ABSTRACT
Protein restriction implies the functional involvement of several systems and organs, including the skeletal muscle, because it is a protein reservoir in the body. This study sought to analyze the morphological and morphometric features of the muscle fibers and neuromuscular junctions (NMJs) of the extensor digitorum longus (EDL) muscle in rats at 365 days of age, submitted to maternal protein restriction during the gestation and lactation periods. Wistar rats were divided into two groups: a Control Group - mothers fed a normal-protein diet (17 % protein) during pregnancy and lactation; and a Restricted Group - mothers fed a low-protein diet (6 % protein) during pregnancy and lactation. The pups were kept with the mother throughout the lactation period (21 days), after which the offspring received a normal protein diet until 365 days of age. Histological (HE) and histoenzymological (NADH-TR) studies were conducted on the muscle fibers. The muscle was subjected to Nonspecific Esterase reaction to stain the Neuromuscular Junctions. Regarding the animals from the restricted group: the histologic analysis of the muscle fibers showed the presence of centralized nuclei and a diminished area; the histoenzymological study showed the different types of muscle fibers were randomly distributed in the EDL muscle and the area of the Type IIa muscle fiber was smaller; the ultrastructural study revealed disorganization of the Z line, and the presence of lipid droplets and vacuoles containing myelin figures in subsarcolemmal and intramiofibrilar regions; while the analysis of the NMJs exhibited no significant differences between the groups. Protein restriction in the pregnancy and lactation period may have affected the development of skeletal muscle, producing a permanent muscle-fiber deficit in the EDL muscle of the offspring.
La restricción proteica implica compromiso funcional de diversos sistemas y órganos, entre ellos, el músculo estriado esquelético, por ser una reserva de proteína del organismo. De esa forma, el presente trabajo procuró analizar las características morfológicas y morfométricas de las fibras musculares y de las intersecciones neuromusculares (JNMs) del músculo extensor largo de los dedos (EDL) en ratas de 365 días de edad, sometidas a restricción proteica materna durante los periodos de gestación y lactancia. Las ratas Wistar fueron separadas en dos grupos: El grupo Control - madres alimentadas durante la gestación y lactancia con ración normoproteica (17 % de proteína) y Grupo con restricción madres alimentadas durante la gestación y lactancia con ración hipoproteica (6 % de proteína). Las crías permanecieron con la madre durante todo el periodo de lactancia (21 días) y después de este periodo la prole recibió ración normoproteica hasta los 365 días de edad. Se realizó un estudio histológico (HE) e histoenzimológico (NADH-TR) de las fibras musculares. Para la marcación de las JNMs, el músculo fue sometido a la reacción de Esterasa Inespecífica. El análisis histológico de las fibras musculares de los animales del Grupo con restricción mostró la presencia de núcleos centralizados y una disminución del área en el grupo con restricción. En el estudio histoenzimológico, el músculo EDL presentó una distribución aleatoria de los diferentes tipos de fibras musculares y el área de las fibras musculares del tipo IIa fue menor en el grupo con restricción. En relación al estudio ultraestructural, en los animales del grupo con restricción se observó desorganización de la línea Z, presencia de pequeñas gotas de lípidos y vacuolas que abrigaban figuras de mielina en las regiones subsarcolemal e intramiofibrilar. En el análisis de las JNMs no hubo diferencias significativas. La restricción proteica impuesta en el periodo de gestación y lactancia puede haber afectado el desarrollo del músculo esquelético, produciendo un déficit permanente en las fibras musculares del músculo EDL de la prole.
Subject(s)
Animals , Male , Female , Rats , Diet, Protein-Restricted , Muscle Fibers, Skeletal/pathology , Muscle, Skeletal/pathology , Prenatal Exposure Delayed Effects , Rats, WistarABSTRACT
Melatonin regulates the reproductive cycle, energy metabolism and may also act as a potential antioxidant indoleamine. The present study was undertaken to investigate whether long-term melatonin treatment can induce reproductive alterations and if it can protect ovarian tissue against lipid peroxidation during ovulation. Twenty-four adult female Wistar rats, 60 days old (± 250-260 g), were randomly divided into two equal groups. The control group received 0.3 mL 0.9 percent NaCl + 0.04 mL 95 percent ethanol as vehicle, and the melatonin-treated group received vehicle + melatonin (100 µg·100 g body weight-1·day-1) both intraperitoneally daily for 60 days. All animals were killed by decapitation during the morning estrus at 4:00 am. Body weight gain and body mass index were reduced by melatonin after 10 days of treatment (P < 0.05). Also, a marked loss of appetite was observed with a fall in food intake, energy intake (melatonin 51.41 ± 1.28 vs control 57.35 ± 1.34 kcal/day) and glucose levels (melatonin 80.3 ± 4.49 vs control 103.5 ± 5.47 mg/dL) towards the end of treatment. Melatonin itself and changes in energy balance promoted reductions in ovarian mass (20.2 percent) and estrous cycle remained extensive (26.7 percent), arresting at diestrus. Regarding the oxidative profile, lipid hydroperoxide levels decreased after melatonin treatment (6.9 percent) and total antioxidant substances were enhanced within the ovaries (23.9 percent). Additionally, melatonin increased superoxide dismutase (21.3 percent), catalase (23.6 percent) and glutathione-reductase (14.8 percent) activities and the reducing power (10.2 percent GSH/GSSG ratio). We suggest that melatonin alters ovarian mass and estrous cyclicity and protects the ovaries by increasing superoxide dismutase, catalase and glutathione-reductase activities.