Physiological Responses to Low-Volume Interval Training in Women.

Interval training is a form of exercise that involves intermittent bouts of relatively intense effort interspersed with periods of rest or lower-intensity exercise for recovery. Low-volume high-intensity interval training (HIIT) and sprint interval training (SIT) induce physiological and health-related adaptations comparable to traditional moderate-intensity continuous training (MICT) in healthy adults and those with chronic disease despite a lower time commitment. However, most studies within the field have been conducted in men, with a relatively limited number of studies conducted in women cohorts across the lifespan. This review summarizes our understanding of physiological responses to low-volume interval training in women, including those with overweight/obesity or type 2 diabetes, with a focus on cardiorespiratory fitness, glycemic control, and skeletal muscle mitochondrial content. We also describe emerging evidence demonstrating similarities and differences in the adaptive response between women and men. Collectively, HIIT and SIT have consistently been demonstrated to improve cardiorespiratory fitness in women, and most sex-based comparisons demonstrate similar improvements in men and women. However, research examining insulin sensitivity and skeletal muscle mitochondrial responses to HIIT and SIT in women is limited and conflicting, with some evidence of blunted improvements in women relative to men. There is a need for additional research that examines physiological adaptations to low-volume interval training in women across the lifespan, including studies that directly compare responses to MICT, evaluate potential mechanisms, and/or assess the influence of sex on the adaptive response. Future work in this area will strengthen the evidence-base for physical activity recommendations in women.

Colored-Light Preference in Zebrafish (Danio rerio).

Over the past decade, the zebrafish has been increasingly employed in biomedical neuroscience research due to its numerous evolutionarily conserved features with mammals. Its simple brain and the several molecular tools available for this species make the zebrafish an appealing model to study mechanisms of complex brain functions, including learning and memory. Most learning paradigms developed for the zebrafish have employed visual stimuli as the associative cue. Spontaneous color preference is a potential confound in such studies. It has been analyzed in zebrafish using colored objects, but with conflicting results. It has rarely been explored with colored light, despite the increasing use of computer-generated visual stimuli. Here, we employ a light emitting diode (RGB-system) light-based color preference task in the plus-maze. In two independent experiments, zebrafish were tested in a four-choice or dual-choice condition by using four different-colored lights (red, green, blue and yellow). Our results suggest a light preference hierarchy that depends on context, since yellow was preferred over green in the four-choice condition whereas blue was preferred over all other colors in the two-choice condition. These results are useful for future color-light-based learning experiments in zebrafish.

Developmental stage-dependent deficits induced by embryonic ethanol exposure in zebrafish: A neurochemical analysis.

FASD results from the developing fetus being exposed to alcohol, and is characterized by morphological, behavioural and cognitive deficits. However, the expression, severity and age of onset of these symptoms has been found to show variation. This variation may partly be due to the developmental stage at which alcohol reached the developing fetus. Previously, alcohol was shown to lead to significant concentration dependent behavioural as well as neurochemical changes detected in adult zebrafish when this substance was administered at 24 h post-fertilization (hpf) for 2 h. This alcohol exposure method arguably mimicked the milder, and more prevalent, forms of human FASD. However, whether the observed changes depended upon the developmental stage, i.e., the timing, of alcohol exposure has not been systematically analyzed. Here, we employ the same alcohol dosing regimen, where zebrafish eggs are immersed into 0% or 1% (vol/vol) alcohol for 2 h, but we perform the immersion at 5, 10, 16, 24, 36, or 48 hpf. We previously developed a sensitive HPLC method to quantify neurochemicals, and found levels of dopamine, serotonin and their metabolites DOPAC and 5-HIAA to be affected by embryonic alcohol treatment. Here, using the same method, we compare whole-brain levels of these neurochemicals in the embryonic alcohol exposed and control zebrafish at their age of 30 days post-fertilization (dpf). Consistent with previous reports, we found significant reduction of levels of dopamine, serotonin and their metabolites in the fish exposed to alcohol at 24 hpf. However, we also found significant dependency on the developmental stage at which alcohol was administered with particularly robust impairments when the exposure was at the early or middle of the developmental periods probed. Our results now demonstrate that one can detect functional abnormalities in the zebrafish brain induced by embryonic alcohol as early as 30 dpf and that the neurochemical deficits are dependent upon the developmental stage at which alcohol is administered.