Gender-related differences in the brown adipose tissue (BAT) response to overfeeding rats on a cafeteria diet were studied by assessing the balance between the expression of beta-adrenoceptors (beta1-, beta2-, beta3-AR) and alpha2A-AR and their relation to the expression of uncoupling proteins (UCP1, UCP2, UCP3). Cafeteria diet feeding for 15 days, which involved a similar degree of hyperphagia in both sexes, led to a greater body weight excess in females than in males and a lower activation of thermogenesis. Gender-related differences were found for different adrenoceptor expression and protein levels, which might explain, in part, sex differences in the thermogenic parameters. The lower expression of alpha2A-AR in females than in males could be responsible for the higher expression of UCP1 and thermogenic capacity under non-hyperphagic conditions. However, in a situation of high adrenergic stimulation--as occurs with overfeeding--as there is a preferential recruitment of the beta3-AR by noradrenaline compared with other adrenergic receptors, the higher levels of beta3-AR in males rats than in females could be responsible for the greater thermogenic capacity and the lesser weight gain in males. Thus, the alpha2/beta3 balance in BAT could be a key in the thermogenic control.
OBJECTIVE: To investigate the effects of short term (15 days) cafeteria diet feeding on the expression of b b 3 -AR in vivo and its association with lipolytic stimulation induced by b b 3 -AR agonist CGP12177A in isolated white adipocytes. ANIMALS: Six female and 6 male Wistar rats (at 4 weeks of age) were fed on a cafeteria diet plus standard diet for 15 days. The remaining 12 age-and sex-matched rats always received standard diet only. MEASUREMENTS: White gonadal adipose tissue was isolated and used for the determination of b b 3 -AR and leptin expression, and for in vitro studies of lipolytic activity. RESULTS: Control male rats had higher levels of both b b 3 -AR and leptin mRNA in white adipose tissue than their female counterparts. Both male and female rats up-regulated the levels of both b b 3 -AR and leptin mRNA in response to 15 day cafeteria diet feeding. Noradrenaline-and isoprenaline-induced lipolysis were signi®cantly increased in fat cells from control females compared to their male counterparts. CGP12177A stimulation resulted in signi®cantly higher glycerol release in fat cells from cafeteria diet-fed female rats, whereas there were no differences due to dietary treatment in male rats. The maximal lipolytic response of forskolin (stimulating adenylyl cyclase) and dibutyryl cyclic AMP (cyclic AMP analogous) was not affected by sex or cafeteria diet feeding. CONCLUSION: Cafeteria diet feeding brings about higher excess body weight and impaired adipose tissue lipolytic activity in female rats compared to male rats. Thus, the higher levels of b b 3 -AR mRNA induced by cafeteria feeding are not indicative per se of an increase of the lipolytic response of the adipocytes. The changes seen in other adrenoceptor subtypes (b b 1 and b b 2 ) may be more determinant of the overall lipolytic response of adipocytes.
El estudio realizado tiene como objetivo averiguar si la aplicación de metodologías didácticas activas en la etapa de educación primaria tiene consecuencias en el rendimiento académico de este alumnado en los inicios de la etapa de la educación secundaria obligatoria. Para ello se ha planteado una investigación de carácter cuantitativo, con un diseño cuasi experimental, donde se comparan en primero de la ESO los resultados del alumnado, que ha cursado educación primaria en dos centros públicos de una misma zona geográfica de la isla de Mallorca, con lo que se controlan las variables extrañas: en el primer centro se aplican desde siempre metodologías activas, mientras que en el otro se siguen metodologías tradicionales. La totalidad del alumnado de ambos centros se escolariza en secundaria en el mismo instituto, único de la zona. Los resultados obtenidos, a partir del estudio de los últimos seis años de cada centro para tener una secuencia y evitar características individuales de cursos concretos, nos muestran que no existen diferencias estadísticamente significativas en los resultados académicos por centro de procedencia. Estos resultados ponen de manifiesto que la utilización de metodologías activas en educación primaria no supone ninguna desventaja en cuanto al rendimiento académico cuando este alumnado cursa primero de la ESO en una metodología tradicional.
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