Cíntia Helena Santuzzi

Uso combinado da laserterapia de baixa potência e da inibição da ciclooxigenase-2 na reepitelização de ferida incisional em pele de camundongos: um estudo pré-clínico

BACKGROUND Low level laser therapy and cyclooxygenase-2 (ICOX2) selective inhibitors have been widely used to modulate inflammatory response; however, their effect on wound reepithelialization are not well understood. OBJECTIVE To evaluate the isolated and combined effects of low level laser therapy and ICOX2 in the reepithelization of skin incisional wounds in mice. METHODS We induced a 1-cm wound on the back of each mouse, which were divided into four groups (N = 20): control, laser therapy, treated with celecoxib and combined therapy. The animals in the celecoxib and combined therapy groups were treated with celecoxib for 10 days before skin incision. The experimental wounds were irradiated with He-Ne low power laser (632nm, dose: 4J/cm2) in scanning for 12 seconds during three consecutive days in the laser therapy and combined therapy groups. The animals were sacrificed 3 days after surgery. Samples of the wounds were collected and stained (Massons Trichrome) for histomorphometric analysis. RESULTS Both the laser therapy group and the celecoxib group showed an increase in skin reepithelialization compared to the control group; however, the combined therapy group showed no differences. As for keratinization, the laser therapy and combined therapy groups showed a reduction in keratinocytes compared with the control group. CONCLUSION The results show that the use of low level laser therapy and ICOX2 in isolation increases epithelial cells, but only low level laser therapy reduced skin keratinocytes. The combined treatment restores innate epithelialization and decreases keratinization in spite of accelerating wound contraction with improvement in the organization of the wound in the skin of mice.

Combined aliskiren and L-arginine treatment has antihypertensive effects and prevents vascular endothelial dysfunction in a model of renovascular hypertension.

Angiotensin II is a key player in the pathogenesis of renovascular hypertension, a condition associated with endothelial dysfunction. We investigated aliskiren (ALSK) and L-arginine treatment both alone and in combination on blood pressure (BP), and vascular reactivity in aortic rings. Hypertension was induced in 40 male Wistar rats by clipping the left renal artery. Animals were divided into Sham, 2-kidney, 1-clip (2K1C) hypertension, 2K1C+ALSK (ALSK), 2K1C+L-arginine (L-arg), and 2K1C+ALSK+L-arginine (ALSK+L-arg) treatment groups. For 4 weeks, BP was monitored and endothelium-dependent and independent vasoconstriction and relaxation were assessed in aortic rings. ALSK+L-arg reduced BP and the contractile response to phenylephrine and improved acetylcholine relaxation. Endothelium removal and incubation with N-nitro-L-arginine methyl ester (L-NAME) increased the response to phenylephrine in all groups, but the effect was greater in the ALSK+L-arg group. Losartan reduced the contractile response in all groups, apocynin reduced the contractile response in the 2K1C, ALSK and ALSK+L-arg groups, and incubation with superoxide dismutase reduced the phenylephrine response in the 2K1C and ALSK groups. eNOS expression increased in the 2K1C and L-arg groups, and iNOS was increased significantly only in the 2K1C group compared with other groups. AT1 expression increased in the 2K1C compared with the Sham, ALSK and ALSK+L-arg groups, AT2 expression increased in the ALSK+L-arg group compared with the Sham and L-arg groups, and gp91phox decreased in the ALSK+L-arg group compared with the 2K1C and ALSK groups. In conclusion, combined ALSK+L-arg was effective in reducing BP and preventing endothelial dysfunction in aortic rings of 2K1C hypertensive rats. The responsible mechanisms appear to be related to the modulation of the local renin-angiotensin system, which is associated with a reduction in endothelial oxidative stress.

High-frequency transcutaneous electrical nerve stimulation reduces pain and cardio-respiratory parameters in an animal model of acute pain: Participation of peripheral serotonin

The objective of this study was to investigate the effect of high-frequency transcutaneous electrical nerve stimulation (HF-TENS) in antihyperalgesia, assessed through changes of sciatic nerve activity and its effects on cardiorespiratory parameters, using formalin-induced nociception in anesthetized rats. The animals were divided into formalin (FORM) and HF-TENS groups. All rats received injections of 5% formalin (50 μl, right hind-paw). The sciatic nerve activity and cardiopulmonary parameters (mean arterial pressure, heart rate, and respiratory frequency) were measured, and then the serum levels of serotonin (5-HT) were determined by an enzyme-linked immunosorbent assay kit. The formalin injection was able to increase the sciatic nerve activity, heart rate, and respiratory frequency. The treatment with HF-TENS significantly reduced the sciatic nerve activity and respiratory frequency 20 minutes after formalin injection and was able to increase serum 5-HT. Furthermore, when comparing the groups, reductions in the mean arterial pressure, heart rate, respiratory frequency, and sciatic nerve activity were shown at different times. Thus, we concluded that HF-TENS was capable of inducing analgesia, which was most likely related to increased serotonin release. Moreover, we demonstrated that TENS was able to block the adverse cardiovascular and respiratory changes induced by pain. Further neurophysiological studies are necessary to clarify the intrinsic mechanisms underlying HF-TENS-induced analgesia.

Combined Aliskiren and L-arginine treatment reverses renovascular hypertension in an animal model

Renovascular hypertension is characterized by increased renal sympathetic activity, angiotensin II and by endothelial dysfunction. The purpose of this study was to determine the role of renal sympathetic nerve activity (RSNA) in mediating the anti-hypertensive effects of aliskiren (ALSK) and L-arginine (L-ARG) in a rat renovascular hypertension model. Hypertension was induced by clipping the right renal artery, and the following five groups were divided: SHAM operated; 2-kidney, 1-clip (2K1C); 2K1C plus ALSK; 2K1C plus L-ARG; and 2K1C plus ALSK+ L-ARG. The systolic blood pressure (SBP) of 2K1C rats increased from 114.4±5.2 to 204±12.7 mm Hg (P<0.05) and was only reduced by ALSK+L-ARG treatment (138.4±4.37 mm Hg). The 2K1C hypertension increased the baseline RSNA (SHAM: 62.4±6.39 vs. 2K1C: 97.4±8.43%). L-ARG or ALSK+L-ARG treatment significantly decreased baseline RSNA (2K1C L-ARG:70.7±2.39; 2K1C ALSK+L-ARG: 69.3±4.23%), but ALSK treatment alone did not (2K1C ALSK: 84.2±2.5%). Urinary water, Na+, Cl− and urea excretion were similar in the 2K1C L-ARG, 2K1C ALSK+L-ARG and SHAM groups. The combination of ALSK+L-ARG restored urine flow and increased the glomerular filtration rate. The nNOS expression in the non clipped kidney was significantly increased in 2K1C ALSK+L-ARG rats. In conclusion, combined ALSK+L-ARG treatment normalizes SBP and prevents renal dysfunction in 2K1C hypertensive rats.

Effects of acute administration of selective serotonin reuptake inhibitors on sympathetic nerve activity

Serotonergic mechanisms have an important function in the central control of circulation. Here, the acute effects of three selective serotonin (5-HT) reuptake inhibitors (SSRIs) on autonomic and cardiorespiratory variables were measured in rats. Although SSRIs require 2-3 weeks to achieve their full antidepressant effects, it has been shown that they cause an immediate inhibition of 5-HT reuptake. Seventy male Wistar rats were anesthetized with urethane and instrumented to record blood pressure, heart rate, renal sympathetic nerve activity (RSNA), and respiratory frequency. At lower doses, the acute cardiovascular effects of fluoxetine, paroxetine and sertraline administered intravenously were insignificant and variable. At middle and higher doses, a general pattern was observed, with significant reductions in sympathetic nerve activity. At 10 min, fluoxetine (3 and 10 mg/kg) reduced RSNA by -33±4.7 and -31±5.4%, respectively, without changes in blood pressure; 3 and 10 mg/kg paroxetine reduced RSNA by -35±5.4 and -31±5.5%, respectively, with an increase in blood pressure +26.3±2.5; 3 mg/kg sertraline reduced RSNA by -59.4±8.6%, without changes in blood pressure. Sympathoinhibition began 5 min after injection and lasted approximately 30 min. For fluoxetine and sertraline, but not paroxetine, there was a reduction in heart rate that was nearly parallel to the sympathoinhibition. The effect of these drugs on the other variables was insignificant. In conclusion, acute peripheral administration of SSRIs caused early autonomic cardiovascular effects, particularly sympathoinhibition, as measured by RSNA. Although a peripheral action cannot be ruled out, such effects are presumably mostly central.

Alterações morfofuncionais musculares em resposta ao alongamento passivo em modelo animal de imobilização prolongada de membro posterior

INTRODUCAO: O alongamento passivo ou estatico (EAL) e frequentemente utilizado em programas de reabilitacao e na area desportiva; porem, as alteracoes morfofuncionais ocorridas ainda nao estao bem claras, principalmente apos imobilizacao prolongada. OBJETIVOS: Examinar as alteracoes morfofuncionais musculares produzidas em resposta a tres semanas de exercicios de EAL em um modelo animal de imobilizacao prolongada de membro posterior (MP) em posicao encurtada. METODOS: Foram utilizados 32 ratos Wistar divididos em quatro grupos (n = 8, em cada): A - grupo controle (CONT), B - grupo imobilizado por 21 dias (IMOB), C - grupo remobilizado por 21 dias (LIVRE), D - grupo alongados por 21 dias (ALONG). Foram comparadas as variacoes morfofuncionais entre grupos experimentais. As variaveis foram: peso corporal e muscular, comprimento muscular e osseo, numero de miofibrilas e quantidade de colageno, determinadas atraves de histomorfometria muscular por contraste de cor. RESULTADOS: A IMOB do biceps femoral em posicao encurtada produziu uma importante hipotrofia com hiperplasia muscular compensatoria, alem do aumento (p < 0,05) na deposicao de colageno no perimisio e intramuscular de ratos. A remobilizacao livre ou o alongamento passivo reduziram significativamente (p < 0,05) estas alteracoes morfofuncionais observados no grupo IMOB. CONCLUSAO: Atraves desses resultados, pode-se concluir que tanto o EAL quanto a remobilizacao livre promovem a restauracao das alteracoes morfofuncionais no biceps femoral esquerdo induzida pela imobilizacao prolongada, embora somente o EAL foi capaz de reduzir a relacao entre colageno/musculo.

Sertraline inhibits formalin-induced nociception and cardiovascular responses.

The objective of the present study was to determine the antihyperalgesic effect of sertraline, measured indirectly by the changes of sciatic afferent nerve activity, and its effects on cardiorespiratory parameters, using the model of formalin-induced inflammatory nociception in anesthetized rats. Serum serotonin (5-HT) levels were measured in order to test their correlation with the analgesic effect. Male Wistar rats (250-300 g) were divided into 4 groups (N = 8 per group): sertraline-treated group (Sert + Saline (Sal) and Sert + Formalin (Form); 3 mg·kg−1·day−1, ip, for 7 days) and saline-treated group (Sal + Sal and Sal + Form). The rats were injected with 5% (50 µL) formalin or saline into the right hind paw. Sciatic nerve activity was recorded using a silver electrode connected to a NeuroLog apparatus, and cardiopulmonary parameters (mean arterial pressure, heart rate and respiratory frequency), assessed after arterial cannulation and tracheotomy, were monitored using a Data Acquisition System. Blood samples were collected from the animals and serum 5-HT levels were determined by ELISA. Formalin injection induced the following changes: sciatic afferent nerve activity (+50.8 ± 14.7%), mean arterial pressure (+1.4 ± 3 mmHg), heart rate (+13 ± 6.8 bpm), respiratory frequency (+4.6 ± 5 cpm) and serum 5-HT increased to 1162 ± 124.6 ng/mL. Treatment with sertraline significantly reduced all these parameters (respectively: +19.8 ± 6.9%, -3.3 ± 2 mmHg, -13.1 ± 10.8 bpm, -9.8 ± 5.7 cpm) and serum 5-HT level dropped to 634 ± 69 ng/mL (P < 0.05). These results suggest that sertraline plays an analgesic role in formalin-induced nociception probably through a serotonergic mechanism.

Diferenças de gênero no limiar sensitivo para estimulação elétrica nervosa em adultos jovens

OBJETIVO: Investigar diferencas de genero no limiar neuronal sensitivo (LNS) para estimulacao eletrica nervosa transcutânea (TENS) entre adultos jovens, e os presumiveis efeitos da termoterapia previa. METODOS: Foram divididos por genero, 30 estudantes jovens sadios (15 homens e 15 mulheres entre 6/11 ciclo estral) com 22±2 anos de idade. TENS foi aplicada simultaneamente nos joelhos direito e esquerdo dos sujeitos com frequencia de 20 Hz e duracao de pulso 230µs. A amplitude da corrente eletrica (mǺ) foi aumentada gradativamente para registro do limiar de percepcao (LS) e tolerância (LT), antes/apos termoterapia. O aquecimento no joelho-D foi realizado por luz infravermelha (250 W) a 0≈70 cm perpendicularmente, e o resfriamento do joelho-E por compressa de gelo, ambos realizados durante 15 minutos. A temperatura tecidual foi registrada por termometria digital. Os dados foram analisados e diferencas estabelecidas em p<0.05. RESULTADOS: A temperatura tecidual apos termoterapia foi diferente (p<0.05) entre generos. No LS basal para TENS nao houve diferencas entre generos, porem, a termoterapia alteou o LS em ambos os sexos. O LT basal foi menor (p<0.05) em mulheres, entretanto, apos a termoterapia aumentou (p<0.05) em ambos os sexos. CONCLUSAO: Os LNS para TENS sao genero-termo-dependentes em jovens sadios.

Role of Renal Nerves in the Treatment of Renovascular Hypertensive Rats with L-Arginine

The purpose was to determine the role of renal nerves in mediating the effects of antihypertensive treatment with L-arginine in a renovascular hypertension model. The 2K1C (two-kidney one-clip model) hypertensive rats were submitted to bilateral surgical-pharmacological renal denervation. The animals were subdivided into six experimental groups: normotensive control rats (SHAM), 2K1C rats, 2K1C rats treated with L-arginine (2K1C + L-arg), denervated normotensive (DN) rats, denervated 2K1C (2K1C + DN) rats, and denervated 2K1C + L-arg (2K1C + DN + L-arg) rats. Arterial blood pressure, water intake, urine volume, and sodium excretion were measured. The 2K1C rats exhibited an increase in the mean arterial pressure (MAP) (from 106 ± 3 to 183 ± 5.8 mmHg, P < 0.01), whereas L-arg treatment induced a reduction in the MAP (143 ± 3.4 mmHg) without lowering it to the control level. Renal nerve denervation reduced the MAP to normotensive levels in 2K1C rats with or without chronic L-arg treatment. L-arg and denervation induced increases in water intake and urine volume, and L-arg caused a significant natriuretic effect. Our results suggest that renal sympathetic activity participates in the genesis and the maintenance of the hypertension and also demonstrate that treatment with L-arg alone is incapable of normalizing the MAP and that the effect of such treatment is not additive with the effect of kidney denervation.