Navegando por Palavras-chave "catecholamines"
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- ItemSomente MetadadadosActivating cAMP/PKA signaling in skeletal muscle suppresses the ubiquitin-proteasome-dependent proteolysis: implications for sympathetic regulation(Amer Physiological Soc, 2014-07-01) Silveira, W. A.; Goncalves, D. A.; Graca, F. A.; Andrade-Lopes, A. L. [UNIFESP]; Bergantin, L. B. [UNIFESP]; Zanon, N. M.; Godinho, R. O. [UNIFESP]; Kettelhut, I. C.; Navegantes, L. C. C.; Universidade de São Paulo (USP); Universidade Federal de São Paulo (UNIFESP)Although we have recently demonstrated that plasma catecholamines induce antiproteolytic effects on skeletal muscle (Graca FA, Goncalves DAP, Silveira WA, Lira EC, Chaves VE, Zanon NM, Garofalo MAR, Kettelhut IC, Navegantes LCC. Am J Physiol Endocrinol Metab. 305: E1483-E1494, 2013), the role of the muscle sympathetic innervation and, more specifically, norepinephrine (NE) in regulating the ubiquitin (Ub)-proteasome system (UPS) remains unknown. Based on previous findings that chemical sympathectomy acutely reduces UPS activity, we hypothesized that muscle NE depletion induces adrenergic supersensitivity in rat skeletal muscles. We report that surgical sympathetic denervation (SDEN), a condition in which only muscle NE from both hindlimbs is depleted, transiently reduced the overall proteolysis and the UPS activity (similar to 25%) in both soleus and extensor digitorum longus muscles. This antiproteolytic response was accompanied by increased activity of adenylyl cyclase (112%), levels of cyclic adenosine monophosphate (cAMP; 191%), and the serine phosphorylation of cAMP response element-binding protein (32%). in extensor digitorum longus from normal rats, NE (10(-4) M) in vitro increased the levels of cAMP (115%) and the serine phosphorylation of both cAMP response element-binding protein (2.7-fold) and forkhead box class O1 transcription factor. Similar effects were observed in C2C12 cells incubated with forskolin (10 mu M). in parallel, NE significantly reduced the basal UPS (21%) activity and the mRNA levels of atrophy-related Ub-ligases. Similar responses were observed in isolated muscles exposed to 6-BNZ-cAMP (500 mu M), a specific PKA activator. the phosphorylation levels of Akt were not altered by SDEN, NE, forskolin or 6-BNZ-cAMP. Our results demonstrate that SDEN induces muscle adrenergic supersensitivity for cAMP leading to the suppression of UPS, and that the suppressive effects of NE on UPS activity and expression of Ubligases can be mediated by the activation of cAMP/PKA signaling, with the inhibition of forkhead box class O1 transcription factor.
- ItemSomente Metadadadosalpha(1)-adrenoceptor subtypes in rat epididymis and the effects of sexual maturation(Soc Study Reproduction, 2002-02-01) Queiroz, DBC [UNIFESP]; Mendes, F. R. [UNIFESP]; Porto, C. S. [UNIFESP]; Avellar, MCW [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)We have characterized the expression of alpha(1)-adrenoceptor in epididymis from rats in different stages of sexual maturation: 40 (immature), 60 (young adult), and 120 (adult) days of age. Plasma testosterone levels were low in the immature animals but increased significantly in the 60- and 120-day-old animals. These changes were followed by a progressive increase in rat body weight and in caput and cauda epididymis relative weight., Reverse transcription polymerase chain reaction assay indicated that alpha(1a)-, alpha(1b)-, and alpha(1d)-adrenoceptor transcripts were present in both caput and cauda epididymis from adult rats.. Ribonuclease protection assays further indicated that the expression of these alpha(1)-adrenoceptor transcripts differed with age and epididymal region analyzed. Prazosin (nonselective alpha(1) antagonist), 5-methyl urapidil. (alpha(1A)-selective), and BMY 7378 (alpha(1D)-selective) displaced [H-3]prazosin binding curves in caput and cauda epididymis from 40- and 120-day-old rats. the potency order for these antagonists, as calculated from the negative logarithm: of the inhibition constant (pK(i)) values for the high-affinity sites, indicated a predominant population of alpha(1A)-adrenoceptor subtype in caput and cauda epididymis from adult animals. Differences in pK(i) values. in caput and cauda epididymis from immature and adult animals also suggested that the relative amount of alpha(1)-adrenoceptors, at the protein level, is modulated by sexual maturation. Taken together, the changes in alpha(1)-adrenoceptor expression during sexual maturation may suggest specific roles for these receptors in epididymal function.
- ItemSomente MetadadadosCatecholamine effects on human melanoma cells evoked by alpha(1)-adrenoceptors(Springer, 2004-08-01) Scarparo, A. C.; Sumida, D. H.; Patrao, MTCC; Avellar, MCW; Visconti, M. A.; Castrucci, AMD; Universidade de São Paulo (USP); Univ Nacl Estadual São Paulo; Universidade Federal de São Paulo (UNIFESP)The biological effects of catecholamines in mammalian pigment cells are poorly understood. Our previous results showed the presence of alpha(1)-adrenoceptors in SK-Mel 23 human melanoma cells. the aims of this work were to (1) characterize catecholamine effects on proliferation, tyrosinase activity and expression, (2) identify the alpha(1)-adrenoceptor subtypes, and (3) verify whether chronic norepinephrine (NE) treatment modified the types and/or pharmacological characteristics of adrenoceptors present in SK-Mel 23 human melanoma cells. Cells treated with the alpha(1)-adrenergic agonist, phenylephrine (PHE, 10(-5) or 10(-4) M), for 24-72 h, exhibited decreased cell proliferation and enhanced tyrosinase activity, but unaltered tyrosinase expression as compared with the control. the proliferation and tyrosinase activity responses were inhibited by the alpha(1)-adrenergic antagonist prazosin, suggesting they were evoked by alpha(1)-adrenoceptors. the presence of actinomycin D, a transcription inhibitor, did not diminish PHE-induced effects. RT-PCR assays, followed by cloning and sequencing, demonstrated the presence of alpha(1A)- and alpha(1B)-adrenoceptor subtypes. NE-treated cells (24 or 72 h) were used in competition assays, and showed no significant change in the competition curves of alpha(1)-adrenoceptors as compared with control curves. Other adrenoceptor subtypes were not identified in these cells, and NE pretreatment did not induce their expression. in conclusion, the activation of SK-Mel 23 human melanoma alpha(1)-adrenoceptors elicit biological effects, such as proliferation decrease and tyrosinase activity increase. Desensitization or expression of other adrenoceptor subtypes after chronic NE treatment were not observed.
- ItemSomente MetadadadosCatecholamine production along the nephron(Karger, 2007-01-01) Di Marco, Giovana Seno [UNIFESP]; Vio, Carlos P.; Santos, Oscar Fernando Pavão dos [UNIFESP]; Schor, Nestor [UNIFESP]; Casarini, Dulce Elena [UNIFESP]; Universidade Federal de São Paulo (UNIFESP); Pontificia Univ Catolica ChileThe present work proposes an extra neural site of catecholamine production along the nephron. LLC-PK1, MDCK, and mIMCD-3 (proximal and distal tubules and inner medullary collecting duct, respectively) presented the following amine concentrations in the cell homogenates: Norepinephrine = 275 +/- 34, 56 +/- 16 and 255 +/- 21; Epinephrine = 161 +/- 20, 83 +/- 17 and 53 +/- 7; and Dopamine = 63 +/- 15, 39 +/- 6 and 36 +/- 7 pg mg cell protein (Means +/- SEM), respectively. the culture medium showed Norepinephrine = 168 +/- 25, 22 +/- 3 and 135 +/- 8; Epinephrine = 32 +/- 6, 152 +/- 17 and 39 +/- 5; and Dopamine = 27 +/- 9, 241 +/- 34 and 26 +/- 5 pg/mg cell protein, respectively. the synthesis enzymes as tyrosine hydroxylase, dopa decarboxylase and dopamine beta-hydroxylase were detected by Western blotting. Biopterin, the enzymatic cofactor of tyrosine hydroxylase, was quantified in the intracellular and medium of mIMCD-3 cells (17 +/- 4 and 24 +/- 3 nmol/mg cell protein, respectively) and in the medium of MDCK cells (19 +/- 4 nmol/mg cell protein). the data confirmed that the proximal tubule is an important source of dopa decarboxilase and Dopamine and epithelial cell along the nephron express the biochemical pathway for catecholamine production. Copyright (c) 2007 S. Karger AG, Basel.
- ItemAcesso aberto (Open Access)Catecholamine response to exercise in individuals with different levels of paraplegia(Associação Brasileira de Divulgação Científica, 2000-08-01) Steinberg, Lia Likier [UNIFESP]; Lauro, Flávio Antônio Ascânio [UNIFESP]; Sposito, Maria de Matilde de Mello [UNIFESP]; Tufik, Sergio [UNIFESP]; Mello, Marco Tulio de [UNIFESP]; Naffah-Mazzacoratti, Maria da Graca [UNIFESP]; Cavalheiro, Esper Abrão [UNIFESP]; Silva, Antonio Carlos da [UNIFESP]; Universidade Federal de São Paulo (UNIFESP); Universidade Federal de UberlândiaThe purpose of this study was to investigate the effect of the level of injury on the serum level of norepinephrine (Nor) and epinephrine (Epi) at rest and after maximal exercise in individuals with paraplegia. Twenty-six male spinal cord-injured subjects with complete paraplegia for at least 9 months were divided into two groups of 13 subjects each according to the level of injury, i.e., T1-T6 and T7-T12. Serum Nor and Epi concentrations were measured by HPLC-ECD, at rest (PRE) and immediately after a maximal ergospirometric test (POST). Statistical analysis was performed using parametric and non-parametric tests. Maximal heart rate, peak oxygen uptake, and PRE and POST Nor were lower in the T1-T6 than in the T7-T12 group (166 ± 28 vs 188 ± 10 bpm; 18.0 ± 6.0 vs 25.8 ± 4.1 ml kg-1 min-1; 0.54 ± 0.26 vs 0.99 ± 0.47 nM; 1.48 ± 1.65 vs 3.07 ± 1.44 nM). Both groups presented a significant increase in Nor level after exercise, while only the T7-T12 group showed a significant increase in Epi after exercise (T1-T6: 0.98 ± 0.72 vs 1.11 ± 1.19 nM; T7-T12: 1.24 ± 1.02 vs 1.89 ± 1.57 nM). These data show that individuals with paraplegia above T6 have an attentuated catecholamine release at rest and response to exercise as compared to subjects with injuries below T6, which might prevent a better exercise performance in the former group.
- ItemSomente MetadadadosEffect of an aerobic exercise program on blood pressure and catecholamines in normotensive and hypertensive subjects(Assoc Bras Divulg Cientifica, 1996-05-01) Arida, Ricardo Mario [UNIFESP]; Naffah-Mazzacoratti, Maria da Graca [UNIFESP]; Soares, J.; Cavalheiro, Esper Abrão [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)Interrelations between physical exercise, monoamines and hypertension are postulated by various investigators. The purpose of the present study was to determine and compare catecholamine levels at rest and after a 12-week aerobic exercise program in 11 sedentary normotensive (N) and 8 hypertensive (H) men. Plasma catecholamines were determined by high performance liquid chromatography with electrochemical detection. A significant post-exercise increase in plasma noradrenaline was observed in the N and H groups (P<0.01) both before and after the aerobic exercise program. The hypertensive group showed a significant reduction of the sum of 7 skinfold thickness scores after the aerobic exercise program (from 178.7 +/- 65.6 to 144.0 +/- 47.4 mm) although no significant difference was observed when the body mass index was compared. A significant reduction in diastolic blood pressure at rest was observed in the H group after the aerobic exercise program (from 99.2 +/- 2.0 to 85.0 +/- 5.5). There were no significant differences in catecholamine concentrations between groups before and after the 12-week aerobic exercise program at rest and post-exercise. These data show a relationship between physical exercise and hypertension that was not related to changes in plasma catecholamine levels.
- ItemAcesso aberto (Open Access)Effects of acupuncture on behavioral, cardiovascular and hormonal responses in restraint-stressed Wistar rats(Associação Brasileira de Divulgação Científica, 1997-12-01) Guimarães, C.m.; Pinge, M.c.m.; Yamamura, Ysao [UNIFESP]; Mello, Luiz Eugenio Araujo de Moraes [UNIFESP]; A01; Universidade Federal de São Paulo (UNIFESP)Stress is a well-known entity and may be defined as a threat to the homeostasis of a being. In the present study, we evaluated the effects of acupuncture on the physiological responses induced by restraint stress. Acupuncture is an ancient therapeutic technique which is used in the treatment and prevention of diseases. Its proposed mechanisms of action are based on the principle of homeostasis. Adult male Wistar EPM-1 rats were divided into four groups: group I (N = 12), unrestrained rats with cannulas previously implanted into their femoral arteries for blood pressure and heart rate measurements; group II (N = 12), rats that were also cannulated and were submitted to 60-min immobilization; group III (N = 12), same as group II but with acupuncture needles implanted at points SP6, S36, REN17, P6 and DU20 during the immobilization period; group IV (N = 14), same as group III but with needles implanted at points not related to acupuncture (non-acupoints). During the 60-min immobilization period animals were assessed for stress-related behaviors, heart rate, blood pressure and plasma corticosterone, noradrenaline and adrenaline levels. Group III animals showed a significant reduction (60% on average, P<0.02) in restraint-induced behaviors when compared to groups II and IV. Data from cardiovascular and hormonal assessments indicated no differences between group III and group II and IV animals, but tended to be lower (50% reduction on average) in group I animals. We hypothesize that acupuncture at points SP6, S36, REN17, P6 and DU20 has an anxiolytic effect on restraint-induced stress that is not due to a sedative action
- ItemSomente MetadadadosEndocrinological and catecholaminergic alterations during sleep deprivation and recovery in male rats(Blackwell Publishing Ltd, 2005-03-01) Andersen, Monica Levy [UNIFESP]; Martins, Paulo José Forcina [UNIFESP]; D'Almeida, Vânia [UNIFESP]; Bignotto, Magda [UNIFESP]; Tufik, Sergio [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)Since previous data of our group showed increased concentrations in HPA axis hormones in sleep deprived rats, we hypothesized that this augmentation could produce effects in other hormonal systems, particularly in the sexual system. Considering that little is known about how the hormonal system changes during the recovery period after sleep deprivation (SD), our objective was to examine from what point SD alters sexual and stress-related hormones along with plasma catecholamine concentrations during 4 days. We also sought to verify the time course of their recovery after an equivalent period of recovery sleep. Rats were deprived of sleep by the platform technique for 1-4 days and were allowed to recover for the same period. Plasma catecholamines [dopamine (DA) and noradrenaline (NOR)], testosterone, estrone, progesterone, prolactin, corticosterone and adrenocorticotropic hormone (ACTH) concentrations were measured. Comparisons between groups showed that the SD procedure used in the present study produced marked alterations in almost all studied hormones from 24 h of SD, except for estrone and prolactin (which required 96 h of SD to become altered). Testosterone and estrone decreased, whereas progesterone, prolactin, corticosterone, ACTH, DA and NOR increased. During recovery period, progesterone, prolactin and corticosterone concentrations returned to control levels, whereas testosterone, estrone, NOR and DA did not. in addition, after 48 h of recovery ACTH and NOR decreased below control concentrations, remaining low until 96 h of sleep recovery. Thus, SD showed long lasting, differential effects upon these neurochemicals suggesting that each has its own pattern of responses to SD as well as variable periods of recovery.
- ItemAcesso aberto (Open Access)Heterogeneity of glomerular perfusion and filtration induced by epinephrine and norepinephrine(Associação Brasileira de Divulgação Científica, 1997-08-01) Boim, Mirian Aparecida [UNIFESP]; Stella, Sergio R. [UNIFESP]; Pereira, A.b. [UNIFESP]; Schor, Nestor [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)The role of catecholamines in the distribution of intrarenal blood flow and in single-nephron glomerular filtration rate (SNGFR) was evaluated in anesthetized Wistar rats by the Hanssen technique. Epinephrine (EPI) and norepinephrine (NOR) were infused to produce elevations of 20-30 mmHg in mean arterial pressure. Superficial and juxtamedullary nephron perfusion and filtration were determined by the presence of Prussian blue dye. In the control group, 100% of the nephrons presented a homogeneous pattern of perfusion and filtration. In contrast, a heterogeneous distribution of the dye was found even in the larger arteries (arciform and radial), indicating variable perfusion and filtration in both superficial and juxtamedullary nephrons. The effects of EPI and NOR were also evaluated in the superficial cortex by the micropuncture technique in two additional groups of Munich-Wistar rats. Mean SNGFR was 27% and 54% lower in the EPI- and NOR-treated groups, respectively. No change in mean intraglomerular hydraulic pressure was observed after EPI or NOR infusion in spite of a highly scattered pattern, indicating an important variability in perfusion along the superficial cortex, and/or different sensitivity of the pre- and post-glomerular arterioles. The present data suggest that EPI and NOR may affect intrarenal hemodynamics by modifying perfusion and filtration in both superficial and juxtamedullary glomeruli and not by shifting blood flow from superficial to juxtamedullary nephrons. The heterogeneous pattern of perfusion was a consequence of differential vasoconstriction along the intrarenal arteries, probably due to different density and/or sensitivity of the adrenergic receptor subtypes present in the intrarenal vascular tree.
- ItemSomente MetadadadosPurification and characterization of the active form of tyrosine hydroxylase from mesangial cells in culture(Wiley-Blackwell, 2002-01-01) Arita, D. Y.; Di Marco, G. S.; Schor, N.; Casarini, D. E.; Universidade Federal de São Paulo (UNIFESP)The capacity of mesangial cells (MC) to produce catecholamines (CAs) has been investigated in our laboratory. To study the CA cascade, it is necessary to examine some steps in their metabolic pathway. Tyrosine hydroxylase (TH) catalyzes the rate-limiting step in the biosynthesis of these biogenic amines (dopamine (DA), norepinephrine (NE), and epinephrine (EPI)). Since the glomerular mesangium is their target in the regulation of renal sodium transport and renin secretion, the aim of the study was to determine the presence of TH in those cells in culture. the CA levels were detected in immortalized MC by high-performance liquid chromatography with electrochemical detection. the following concentrations were found in the intracellular region and in the medium, respectively: NE=284 +/- 31 and 134 +/- 22, EPI = 75 +/- 14 and 22 +/- 5, and DA=42 +/- 14, 40 +/- 20 pg/mg cell protein. the enzymatic activity of the cell lysate and medium was measured based on L-dopa formation. in the presence of o-phenanthroline, both samples presented 39% inhibition. the biopterin was detected in the intracellular and in the medium (64.87 and 631.99 pmol/mg protein, respectively) using high-performance liquid chromatography with ultraviolet detection. the cell lysate was submitted to a DEAE-Sephacel column, followed by gel filtration, and Heparin-Sepharose. TH was purified 613.16-fold with a specific activity of 466.0 pg/mg cell protein. Immunoblotting using monoclonal antibody revealed the presence of TH in the different purification steps. Purified TH was sequenced, presenting an alignment with amino-terminal sequence of mouse enzyme. Our results demonstrated the presence of active TH in MC, suggesting that these cells are able to produce CA in vivo, and establishing a convenient purification method for TH that can be applied to the study of the molecular properties of the enzyme modified in vivo by different physiological and pathophysiological stimuli.
- ItemSomente MetadadadosRostral ventrolateral medulla: An integrative site for muscle vasodilation during defense-alerting reactions(Kluwer Academic/plenum Publ, 2003-10-01) Cravo, S. L.; Possas, O. S.; Ferreira-Neto, M. L.; Universidade Federal de São Paulo (UNIFESP)1. Evidence gathered over the last 30 years has firmly established that the rostral ventrolateral medulla (RVLM) is a major vasomotor center in the brainstem, harboring sympathetic premotor neurons responsible for generating and maintaining basal vasomotor tone and resting levels of arterial blood pressure. Although the RVLM has been almost exclusively classified as a vasopressor area, in this report we review some evidence suggesting a prominent role of the RVLM in muscle vasodilation during defense-alerting responses.2. Defense-alerting reactions are a broad class of behavior including flexion of a limb, fight/flight responses, apologies, etc. They comprise species-distinctive motor and neurovegetative adjustments. Cardiovascular responses include hypertension, tachycardia, visceral vasoconstriction, and muscle vasodilation. Since defense-alerting reactions generally involve intense motor activation, muscle vasodilation is regarded as a key feature of these responses.3. in anesthetized or unanesthetized-decerebrate animals, natural or electrical stimulation of cutaneous and muscle afferents produced hypertension, tachycardia, and vasodilation restricted to the stimulated limb.4. Unilateral inactivation of the RVLM contralateral to the stimulated limb abolished cardiovascular adjustments to stimulation of cutaneous and muscle afferents. Within the RVLM glutamatergic synapses mediate pressor responses, whereas GABAergic synapses mediates muscle vasodilation.5. in urethane-anesthetized rats, electrical stimulation of the hypothalamus elicited hypertension, tachycardia, visceral vasoconstriction, and hindlimb vasodilation. the hindlimb vasodilation induced by hypothalamic stimulation is a complex response, involving reduction of sympathetic vasoconstrictor tone, release of catecholamines by the adrenal medulla, and a still unknown system that may use nitric oxide as a mediator.6. Blockade of glutamatergic transmission within the RVLM selectively blocks muscle vasodilation induced by hypothalamic stimulation.7. the results obtained suggest that, besides its role in the generation and maintenance of the sympathetic vasoconstrictor drive, the RVLM is also critical for vasodilatory responses during defense reactions. the RVLM may contain several, distinctive mechanisms for muscle vasodilation. Anatomical and functional characterization of these pathways may represent a breakthrough in our understanding of cardiovascular control in normal and/or pathological conditions.