Equal BMD After Daily Or Triweekly Exercise In Growing Rats

The purpose of this study was to examine the efficacy of continuous resistance training (3 days/wk) compared to interrupted resistance training where 20-24 h separated an exercise bout (i.e. 6 days/wk) for enhancing bone mineral density (BMD) in growing male rats. The total volume of work performed per week between the two resistance training programs was equivalent by design. Young male rats were randomly divided into Control (Con, n = 9), 3 days/wk resistance trained group (RT3, n = 9), and 6 days/wk resistance trained group (RT6, n = 9). The RT3 and RT6 groups were conditioned to climb a vertical ladder with weights appended to their tail for a total of 6 wks. After 6 wks, BMD (assessed via DXA) from the left tibia was significantly greater for RT3 (0.242 +/- 0.004 g/cm(2)) and RT6 (0.244 +/- 0.004 g/cm(2)) compared to Con (0.226 +/- 0.003 g/cm(2) ). Further, serum osteocalcin (oc, in ng/ml) was significantly greater for RT3 (75.8 +/- 4.4) and RT6 (73.5 +/- 3.8) compared to Con (53.4 +/- 2.4). There was no significant difference in BMD or serum OC between RT3 and RT6 groups. The results indicate that both resistance training programs were equally effective in elevating bone mineral density in young, growing rats

Resistance Training and Bone Mineral Density During Growth

This study examined the efficacy of two different resistance training programs in enhancing bone modeling and bone mineral density (BMD) in maturating rats. One exercise mode involved lifting a lighter weight with more repetitions (LI), while the other regimen involved lifting a heavier weight with fewer repetitions (HI) where the total volume of work between exercise programs was equivalent by design. Twenty-three male rats were randomly divided into control (Con, n = 8), LI (n = 7), and HI (n = 8) groups. The LI and HI groups were conditioned to climb a vertical ladder with weights appended to their tail 4 days/wk for 6 wks. After training, serum osteocalcin (OC) was significantly (p \u3c 0.05) higher in both HI (45.2 +/- 1.7 ng/ml) and Ll (39.1 +/- 2.2 ng/ml) when compared to Con (29.9 +/- 0.9 ng/ml). Left tibial BMD was significantly (p \u3c 0.05) greater for HI (0.231 +/- 0.004 g/cm(2)) when compared to both LI (0.213 +/- 0.003 g/cm(2)) and Con (0.206 +/- 0.005 g/cm(2)) with no significant difference between Ll and Con. The results indicate that both HI and LI are effective in elevating serum OC, implicating an osteogenic response; however, only HI resulted in a significant elevation in BMD

Oxytocin, Cortisol, and Cognitive Control During Acute and Naturalistic Stress

Although stress is a strong risk factor for poor health, especially for women, it remains unclear how stress affects the key neurohormones cortisol and oxytocin, which influence stress-related risk and resilience. Whereas cortisol mediates energy mobilization during stress, oxytocin has anti-inflammatory, anxiolytic, and analgesic effects that support social connection and survival across the lifespan. However, how these neurohormones interrelate and are associated with cognitive control of emotional information during stress remains unclear. To address these issues, we recruited 37 college-aged women (Mage = 19.19, SD = 1.58) and randomly assigned each to a one-hour experimental session consisting of either an acute stress (emotionally stressful video) or control (non-stressful video) condition in a cross-sectional manner across the semester. Salivary cortisol and oxytocin samples were collected at baseline and after the video, at which point participants also completed measures assessing affect and an emotional Stroop task. As hypothesized, the emotional stressor induced negative emotions that were associated with significant elevations in cortisol and faster Stroop reaction times. Moreover, higher baseline oxytocin predicted greater positive affect after the stressor and also better cognitive accuracy on the Stroop. Analyses examining the naturalistic stress effects revealed that basal oxytocin levels rose steeply three weeks before the semester’s end, followed by rising cortisol levels one week later, with both neurohormones remaining elevated through the very stressful final exam period. Considered together, these data suggest that women’s collective experiences of stress may be potentially buffered by a synchronous oxytocin surge that enhances cognitive accuracy and reduces stress “when the going gets tough”

Interrupted Vs. Uninterrupted Training on BMD During Growth

This study compared a resistance training program where the exercise was uninterrupted (UT, i.e., continuous repetitions) against a resistance training program where the exercise was interrupted (IT, i.e., 3 exercise sessions during a training day) for enhancing bone modeling and bone mineral density (BMD) in maturating animals. The total volume of work performed between the two resistance training programs was equivalent by design. 24 young male rats were randomly divided into Control (Con, n = 8), UT (n = 8) and IT (n=8) resistance trained groups. The UT and IT groups were conditioned to climb a vertical ladder with weights appended to their tail 3 days/wk for 6 wks. After the 6-wk program, serum osteocalcin was not significantly different between groups, whereas the adjusted urinary deoxypyridinoline (DPD) was significantly lower for both UT (81.03 +/- 5.53) and IT (88.30 +/- 7.29) compared to Con (128.13 +/- 9.99). Tibial BMD (assessed via DXA) was significantly greater for UT (0.222 +/- 0.005g/cm(2)) and IT (0.219 +/- 0.003g/cm(2)) when compared to Con (0.205 +/- 0.004g/cm(2)). There was no significant difference in DPD or BMD between UT and IT groups. The results indicate that both interrupted and continuous, uninterrupted resistance training programs were equally effective in stimulating bone modeling

Alcohol-Induced Suppression Of Gluconeogenesis Is Greater In Ethanol Fed Female Rat Hepatocytes Than Males

The impact of alcohol-induced suppression on hepatic gluconeogenesis (HGN) after chronic ethanol consumption between males and females is unknown. To determine the effects of chronic alcohol consumption (8 weeks) on HGN, the isolated hepatocyte technique was used on 24 h fasted male and female Wistar rats. Livers were initially perfused with collagenase and the hepatocytes were isolated. Aliquots of the cell suspension were placed in Krebs-Henseleit buffer and incubated for 30 min with lactate, [U-C-14]lactate, and nine different concentrations of ethanol (EtOH). Dose-effect curves were generated for the determination of maximal and half-maximal alcohol-induced inhibition on HGN. There was no significant difference in HGN (lactate only and no EtOH) between males and females fed the control diet (88.5 +/- 5.1 nmol/mg protein/30 min). Similarly, the HGN (lactate only and no EtOH) in males fed the ethanol diet (ME) were not significantly different (82.8 +/- 3.5 nmol/mg protein/30 min) compared to controls. In contrast, the females chronically fed the ethanol diet (FE) had significantly (P \u3c .05) lower HGN (67.8 +/- 4.6 nmol/mg protein/30 min) compared to both ME and controls. With alcohol in the incubation medium, the HGN significantly (P \u3c .05) declined in all groups. While alcohol suppressed HGN to a larger (P \u3c .05) extent in ME (45.8 +/- 3.7 nmol/mg protein/30 min) compared to controls (64.0 +/- 3.8 nmol/mg protein/30 min), the inhibition was even greater (P \u3c .05) in FE (32.7 +/- 3.2 nmol/mg protein/30 min). The more pronounced effect of chronic alcohol consumption on HGN in the presence of ethanol in female hepatocytes was supported by the concomitant decreases (P \u3c .05) in C-14-lactate incorporation into C-14-glucose, lactate uptake, and C-14-lactate uptake. The results suggest that chronic alcohol consumption elicits a greater reduction on HGN in the presence of ethanol in the hepatocytes of females compared to males

Sex Differences in Hepatic Gluconeogenic Capacity After Chronic Alcohol Consumption

Alcohol-induced hypoglycemia has traditionally been attributed to the amount of ethanol consumed rather than any inherent decline in glucose output capacity by the gluconeogenic organs and/or an increase in skeletal muscle glucose uptake. Further, while the potential for sex differences that might impact glucose homeostasis following chronic alcohol consumption has been recognized, direct evidence has been noticeably absent. This paper will provide a brief review of past and present reports of the potential for sex differences in glucose homeostasis following chronic ethanol consumption. This paper will also provide direct evidence from our laboratory demonstrating sex differences from chronic alcohol consumption resulting in a decrement in glucose appearance and more importantly, a specific decline in hepatic gluconeogenic (HGN) capacity in the absence and presence of ethanol. All our studies involved 8 weeks of chronic alcohol consumption in male and female Wistar rats, as well as a 24 to 48 hour fast to deplete hepatic glycogen stores. Under the conditions of chronic alcohol consumption and an acute dose of ethanol, we provide in vivo evidence of an early decline in whole body glucose appearance in females fed an ethanol diet compared to controls. While the decline was also observed in males fed the alcohol diet, it occurred much later compared to ethanol fed females. The site for the decline in whole body glucose production (i.e., either the kidneys or the liver) was beyond the scope of our prior in vivo study. In a follow-up study using the in situ perfused liver preparation, we provide additional evidence for a specific reduction in HGN capacity from lactate in ethanol fed females compared to ethanol fed males in the absence of alcohol in the perfusion medium. Finally, employing the isolated hepatocyte technique, we report decrements in HGN from lactate in ethanol fed females compared to ethanol fed males in the presence of ethanol in the incubation medium. The mechanism for the specific decline in HGN within the liver of ethanol fed females remains to be determined. To the extent that our observations in animals can be extrapolated to humans, we conclude that alcoholic women are more susceptible to ethanol-induced hypoglycemia compared to alcoholic men

La Correspondencia de España : diario universal de noticias: Año LXIV Número 20379 - 1913 noviembre 28

Stress is strongly associated with several mental and physical health problems that involve inflammation, including asthma, cardiovascular disease, certain types of cancer, and depression. It has been hypothesized that better cognitive control of emotional information may lead to reduced inflammatory reactivity to stress and thus better health, but to date no studies have examined whether differences in cognitive control predict pro-inflammatory cytokine responses to stress. To address this issue, we conducted a laboratory-based experimental study in which we randomly assigned healthy young-adult females to either an acute emotional stress (emotionally evocative video) or no-stress (control video) condition. Salivary levels of the key pro-inflammatory cytokines IL-1β, IL-6, and IL-8 were measured before and after the experimental manipulation, and following the last cytokine sample, we assessed participants' cognitive control of emotional information using an emotional Stroop task. We also assessed participants' cortisol levels before and after the manipulation to verify that documented effects were specific to cytokines and not simply due to increased nonwater salivary output. As hypothesized, the emotional stressor triggered significant increases in IL-1β, IL-6, and IL-8. Moreover, even in fully adjusted models, better cognitive control following the emotional (but not control) video predicted less pronounced cytokine responses to that stressor. In contrast, no effects were observed for cortisol. These data thus indicate that better cognitive control specifically following an emotional stressor is uniquely associated with less pronounced pro-inflammatory cytokine reactivity to such stress. These findings may therefore help explain why superior cognitive control portends better health over the lifespan