Effects of perinatal protein restriction on the oxidative balance in the hypothalamus of 60-day-old rats / Efeitos da restrição proteica perinatal sobre o balanço oxidativo no hipotálamo de ratos de 60 dias de idade

ABSTRACT Objective Evaluate the effects of maternal low-protein diet on the oxidative stress in the hypothalamus of 60-day-old rats. Methods Male Wistar rats were divided into two experimental groups according to the mother's diet during pregnancy and lactation; control group (NP:17% casein n=6) and a malnourished group (LP:8% casein n=6). At 60 days of life, the rats were sacrificed for the collection of the hypothalamus for further biochemical analysis. Results Our results showed an increase in oxidative stress in malnourished group, observed through an increase in carbonyl content (p=0.0357), a reduction in the activity of the glutathione-S-transferase enzyme (p=0.0257), and a reduction in the non-enzymatic antioxidant capacity evidenced by the decrease in the ratio reduced glutathione/oxidized glutathione (p=0.0406) and total thiol levels (p=0.0166). Conclusion A low-protein diet during pregnancy and lactation is closely associated with increased oxidative stress and reduced antioxidant capacity in the hypothalamus of sixty-day-old rats.

RESUMO Objetivo Avaliar os efeitos da restrição proteica materna sobre o estresse oxidativo no hipotálamo de ratos de 60 dias de idade. Métodos Ratos Wistar machos foram divididos em dois grupos experimentais de acordo com a dieta da mãe durante a gestação e lactação: grupo controle (NP: 17% caseína n=6) e grupo desnutrido (LP: 8% caseína n=6). Aos 60 dias de vida, os ratos foram sacrificados para coleta do hipotálamo para posterior análise bioquímica. Resultados Os resultados demonstraram aumento do estresse oxidativo no grupo desnutrido, observado através do aumento do conteúdo de cabonilas (p=0,0357) e redução da atividade da enzima glutationa-S-transferase (p=0,0257) e da capacidade antioxidante não enzimática, evidenciada pela queda da razão glutationa reduzida/glutationa oxidada (p=0,0406) e dos níveis de tióis totais (p=0,0166). Conclusão Uma dieta com baixo teor de proteínas durante a gestação e lactação está intimamente associada ao aumento do estresse oxidativo e à redução da capacidade antioxidante no hipotálamo de ratos de 60 dias de vida.

Fluoxetine administration in juvenile overfed rats improves hypothalamic mitochondrial respiration and REDOX status and induces mitochondrial biogenesis transcriptional expression.

Nutritional imbalance in early life may disrupt the hypothalamic control of energy homeostasis and increase the risk of metabolic disease. The hypothalamic serotonin (5-hydroxytryptamine; 5-HT) system based in the hypothalamus plays an important role in the homeostatic control of energy balance, however the mechanisms underlying the regulation of energy metabolism by 5-HT remain poorly described. Several crucial mitochondrial functions are altered by mitochondrial stress. Adaptations to this stress include changes in mitochondrial multiplication (i.e, mitochondrial biogenesis). Due to the scarcity of evidence regarding the effects of serotonin reuptake inhibitors (SSRI) such as fluoxetine (FLX) on mitochondrial function, we sought to investigate the potential contribution of FLX on changes in mitochondrial function and biogenesis occurring in overfed rats. Using a neonatal overfeeding model, male Wistar rats were divided into 4 groups between 39 and 59 days of age based on nutrition and FLX administration: normofed + vehicle (NV), normofed + FLX (NF), overfed + vehicle (OV) and overfed + FLX (OF). We found that neonatal overfeeding impaired mitochondrial respiration and increased oxidative stress biomarkers in the hypothalamus. FLX administration in overfed rats reestablished mitochondrial oxygen consumption, increased mitochondrial uncoupling protein 2 (Ucp2) expression, reduced total reactive species (RS) production and oxidative stress biomarkers, and up-regulated mitochondrial biogenesis-related genes. Taken together our results suggest that FLX administration in overfed rats improves mitochondrial respiratory chain activity and oxidative balance and increases the transcription of genes employed in mitochondrial biogenesis favoring mitochondrial energy efficiency in response to early nutritional imbalance.

Serotonin transporter inhibition during neonatal period induces sex-dependent effects on mitochondrial bioenergetics in the rat brainstem.

The serotonin reuptake is mainly regulated by the serotonin transporters (SERTs), which are abundantly found in the raphe nuclei, located in the brainstem. Previous studies have shown that dysfunction in the SERT has been associated with several disorders, including depression and cardiovascular diseases. In this manuscript, we aimed to investigate how gender and the treatment with a serotonin selective reuptake inhibitor (SSRI) could affect mitochondrial bioenergetics and oxidative stress in the brainstem of male and female rats. Fluoxetine, our chosen SSRI, was used during the neonatal period (i.e., from postnatal Day 1 to postnatal Day 21-PND1 to PND21) in both male and female animals. Thereafter, experiments were conducted in adult rats (60 days old). Our results demonstrate that, during lactation, fluoxetine treatment modulates the mitochondrial bioenergetics in a sex-dependent manner, such as improving male mitochondrial function and female antioxidant capacity.