Effects of photobiomodulation and swimming on gene expression in rats with the tibialis anterior muscle injury.

The aim of the present study was to evaluate the effects of photobiomodulation (low-level laser therapy (LLLT)) and aquatic exercise on the expression of genes related to muscle regeneration in rats. Wistar rats were divided into five groups: control group (n = 15), non-treated injury group (n = 15), injury+LLLT group (n = 15), injury+aquatic exercise group (n = 15), and injury+LLLT+aquatic exercise group (n = 15). Cryoinjury was performed on the belly of the tibialis anterior (TA) muscle. LLLT was performed daily with an AlGaAs laser (830 nm; beam spot of 0.0324 cm2, output power of 100 mW, energy density of 180 J/cm2, and 58-s exposure time). Animals were euthanized at 7, 14, and 21 days. The TA muscles were removed for gene expression analysis of TGF-ß, Myogenin, and MyoD. The results were statistically analyzed at a significance level of 5%. The cryoinjury increased the expression of genes related to muscle regeneration-MyoD, Myogenin, and TGF-ß-compared to the control group (p < 0.05); the photobiomodulation increased the expression of these genes at day 7 (p < 0.05), decreasing until day 21; and the aquatic exercise increases the expression of the three genes over time. When the two treatments were combined, the expression of the analyzed genes also increased over time. In summary, the results of our study suggest that photobiomodulation (LLLT), when applied alone in cryoinjury, is able to increase the gene expression of MyoD, Myogenin, and TGF-ß at the acute phase, while when combined with aquatic exercises, there is an increase in expression of these genes specially at the long-term treatment.

Maternal exposure to fluoxetine during gestation and lactation induces long lasting changes in the DNA methylation profile of offspring's brain and affects the social interaction of rat.

Fluoxetine (FLX) is an antidepressant from the selective serotonin reuptake inhibitor class that has largely been used for the treatment of depression in pregnancy. However, increasing evidences have indicated the potential of early maternal exposure to FLX to induce molecular and neuro functional effects on the offspring. In the present study we evaluated possible long lasting impacts of the maternal exposure to FLX during gestation and lactation. Female Wistar rats were gavaged with 5 mg/kg of FLX during the period that comprehends the first day of pregnancy (PD0) and the last day of lactation (LD21) (Group FLX). Control group (CTL) received a proportional volume of water. On the postnatal day 75 (PND75), male rats were euthanized and hippocampus, cortex, hypothalamus, and periaqueductal gray area (PAG) were removed. Global DNA methylation was quantified using a high-throughput ELISA-based method. In order to address neuro functional changes animals (PND75) were evaluated in the elevated plus maze and social interaction tests as well as submitted to repeated restraint stress. An increase in the global DNA methylation profile of hippocampus (p = 0.0399) was associated with the early exposure to FLX, whereas no significant change was observed in the hypothalamus (p = 0.6556), cortex (p = 0.9402) or PAG (p = 0.3822). Furthermore, early exposure to FLX was also associated with a reduction in the social interaction time (p = 0.0084) and to a decreased in the plasma corticosterone level when animals were submitted to the restraint stress (p < 0.0001). No significant change in the elevated plus maze test was associated with the early exposure to FLX. In summary, our data demonstrate that maternal exposure to FLX during gestation and lactation results in a long lasting impact on the DNA methylation of hippocampus, and affects the social behavior and the corticosterone response to stress.

Effects of chronic restraint stress on the global DNA methylation profile of rat lung cells: Modulation by physical exercise.

The potential of behavioral stress to affect epigenetic mechanisms of non-encephalic tissues is still underestimated. In the present study we evaluated the effects of chronic behavioral stress on the DNA methylation profile of rat lung cells. Furthermore, we evaluated the potential of physical exercise to modulate the changes evoked by behavioral stress in lung cells. Male Wistar rats were divided into four experimental groups: (1) animals submitted to chronic restraint stress (CRS) (ST group) during the period of the 67th-80th postnatal day (PND); (2) animals submitted to physical exercise (EX group) during the 53rd-79th PND; (3) animals submitted to swimming during the 53rd-79th PND and to CRS during the 67th-80th PND (EX-ST group); and (4) animals not submitted to stress or swimming protocols (CTL). Global DNA methylation was quantified using an ELISA-based approach and gene expression was evaluated by real time PCR. A decreased global DNA methylation profile was observed in the ST group, however physical exercise demonstrated protection of lung cells from this stress-related hypomethylation. Increased expression of the Dnmt1 gene was evidenced in the ST group, whereas physical exercise was shown to protect lung cells from this stress-related effect in the EX-ST group. Comparative analysis of the ST and EX groups revealed opposite effects on the expression of Dnmt3a and Dnmt3b; however, a stress-related increase in expression of Dnmt3a and Dnmt3b was not seen in the EX-ST group. Our data showed that behavioral stress induced significant changes in the DNA methylation profile of rat lung cells and that this could be modulated by physical exercise.