Anderson Apolonio Pedroza

Effect of fluoxetine treatment on mitochondrial bioenergetics in central and peripheral rat tissues

Recent investigations have focused on the mitochondrion as a direct drug target in the treatment of metabolic diseases (obesity, metabolic syndrome). Relatively few studies, however, have explicitly investigated whether drug therapies aimed at changing behavior by altering central nervous system (CNS) function affect mitochondrial bioenergetics, and none has explored their effect during early neonatal development. The present study was designed to evaluate the effects of chronic treatment of newborn male rats with the selective serotonin reuptake inhibitor fluoxetine on the mitochondrial bioenergetics of the hypothalamus and skeletal muscle during the critical nursing period of development. Male Wistar rat pups received either fluoxetine (Fx group) or vehicle solution (Ct group) from the day of birth until 21 days of age. At 60 days of age, mitochondrial bioenergetics were evaluated. The Fx group showed increased oxygen consumption in several different respiratory states and reduced production of reactive oxygen species, but there was no change in mitochondrial permeability transition pore opening or oxidative stress in either the hypothalamus or skeletal muscle. We observed an increase in glutathione S-transferase activity only in the hypothalamus of the Fx group. Taken together, our results suggest that chronic exposure to fluoxetine during the nursing phase of early rat development results in a positive modulation of mitochondrial respiration in the hypothalamus and skeletal muscle that persists into adulthood. Such long-lasting alterations in mitochondrial activity in the CNS, especially in areas regulating appetite, may contribute to permanent changes in energy balance in treated animals.

Mitochondrial bioenergetics and oxidative status disruption in brainstem of weaned rats: Immediate response to maternal protein restriction.

Mitochondrial bioenergetics dysfunction has been postulated as an important mechanism associated to a number of cardiovascular diseases in adulthood. One of the hypotheses is that this is caused by the metabolic challenge generated by the mismatch between prenatal predicted and postnatal reality. Perinatal low-protein diet produces several effects that are manifested in the adult animal, including altered sympathetic tone, increased arterial blood pressure and oxidative stress in the brainstem. The majority of the studies related to nutritional programming postulates that the increased risk levels for non-communicable diseases are associated with the incompatibility between prenatal and postnatal environment. However, little is known about the immediate effects of maternal protein restriction on the offsprings brainstem. The present study aimed to test the hypothesis that a maternal low-protein diet causes tissue damage immediately after exposure to the nutritional insult that can be assessed in the brainstem of weaned offspring. In this regard, a series of assays was conducted to measure the mitochondrial bioenergetics and oxidative stress biomarkers in the brainstem, which is the brain structure responsible for the autonomic cardiovascular control. Pregnant Wistar rats were fed ad libitum with normoprotein (NP; 17% casein) or low-protein (LP; 8% casein) diet throughout pregnancy and lactation periods. At weaning, the male offsprings were euthanized and the brainstem was quickly removed to assess the mitochondria function, reactive oxygen species (ROS) production, mitochondrial membrane electric potential (ΔΨm), oxidative biomarkers, antioxidant defense and redox status. Our data demonstrated that perinatal LP diet induces an immediate mitochondrial dysfunction. Furthermore, the protein restriction induced a marked increase in ROS production, with a decrease in antioxidant defense and redox status. Altogether, our findings suggest that LP-fed animals may be at a higher risk for oxidative metabolism impairment throughout life than NP-fed rats, due to the immediate disruption of the mitochondrial bioenergetics and oxidative status caused by the LP diet.

Neonatal SSRI exposure improves mitochondrial function and antioxidant defense in rat heart

Protein restriction during prenatal, postnatal, or in both periods has a close relationship with subsequent development of cardiovascular disease in adulthood. Elevated brain levels of serotonin and its metabolites have been found in malnourished states. The aim in the present study was to investigate whether treatment with fluoxetine (Fx), a selective serotonin reuptake inhibitor, mimics the detrimental effect of low-protein diet during the perinatal period on the male rat heart. Our hypothesis is that increased circulating serotonin as a result of pharmacologic treatment with Fx leads to cardiac dysfunction similar to that observed in protein-restricted rats. Male Wistar rat pups received daily subcutaneous injection of Fx or vehicle from postnatal day 1 to postnatal day 21. Male rats were euthanized at 60 days of age and the following parameters were evaluated in the cardiac tissue: mitochondrial respiratory capacity, respiratory control ratio, reactive oxygen species (ROS) production, mitochondrial membrane potential, and biomarkers of oxidative stress and antioxidant defense. We found that Fx treatment increased mitochondrial respiratory capacity (123%) and membrane potential (212%) and decreased ROS production (55%). In addition we observed an increase in the antioxidant capacity (elevation in catalase activity (5-fold) and glutathione peroxidase (4.6-fold)). Taken together, our results suggest that Fx treatment in the developmental period positively affects the mitochondrial bioenergetics and antioxidant defense in the cardiac tissue.

Serotonin modulation in neonatal age does not impair cardiovascular physiology in adult female rats: Hemodynamics and oxidative stress analysis.

AIMS The present study investigates the effects of neonatal serotonin modulation in female rats on cardiac parameters related to hemodynamics and oxidative metabolism in the mature animal. MAIN METHODS Female Wistar rat pups were administered daily subcutaneous injections of fluoxetine (Fx-treated group) or vehicle solution (Ct-group) from the 1st to 21st day of life. At 60days of age, animals from both groups were either used for cardiovascular evaluation or sacrificed for tissue collection for biochemical assays. KEY FINDINGS We found that body weight in the Fx-treated group was less than that in the control. When analyzing hemodynamic parameters (i.e., arterial blood pressure, heart rate-HR, sympathetic and vagal tonus, or intrinsic HR), we did not observe significant difference in the Fx-treated group. Evaluating oxidative stress in brainstem and heart by measuring carbonyl content and malondialdehyde-MDA formation, we observe a decrease in carbonyl content only in the Fx-treated group (60.3%, in brainstem; 58.2%, in heart), without difference in the MDA levels. This observation is consonant with an increase in superoxide dismutase-SOD and catalase-CAT activity in brainstem and heart in the Fx-treated group (SOD: 82.7% and CAT: 23.7 in brainstem; SOD: 60.6%, and CAT: 40.7 in heart), with no changes in glutathione S-transferase activity and reduced glutathione levels. With regard to oxidative metabolism markers, citrate synthase activity was higher in brainstem in the Fx-treated group (20%). SIGNIFICANCE Our data suggest that serotonin modulation by Fx-treatment at an early age does not induce hemodynamic alteration, although it modulates oxidative metabolism in cardiac-related tissues.

Can fish oil supplementation and physical training improve oxidative metabolism in aged rat hearts

AIMS It is well known that in the aging process a variety of physiological functions such as cardiac physiology and energy metabolism decline. Imbalance in production and elimination of reactive oxygen species (ROS) may induce oxidative stress. Research shows that oxidative stress is an important factor in the aging process. Studies suggest that ɷ-3 polyunsaturated fatty acids (PUFAs) and moderate physical exercise modulate the ROS system. Therefore, the present study aimed to investigate whether ɷ-3 present in fish oil supplementation coupled with moderate physical training could improve antioxidant and metabolic enzymes in the hearts of adult and aged rats and, if these effects could be associated to glycemia, plasma lipid profile or murinometric parameters. MAIN METHODS Adult (weighing 315.1±9.3g) and aged rats (weighing 444.5±11.8g) exercised and receive fish oil supplementation for 4weeks. Then they were used to evaluate murinometric parameters, fasting glucose and lipid profile. After this, their hearts were collected to measure the levels of malondialdehyde (MDA), antioxidant enzyme activity (superoxide dismutase-SOD, catalase-CAT, glutathione peroxidase-GPx) and oxidative metabolism marker (citrate synthase-CS activity). KEY FINDINGS Fish oil supplementation increases HDL concentration and activity of CAT and CS. Moreover, physical training coupled with fish oil supplementation induces additional effects on SOD, GPx and CS activity mainly in aged rats. SIGNIFICANCE Our data suggest that combined treatment in aged rat hearts improves the antioxidant capacities and metabolic enzyme that can prevent the deleterious effects of aging.

Maternal low-protein diet in female rat heart: possible protective effect of estradiol.

Several studies have shown that maternal low-protein (LP) diet induces detrimental effects in cardiovascular system and oxidative stress in male animals. Additional studies suggested that female has lower incidence of cardiovascular disease. However until present data, the possible effects of estradiol on the undernutrition during gestational and lactation periods are not discussed. The present study was conducted to evaluate the effects of a maternal LP diet during gestational and lactation period on oxidative balance in the female rat hearts ventricles at two ages. Dams were fed with normal protein (NP) or a LP diet during the gestational and lactation period, and their female offspring were divided into age groups (22 or 122 days, corresponding to a low or high estrogen level) composing four experimental groups. Evaluating the nutritional effect showed an increase in oxidative stress biomarkers and decrease in enzymatic defense in LP-22D compared with NP-22D. In contrast, no changes were observed in malondialdehyde and carbonyls, but an increase in glutathione-S-transferase (GST) activity in the LP-122D compared with NP-122D. The global oxy-score in the LP-22D group indicated a predominance of oxidative damage when compared with NP-22D, while in LP-122D group the global oxy-score was restored to NP-122D levels. Evaluating the estradiol effect, our data show a significant decrease in oxidative stress with increase in CAT and GST activity, associated with increase in intracellular thiols. Our data suggest that in situation with low levels of estradiol, hypoproteic diet during gestation and lactation period has detrimental effects on heart, however when estradiol levels raise, the detrimental effects induced are mitigated.

Body composition, biochemical, behavioral and molecular alterations in overfed rats after chronic exposure to SSRI

&NA; Serotonin (5‐HT) plays a regulatory role in coordinating the neural circuits regulating energy balance, with differences in both 5‐HT availability at the synapse and the activity of 5‐HT receptors mediating anorectic (via POMC/CART activation) and orexigenic (via NPY/AgRP activation) responses. In conditions of overweight and obesity the control of energy balance is clearly deregulated, and serotonergic modulation appears to make a significant contribution to weight gain. Fluoxetine (FLX), a selective serotonin reuptake inhibitor (SSRI) that increases 5‐HT availability in the synaptic cleft may thus have potential effects on energy balance. Our aim was to use an overfeeding model to investigate the effects of chronic FLX treatment on energy balance‐related parameters regulated by hypothalamic neuropeptides. Nursing male Wistar rats were assigned to normofed (9 pups/dam) or overfed (3 pups/dam) groups beginning at 3 days of age and continuing until 21 days of age, when commercial chow and water were made available ad libitum until experimental treatments were begun. From 39 through 59 days of age groups were divided according to pharmacological treatment: 1) NV group, normofed + vehicle solution (NaCl 0.9%, 10 ml/kg b.w.), 2) NF group, normofed + FLX (10 mg/kg b.w., in vehicle solution, 10 ml/kg b.w.) 3), OV, overfed + vehicle solution and 4) OF, overfed + FLX. At 60 days of age, body weight, white and brown adipose tissue content, and food intake were determined, and serum biochemical parameters and hypothalamic neuropeptide gene expression were measured. Results showed that FLX induced reductions in several murinometric indices, improvement of adipose profile, hypophagic behavior, reduction in serum parameters, and positive modulation of hypophagia‐related genes. These data suggest that the beneficial effects of FLX‐treatment on overfeeding‐induced physical and behavioral effects in rats was due to hypothalamic alterations that led to improvement in energy balance in animals with a compromised metabolism. HighlightsFluoxetine treatment altered the pattern of fat mass in overfed rats.Overfed but not normofed rats reduced food intake after chronic fluoxetine exposure.Fluoxetine‐treated overfed rats improved energy balance‐related gene expression.

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.

Effect of moderate exercise on peritoneal neutrophils from juvenile rats

Previous studies showed that moderate exercise in adult rats enhances neutrophil function, although no studies were performed in juvenile rats. We evaluated the effects of moderate exercise on the neutrophil function in juvenile rats. Viability and neutrophils function were evaluated. Moderate exercise did not impair the viability and mitochondrial transmembrane potential of neutrophils, whereas there was greater reactive oxygen species production (164%; p < 0.001) and phagocytic capacity (29%; p < 0.05). Our results suggest that moderate exercise in juvenile rats improves neutrophil function, similar to adults.