Hyperandrogenism Protects Against High Blood Pressure by Nongenomic Mechanisms and Obesity Causes Hypertension in Females with Polycystic Ovary Syndrome.

BACKGROUND: Androgens induce vasorelaxation and reduce blood pressure in different mammals, including humans. Most women with polycystic ovary syndrome (PCOS), with hyperandrogenism, are obese and exhibit hypertension; thus, the fact that androgens increase blood pressure (BP) is controversial. Our aim was to determine whether hypertension is produced by androgen excess and/or obesity. METHODS: Experiments were performed in dehydroepiandrosterone; (DHEA, s.c)-induced PCOS model. BP from nonobese and obese rats with PCOS (fed a normal or high-fat diet, respectively) was evaluated weekly for 10 weeks by plethysmography and compared between them. We determined whether androgen receptors are responsible for androgen action on BP in rats with PCOS; a group of DHEA-treated rats was implanted with pellets of an antiandrogen and was compared with nonobese rats with PCOS. Isometric tension from aortas of nonobese and obese rats was recorded and compared to explore the integrity of the vascular endothelium when acetylcholine-induced endothelium-dependent vascular relaxation on phenylephrine contraction. Additionally, BP was obtained from 30 women diagnosed with PCOS: nonobese (BMI ≤25) and obese women (BMI ≥35) and compared with healthy counterparts; 15 obese and 15 nonobese women. RESULTS: Nonobese rats and women with PCOS showed hypotension, while obese rats and women with PCOS displayed hypertension. Healthy obese women were hypertensive and nonobese women remained normotensive. Antiandrogen did not modify the BP values in nonobese rats with PCOS, and obese rats with PCOS revealed marked endothelial dysfunction. CONCLUSIONS: Our findings show that obesity is responsible for hypertension in PCOS and partial endothelial damage was observed, which may contribute to elevated BP. Remarkably, hyperandrogenism is capable of regulating BP to low values that are androgen receptor-independent.

Deletion of the ATP20 gene in Ustilago maydis produces an unstable dimer of F1FO-ATP synthase associated with a decrease in mitochondrial ATP synthesis and a high H2O2 production.

The F1FO-ATP synthase uses the energy stored in the electrochemical proton gradient to synthesize ATP. This complex is found in the inner mitochondrial membrane as a monomer and dimer. The dimer shows higher ATPase activity than the monomer and is essential for cristae folding. The monomer-monomer interface is constituted by subunits a, i/j, e, g, and k. The role of the subunit g in a strict respiratory organism is unknown. A gene knockout was generated in Ustilago maydis to study the role of subunit g on mitochondrial metabolism and cristae architecture. Deletion of the ATP20 gene, encoding the g subunit, did not affect cell growth or glucose consumption, but biomass production was lower in the mutant strain (gΔ strain). Ultrastructure observations showed that mitochondrial size and cristae shape were similar in wild-type and gΔ strains. The mitochondrial membrane potential in both strains had a similar magnitude, but oxygen consumption was higher in the WT strain. ATP synthesis was 20 % lower in the gΔ strain. Additionally, the mutant strain expressed the alternative oxidase in the early stages of growth (exponential phase), probably as a response to ROS stress. Dimer from mutant strain was unstable to digitonin solubilization, avoiding its isolation and kinetic characterization. The isolated monomeric state activated by n-dodecyl-ß-D-maltopyranoside showed similar kinetic constants to the monomer from the WT strain. A decrease in mitochondrial ATP synthesis and the presence of the AOX during the exponential growth phase suggests that deletion of the g gene induces ROS stress.

Androgens and Non-Genomic vascular responses in hypertension.

Arterial hypertension is a global public health concern. In the last few years, the interest in androgen deficiency has been growing, and the association between androgens and high blood pressure (BP) is still controversial. One purpose of this review was to summarize the available findings in order to clarify whether male sex steroid hormones have beneficial or harmful effect on BP. The second purpose was to enhance the recognition of the acute non-genomic sex-independent vasorelaxing effect of androgens. Remarkably, BP variation is expected to be a consequence of the androgen-induced vasorelaxation which reduces systemic BP; hence the in vivo vasodepressor, hypotensive, and antihypertensive responses of androgens were also analyzed. This article reviews the current understanding of the physiological regulation of vascular smooth muscle contractility by androgens. Additionally, it summarizes older and more recent data on androgens, and some of the possible underlying mechanisms of relaxation, structural-functional differences in the androgen molecules, and their designing ability to induce vasorelaxation. The clinical relevance of these findings in terms of designing future therapeutics mainly the 5-reduced metabolite of testosterone, 5ß-dihydrotestosterone, is also highlighted. Literature collected through a PubMed database search, as well as our experimental work, was used for the present review.

Moderate exercise combined with metformin-treatment improves mitochondrial bioenergetics of the quadriceps muscle of old female Wistar rats.

Sarcopenia is a syndrome that leads to physical disability and that deteriorates elderly people´s life quality. The etiology of sarcopenia is multifactorial, but mitochondrial dysfunction plays a paramount role in this pathology. Our research group has shown that the combined treatment of metformin (MTF) and exercise has beneficial effects for preventing muscle loss and fat accumulation, by modulating the redox state. To get an insight into the mechanism of the combined treatment, the mitochondrial bioenergetics was studied in the mitochondria isolated from old female Wistar rats quadriceps muscles. The animals were divided into six groups; three performed exercise on a treadmill for 5 days/week for 20 months, and the other three were sedentary. Also, two groups of each were treated with MTF for 6 or 12 months. The rats were euthanized at 24 months. The mitochondria were isolated and supercomplexes formation along with oxygen consumption, ATP synthesis, and ROS generation were evaluated. Our results showed that the combined treatment for 12 months increased the complex I and IV activities associated with the supercomplexes, simultaneously, ATP synthesis increased while ROS production decreased, indicating a tightly coupled mitochondria. The role of exercise plus the MTF treatment against sarcopenia in old muscles is discussed.

Steady-state persistence of respiratory syncytial virus in a macrophage-like cell line and sequence analysis of the persistent viral genome.

Long-term infection by human respiratory syncytial virus (hRSV) has been reported in immunocompromised patients. Cell lines are valuable in vitro model systems to study mechanisms associated with viral persistence. Persistent infections in cell cultures have been categorized at least as in "carrier-state", where there exist a low proportion of cells infected by a lytic virus, and as in "steady-state", where most of cells are infected, but in absence of cytophatic effect. Here, we showed that hRSV maintained a steady-state persistence in a macrophage-like cell line after 120 passages, since the viral genome was detected in all of the cells analyzed by fluorescence in situ hybridization, whereas only defective viruses were identified by sucrose gradients and titration assay. Interestingly, eight percent of cells harboring the hRSV genome revealed undetectable expression of the viral nucleoprotein N; however, when this cell population was sorted by flow cytometry and independently cultured, viral protein expression was induced at detectable levels since the first post-sorting passage, supporting that sorted cells harbored the viral genome. Sequencing of the persistent hRSV genome obtained from virus collected from cell-culture supernatants, allowed assembling of a complete genome that displayed 24 synonymous and 38 nonsynonymous substitutions in coding regions, whereas extragenic and intergenic regions displayed 12 substitutions, two insertions and one deletion. Previous reports characterizing mutations in extragenic regulatory sequences of hRSV, suggested that some mutations localized at the 3' leader region of our persistent virus might alter viral transcription and replication, as well as assembly of viral nucleocapsids. Besides, substitutions in P, F and G proteins might contribute to altered viral assembly, budding and membrane fusion, reducing the cytopathic effect and in consequence, contributing to host-cell survival. Full-length mutant genomes might be part of the repertoire of defective viral genomes formed during hRSV infections, contributing to the establishment and maintenance of virus persistence.

Hypogonadal hypertension in male Sprague-Dawley rats is renin-angiotensin system-dependent: role of endogenous androgens.

BACKGROUND: Acutely, testosterone (TES) and other androgens are efficacious vasodilators, both in vitro and in vivo; however, their long-term effects on arterial blood pressure (BP) remain unclear. It was hypothesized that endogenous androgens exert long-term anti-hypertensive effects on systemic BP through a combination of genomic and nongenomic effects to enhance vasodilation of the systemic vasculature. METHODS: The long-term effects of endogenous TES and exogenous TES replacement therapy (TRT) on BP were studied in intact (InT) and castrated (CsX) male Sprague-Dawley (SD) and testicular-feminized male (Tfm, androgen receptor defective) rats (12 weeks old). Systolic BP (tail-cuff plethysmography) was determined weekly for 15 weeks in InT-control and CsX rats. Some CsX-SD rats received androgen replacement therapy at 10-15 weeks with TES-enanthate (TRT; 1.75 mg/kg, 2x/week) or DHT-enanthate (DRT; 1.00 mg/kg. 2x/week) and a separate group of CsX-SD rats received losartan-potassium in drinking water (LST, 250 mg/L) for the entire 15 week period. Expression of renin, angiotensinogen (Agt), angiotensin converting enzyme (ACE), and angiotensin II type I receptor (AT1R) mRNA in kidney and aorta were determined by real-time PCR (rt-PCR) and plasma renin levels were determined by radioimmunoassay. RESULTS: There was a progressive rise in BP over 10 weeks in CsX (109 ± 3.3 vs. 143 ± 3.5 mmHg), while BP remained stable in InT-control (109 ± 3.0 vs. 113 ± 0.3). BP gradually declined to normal in CsX-TRT rats (113 ± 1.3), while BP remained elevated in CsX (140 ± 1.2) and normal in InT-control (113 ± 0.3). LST prevented the development of hypertension in CsX at 10 weeks (100 ± 1.5 in CsX + LST vs. 143 ± 3.5 in CsX). During the next 5 weeks with TES-RT, BP declined in CsX-TRT (113 ± 1.3) and remained lower in CsX + LST (99 ± 0.4). DHT-RT reduced BP in CxS to a similar extent. In Tfm, CsX resulted in a similar rise in BP (109 ± 0.7 vs. 139 ± 0.4 mmHg), but TRT reduced BP more rapidly and to a greater extent (106 ± 2.8). rt-PCR of the kidney revealed that CsX increased expression of mRNA for renin (92%), ACE (58%), and AT1R (80%) compared to InT, while TES RT normalized expression of renin, AT1R, and ACE mRNA to levels of InT rats. Plasma renin levels exhibited changes similar to those observed for renin mRNA expression. CONCLUSIONS: This is the first study to examine the long-term effects of endogenous and exogenous androgens on BP in male SD and Tfm rats. These data reveal that endogenous androgens (TES) exert anti-hypertensive effects that appear to involve non-genomic and possibly genomic mechanism(s), resulting in reductions in RAS expression in the kidney and enhanced systemic vasodilation.

Androgens are effective bronchodilators with anti-inflammatory properties: A potential alternative for asthma therapy.

Changes in plasma androgen levels in asthmatic men may be linked to asthma severity, seemingly acting through nongenomic and genomic effects. Nongenomic effects include rapid relaxation of carbachol or antigenic challenge pre-contracted guinea pig airway smooth muscle (ASM) in vitro: testosterone (TES) blocks l-type voltage dependent Ca2+ channels, stored operated Ca2+ channels, inositol 1,4,5-trisphosphate receptors and promotes prostaglandin E2 biosynthesis. In ASM at rest, TES lowers basal intracellular Ca2+ concentration and tension, maintaining a proper airway patency keeping steady smooth muscle tension and basal intracellular Ca2+ concentration at rest. Moreover, the bronchospasm in sensitized guinea-pigs was ablated by dehydroepiandrosterone (DHEA), a precursor of steroids, TES and its metabolites 5α- and 5ß-dihydrotestosterone (DHT). On the other hand, genomic effects related to androgens' anti-inflammatory properties in asthma have been recently studied. Briefly, TES negatively regulates type 2 immune response sustained by CD4+ Th2 and group 2 innate lymphoid cells, diminishing allergic airway inflammation in males. Also, novel findings establish that TES decreases interleukin (IL)-17A protein expression produced by CD4+ Th17 cells and therefore neutrophilic airway inflammation. Clearly, DHEA, TES or its 5ß-reduced metabolite that possesses minimal androgenic effect, might have potential therapeutic capacities in the treatment of severe asthma via mechanisms distinct from corticosteroid treatment.

Hypotestosteronemia is an important factor for the development of hypertension: elevated blood pressure in orchidectomized conscious rats is reversed by different androgens.

PURPOSE: Hypotestosteronemia is an aging-associated disease. Little is known about experimental evidence linking androgen deficiency to hypertension. Various androgens are acute vasodilators, both in vitro and in vivo. We aimed to systematically investigate blood pressure (BP) in male normotensive intact or orchidectomized (ORX) Wistar and Wistar-Kyoto rats. Furthermore, we studied the acute antihypertensive responses of testosterone (TES), its precursor (DHEA), or its 5ß-reduced metabolite (5ß-DHT) in conscious, unrestrained, hypertensive Wistar rats caused by orchidectomy to determine their potency and efficacy. Similarly, the mechanism of their action mediated by nitric oxide (NO) was studied in vivo. METHODS: BP of ORX rats was evaluated weekly for 18 weeks by tail cuff plethysmography. Subsequently, BP of ORX Wistar rats was measured by chronic indwelling vascular catheters, arterial, and venous catheters were implanted under anesthesia for BP recording and androgen administration, respectively. Then, a dose-response curve of each androgen was performed. Likewise, the dose-response curve of 5ß-DHT, the most potent androgen, was repeated in the presence of a nonselective NO synthase inhibitor (L-NAME) or an inhibitor of endothelial NO synthesis (Endothelin-1). RESULTS: ORX rats progressively increased systolic/diastolic BP (167 ± 2.8/141 ± 3.3 mmHg) over 18 weeks. No difference was found between strains. The BP was reduced in a dose-dependent manner caused by i.v. bolus injection of each androgen, with a rank order of potency of: 5ß-DHT = DHEA>>TES. Dose-dependent antihypertension induced by 5ß-DHT in ORX rats was not abolished in the presence of L-NAME or Endothelin-1. CONCLUSIONS: These in vivo experimental findings reveal that hypotestosteronemia is a determining factor for the development of hypertension which is powerfully reduced by androgen administration, and 5ß-DHT induces a potent and effective antihypertensive response by a NO-independent mechanism.

Mitochondrial respirasome works as a single unit and the cross-talk between complexes I, III2 and IV stimulates NADH dehydrogenase activity.

Ustilago maydis is an aerobic basidiomycete that depends on oxidative phosphorylation for its ATP supply, pointing to the mitochondrion as a key player in its energy metabolism. Mitochondrial respiratory complexes I, III2, and IV occur in supramolecular structures named respirasome. In this work, we characterized the subunit composition and the kinetics of NADH:Q oxidoreductase activity of the digitonine-solubilized respirasome (1600 kDa) and the free-complex I (990 kDa). In the presence of 2,6-dimethoxy-1,4-benzoquinone (DBQ) and cytochrome c, both the respirasome NADH:O2 and the NADH:DBQ oxidoreductase activities were inhibited by rotenone, antimycin A or cyanide. A value of 2.4 for the NADH oxidized/oxygen reduced ratio was determined for the respirasome activity, while ROS production was less than 0.001% of the oxygen consumption rate. Analysis of the NADH:DBQ oxidoreductase activity showed that respirasome was 3-times more active and showed higher affinity than free-complex I. The results suggest that the contacts between complexes I, III2 and IV in the respirasome increase the catalytic efficiency of complex I and regulate its activity to prevent ROS production.

Streptozotocin-Induced Adaptive Modification of Mitochondrial Supercomplexes in Liver of Wistar Rats and the Protective Effect of Moringa oleifera Lam.

The increasing prevalence of diabetes continues to be a major health issue worldwide. Alteration of mitochondrial electron transport chain is a recognized hallmark of the diabetic-associated decline in liver bioenergetics; however, the molecular events involved are only poorly understood. Moringa oleifera is used for the treatment of diabetes. However, its role on mitochondrial functionality is not yet established. This study was aimed to evaluate the effect of M. oleifera extract on supercomplex formation, ATPase activity, ROS production, GSH levels, lipid peroxidation, and protein carbonylation. The levels of lipid peroxidation and protein carbonylation were increased in diabetic group. However, the levels were decreased in Moringa-treated diabetic rats. Analysis of in-gel activity showed an increase in all complex activities in the diabetic group, but spectrophotometric determinations of complex II and IV activities were unaffected in this treatment. However, we found an oxygen consumption abolition through complex I-III-IV pathway in the diabetic group treated with Moringa. While respiration with succinate feeding into complex II-III-IV was increased in the diabetic group. These findings suggest that hyperglycemia modifies oxygen consumption, supercomplexes formation, and increases ROS levels in mitochondria from the liver of STZ-diabetic rats, whereas M. oleifera may have a protective role against some alterations.

Vasoactive androgens: Vasorelaxing effects and their potential regulation of blood pressure.

BACKGROUND: Testosterone, 5α- and 5ß-dihydrotestosterone (-DHT) induce an acute in vitro vasorelaxation and in vivo vasodepressor, hypotensive and antihypertensive responses. Our aim was to study whether androgen-induced blood pressure (BP) reduction is involved with a blockade of Ca2+ influx through L-type voltage-operated calcium channels (L-VOCCs) and/or the signaling pathways of α1-adrenoceptors to induce vasoconstriction, which are one of the major mechanisms of BP maintenance. MATERIALS AND METHODS: The relaxing potency and efficacy of each androgen in large conduit (thoracic aorta) and resistance (mesenteric) arteries from male hypertensive (SHR) and normotensive (WKY) rats were established. Blood vessels were isometrically recorded and precontracted with KCl or phenylephrine (Phe). RESULTS: Androgens induced concentration-dependent vasorelaxation in precontracted arteries from SHR and WKY rats. 5ß-DHT was always the most potent vasorelaxant in arteries from SHR. The KCl-induced contraction resulted significantly more sensitive to androgen-induced vasorelaxation than the Phe-induced contraction. On Phe-induced contraction, 5ß-DHT was more potent in the mesenteric artery than in the thoracic aorta. CONCLUSIONS: The vasorelaxation induced by androgens is mainly mediated by blocking L-VOCCs and in lesser extent by the blockade of multiple signaling pathways operative during α-adrenoceptor-induced vasoconstriction. 5ß-DHT regulates vascular resistance and BP by mainly acting in the mesenteric arterial bed, which may explain its outstanding antihypertensive response previously reported.

Antihypertensive responses of vasoactive androgens in an in vivo experimental model of preeclampsia.

Dehydroepiandrosterone (DHEA), testosterone (TES) and its 5-reduced metabolites induce a nongenomic vasorelaxation in several vascular beds of mammals; similarly these hormones produce systemic hypotensive and antihypertensive responses in normotensive and hypertensive male rats. Thus, it was hypothesized that the antihypertensive response of androgens, whose levels are elevated during gestation, protect against gestational hypertension. An animal model of preeclampsia was induced in female Wistar rats using DOCA-salt-treated pregnant (PT) and normal pregnant (NP) rats. In vivo experiments in conscious rats revealed that bolus intravenous injections of DHEA, TES, 5α- or 5ß-dihydrotestosterone (-DHT) log -1.0 to 2.0µmolk-1min-1, produced substantial transient reductions in arterial blood pressure (BP), without significant changes in heart rate (HR). Mean arterial blood pressure (MAP) was reduced significantly in both groups. PT rats were more sensitive to the antihypertensive responses of androgens than NP. DHEA and 5ß-DHT were the most potent to reduce MAP: 66±07 and 69±2.0mmHg in PT but only 33±0.5 and 35±1.2mmHg in NP rats, respectively. In isolated aortas of PT and NP, the concentration-response curves to each androgen (0.1-100µM) indicated that KCl-induced pre-contraction is more sensitive to all androgens than phenylephrine (Phe) pre-contractions. Notably, 5ß-DHT is the greatest vasorelaxant with KCl-induced contraction than with Phe contraction of both groups, suggesting a preferential blockade on L-VOCCs. TES exhibited minor vasorelaxing effect of aortas pre-contracted with KCl, compared to its precursor DHEA and its 5-reduced metabolites. These data show that these androgens exert acute vasorelaxing effects in vitro and remarkably, reduce the BP in vivo in PT and NP at term pregnancy. Moreover, a deficit in feto-placental androgen production during pregnancy may trigger the development of preeclampsia or gestational hypertension.

Structural and kinetics characterization of the F1F0-ATP synthase dimer. New repercussion of monomer-monomer contact.

Ustilago maydis is an aerobic basidiomycete that fully depends on oxidative phosphorylation for its supply of ATP, pointing to mitochondria as a key player in the energy metabolism of this organism. Mitochondrial F1F0-ATP synthase occurs in supramolecular structures. In this work, we isolated the monomer (640kDa) and the dimer (1280kDa) and characterized their subunit composition and kinetics of ATP hydrolysis. Mass spectrometry revealed that dimerizing subunits e and g were present in the dimer but not in the monomer. Analysis of the ATPase activity showed that both oligomers had Michaelis-Menten kinetics, but the dimer was 7 times more active than the monomer, while affinities were similar. The dimer was more sensitive to oligomycin inhibition, with a Ki of 24nM, while the monomer had a Ki of 169nM. The results suggest that the interphase between the monomers in the dimer state affects the catalytic efficiency of the enzyme and its sensitivity to inhibitors.

Olanzapine-induced early cardiovascular effects are mediated by the biological clock and prevented by melatonin.

Second generation antipsychotics (SGA) are associated with adverse cardiometabolic side effects contributing to premature mortality in patients. While mechanisms mediating these cardiometabolic side effects remain poorly understood, three independent studies recently demonstrated that melatonin was protective against cardiometabolic risk in SGA-treated patients. As one of the main target areas of circulating melatonin in the brain is the suprachiasmatic nucleus (SCN), we hypothesized that the SCN is involved in SGA-induced early cardiovascular effects in Wistar rats. We evaluated the acute effects of olanzapine and melatonin in the biological clock, paraventricular nucleus and autonomic nervous system using immunohistochemistry, invasive cardiovascular measurements, and Western blot. Olanzapine induced c-Fos immunoreactivity in the SCN followed by the paraventricular nucleus and dorsal motor nucleus of the vagus indicating a potent induction of parasympathetic tone. The involvement of a SCN-parasympathetic neuronal pathway after olanzapine administration was further documented using cholera toxin-B retrograde tracing and vasoactive intestinal peptide immunohistochemistry. Olanzapine-induced decrease in blood pressure and heart rate confirmed this. Melatonin abolished olanzapine-induced SCN c-Fos immunoreactivity, including the parasympathetic pathway and cardiovascular effects while brain areas associated with olanzapine beneficial effects including the striatum, ventral tegmental area, and nucleus accumbens remained activated. In the SCN, olanzapine phosphorylated the GSK-3ß, a regulator of clock activity, which melatonin prevented. Bilateral lesions of the SCN prevented the effects of olanzapine on parasympathetic activity. Collectively, results demonstrate the SCN as a key region mediating the early effects of olanzapine on cardiovascular function and show melatonin has opposing and potentially protective effects warranting additional investigation.

Antihypertensive effects of androgens in conscious, spontaneously hypertensive rats.

Androgens are vasoactive steroids that induce acute vasodilation in a number of isolated vascular beds from different species, but the effects of these hormones on systemic blood pressure (BP) have been studied little. Although it has been reported that androgens exert systemic hypotensive effects through peripheral vasodilation in normotensive rats, there have not been any reports of systemic hypotensive effects of androgens in animals with hypertension. This study was designed to evaluate the acute effects of testosterone (TES) and its 5-reduced metabolites on systemic BP in hypertensive rats and to test the hypothesis that hypotestosteronemia may be involved in the pathogenesis of hypertension. Chronic, indwelling catheters were implanted in carotid artery and jugular vein of 18-21-week-old male spontaneously hypertensive rats (SHR) and normotensive-control Wistar-Kyoto (WKY) rats, for BP recording and drug administration, respectively. Bolus injections of TES, 5α- or 5ß-dihydrotestosterone (5α- and 5ß-DHT), were administrated cumulatively to conscious rats at doses of 0.1-100µmolkg-1min-1. 5ß-DHT was also administrated during the pressor effect of Bay K 8644, an L-type voltage-operated Ca2+ channel (L-VOCC) agonist. In separate experiments, BP of orchidectomized normotensive male WKY and Wistar rats, with or without androgen-replacement therapy, was evaluated weekly for 10 weeks by tail-cuff plethysmography. TES and its metabolites reduced BP in a dose-dependent manner, while heart rate was reduced with some androgens at the highest doses. The hypotensive effects of androgens were markedly greater in SHR, with a rank order potency of: 5ß-DHT>TES>5α-DHT. 5ß-DHT, the most potent antihypertensive androgen, abolished the pressor response to Bay K 8644 in SHR. TES deprivation by orchidectomy increased BP in normotensive WKY and Wistar rats, but this hypertension was prevented by TES replacement therapy. BP responses to androgens are androgen structure-dependent. These data indicate that: 1) androgens play a significant role in the control of BP and may contribute to the pathogenesis of hypertension; 2) blockade of L-VOCC is involved in the antihypertensive effects of androgens, which are non-genomically mediated; and 3) hypotestosteronemia may be a risk factor for hypertension.

Sex steroids effects on guinea pig airway smooth muscle tone and intracellular Ca2+ basal levels.

Testosterone (TES), other androgens and female sex steroids induce non-genomic rapid relaxing effects in airway smooth muscle (ASM). In guinea pig ASM, basal tension was relaxed by dehydroepiandrosterone (DHEA) and TES; 17ß-estradiol (E2) had a small effect. Blockers of L-type voltage dependent Ca2+ channel (L-VDCC, D-600) and store operated Ca2+ channel (SOC, 2-APB) also relaxed the basal tone. In tracheal myocytes, DHEA and TES diminished intracellular basal Ca2+ concentrations (b[Ca2+]i) as D-600+2-APB but to a higher extend. TES after D-600+2APB or Pyr3, a blocker of canonical transient receptor potential 3 (TRPC3), further decreased b[Ca2+]i rendering this response equal to TES alone. With indomethacin, the b[Ca2+]i decrease induced by the blockade of L-VDCC and TRPC3 was not changed by the addition of TES. PGE2 or forskolin addition after D600+2-APB, decreased b[Ca2+]i resembling TES response. An adenylate cyclase inhibitor followed by D-600+2-APB lowered b[Ca2+]i, TES showed no further effect. Carbachol-induced [Ca2+]i increment was reduced by TES or DHEA. 17ß-estradiol diminished KCl-induced contraction and, in tracheal myocytes, the voltage-dependent inward Ca2+ current. CONCLUSION: DHEA and TES diminish ASM tone and b[Ca2+]i by blocking L-VDCC and probably a constitutively active TRPC3, and by PGE2 synthesis. E2 lowers ASM basal tone by blocking only L-VDCC.

Multiple functions of syncytiotrophoblast mitochondria.

The human placenta plays a central role in pregnancy, and the syncytiotrophoblast cells are the main components of the placenta that support the relationship between the mother and fetus, in apart through the production of progesterone. In this review, the metabolic processes performed by syncytiotrophoblast mitochondria associated with placental steroidogenesis are described. The metabolism of cholesterol, specifically how this steroid hormone precursor reaches the mitochondria, and its transformation into progesterone are reviewed. The role of nucleotides in steroidogenesis, as well as the mechanisms associated with signal transduction through protein phosphorylation and dephosphorylation of proteins is discussed. Finally, topics that require further research are identified, including the need for new techniques to study the syncytiotrophoblast in situ using non-invasive methods.

Systemic hypotensive effects of testosterone are androgen structure-specific and neuronal nitric oxide synthase-dependent.

Testosterone (TES) and other androgens exert a direct vasorelaxing action on the vasculature in vitro that is structurally specific and independent of cytosolic androgen receptor (AR). The effects of intravenous androgen infusions on mean arterial blood pressure (BP) and heart rate (HR) were determined in conscious, unrestrained, chronically catheterized, ganglionically blocked (hexamethonium, HEX; 30 mg/kg ip) male Sprague-Dawley (SD) and testicular-feminized male (Tfm; AR-deficient) rats, 16-20 wk of age. BP and HR were recorded at baseline and with increasing doses of androgens (0.375-6.00 µmol·kg(-1)·min(-1) iv; 10 min/dose). Data are expressed as means ± SE (n = 5-8 rats/group). In SD rats, baseline BP and HR averaged 103 ± 4 mmHg and 353 ± 12 beats/min (bpm). TES produced a dose-dependent reduction in BP to a low of 87 ± 4 mmHg (Δ16%), while HR was unchanged (354 ± 14 bpm). Neither BP (109 ± 3 mmHg) nor HR (395 ± 13 bpm) were altered by vehicle (10% EtOH in 0.9% saline; 0.15 ml·kg(-1)·min(-1), iv). In Tfm, TES produced a similar reduction in BP (99 ± 3 to 86 ± 3 mmHg, Δ13%); HR was unchanged (369 ± 18 bpm). In SD, 5ß-dihydrotestosterone (genomically inactive metabolite) produced a greater reduction in BP than TES (102 ± 2 to 79 ± 2 mmHg, Δ23%); HR was unchanged (361 ± 9). A 20-µg iv bolus of sodium nitroprusside in both SD and Tfm rats reduced BP 30-40 mmHg, while HR was unchanged, confirming blockade by HEX. Pretreatment of SD rats with neuronal nitric oxide synthase (nNOS) inhibitor (S-methyl-thiocitrulline, SMTC; 20 µg·kg(-1)·min(-1) × 30 min) abolished the hypotensive effects of TES infusion on BP (104 ± 2 vs. 101 ± 2 mmHg) and HR (326 ± 11 vs. 324 ± 8 bpm). These data suggest the systemic hypotensive effect of TES and other androgens involves a direct vasodilatory action on the peripheral vasculature which, like the effect observed in isolated arteries, is structurally specific and AR-independent, and involves activation of nNOS.

Mitochondrial proteases act on STARD3 to activate progesterone synthesis in human syncytiotrophoblast.

BACKGROUND: STARD1 transports cholesterol into mitochondria of acutely regulated steroidogenic tissue. It has been suggested that STARD3 transports cholesterol in the human placenta, which does not express STARD1. STARD1 is proteolytically activated into a 30-kDa protein. However, the role of proteases in STARD3 modification in the human placenta has not been studied. METHODS: Progesterone determination and Western blot using anti-STARD3 antibodies showed that mitochondrial proteases cleave STARD3 into a 28-kDa fragment that stimulates progesterone synthesis in isolated syncytiotrophoblast mitochondria. Protease inhibitors decrease STARD3 transformation and steroidogenesis. RESULTS: STARD3 remained tightly bound to isolated syncytiotrophoblast mitochondria. Simultaneous to the increase in progesterone synthesis, STARD3 was proteolytically processed into four proteins, of which a 28-kDa protein was the most abundant. This protein stimulated mitochondrial progesterone production similarly to truncated-STARD3. Maximum levels of protease activity were observed at pH7.5 and were sensitive to 1,10-phenanthroline, which inhibited steroidogenesis and STARD3 proteolytic cleavage. Addition of 22(R)-hydroxycholesterol increased progesterone synthesis, even in the presence of 1,10-phenanthroline, suggesting that proteolytic products might be involved in mitochondrial cholesterol transport. CONCLUSION: Metalloproteases from human placental mitochondria are involved in steroidogenesis through the proteolytic activation of STARD3. 1,10-Phenanthroline inhibits STARD3 proteolytic cleavage. The 28-kDa protein and the amino terminal truncated-STARD3 stimulate steroidogenesis in a comparable rate, suggesting that both proteins share similar properties, probably the START domain that is involved in cholesterol binding. GENERAL SIGNIFICANCE: Mitochondrial proteases are involved in syncytiotrophoblast-cell steroidogenesis regulation. Understanding STARD3 activation and its role in progesterone synthesis is crucial to getting insight into its action mechanism in healthy and diseased syncytiotrophoblast cells.