Efecto de un protocolo de ejercicio por cuatro semanas sobre el peso corporal y la glucemia en rata Wistar

Tissue glucose requirements augment during exercise, particularly in skeletal muscle. Glucose levels rise during moderate intensity exercise (60-75% VO2máx) due to an increase in the glucagon-insulin relationship (Engler, 2006). In this study we determined the effect of aerobic resistance exercise during four weeks on the body weight and blood sugar levels of Wistar rats. Experimental animals received training in a treadmill (Modular Enclosed Treadmill; Columbus Instrument, Columbus, OH, USA) with zero degrees of inclination and a 10 mV electric device incorporated. The exercise protocol was applied in 30 min sessions per day at a velocity of 10 m/min. with a frequency of 5 times a week for 4 weeks. Body weights and blood sugar levels were measured. At 12 hour fasting oral glucose tolerance curve (OGTC) was performed before and after the 4 weeks of exercise. The differences between the groups were analyzed using Student´s t tests, a p ≤ 0.05 was considered significant. After 4 weeks of training, the groups showed no significant differences in their body weights 262.0 ± 31.78 at the beginning, and 292.01 ± 35.62 g at the end of 4 weeks in the control group vs. 282.75 ± 25.91 g at the beginning, and 301.47 ± 31.38 g at the end of 4 weeks in the trained rats; p > 0.05). Similarly, blood glucose levels before and after 4 weeks of application of the exercise protocol were not significantly modified between the groups (73.5 ± 3.8 and 83.5 ± 2.38 g/dL in control group vs. 91.0 ± 7.43 and 85.7 ± 7.0 g/dL in the trained animals; p > 0.05). Likewise, the OGTC was comparable in both groups, before and after the application of the exercise protocol.Durante el ejercicio, los requerimientos de glucosa por los tejidos se incrementan, particularmente en el músculo esquelético; durante el ejercicio de intensidad moderada (60-75% VO2máx); el incremento de glucosa es debido a un aumento en la relación glucagon venoso-insulina (Engler 2006). En el presente trabajo se determinó el efecto del ejercicio de resistencia aeróbica durante cuatro semanas sobre el peso corporal y los niveles de glucosa sanguínea en ratas Wistar. Los animales recibieron entrenamiento en una banda sinfín (Modular Enclosed Treadmill; Columbus Instrument, Columbus, OH, USA), cero grados de inclinación, con incorporación de dispositivo eléctrico de 10 mV. El protocolo de marcha se aplicó en sesiones de 30 min/día, a una velocidad de 10 m/min con una frecuencia de 5 veces/semana durante 4 semanas.  Se midió el peso corporal y la glucosa sanguínea. Se determinó la Curva de Tolerancia Oral a la Glucosa (CTOG) en sangre en ayuno de 12 horas al inicio y al fin de cuatro semanas de ejercicio. La diferencia entre los grupos se analizó mediante la prueba estadística t de Student para comparación de medias, considerando una p≤0.05 como significativa. Después de cuatro semanas de entrenamiento, los grupos no mostraron diferencias significativas en el peso corporal 262.0±31.78 g al inicio y 292.01±35.62 g al final en el grupo control (p>0.05) vs. 282.75±25.91 g al inicio y 301.47±31.38 al final en el grupo de ratas entrenadas (p>0.05). Asimismo, los niveles de glucosa sanguínea antes y después del protocolo de ejercicio no se modificaron significativamente entre los grupos de estudio, siendo en el grupo control de 73.5±3.8 g/dL al inicio y 83.5±2.38 g/dL después de las 4 semanas de estudio; mientras que en el grupo experimental el nivel de glucosa sanguíneo disminuyó de 91.0±7.43 g/dL al inicio a 85.7±7.0 g/dL al final de las 4 semanas del protocolo de entrenamiento; sin embargo, esta diferencia no fue significativa entre los grupos (p>0.05). La CTOG antes y después del protocolo de ejercicio tendió a ser similar en ambos grupos de estudio.&nbsp

Progesterone regulates corticosterone elevation and alterations in spatial memory and exploratory behavior induced by stress in Wistar rats

The hippocampus is sensitive to high levels of glucocorticoids during stress responses; it suffers biochemical and cellular changes that affect spatial memory and exploratory behavior, among others. We analyzed the influence of the neurosteroid progesterone (PROG) on stress-induced changes in urinary corticosterone (CORT) levels, spatial memory and exploratory behavior.Castrated adult male rats were implanted with PROG or vehicle (VEHI),and then exposed for ten days to chronic stress created by overcrowding or ultrasonic noise. PROG and CORT levels were assessed in urine using highperformanceliquid chromatography (HPLC). Implanted PROG inhibited the rise of stress-induced CORT, prevented spatial memory impairment in the Morris water maze, and eliminated increased exploratory behavior in the hole-board test. These results suggest a protective role of PROG, possibly mediated by its anxiolytic mechanisms, against corticosteroids elevation and the behavioral deficit generated by stressful situations

Effects of Cannabinoids on Caffeine Contractures in Slow and Fast Skeletal Muscle Fibers of the Frog

The effect of cannabinoids on caffeine contractures was investigated in slow and fast skeletal muscle fibers using isometric tension recording. In slow muscle fibers, WIN 55,212-2 (10 and 5 μM) caused a decrease in tension. These doses reduced maximum tension to 67.43 ± 8.07% (P = 0.02, n = 5) and 79.4 ± 14.11% (P = 0.007, n = 5) compared to control, respectively. Tension-time integral was reduced to 58.37 ± 7.17% and 75.10 ± 3.60% (P = 0.002, n = 5), respectively. Using the CB1 cannabinoid receptor agonist ACPA (1 μM) reduced the maximum tension of caffeine contractures by 68.70 ± 11.63% (P = 0.01, n = 5); tension-time integral was reduced by 66.82 ± 6.89% (P = 0.02, n = 5) compared to controls. When the CB1 receptor antagonist AM281 was coapplied with ACPA, it reversed the effect of ACPA on caffeine-evoked tension. In slow and fast muscle fibers incubated with the pertussis toxin, ACPA had no effect on tension evoked by caffeine. In fast muscle fibers, ACPA (1 μM) also decreased tension; the maximum tension was reduced by 56.48 ± 3.4% (P = 0.001, n = 4), and tension-time integral was reduced by 57.81 ± 2.6% (P = 0.006, n = 4). This ACPA effect was not statistically significant with respect to the reduction in tension in slow muscle fibers. Moreover, we detected the presence of mRNA for the cannabinoid CB1 receptor on fast and slow skeletal muscle fibers, which was significantly higher in fast compared to slow muscle fiber expression. In conclusion, our results suggest that in the slow and fast muscle fibers of the frog cannabinoids diminish caffeine-evoked tension through a receptor-mediated mechanism

MODULACION ADRENERGICA DE LA TENSION PRODUCIDA POR k+ Y DE LOS CANALES DE CA2+ EN LAS FIBRAS MéSCULARES LENTAS DE POLLO

Facultad de Medicin

COVID-19 Pneumonia in Fully Vaccinated Adults during the Dominance of the Omicron Sublineages BA.1.1 and BA.2 in Mexico

Background and Objectives: A nationwide retrospective cohort study was conducted to evaluate the factors associated with the risk of laboratory-confirmed coronavirus disease 2019 (COVID-19)-related pneumonia in fully vaccinated adults during the dominance of the Omicron sublineages in Mexico. Materials and Methods: Fully COVID-19-vaccinated adults with laboratory-positive illness and symptom onset from April to mid-June 2022 were eligible. We computed the eta-squared (η2) to evaluate the effect size of the study sample. The characteristics predicting pneumonia were evaluated through risk ratios (RRs), and the 95% confidence intervals (CIs) were computed through generalized linear models. Results: The data from 35,561 participants were evaluated, and the overall risk of pneumonia was 0.5%. In multiple analyses, patients aged ≥ 60 years old were at increased risk of developing pneumonia (vs. 20–39 years old: RR = 1.031, 95% CI = 1.027–1.034). Chronic pulmonary obstructive disease, type 2 diabetes mellitus, arterial hypertension, chronic kidney disease (any stage), and immunosuppression (any cause) were also associated with a higher pneumonia risk. The η2 of all the variables included in the multiple models was Conclusions: Our study suggests that, even when fully COVID-19-vaccinated, older adults and those with chronic conditions were at increased risk of pneumonia during the dominance of the Omicron sublineages BA.1.1 and BA.2