Renata Roland Teixeira

Chronic Stress Induces a Hyporeactivity of the Autonomic Nervous System in Response to Acute Mental Stressor and Impairs Cognitive Performance in Business Executives

The present study examined the incidence of chronic stress in business executives (109 subjects: 75 male and 34 female) and its relationship with cortisol levels, cognitive performance, and autonomic nervous system (ANS) reactivity after an acute mental stressor. Blood samples were collected from the subjects to measure cortisol concentration. After the sample collection, the subjects completed the Lipp Inventory of Stress Symptoms for Adults and the Stroop Color-Word Test to evaluate stress and cognitive performance levels, respectively. Saliva samples were collected prior to, immediately after, and five minutes after the test. The results revealed that 90.1% of the stressed subjects experienced stress phases that are considered chronic stress. At rest, the subjects with chronic stress showed higher cortisol levels, and no gender differences were observed. No differences were found between the stressed and non-stressed subjects regarding salivary amylase activity prior to test. Chronic stress also impaired performance on the Stroop test, which revealed higher rates of error and longer reaction times in the incongruent stimulus task independently of gender. For the congruent stimulus task of the Stroop test, the stressed males presented a higher rate of errors than the non-stressed males and a longer reaction time than the stressed females. After the acute mental stressor, the non-stressed male group showed an increase in salivary alpha-amylase activity, which returned to the initial values five minutes after the test; this ANS reactivity was not observed in the chronically stressed male subjects. The ANS responses of the non-stressed vs stressed female groups were not different prior to or after the Stroop test. This study is the first to demonstrate a blunted reactivity of the ANS when male subjects with chronic psychological stress were subjected to an acute mental stressor, and this change could contribute to impairments in cognitive performance.

Peel of araticum fruit (Annona crassiflora Mart.) as a source of antioxidant compounds with α-amylase, α-glucosidase and glycation inhibitory activities

Annona crassiflora Mart., whose fruit is popularly known as araticum, is a member of the Annonaceae family found in the Brazilian Cerrado. Although this plant has several medicinal uses, its bioactive molecules are not fully understood. A bioguided assay was performed to identify the main bioactive compounds of A. crassiflora fruit peel from the ethanol extract fractions with antioxidant capacity and α-amylase, α-glucosidase and glycation inhibitory activities. Ethyl acetate and n-butanol fractions showed, respectively, higher antioxidant capacity (DPPH IC50 1.5±0.1 and 0.8±0.1μgmL-1, ORAC 3355±164 and 2714±79μmoltroloxeq/g, and FRAP 888±16 and 921±9μmoltroloxeq/g) and inhibitory activities against α-amylase (IC50 4.5±0.8 and 1.7±0.3μgmL-1), α-glucosidase (IC50 554.5±158.6 and 787.8±140.6μgmL-1) and glycation (IC50 14.3±3.3 and 16.0±4.2μgmL-1), and lower cytotoxicity, compared to the other fractions and crude ethanol extract. The HPLC-ESI-MS/MS analysis identified various biomolecules known as potent antioxidants, such as chlorogenic acid, (epi)catechin, procyanidins, caffeoyl-hexosides, quercetin-glucosides and kaempferol. The fruit peel of A. crassiflora, a specie from Cerrado, the Brazilian Savanna, provided a source of antioxidant compounds with properties to block carbohydrate digestive enzymes and formation of glycation products. Thus, there is potential to use the by-products of araticum in order to identify and isolate phytochemicals for application in nutraceutical supplements, food additives and pharmaceuticals products.

Salivary Surrogates of Plasma Nitrite and Catecholamines during a 21-Week Training Season in Swimmers

The collection of samples of saliva is noninvasive and straightforward, which turns saliva into an ideal fluid for monitoring the adaptive response to training. Here, we investigated the response of the salivary proteins alpha-amylase (sAA), chromogranin A (sCgA), and the concentration of total protein (sTP) as well as salivary nitrite (sNO2) in relation to plasma catecholamines and plasma nitrite (pNO2), respectively. The variation in these markers was compared to the intensity and load of training during a 21-week training season in 12 elite swimmers. Overall, the salivary proteins tracked the concentration of plasma adrenaline and were inversely correlated with the training outcomes. No correlations were observed between sNO2 and pNO2. However, sNO2 correlated positively with the intensity and load of training. We argue that the decrease in sympathetic activity is responsible for the decrease in the concentration of proteins throughout the training season. Furthermore, the increase in nitrite is likely to reflect changes in hemodynamics and regulation of vascular tone. The association of the salivary markers with the training outcomes underlines their potential as noninvasive markers of training status in professional athletes.

Identification of calmodulin-binding proteins in brain of worker honeybees

Calmodulin is a Ca(+2)-binding protein important in a variety of cell functions. The Ca(+2)/calmodulin complex interacts with and regulates various enzymes and target proteins, known as calmodulin-binding proteins (CaMBPs). In this study, we revealed a comparative identification of the CaMBPs composition in the worker honeybee (Apis mellifera) brain, considering two different honeybee behaviors in the colony. To this end, the CaMBPs of forager and nurse workers were purified by affinity chromatography, separated in 1D gel, digested and submitted to peptide mass fingerprinting (PMF). In the PMF analysis, 15 different proteins, considered behavior-specific proteins, were identified, one of them exclusively in forager workers and 10 in nurses. All the proteins were classified in terms of their function and cell localization, revealing a greater expression of metabolism-related CaMBPs in both worker subcastes. Protein sequences were then analyzed for the presence of the calmodulin-binding sites. Therefore, the honeybee brain CaMBPs profiles presented differences between worker subcastes. This is the first identification of calmodulin-binding proteins in the brain of A. mellifera upon nursing and foraging behaviors in the colony and this diversity of target proteins for Ca(+2)/CaM may be involved in terms of the function of these proteins in the nervous system.

The Role of Metformin in Controlling Oxidative Stress in Muscle of Diabetic Rats

Metformin can act in muscle, inhibiting the complex I of the electron transport chain and decreasing mitochondrial reactive oxygen species. Our hypothesis is that the inhibition of complex I can minimize damage oxidative in muscles of hypoinsulinemic rats. The present study investigated the effects of insulin and/or metformin treatment on oxidative stress levels in the gastrocnemius muscle of diabetic rats. Rats were rendered diabetic (D) with an injection of streptozotocin and were submitted to treatment with insulin (D+I), metformin (D+M), or insulin plus metformin (D+I+M) for 7 days. The body weight, glycemic control, and insulin resistance were evaluated. Then, oxidative stress levels, glutathione antioxidant defense system, and antioxidant status were analyzed in the gastrocnemius muscle of hypoinsulinemic rats. The body weight decreased in D+M compared to ND rats. D+I and D+I+M rats decreased the glycemia and D+I+M rats increased the insulin sensitivity compared to D rats. D+I+M reduced the oxidative stress levels and the activity of catalase and superoxide dismutase in skeletal muscle when compared to D+I rats. In conclusion, our results reveal that dual therapy with metformin and insulin promotes more benefits to oxidative stress control in muscle of hypoinsulinemic rats than insulinotherapy alone.

Response of salivary markers of autonomic activity to elite competition.

We investigated the response of salivary total protein (TP), alpha-amylase (sAA) and chromogranin A (CgA) to sporting competition and their relation with positive and negative affect. 11 professional swimmers were examined during the first day of a national contest and on a recreated event that matched time-of-the-day and day-of-the-week assessments 2 weeks later. Total protein was determined by the Bradford method and sAA and CgA by Western blotting upon awakening, 30 and 60 min post awakening, immediately before warming up for competition and 5, 20 and 60 min after competition. Psychometric instruments included the Positive Affect and Negative Affect Schedule-X. The concentrations of TP, sAA and CgA differed from controls only prior to and 5 min after the event. We observed positive correlations between higher negative affect scores with higher levels of TP, sAA and CgA prior to the event on the competition day. All 3 markers showed a similar reactivity to sporting competition, which may be attributed to the mechanisms responsible for protein secretion into saliva when collection is performed with no exogenous stimulation. TP is an attractive marker in sports psychology since its determination is faster and cheaper than traditional kinetic or immune assays.

The Relationship Between the Cortisol Awakening Response, Mood States, and Performance

Abstract Díaz, MM, Bocanegra, OL, Teixeira, RR, Tavares, M, Soares, SS, and Espindola, FS. The relationship between the cortisol awakening response, mood states, and performance. J Strength Cond Res 27(5): 1340–1348, 2013—This study examined the variation in the diurnal profile of cortisol, with an emphasis on the cortisol awakening response (CAR), in relation to mood states and performance during a professional swimming contest. Eleven athletes were examined during 2 consecutive days of competition and during a recreated event 2 weeks later that was matched to the time of the day and day of the week of the competition. On each day, salivary cortisol was determined upon awakening (07:00 hours); 30 and 60 minutes post-awakening; immediately before warming up for competition (16:00 hours); and 5 minutes (18:20 hours), 20 minutes (18:40 hours), and 40 minutes (19:00 hours) after competition. Psychometric instruments included the Profile of Mood States and self-reports of performance. Cortisol awakening responses did not differ between days of competition and control and were not related to performance on any day. However, a difference was observed in the concentration of cortisol before and after the contest between the competition and control days. Higher levels of cortisol before competition were associated with feelings of tension, anxiety, and hostility. The perceived demands of the day ahead might not produce the same magnitude of variation in the CAR in well-trained men. Explanations for this probably include better coping mechanisms and responses to the phase and time of competition.

Salivary Nitric Oxide and Alpha-Amylase as Indexes of Training Intensity and Load

This study examined the variation in salivary nitric oxide (NO), alpha-amylase (sAA) and serum markers of muscle injury during 21 weeks of training in elite swimmers. Samples of saliva and blood were collected once a month during 5 months from 11 male professional athletes during their regular training season. The variation in each marker throughout the 21 weeks was compared with the dynamics of training volume, intensity and load. Unstimulated whole saliva was assessed for NO and sAA whereas venous blood was assessed for lactate dehydrogenase, creatine kinase, and γ-glutamyltransferase. Nitric oxide and sAA showed a proportional response to the intensity of training. However, whereas the concentration of NO increased across the 21 weeks, the activity of sAA decreased. Similar variations in the concentration of NO and the markers of muscle injury were also observed. The higher concentration of NO might be attributed to changes in haemodynamics and muscle regenerative processes. On the other hand, autonomic regulation towards parasympathetic predominance might have been responsible for the decrease in sAA activity. These findings provide appealing evidence for the utilization of salivary constituents in sports medicine to monitor training programmes.

Comparative analysis of two immunohistochemical methods for antigen retrieval in the optical lobe of the honeybee Apis mellifera: Myosin-v assay

The present study compared two heating methods currently used for antigen retrieval (AR) immunostaining: the microwave oven and the steam cooker. Myosin-V, a molecular motor involved in vesicle transport, was used as a neuronal marker in honeybee Apis mellifera brains fixed in formalin. Overall, the steam cooker showed the most satisfactory AR results. At 100 ºC, tissue morphology was maintained and revealed epitope recovery, while evaporation of the AR solution was markedly reduced; this is important for stabilizing the sodium citrate molarity of the AR buffer and reducing background effects. Standardization of heat-mediated AR of formalin-fixed and paraffin-embedded tissue sections results in more reliable immunostaining of the honeybee brain.

Royal jelly decreases corticosterone levels and improves the brain antioxidant system in restraint and cold stressed rats

Restraint and cold stress induces the hypothalamic-pituitary-adrenal (HPA) axis to release corticosterone from the adrenal gland, which can worsen the antioxidant defense system in the central nervous system. Here, we investigated the corticosterone levels and the antioxidant defense system in the cerebellum and brain, as well as in its isolated regions, such as cerebral cortex, striatum and hippocampus of stressed rats supplemented with royal jelly (RJ). Wistar rats were supplemented with RJ for 14days and the stress induction started on the 7th day. Stressed rats increased corticosterone levels, glycemia and lipid peroxidation in the brain and cerebellum, cerebral cortex and hippocampus besides reduced glutathione defense system in the brain and striatum. Rats supplemented with RJ decreased corticosterone, maintained glycemia and decreased lipid peroxidation in the brain, cerebellum, as well as striatum and hippocampus, besides improved glutathione defense system in cerebral cortex and striatum. This study suggests an anti-stress and neuroprotective effect of RJ under stress conditions.