Brazilian Journal of Medical and Biological Research
URI permanente para esta coleçãohttps://thoth.dti.ufv.br/handle/123456789/13549
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Item Effects of caffeine on central and peripheral fatigue following closed- and open-loop cycling exercises(Associação Brasileira de Divulgação Científica, 2022-02-28) Couto, P. G.; Silva-Cavalcante, M. D.; Mezêncio, B.; Azevedo, R. A.; Cruz, R.; Bertuzzi, R.; Lima-Silva, A. E.; Kiss, M. A. P. D.We examined whether endurance performance and neuromuscular fatigue would be affected by caffeine ingestion during closed- and open-loop exercises. Nine cyclists performed a closed-loop (4,000-m cycling time trial) and an open-loop exercise (work rate fixed at mean power of the closed-loop trial) 60 min after ingesting caffeine (CAF, 5 mg/kg) or placebo (PLA, cellulose). Central and peripheral fatigue was quantified via pre- to post-exercise decrease in quadriceps voluntary activation and potentiated twitch force, respectively. Test sensitivity for detecting caffeine-induced improvements in exercise performance was calculated as the mean change in time divided by the error of measurement. Caffeine ingestion reduced the time of the closed-loop trial (PLA: 375.1±14.5 s vs CAF: 368.2±14.9 s, P=0.024) and increased exercise tolerance during the open-loop trial (PLA: 418.2±99.5 s vs CAF: 552.5±106.5 s, P=0.001), with similar calculated sensitivity indices (1.5, 90%CI: 0.7-2.9 vs 2.8, 90%CI: 1.9-5.1). The reduction in voluntary activation was more pronounced (P=0.019) in open- (-6.8±8.3%) than in closed-loop exercises (-1.9±4.4%), but there was no difference between open- and closed-loop exercises for the potentiated twitch force reduction (-25.6±12.8 vs -26.6±12.0%, P>0.05). Caffeine had no effect on central and peripheral fatigue development in either mode of exercise. In conclusion, caffeine improved endurance performance in both modes of exercise without influence on post-exercise central and peripheral fatigue, with the open-loop exercise imposing a greater challenge to central fatigue tolerance.Item Plant stem cell extract from Coffea canephora shows antioxidant, anti-inflammatory, and skin regenerative properties mediated by suppression of nuclear factor-κB(Associação Brasileira de Divulgação Científica, 2023-06-30) Guidoni, M.; Sousa Júnior, A.D. de; Aragão, V.P.M.; Silva, M.V. Toledo e; Barth, T.; Clarindo, W.R.; Endringer, D.C.; Fronza, M.Plant cell cultures have become a promising production platform of bioactive compounds for biomedical and cosmetic uses in the last decades. However, the success so far has been limited. The study aimed to evaluate the effectiveness of this unique biotechnology process to obtain a bioactive stem cell extract of Coffea canephora (SCECC) with antioxidant, anti-inflammatory, and regenerative properties. Total phenolic and flavonoid contents were determined in the SCECC by spectrophotometry. The chemical composition of the extracts was characterized by mass spectrometry. Antioxidant activity was evaluated using the colorimetric methods of free radical scavenging 2,2'-azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) and the ferric reducing ability of plasma (FRAP). The anti-inflammatory activity was determined in lipopolysaccharide-stimulated RAW 264.7 macrophages through the production of superoxide anion (O2•-), nitric oxide (NO), tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and the activity of nuclear factor kappa B (NF-κB). Moreover, the ability of SCECC to stimulate the proliferation and migration of fibroblasts was assessed. Five compounds were tentatively identified, two flavonoids, two phenolic acids, and one sugar. High phenolic content and antioxidant activity were observed in the SCECC. SCECC promoted the proliferation and migration of fibroblasts and suppressed the pro-inflammatory mediators O2•-, NO, TNF-α, and IL-6 in a dose-dependent manner. Moreover, SCECC inhibited the NF-κB transcription factor. Therefore, we obtained evidence that the extract from C. canephora stem cells can be used as a natural agent against skin damage. Hence, it could be of interest in cosmetics for preventing skin aging.Item Kahweol, a natural diterpene from coffee, induces peripheral antinociception by endocannabinoid system activation(Associação Brasileira de Divulgação Científica, 2021) Guzzo, L.S.; Oliveira, C.C.; Ferreira, R.C.M.; Machado, D.P.D.; Castor, M.G.M.; Perez, A.C.; Piscitelli, F.; Marzo, V. Di; Romero, T.R.L.; Duarte, I.D.G.Kahweol is a compound derived from coffee with reported antinociceptive effects. Based on the few reports that exist in the literature regarding the mechanisms involved in kahweol-induced peripheral antinociceptive action, this study proposed to investigate the contribution of the endocannabinoid system to the peripheral antinociception induced in rats by kahweol. Hyperalgesia was induced by intraplantar injection of prostaglandin E2 (PGE2) and was measured with the paw pressure test. Kahweol and the drugs to test the cannabinoid system were administered locally into the right hind paw. The endocannabinoids were purified by open-bed chromatography on silica and measured by LC-MS. Kahweol (80 mg/paw) induced peripheral antinociception against PGE2-induced hyperalgesia. This effect was reversed by the intraplantar injection of the CB1 cannabinoid receptor antagonist AM251 (20, 40, and 80 mg/paw), but not by the CB2 cannabinoid receptor antagonist AM630 (100 mg/paw). Treatment with the endocannabinoid reuptake inhibitor VDM11 (2.5 mg/paw) intensified the peripheral antinociceptive effect induced by low-dose kahweol (40 mg/paw). The monoacylglycerol lipase (MAGL) inhibitor, JZL184 (4 mg/paw), and the dual MAGL/fatty acid amide hydrolase (FAAH) inhibitor, MAFP (0.5 mg/paw), potentiated the peripheral antinociceptive effect of low-dose kahweol. Furthermore, kahweol increased the levels of the endocannabinoid anandamide, but not of the other endocannabinoid 2-arachidonoylglycerol nor of anandamide-related N-acylethanolamines, in the plantar surface of the rat paw. Our results suggested that kahweol induced peripheral antinociception via anandamide release and activation of CB1 cannabinoid receptors and this compound could be used to develop new drugs for pain relief.Item Caffeine intake by patients with autosomal dominant polycystic kidney disease(Associação Brasileira de Divulgação Científica, 2012) Vendramini, L.C.; Nishiura, J.L.; Baxmann, A.C.; Heilberg, I.P.Because caffeine may induce cyst and kidney enlargement in autosomal dominant polycystic kidney disease (ADPKD), we evaluated caffeine intake and renal volume using renal ultrasound in ADPKD patients. Caffeine intake was estimated by the average of 24-h dietary recalls obtained on 3 nonconsecutive days in 102 ADPKD patients (68 females, 34 males; 39 ± 12 years) and compared to that of 102 healthy volunteers (74 females, 28 males; 38 ± 14 years). The awareness of the need for caffeine restriction was assessed. Clinical and laboratory data were obtained from the medical records of the patients. Mean caffeine intake was significantly lower in ADPKD patients versus controls (86 vs 134 mg/day), and 63% of the ADPKD patients had been previously aware of caffeine restriction. Caffeine intake did not correlate with renal volume in ADPKD patients. There were no significant differences between the renal volumes of patients in the highest and lowest tertiles of caffeine consumption. Finally, age-adjusted multiple linear regression revealed that renal volume was associated with hypertension, chronic kidney disease stage 3 and the time since diagnosis, but not with caffeine intake. The present small cross-sectional study indicated a low level of caffeine consumption by ADPKD patients when compared to healthy volunteers, which was most likely due to prior awareness of the need for caffeine restriction. Within the range of caffeine intake observed by ADPKD patients in this study (0-471 mg/day), the renal volume was not directly associated with caffeine intake.Item Effects of caffeine on time to exhaustion in exercise performed below and above the anaerobic threshold(Associação Brasileira de Divulgação Científica, 1998) Denadai, B.S; Denadai, M.L.D.R.Controversy still exists concerning the potential ergogenic benefit of caffeine (CAF) for exercise performance. The purpose of this study was to compare the effects of CAF ingestion on endurance performance during exercise on a bicycle ergometer at two different intensities, i.e., approximately 10% below and 10% above the anaerobic threshold (AT). Eight untrained males, non-regular consumers of CAF, participated in this study. AT, defined as the intensity (watts) corresponding to a lactate concentration of 4 mM, was determined during an incremental exercise test from rest to exhaustion on an electrically braked cycle ergometer. On the basis of these measurements, the subjects were asked to cycle until exhaustion at two different intensities, i.e., approximately 10% below and 10% above AT. Each intensity was performed twice in a double-blind randomized order by ingesting either CAF (5 mg/kg) or a placebo (PLA) 60 min prior to the test. Venous blood was analyzed for free fatty acid, glucose, and lactate, before, during, and immediately after exercise. Rating of perceived exertion and time to exhaustion were also measured during each trial. There were no differences in free fatty acids or lactate levels between CAF and PLA during and immediately after exercise for either intensity. Immediately after exercise glucose increased in the CAF trial at both intensities. Rating of perceived exertion was significantly lower (CAF = 14.1 ± 2.5 vs PLA = 16.6 ± 2.4) and time to exhaustion was significantly higher (CAF = 46.54 ± 8.05 min vs PLA = 32.42 ± 14.81 min) during exercise below AT with CAF. However, there was no effect of CAF treatment on rating of perceived exertion (CAF = 18.0 ± 2.7 vs PLA = 17.6 ± 2.3) and time to exhaustion (CAF = 18.45 ± 7.28 min vs PLA = 19.17 ± 4.37 min) during exercise above AT. We conclude that in untrained subjects caffeine can improve endurance performance during prolonged exercise performed below AT and that the decrease of perceived exertion can be involved in this process.