 0.012 vs. control). Cross-entropy analysis of two-hormone pattern regularity disclosed marked disruption of leptin and LH (P = 0.0099), androstenedione and leptin (P = 0.0075) and T-leptin (P = 0.019) synchrony in girls with polycystic ovarian syndrome. In summary, hyperandrogenemic nonobese adolescents with oligo- or anovulatory polycystic ovarian syndrome manifest: 1) abrogation of the regularity of monohormonal leptin secretory patterns, despite normal mean serum leptin concentrations; 2) loss of the bihormonal synchrony between leptin and LH release; and 3) attenuation of coordinate leptin and androstenedione as well as leptin and T output. In ensemble, polycystic ovarian syndrome pathophysiology in lean adolescents is marked by vivid impairment of the synchronous outflow of leptin, LH and androgens. Whether analogous disruption of leptin-gonadal axis integration is ameliorated by therapy and/or persists into adulthood is not known.

Effects of thyroid hormone on the renal dopaminergic system

This study determined the effects of thyroid hormone on the renal dopaminergic system. Surgical thyroidectomy (Tx) and treatment with 2-thiouracil (Thio) decreased renal cortex Na+/K+ ATPase activity and urinary volume. Tx also decreased urinary Na+ and urinary L-DOPA without changing urinary excretion of Dopamine (DA). Thio treatment decreased slightly urinary L-DOPA and Na+, but increased urinary excretion of DA. In both models of thyroid hormone deficiency, the ratio urinary DA/DOPA increased. Changes after Thio treatment were reversed after one month of drug withdrawal. Treatment with T3 via osmotic minipump increased Na+/K+ ATPase activity and urinary L-DOPA, did not change urinary DA, and increased the ratio DA/DOPA. To further analyze the effects of thyroid hormone deficiency, we administered selective DA1 (SCH-23390), DA2 (Sulpiride), and a non selective (Haloperidol) DA receptor antagonists to Thio treated and control animals. The DA1 antagonist decreased diuresis, natriuresis and urinary L-DOPA in control, but had no effect in Thio treated rats. Sulpiride had no effect in either group. The combination of SCH-23390 plus Sulpiride decreased urinary L-DOPA and urinary volume only in Thio treated animals. Haloperidol decreased urinary volume in Thio treated animals, but had no effect in controls. Our findings suggest that renal DA synthesis is to some extent dependent on thyroid hormone levels, and that the response of DA receptors is altered by thyroid hormone deficiency, indicating a role of this hormone in the regulation of the renal dopaminergic system.

Intermittent hyperaldosteronism in a child due to an adrenal adenoma

Aldosterone producing adenoma (APA) is a rare but potentially curable form of paediatric hypertension. We report a case of APA in a 9-year-old boy, suspected due to persistent hypokalaemia. Neither BP nor initial laboratory investigations disclosed the diagnosis and the presence of an APA was suggested by functional tests and radiological findings. Histologically, a cortical tumour was found associated with a marked medullary hyperplasia of both chromaffin and ganglion cells.

CONCLUSION

This case reinforces the need for further investigations in patients with misleading clinical and laboratory data.

Disruption of the joint synchrony of luteinizing hormone, testosterone, and androstenedione secretion in adolescents with polycystic ovarian syndrome

The present study explores the postulate that the polycystic ovarian syndrome (PCOS) is marked by failure of physiological feedforward and feedback signaling between pituitary LH and ovarian androgens. To this end, we appraised the 3-fold simultaneous overnight release of LH (assayed by high precision immunofluorometry), testosterone (RIA), and androstenedione (RIA) in 12 an- or oligoovulatory adolescents with PCOS (mean +/- SEM age, 16.4 +/- 0.47 yr) and 10 eumenorrheic girls (age, 16.5 +/- 0.45 yr). Gynecological (postmenarchal) ages (years) were also comparable at 4.8 +/- 0.39 (PCOS) and 4.0 +/- 3.6 (control; P = NS). Body mass index and fasting serum insulin and estradiol concentrations were indistinguishable in the two study cohorts. Mean overnight serum concentrations of LH (assayed by both immunofluorometry and Leydig cell bioassay), testosterone, androstenedione, and 17alpha-hydroxyprogesterone were each elevated significantly in patients with PCOS (all P </= 0.027). The bivariate cross-approximate entropy (cross-ApEn) statistic was used as a sensitive barometer of altered within-axis feedback. This scale-invariant metric is designed to quantitate the joint synchrony of putatively linked (neurohormone) time series in a lag-independent pattern-sensitive manner. Here, we applied cross-ApEn to the coupled release of LH and testosterone, LH and androstenedione, and testosterone and androstenedione. Statistical comparisons of the two adolescent study cohorts unveiled consistently elevated cross-ApEn in patients with PCOS, denoting disruption of the pairwise synchrony of LH and testosterone (P = 0.0055), LH and androstenedione (P = 0.0076), and testosterone and androstenedione (P = 0.014) secretion. As an analytically distinct technique to monitor coordinate hormone release, we also applied cross-correlation analysis with variable lag. This appraisal revealed that adolescents with PCOS further exhibit 1) loss of rapid feedforward coupling between LH and testosterone output, 2) erosion of the time-lagged positive linkages between LH and androstenedione secretion, and 3) attenuation of the coordinate relationship between testosterone and androstenedione release. In summary, based on complementary, but independent, statistical tools, the present two-variable analyses unmask vivid deterioration of the joint synchrony of LH-testosterone, LH-androstenedione, and testosterone-androstenedione secretion in adolescents with PCOS. The multiplicity of the bihormonal coupling defects points to impaired feedforward and feedback signaling interfaces among the hypothalamus, pituitary gland, and ovary. Disruption of interandrogen synchrony also identifies pathophysiological dissociation of testosterone and androstenedione cosecretion. Whether presumptive failure of integrative hypothalamo-pituitary-gonadal control emerges prepubertally in girls at risk for PCOS or persists in adults with PCOS is not known.

L-Dopa uptake and dopamine production in proximal tubular cells are regulated by beta(2)-adrenergic receptors

This study assessed the role of adrenergic receptors on the regulation of the uptake of L-dopa and the production of dopamine by renal tubular cells. Scatchard analysis showed two L-dopa uptake sites with different affinities (K(m) 0.316 vs 1.53 microM). L-Dopa uptake was decreased by the nonselective adrenergic agonists epinephrine or norepinephrine (40%), by the beta-selective agonist isoproterenol or the beta(2)-selective agonist terbutaline (60%), but not by alpha-selective agonists (all 1 microM). The effect of norepinephrine, isoproterenol, or terbutaline was unaffected by addition of the beta(1)-antagonist atenolol, abolished by ICI-118, 551, a beta(2)-antagonist (both 0.1 microM), and mimicked by the addition of dibutyryl-cAMP (1 microM). Preincubation with terbutaline decreased the number of high-affinity uptake sites (V(max) = 1.10 +/- 0.3 vs. 0.5 +/- 0.1 pmol. mg protein(-1). min(-1)) without changing their affinity. Norepinephrine or terbutaline decreased dopamine production by isolated cells, and this effect was abolished by ICI-118,551 (0.1 microM). In vivo administration of ICI-118,551 reduced the urinary excretion of L-dopa and increased the excretion of 3,4-dihydroxyphenylacetic acid without significant changes in plasma L-dopa concentrations. These results demonstrate that stimulation of beta(2)-adrenergic receptors decreases the number of high-affinity L-dopa uptake sites in isolated tubular cells resulting in a reduction of the uptake of L-dopa and the production of dopamine and provide evidence for the presence of this mechanism in the intact animal.

A preponderance of basic luteinizing hormone (LH) isoforms accompanies inappropriate hypersecretion of both basal and pulsatile LH in adolescents with polycystic ovarian syndrome

We recently demonstrated that adolescent girls with polycystic ovarian syndrome (PCOS) exhibit augmented LH secretion due to an increase in immunofluorometric and deconvolution-estimated LH secretory burst mass and pulse frequency. Concurrently, we inferred either a prolongation of apparent (endogenous) LH half-life or elevated basal (nonpulsatile) LH release in PCOS. The in vivo half-life of LH molecules can be affected by the oligosaccharide side-chains, which also modify in vitro bioactivity and electrostatic change. Accordingly, as a surrogate estimator of altered endogenous LH half-life and/or biopotency in PCOS, we characterized the isoelectric properties of secreted LH isoforms and determined their in vitro biological activity in adolescent girls with PCOS compared with healthy age-matched eumenorrheic controls. To this end, 12-h (overnight) serum samples from PCOS patients (n = 12) and normal adolescents (n = 10) were pooled by subject. Bioactive LH concentrations were then quantitated in a rat Leydig cell in vitro bioassay, and immunological activity was determined by immunofluorometry. The distribution of LH isoforms was evaluated by preparative chromatofocusing (pH window, 10.5 to <4.0) of samples further combined to yield three independent serum pools for each of the patient and control groups. Fasting serum concentrations of 17-hydroxyprogesterone (17-OHP), androstenedione, testosterone, estrone, estradiol, and sex hormone-binding globulin were determined as possible endocrine correlates of LH isotypes. Mean serum concentrations of immunoreactive and bioactive LH in adolescents with PCOS were 3 and 2 times higher than values in controls: immunoreactive: PCOS, 7.8+/-0.9; controls: 2.6+/-0.3 IU/L (P < 0.001); and bioactive: PCOS, 52+/-10; controls, 25+/-4.1 IU/L (P = 0.002), respectively. Bioactive LH concentrations correlated positively with 17-OHP (P = 0.022), androstenedione (P = 0.012), and testosterone (P = 0.046) concentrations in PCOS. Chromatofocusing of LH isoforms disclosed greater LH immunoreactivity at pI values greater than 8 and 7.99-7.0 in adolescents with PCOS compared with controls (P = 0.031). The percentage of basic LH isoforms was related positively to serum concentrations of 17-OHP (P = 0.032), androstenedione (P = 0.046), and testosterone (P = 0.040). In conclusion, the present isotype analysis demonstrates elevated in vitro LH bioactivity and a preponderance of basic LH isoforms in girls with PCOS. Since previously reported heterologous in vivo assays of LH kinetics point toward accelerated removal of such alkaline isotypes, our findings would favor the earlier alternative hypothesis of inappropriate hypersecretion of basal (interpulse) LH rather than prolongation of the LH half-life as the mechanism for elevated interpulse serum LH concentrations in adolescents with PCOS. In ensemble, the foregoing data thus suggest 3-fold amplification of basal LH secretion as well as both a heightened amplitude and frequency of the pulsatile mode of LH release in PCOS.

Influence of age on stress responses to metabolic cage housing in rats

1. We studied the effect of isolation stress in 3- and 12-month-old rats individually housed in metabolic cages for 7 days. Urine (24 hr) was collected daily from one group of animals of each age. The other group was tested in an open field and on a hot plate on days 1 and 7. 2. Total deambulation in the open-field test was lower in young than in older rats both on day 1 (54.7 +/- 9.9 vs 80 +/- 8.9 crossings/session; P < 0.04) and on day 7 (21 +/- 9 vs 48 +/- 7 crossings per session; P < 0.04) and decreased significantly in the two groups when tested on day 7 (P < 0.03). Latency to paw-licking in the hot-plate test was longer in young than in older animals on day 1 (14 +/- 2 vs 8 +/- 4 sec; P < 0.05) but was similar in the two groups on day 7. 3. Urinary excretions of norepinephrine (NE) and epinephrine (E) were determined by HPLC with electrochemical detection. Urinary NE in day 1 was similar in young and older animals (2627 +/- 828 vs 3069 +/- 598 ng/24 hr). In young animals NE excretion decreased along the study and was significantly (P < 0.02) lower than on day 1 during the last 3 days of the study. Conversely, in older animals urinary excretion of NE remained similar throughout the study. On day 7 urinary excretion of NE in older animals was about two fold that in young rats. Urinary E was similar in young and older rats (341 +/- 127 vs 532 +/- 256 ng/24 hr) on day 1 and showed a tendency to increase throughout the study. 4. Urinary monoamine oxidase inhibitory (IMAO) activity was determined by testing the ability of urine extracts to inhibit rat liver MAO activity in vitro and was higher in young than in older animals throughout the study (day 1, 54.8 +/- 4.2 vs 25.1 +/- 5.1%; P < 0.02). In young rats excretion of IMAO was significantly higher during the last 3 days of the study than on day 1 (P < 0.05). In older animals urinary IMAO showed a tendency to increase at the end of the study. 5. Isolation stress caused by housing rats in metabolic cages results in different behavioral and metabolic responses in young and older animals. Young animals exhibit a lower locomotor and analgesic response and excrete lower amounts of NE and higher IMAO activity in the urine than older rats. The metabolic and behavioral responses to isolation stress are highly dependent on the age of the animals tested. These results should be taken into consideration when designing experiments requiring the use of metabolic cages.

Effect of glucocorticoids on renal dopamine production

This study assess the effects of glucocorticoids on dopamine excretion and evaluates the participation of renal dopamine in the effects of glucocorticoids on renal function and Na+ excretion. Dexamethasone (i.m.; 0.5 mg/kg) was administered to male Wistar rats on day 2 or on days 2 and 5. Daily urinary excretions of Na+, dihydroxyphenylalanine (DOPA), dopamine and dihydroxyphenylacetic acid were determined from day 1 to day 7. Renal function was evaluated 8 h after dexamethasone administration in a separate group. The first dose of dexamethasone increased about 100% diuresis and natriuresis, increased urinary DOPA and renal plasma flow, and did not affect urinary dopamine or the other parameters evaluated. These effects were not affected by previous administration of haloperidol. The second dexamethasone dose increased about 200% diuresis and natriuresis, increased urinary dopamine, DOPA, dihydroxyphenylacetic acid, Uosm x V and both glomerular filtration rate and renal plasma flow. Carbidopa administered before the second dexamethasone dose blunted both the diuretic and the natriuretic response whereas haloperidol abolished or blunted all the effects of the second dexamethasone dose. These results show that modifications in renal dopamine production produced by corticoids may contribute to the effects of these hormones on Na+ balance and diuresis and suggest that regardless the factor that promotes an increase in renal perfusion and glomerular filtration rate during long term administration of glucocorticoids, a dopaminergic mechanism is actively involved in the maintenance of these hemodynamic changes.

Augmented frequency and mass of LH discharged per burst are accompanied by marked disorderliness of LH secretion in adolescents with polycystic ovary syndrome

The aim of this study was to quantify pulsatile LH secretion, burst frequency and mass, LH half-life, and the approximate entropy (ApEn) or (dis-) orderliness of LH release in adolescents with polycystic ovary syndrome (PCOS), combining a high-precision immunofluorimetric LH assay with deconvolution techniques. We sampled LH concentration profiles every 20 min overnight in 12 girls with PCOS (mean +/- S.E.M. age 16.4+/-0.57 years, body mass index (BMI) 24.4+/-1.6 kg/m2) and 11 eumenorrheic early-follicular-phase controls (mean +/- S.E.M. age 16.5+/-0.47 years, BMI 22.2+/-1.0 kg/m2). Fasting serum levels of androstenedione, testosterone, 17-hydroxyprogesterone (17-OHP), estrone, estradiol, FSH and sex hormone-binding globulin (SHBG) were determined. Compared with euandrogenic girls, PCOS adolescents had significantly (P<0.005) elevated serum LH/FSH ratios, 17-OHP, androstenedione, esterone and testosterone levels, decreased SHBG, and similar estradiol. PCOS subjects exhibited a 3-fold higher mean serum LH concentration with almost no overlap with controls (8.8+/-1.2 and 2.8+/-0.3 IU/l respectively, P<0.001). We initially used a conventional serum hormone concentration peak analysis method (Cluster) to evaluate the characteristics of pulsatile LH release. Cluster analysis disclosed a significant increase in serum LH concentration maximal peak height, a higher LH peak frequency and a higher mean serum LH concentration in interpulse nadirs in the PCOS group. Deconvolution analysis of mechanisms underlying the foregoing showed higher frequency in the PCOS group than the controls (7.9+/-0.4 and 5.7+/-0.6 pulses/12 h respectively, P<0.05). The mass of LH released per secretory event was also significantly higher in PCOS subjects than controls (5.4+/-0.57 and 3.4+/-0.56 IU/l respectively, P<0.05). Since the pulsatile production rate is the product of the mean mass of hormone secreted per pulse and the number of pulses per day, we estimated a significantly higher mean pulsatile production rate of (endogenous) LH in the PCOS group (41+/-4.2 IU/l per day in the PCOS group vs 18+/-2.3 IU/l per day in the controls, P<0.01). The mean estimated half-life of endogenous LH disappearance was also significantly higher in patients with PCOS than in controls (110+/-8.5 and 77+/-3.7 min respectively, P<0.01). To quantify the orderliness of LH release, we used ApEn. PCOS patients had remarkably increased disorderliness (higher ApEn) of LH release (1.09+/-0.04 vs 0.77+/-0.08 in controls, P = 0.002). Mean serum LH concentration, mass of LH secreted per burst, and LH production rate in PCOS, but not in normal adolescents, correlated positively with androstenedione (P<0.02, 0.02 and 0.05 respectively). The same parameters also correlated positively with 17-OHP (P<0.05, 0.02 and 0.05 respectively). Stepwise regression analysis unmasked a negative influence of BMI in PCOS on both mass of LH secreted per burst (r = -0.77, P<0.005) and LH production rate (r = -0.70, P<+/0.01). We conclude that PCOS adolescents secrete LH molecules with amplified frequency and burst mass and with markedly disrupted orderliness. A rise in basal (non-pulsatile) LH release, more basic LH isoforms, and/or a prolongation or asymmetry of the LH secretory burst could account for the apparently prolonged LH half-life. Determining whether disorderliness of the amplified pituitary LH release process is an intrinsic abnormality in PCOS. or reflects androgen excess, may help to clarify the pathophysiology of this oligo-ovulatory syndrome in young women.

The codon 213 of the 11beta-hydroxysteroid dehydrogenase type 2 gene is a hot spot for mutations in apparent mineralocorticoid excess

In the kidney, the 11beta-hydroxysteroid dehydrogenase type 2 enzyme (11betaHSD2) inactivates glucocorticoids to their inactive ketoforms and thus prevents endogenous glucocorticoids from occupying the nonselective mineralocorticoid receptor in epithelial tissues. Several mutations have been described in the 11betaHSD2 gene in the congenital syndrome of apparent mineralocorticoid excess. These mutations generate partially or completely inactive 11betaHSD2 enzymes. In the present work, we describe an already known mutation in a new patient affected by apparent mineralocorticoid excess, which results in an arginine-to-cysteine mutation (R213C) in the 11betaHSD2 enzyme. This mutation has been found in two other independent families. In vitro expression studies of this mutant provide evidence that the mutant protein is normally expressed, but its activity is abolished. The CGC-to-TGC (C-toT) transition at codon 213 can be considered a typical CpG-consequence mutation. The present finding suggests that the codon R213 of 11betaHSD2 is a hot spot for mutations in this gene, as shown by the occurrence of an R213C point-mutation in several families unrelated to each other.

Met-enkephalin increase in patients with fibromyalgia under local treatment

Fibromyalgia is a chronic debilitating condition of unknown etiology. The clinical picture suggests increased activity and/or supersensitivity in nociceptive pathways or inadequate activity in endogenous pain attenuation mechanisms. One therapeutic approach in the treatment of this syndrome is the administration of serial local injections of lidocaine hydrochloride in the painful points. To evaluate the effect of this treatment on plasma met-enkephalin (ME) levels we studied 15 patients, all women with fibromyalgia under local treatment in the tender points, grouped as follows: 5 were treated with local injection of lidocaine hydrochloride, 5 were treated with local injection of saline and 5 treated with dry needling. Significant increases in plasma ME concentrations were observed in all groups in the last sampling of each session studied. These results show an increase in plasma ME levels 10 minutes after finishing each session, which is independent of the maneuver employed.

[Early diagnosis of multiple endocrine neoplasia type 2 (MEN 2) by detection of mutated RET proto-oncogene carriers]

RET proto-oncogene mutation results in a dominant autosomic inherited syndrome (MEN 2) presenting three distinct subtypes: MEN 2A, MEN 2B, and familial medullary thyroid carcinoma (FMTC). Detection of RET proto-oncogene mutation is a predictor before clinical or biochemical evidence of the disease is present and leads to preventive thyroid removal since there is no effective treatment for metastases. The aim of the present study was to characterize mutations in the RET proto-oncogene in affected patients and to identify potential carriers in their families. Two families with FMTC (5 and 6 members), 4 with MEN 2A (5, 5, 4 and 3 members) and 2 with MEN 2B (5 and 1 members), were studied. DNA was obtained from blood samples in all patients and from thyroid or from pheonochromocytoma tissues in patients submitted to surgery. PCR amplification was performed using specific primers for exons 10, 11 and 16, followed by direct sequencing. Mutations at codon 634 in exon 11 were found in 16 subjects with FMTC and MEN 2A: TGC --> CGC (cysteine to arginine) in 9 cases, TGC --> TAC (cysteine to tyrosine) in 3, and TGC --> TTC (cysteine to phenilalanine) in 4. A unique mutation of codon 918 in exon 16, ATG --> ACG (methionine to threonine), was found in both MEN 2B affected patients. The mutations detected in DNA from peripheral blood were the same as those present in DNA extracted from tumor material. RET mutations were detected in all affected patients, confirming the diagnosis, and in 10 members of their families. In five of the carriers total thyroidectomy was performed. Anatomopathological study showed C-cells hyperplasia or in-situ microcarcinoma in two children (9 and 12 y) with no clinical signs of diseases and medullary thyroid carcinoma in three adults, who were previously unaware of the presence of thyroid nodules. The early detection of RET mutation followed by total thyroidectomy may prevent the development of the disease, specially in affected families, and avoid the fatal outcome of delayed medullary thyroid carcinoma diagnosis.

Peripheral catecholamine alterations in adolescents with polycystic ovary syndrome

OBJECTIVE

Polycystic ovary syndrome (PCO) is one of the most common endocrine disorders affecting women. Several lines of evidence have suggested the involvement of the sympathetic nervous system (SNS) in this condition. The present work was designed to assess neurochemically SNS activity in patients during the early stages of PCO.

DESIGN AND PATIENTS

Fourteen patients with PCO (aged 14 to 21 years) were studied on a random day and 9 normal regularly cycling adolescents (aged 14 to 20 years) were studied during the early follicular phase (days 2 to 5).

MEASUREMENTS

Hormonal profile was determined in basal conditions. LH and FSH were also measured after i.v. administration of 100 micrograms GnRH. Plasma concentrations of dihydroxyphenylalanine (Dopa), noradrenaline (NA), adrenaline (A), total dopamine (DA) and dihydroxyphenylglycol (DHPG) were determined in basal conditions and in response to GnRH by HPLC with electrochemical detection or a radioenzymatic method. Basal urinary Dopa, catecholamines and catechol metabolites (DHPG, vanillylmandelic acid (VMA), 3-methoxy-4-hydroxyphenylglycol (MHPG), homovanillic acid (HVA), metanephrine (MN) and normetanephrine (NMN)) were determined by HPLC with electrochemical detection.

RESULTS

Basal plasma LH, testosterone, androstenedione, oestrone and LH/FSH ratio were higher (P < 0.01) and serum sex hormone-binding globulin (SHBG) were lower (P < 0.01) in PCO patients than in control subjects. Basal and GnRH-stimulated plasma free Dopa, A, NA and total DA were similar in patients and controls. Plasma DHPG was lower (P < 0.01) in PCO patients (4.20 +/- 0.30 nmol/l) than in controls (8.0 +/- 1.0 nmol/l) throughout the study. Urinary A, NA, DA, Dopa, MN, MHPG, HVA, and VMA were similar in patients and controls. Urinary DHPG was lower (P < 0.01) in PCO patients (0.50 +/- 0.02 mumol/d) than in controls (0.73 +/- 0.09 mumol/d). On the other hand PCO patients had a higher urinary excretion of NMN than controls (PCO: 1.20 +/- 0.10; C: 0.78 +/- 0.10 mumol/d, P < 0.05).

CONCLUSIONS

Our results show the same endocrinological features in adolescent PCO patients as those reported in adults. The results also demonstrate a peripheral catecholaminergic alteration which suggests an alteration in noradrenaline deamination and/or uptake in adolescent patients. This study however does not permit us to conclude that PCO is primarily caused by this sympathetic alteration.

Plasma met-enkephalin and catecholamine changes during the menstrual cycle and pain episode in menstrual migraine

In order to explore opioid, sympathetic and hormonal parameters, we evaluated plasma met-enkephalin (ME), catecholamines (CA), estradiol (E2) and progesterone (P) in different phases of the menstrual cycle and during menstrual crisis in women suffering from menstrual migraine (MM) and in controls. No differences in P and E2 were found between controls and patients. We observed an increase in plasma ME and a decrease in plasma free norepinephrine (NE) levels on day 22 in MM group and an increase in plasma ME, free NE and total epinephrine (E) during pain. Our data, although obtained in a small number of patients, show clear modifications in plasma ME and in the sympathoadrenal function, not only during pain but also in the mid luteal phase.

Demethylation of 3-O-methyldopa in the kidney: a possible source for dopamine in urine

The possibility that demethylation of 3-O-methyldopa (OM-dopa) in the kidney could provide a source for dopamine in the urine was explored in male Wistar rats aged 60-90 days, using in vivo and in vitro approaches. The results showed that endogenous OM-dopa is filtered, reabsorbed and extensively metabolized in the kidney. Infusion of OM-dopa into anesthetized rats increased significantly urinary excretion of Na+, dopa, dopamine, and 3,4 dihydroxyphenylacetic acid. Whole kidney homogenates, slices from renal cortex, and microdissected proximal tubules produced significant amounts of both dopa and dopamine when incubated with OM-dopa. Renal cortex slices produced dose-dependent amounts of dopa and dopa-mine when incubated with 1-100 microM OM-dopa. Incubation of microdissected proximal tubule segments with 1 microM OM-dopa produced a fourfold (P < 0.025) increment in dopa and a twofold (P < 0.05) increment in dopamine (an effect similar to that observed with 1 microM L-dopa). One micromolar OM-dopa or 1 microM L-dopa decreased (P < 0.05) Na(+)-K(+)-adenosinetriphosphatase activity measured at maximal velocity condition in proximal tubules. In conclusion, these experiments show that in vitro the kidney is able to produce dopamine by demethylation of OM-dopa, while the results of the OM-dopa infusion suggest that this conversion may also occur in vivo.

A decreased tubular uptake of dopa results in defective renal dopamine production in aged rats

A major proportion of urinary dopamine derives from the renal decarboxylation of circulating dopa. This study evaluates the effects of aging on renal production of dopamine using 3- and 12-mo-old male Wistar rats. Urinary excretion of Na+, norepinephrine (NE), 3,4-dihydroxyphenylglycol, and dopa were similar in the two groups. Urinary dopamine and 3,4-dihydroxyphenylacetic acid (DOPAC) were lower in older animals (dopamine, 20 +/- 6 vs. 47 +/- 7 nmol/24 h, P < 0.001; DOPAC, 142 +/- 36 vs. 304 +/- 56 nmol/24 h, P < 0.03). Urinary 3-O-methyldopa (OM-dopa) was higher in 12-mo-old rats (6.2 +/- 2.0 vs. 3.3 +/- 0.20 nmol/24 h, P < 0.03). Levels of dopa and NE in renal cortex from 12-mo-old rats were higher (P < 0.001) than in younger animals. Dopamine content in renal cortex from 3-mo-old rats was 295 +/- 64 pmol/g, whereas it was undetectable in 12-mo-old animals. Aromatic-L-amino-acid decarboxylase and monoamine oxidase activities were higher (P < 0.001) in renal cortex from 12-mo-old animals. Catechol-O-methyltransferase activity was similar in both groups. The uptake of dopa by the luminal membrane was explored using brush-border membrane vesicles. The Na(+)-gradient-driven (100 mM) uptake of dopa into vesicles from 3-mo-old animals showed at 10 s an overshoot threefold greater than the equilibrium uptake. The overshoot was blunted in 12-mo-old rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Opioid and sympathetic nervous system activity in cluster headache under verapamil or prednisone treatment

This study was undertaken to evaluate the effect of treatment with prednisone or verapamil on plasma met-enkephalin (ME), neutrophil met-enkephalin containing peptides (NMECP) and free and conjugated plasma catecholamines (CA) in cluster headache (CH) patients. After obtaining a basal sample, patients were randomly selected to be treated with either verapamil (n = 5) or prednisone (n = 5). A second blood sample was obtained 10 days after starting treatment. At this time all patients were free of symptoms. ME (0.49 +/- 0.10 pmol/mL) and NMECP (35.1 +/- 2.4 pmol/mg protein) levels after prednisone treatment were significantly higher (P < 0.05) than in basal conditions (0.29 +/- 0.08 pmol/mL and 27.14 +/- 2.4 pmol/mg protein), while no differences were found in catecholamine levels. No differences in ME, NMECP or CA were found during verapamil treatment. Our results suggest that in CH the two drugs act through different mechanisms. The relief of the bout obtained with prednisone may be related to the opioid system stimulation observed in these patients.

Stressor predictability influences open field behavior, pain sensitivity and brain MAO inhibitory activity (tribulin) in the rat

The effects of predictable or unpredictable shocks on ambulation, pain sensitivity, plasma catecholamines and heart and brain monoamine oxidase (MAO) inhibitory activity were investigated in rats. Animals showed plasma catecholamines and heart MAO inhibitory activity sensitization irrespective of type of treatment, while differences between groups were observed when open field and hot plate tests and brain MAO inhibitory activity were considered. These effects parallel those observed using the classic triadic design leading to the helpless state. Our results suggest that predictability per se is able to generate this phenomenon.

Lack of response of proenkephalin A and sympathetic nervous system in chronic pain associated with lung cancer

Since the discovery of the link between peripheral endogenous opioid peptides and pain regulation, these substances have been studied in relation to certain pain conditions. In order to elucidate the effect of chronic pain on both peripheral opioid system and sympathetic nervous activity, we assayed plasma met-enkephalin (ME), neutrophil met-enkephalin containing peptides (NMECP) and plasma free and conjugated catecholamines (CA) in lung cancer patients with chronic pain related to bone metastases and without pain. No significant difference was found in ME levels when the pain cancer group (0.36 +/- 0.06 pmol/ml) was compared to the pain-free group (0.37 +/- 0.04 pmol/ml); results were similar for NMECP levels (14.1 +/- 1.66 pmol/mg prot and 18.41 +/- 1.93 pmol/mg prot, respectively). CA levels in both groups were also similar. These results differ from those we have reported previously for acute pain, suggesting that a non-permanent painful stimulus may be necessary for peripheral opioid system stimulation.

N-myc oncogene and urinary catecholamines in children with neuroblastoma

This paper reports the analysis of N-myc amplification, urinary vanillylmandelic acid (VMA), and norepinephrine (NE) excretion and survival in 22 children with neuroblastoma and 7 with ganglio-neuroblastoma. Five patients had N-myc amplification (from 30 to more than 200 copies), all of whom had advanced-stage disease. The urinary excretion of VMA was normal in all of them, only one showed increased NE excretion. All patients with stage C-D disease and one copy of N-myc had increased VMA urinary excretion and increased (9/14) or normal (5/14) NE urinary excretion. All patients with stage A or B disease had one copy of N-myc. Half of them showed increased VMA urinary levels, while only 3/10 showed increased NE urinary values. Comparison of cumulative survival curves in relation to N-myc amplification and to VMA and NE urinary excretion showed a clear parallelism. Amplification of N-myc corresponded to normal VMA and NE urinary excretion, and was associated with the worst prognosis (P < 0.01), while increased VMA and/or NE excretion was found in patients with only one copy of N-myc.

Portal pressure, renal function and hormonal profile after acute and chronic captopril treatment in cirrhosis

The acute effects of captopril in cirrhosis are well known but there are few descriptions of the pattern of response to chronic administration of captopril in this disease. Nine nonuraemic cirrhotic patients with ascites and portal hypertension were studied after 1 week on fixed sodium and water intake (balance diet) and following acute and chronic treatment with captopril (three doses of 25 mg every 30 min and 75 mg.day-1 for three weeks, respectively). Whilst on the balance diet, 7/9 patients were unable to excrete the amount of sodium ingested. After the acute administration of captopril, a significant reduction was seen in arterial blood pressure (86.9 vs 77 mm Hg), with no change in the intra-hepatic pressures (free suprahepatic pressure, FSHP: 15.0 vs 12.1 mm Hg and wedged suprahepatic pressure, WSHP: 22.9 vs 20.7 mm Hg). After chronic captopril treatment, a drop was observed in portal pressure (FSHP: 9.4 mm Hg and WSHP 18.8 mm Hg, NS) and the arterial pressure returned to its basal level. The plasma aldosterone concentration decreased, whilst noradrenaline and dopamine increased significantly, the latter more than the former, leading to a reduction in the noradrenaline/dopamine ratio (14.5 vs 5.0). Seven out of nine patients showed enhanced natriuresis and the remaining two, who previously had had a positive sodium balance failed to do so. These haemodynamic, hormonal and renal changes were interpreted as evidence of blockade of angiotensin II generation by captopril, and also as a homoeostatic response by the sympathetic nervous system.

Effects of exercise on myocardial catecholamine content and ischemic injury in dogs with gradual coronary occlusion

The effects of exercise on catecholamine content and the extent of myocardial damage in dogs with Ameroid constrictor occlusion of the left circumflex coronary artery were determined. Tissue samples from both the anterior and posterior walls of the left ventricle were obtained for determination of catecholamine content, and the rest of the ventricles were processed for histologic examination. When subjected to treadmill exercise for 40 days after surgery, obstructed animals performed significantly less exercise than sham-operated animals and showed significantly higher percentages of ischemia and necrosis in the left ventricle than sedentary, obstructed, sham-operated, or control dogs. Levels of norepinephrine and epinephrine in the posterior wall of the left ventricle were significantly lower than in the other groups. Our data show that exercise in this well-known model of chronic coronary artery stenosis produced deleterious effects on the myocardium and suggest a marked heterogeneity of catecholamine stores in the myocardium that may have important functional and electrophysiologic consequences.

Footshock affects heart and brain MAO and MAO inhibitory activity and open field behavior in rats

This study examined the effects, after 1 min or 2 hr, of one footshock session on the activity of MAO in rat heart and brain, the MAO inhibitory activity of these tissues, and the animal's behavior in an open field. Internal ambulation was reduced at both times; the lowest score was registered at 1 min. The number of boluses emitted during the test was higher in the group tested at 2 hr than in the other groups. One min after shocks MAO activity in heart and brain was decreased. In the heart MAO was still decreased 2 hr later, then reaching the lowest levels, while at that time, brain MAO was not different from controls. When assayed separately (MAO A and B), only the A form was found to change. MAO inhibitory activity in heart was increased at both times, the highest activity observed 2 hr after footshock. Brain MAO inhibitory activity was increased only in the 1-min group. Ex vivo competition experiments with clorgyline suggested presence in vivo of a reversible MAO inhibitor. The time-dependent response to stress of both MAO activity and MAO inhibitory activity in the tissues correlates with the responses observed in the open field test. These findings suggest that the observed biochemical changes might be related to increased autonomic activity and to the state of fear and anxiety evoked by the stressful procedure.

Repeated (isolation) stress increases tribulin-like activity in the rat

1. The effect of repeated isolation stress on MAO inhibitory activity (tribulin) in rat tissues as well as on plasma catecholamine levels was investigated. 2. Animals were subjected to a daily period of isolation (9 min) and sacrificed on days 1, 2, 4, and 5. 3. In brain and cerebellum the levels of both inhibitory activities were found to be significantly higher in animals sacrificed on days 1-2 than in either controls or animals sacrificed on days 4-5. 4. In heart and kidney the highest levels of both activities were found in animals sacrificed on days 4-5. 5. Plasma levels of dopamine on day 4 were significantly higher than those in controls or in any of the experimental groups. Plasma levels of epinephrine showed step-by-step increments from day 1 up to day 5, reaching statistical significance only on day 5. Plasma levels of norepinephrine were significantly increased on days 2, 4, and 5. 6. Under the experimental conditions of this study, we have shown a rapid and short-lasting increment of tribulin in the central nervous system. Its disappearance on days 4-5 could be related to adaptation to the novel situation. Changes in the peripheral tissues appeared later, and a similar adaptation was absent during the period of observation. 7. Tribulin would be related to the stressful situation not only as an anxiety-promoting agent but also in contributing to the maintenance of high levels of circulating catecholamines.

24 hour changes in catecholamine content of rat thyroid and submaxillary glands

The occurrence of diurnal rhythmicity in tissue norepinephrine (NE), epinephrine (E) and dopamine (DA) levels of rat thyroid and submaxillary glands was assessed in animals killed at eight time intervals during a 24 hour period. In both tissues significant peak values of NE content were found at the third hour of dark onset (at 23:00 h). Additionally a minimum of NE content of thyroid gland was apparent in rats killed at the fifth hour of photophase (at 11:00 h). As in the case of NE, peak values of E content were found during the scotophase in both tissues examined. In contrast, DA levels exhibited no diurnal rhythmicity in the rat thyroid gland, and an early rise at the beginning of the photophase in the submaxillary glands. These results support an activation of the sympathetic nervous system innervating the thyroid and submaxillary glands at the beginning of the scotophase. Tissue DA levels do not resemble the activity of peripheral sympathetic nerves in the tissues examined.

Long-term systemic hypertension in children after successful repair of coarctation of the aorta

The mechanisms responsible for long-term hypertension in children after successful repair of coarctation of the aorta have not yet been determined. We measured plasma renin activity and aldosterone, adrenalin, and noradrenalin concentrations both under basal conditions and in response to standing and treadmill exercise in 24 normal normotensive children, 16 normotensive postcoarctectomy children, eight hypertensive postcoarctectomy children, and seven children with essential hypertension. Exercise-induced changes in plasma renin activity, aldosterone, adrenalin, and noradrenalin were comparable in the four groups in spite of a significantly greater increase in systolic blood pressure in the children with hypertension. In response to standing, the plasma concentration of noradrenalin increased significantly in normotensive but not in hypertensive children. Hyperresponse of blood pressure to exercise in hypertensive postcoarctectomy children and children with essential hypertension is not related to abnormalities in the sympathetic nervous system or the angiotensin-aldosterone axis. Hypertension could be related to primary baroreceptor alterations, to structural changes in the arterial wall, or both. Twenty percent of normotensive postcoarctectomy children had a blood pressure hyperresponse to exercise and an abnormal noradrenalin response to standing similar to that seen in the hypertensive children. Follow-up of children after coarctectomy may elucidate whether these two abnormalities are indicators of an increased risk of developing long-term recurrent hypertension.

Total plasma dopamine/norepinephrine ratio in catecholamine-secreting tumors. Its relation to hypertension

We used a radioenzymatic method to determine plasma levels of free and total (free plus sulfoconjugated) norepinephrine and dopamine in 20 children with neuroblastoma (two were hypertensive), seven patients with pheochromocytoma, and 39 normotensive controls (24 children and 15 adults). No significant differences were noted between the two control groups. Patients with neuroblastoma and pheochromocytoma showed significantly higher levels of free and total norepinephrine than controls (p less than 0.01), and those with pheochromocytoma had higher levels than those with neuroblastoma (p less than 0.01). Although the differences were not statistically significant, free dopamine was higher in both groups of patients than in controls. Total dopamine was significantly higher in patients than in controls (p less than 0.01). A positive correlation was noted between levels of total norepinephrine and total dopamine in controls (r = 0.41, p less than 0.05) and in patients with neuroblastoma (r = 0.72, p less than 0.001). Such a correlation was not found in patients with pheochromocytoma. The total dopamine/total norepinephrine ratio was higher (p less than 0.005) in patients with neuroblastoma than in controls and patients with pheochromocytoma. Patients with pheochromocytoma had significantly lower ratios than the other groups (p less than 0.001). A negative correlation was found between the ratios in the different groups and either systolic (p less than 0.001) or diastolic (p less than 0.001) blood pressure. Our results not only support a role for plasma dopamine in the regulation of blood pressure but also suggest that, regardless of the actual levels of both catecholamines, a balance has to be achieved in order to maintain normal blood pressure levels.

Stress increases endogenous benzodiazepine receptor ligand-monoamine oxidase inhibitory activity (tribulin) in rat tissues

The presence of both MAO and benzodiazepine (BZ) receptor binding inhibitory activities in rat tissues has been reported previously. The two activities were similarly and unevenly distributed in the tissues. This dual inhibitory activity has been termed tribulin. We report here the effect of 1 1/2 hrs cold restraint stress on tribulin activity in rat tissues together with biochemical evidence to support the concept of a physiological role of tribulin. Stress induced a significant increment of both activities in heart and kidney while no significant changes were observed in the other tissues studied. Hearts and kidneys from stressed rats also showed a significant decrease of MAO activity, a significant increase of dopamine content and a significant decrease of the binding of 3H-Ro 5-4864 to peripheral BZ receptors. Scatchard analysis of the saturation curves carried out using 3H-Ro 5-4864 (0.4-10 nM) showed significant Bmax decreases in both organs. No significant change in either of these inhibitory activities was observed in the other tissues studied. These data provide support for a role of tribulin in the biochemical response to stress.

Increase in plasma catecholamines by intraventricular injection of histamine in conscious rats

Intraventricular administration of histamine (HA; 2.5 and 5 micrograms) caused a significant increase of plasma adrenaline and noradrenaline levels in conscious, freely-moving male rats. The increase of adrenaline was more rapid (5 min after injection) and greater than that of noradrenaline. The plasma adrenaline increase observed 15 min after HA administration was dose-dependent. In contrast, plasma noradrenaline increased maximally in response to the low dose and reached similar values after the largest dose studied. Receptor mediation was examined by means of selective HA antagonists. Pretreatment with mepyramine blunted the adrenaline response at 15 min which suggests mediation at H1 receptors. In contrast, it was ineffective on plasma adrenaline at 5 min and plasma noradrenaline increase. Ranitidine, an H2-receptor antagonist, did not modify adrenaline response but enhanced the HA-induced increase of plasma noradrenaline. These findings suggest that HA activates the central drive to the adrenal medulla and to the peripheral sympathetic system. A participation of peripheral catecholamine secretion in the acute cardiovascular changes induced in rats by centrally injected HA is postulated.

Origins of the sympathetic projections to rat thyroid and parathyroid glands

The present study aimed to characterize the localization and pathways of sympathetic neurons innervating the thyroid and parathyroid glands. In rats subjected to unilateral superior cervical ganglionectomy or unilateral decentralization of the superior cervical ganglion 7 days earlier, ipsilateral depression of thyroid norepinephrine (NE) and epinephrine content to 6-16% of the contralateral intact lobe was observed. In both groups of animals neuronal [3H]NE uptake by the ipsilateral thyroid lobe was suppressed. In unilaterally decentralized rats pineal catecholamine levels remained within normal values whereas in unilaterally ganglionectomized rats a 74% decrease of pineal NE and E content was found. Unilateral section of the external carotid nerve abolished, as did unilateral superior cervical ganglionectomy, neuronal [3H]NE uptake in the ipsilateral thyroid lobe. In contrast external carotid nerve section did not modify the neuronal uptake of [3H]NE in the pineal gland. Either unilateral superior cervical ganglionectomy or external carotid nerve section resulted in similar involution of ipsilateral thyroid lobes of hypophysectomized rats. These results indicate that postganglionic sympathetic perikarya innervating the thyroid-parathyroid territory are located in the middle and/or inferior cervical ganglia and send their axons through the SCG and the external carotid nerve to these glands.

Effect of bromocriptine on plasma catecholamines in normal subjects and prolactin-secreting tumor patients

The effect of short term bromocriptine (5 mg/day, 5 days) on plasma epinephrine (E), norepinephrine (NE), dopamine (DA) and prolactin (PRL) was studied in 4 normal women and 6 bearing PRL-secreting tumors. When studied on placebo no significant differences were found between controls and patients in E, NE and DA plasma levels. Bromocriptine induced: a 70% decrease in PRL levels in both groups, a significant (p less than 0.05) decrease in plasma NE levels in the control group, no significant change in plasma NE levels in the hyperprolactinemic patients when considered as a group. These results do not indicate that bromocriptine is a useful tool in the diagnosis of defective central dopaminergic regulation since individual responses of the PRL-secreting tumor patients were variable. Nevertheless, the impaired response of the group as a whole may be suggesting an underlying alteration of DA2 receptor activity in these tumor patients.

Comparison of single and combined tests for the evaluation of plasma growth hormone secretion in normal short children

Growth hormone (GH) response to provocative tests was compared in normal short children. Seven of 23 children failed to respond to insulin hypoglycemia. Using insulin hypoglycemia followed by L-dopa only 2 of 23 children did not respond and giving bromocriptine combined with insulin hypoglycemia only 1 of 8 children failed to respond. All children submitted to propranolol followed by exercise (n = 14) and to bromocriptine followed by exercise (n = 6) responded with a satisfactory increase in plasma GH levels. The increase elicited by propranolol and exercise was higher than that induced by insulin hypoglycemia alone (p less than 0.005), exercise alone (p less than 0.05) or L-dopa after insulin hypoglycemia (p less than 0.01). The rise of GH induced by bromocriptine and exercise was higher than that obtained with insulin hypoglycemia alone (p less than 0.05). This study suggests that both adrenergic and dopaminergic mechanisms are involved in exercise induced GH release and confirms that combined tests are more useful than a single test to evaluate GH secretion.

Exercise increases endogenous urinary monoamine oxidase benzodiazepine receptor ligand inhibitory activity in normal children

This study shows that in normal children the stress of maximal exercise induced not only activation of the sympathetic nervous system but also an increased urinary output of both MAO inhibitory activity and [3H]flunitrazepam binding to rat cerebellar membranes inhibitory activity.