Effects of passive smoking associated with physical exercise in the skeletal muscles of rats during pregnancy and lactation / Efectos del tabaquismo pasivo asociado con el ejercicio físico en los músculos esqueléticos de ratas durante la gestación y lactancia

The objective of this study was to analyze the effects of passive smoking, in soleus and gastrocnemius muscles associated with physical exercise by swimming during pregnancy and lactation of rats. Twenty-four rats were divided: GF (exposed to cigarette smoke), GC (control), GFN (underwent to the swimming program and exposed to cigarette smoke) and GN (underwent to the swimming program). On the first day of pregnancy procedure of exposure to cigarette smoke began, consisting in 30 minutes twice a day for six weeks. During the same period the swimming program began, which lasted 60 min every day untilthe 21st day of lactation. Soleus and gastrocnemius muscles, were obtained for histological, histochemical, morphometric analysis and fiber profiling. In histology, the groups GF and GFN showed infiltrations, necrotic and phagocytized fibers, centralized nuclei, splittings and coiling; in GN changes were observed due to exercise adaptations, infiltrations, sarcolemal lesion, polymorphic, atrophic and angular fibers. In the histochemical analysis of the groups GF and GFN there was enzymatic activity and amorphous formazan aggregates in subsarcolemmal positions, however in GN the same changes were found in lower frequency and intensity. In regard to the measureof the cross-sectionofmuscle fibers there weren't significant differences among the groups, as well as, in the frequency of types of fibers of the gastrocnemius. It is concluded that aerobic exercise is not enough to impede morphological and histochemical changes caused in an animal model of pregnant and lactating associated with smoking, and the stress not influence the types and size of muscle fibers.

EL objetivo fue analizar los efectos del tabaquismo pasivo sobre los músculos sóleo y gastrocnemio asociado con el entrenamiento corporal de natación durante la preñez y lactancia de ratas. Veinticuatro ratas se dividieron en grupos: GF (expuestos al humo de cigarrillo), GC (control), GFN (sometido al programa de natación y expuesto al humo del cigarrillo) y GN (sometido al programa de natación). El procedimiento de exposición al humo del cigarrillo comenzó primer día de preñez, durante 30 min dos veces al día por seis semanas. Durante el mismo período, comenzó el programa de natación, con una duración de 60 min todos los días hasta el día 21 de lactancia. Se extrajeron los músculos sóleo y gastrocnemio, y se realizó el análisis histológico, morfométrico histoquímico y de perfiles de fibra. En la histología, los grupos GF y GFN mostraron infiltraciones, fibras necróticas y fagocitadas, núcleos centralizados, divisiones y enrollamientos; en GN se observaron cambios debido a las adaptaciones de ejercicio tales como infiltraciones, lesión del sarcolema, y fibras polimórficas, atróficas y angulares. En el análisis histoquímico de los grupos GF y GFN hubo actividad enzimática y se formaron agregados amorfos en posiciones subsarcolemales; en el grupo GN se encontraron los mismos cambios en menor frecuencia e intensidad. No hubo diferencias en las medidas de las secciones transversales de las fibras musculares entre los grupos, así como en la frecuencia de los tipos de fibras del músculo gastrocnemio. Se concluye que el ejercicio aeróbico no es suficiente para impedir los cambios morfológicos e histoquímicos causados en un modelo animal de ratas preñadas en periodo de lactancia asociados con el tabaquismo, y el estrés no influye en el tipo y tamaño de las fibras musculares.

Influência do tabagismo passivo associado ao exercício físico realizado por ratas durante prenhez e lactação, sobre o desenvolvimento dos filhotes / Influence of passive smoking associated with exercise performed by rats during pregnancy and lactation on their offspring growth

OBJETIVOS: o objetivo deste estudo foi avaliar mortalidade, peso e comprimento corporal, e o músculo gastrocnêmio dos filhotes de ratas prenhes submetidas ao programa de natação associado ao tabagismo passivo. MÉTODOS: vinte e quatro ratas foram divididas em quatro grupos: GF (exposto à fumaça de cigarro), GC (Controle), GFN (submetido ao programa de natação e exposto à fumaça de cigarro) e GN (submetido ao programa de natação). A mortalidade e a aferição do peso e comprimento dos filhotes foram realizadas em quatro momentos. O músculo gastrocnêmio dos filhotes foi obtido para avaliação do desenvolvimento muscular. RESULTADOS: a média do nascimento de filhotes foi menor para os grupos GF (10,2) e GFN (10,3) e maior para o GN (12,8). No nascimento, somente o GFN apresentou medidas de peso (p=0,016) e comprimento (p=0,02) significantemente inferiores ao Controle, já na lactação foram os grupos expostos à fumaça de cigarro. O grupo GFN apresentou retardo no desenvolvimento muscular em relação ao GC (p=0,03). CONCLUSÃO: O tabagismo passivo durante a prenhez e lactação exerceu influência negativa sobre o número, peso e comprimento corporal dos filhotes do nascimento ao desmame e sobre o desenvolvimento muscular; o programa de natação influenciou positivamente tais variáveis no momento do nascimento, entretanto, não possibilitou os mesmos benefícios durante a lactação; e a associação destes influenciou negativamente tais medidas.

PURPOSE: the purpose of this study was to evaluate mortality, weight and body length, and the gastrocnemius muscle of the offspring of pregnant rats submitted to a swimming program associated with second-hand smoke. METHODS: twenty-four rats were divided into four groups: GF (exposed to cigarette smoke), GC (control), GFN (submitted to the swimming program and exposed to cigarette smoke), and GN (submitted to the swimming program). The mortality, weight and length of the offspring were measured at four time points. The gastrocnemius muscle of the pups was obtained for evaluation of muscle development. RESULTS: the average number of offspring was lower for GF (10.2) and GFN (10.3) and higher for GN (12.8). At birth, only GFN showed significantly lower weight (p=0.016) and length (p=0.02), whereas during lactation the groups exposed to cigarette smoke showed significantly lower weight. GFN had delayed muscle development compared to GC (p=0.03). CONCLUSIONS: Passive smoking during pregnancy and lactation negatively influenced number, weight and body length of offspring from birth to weaning and muscle development, and the swimming program positively influenced these variables at birth, although it did not provide the same benefits during lactation; and their association negatively affected these measures.