Luciana Taschetto Vey

Exercise modifies amphetamine relapse: Behavioral and oxidative markers in rats

Exercise has been reported to attenuate rewarding symptoms related to addictive drugs mainly by affecting the brain neuroplasticity and neurotransmission. In this study, we investigated the influence of physical exercise on the behavioral and enzymatic status related to drug relapse in rats. Animals were primarily treated with amphetamine (AMPH; 4.0 mg/kg, i.p.) or vehicle (C; NaCl 0.9% solution) in the conditioned place preference (CPP) paradigm for 14 days. Half of each experimental group was then submitted to swimming sessions (60 min/day, 5 days/week) for 5 weeks. Animals were re-exposed to AMPH- or vehicle-CPP paradigm for another 3 days, in order to observe drug relapse and anxiety-like symptoms, which were observed 24h after AMPH reconditioning in CPP, and elevated plus maze (EPM), respectively, and brain biochemical evaluations were carried out subsequently. While AMPH was related to place preference and anxiety, indicating drug addiction and abstinence symptoms, respectively, physical activity was able to prevent relapse symptoms after AMPH reconditioning, as observed through consecutive decreased CPP and anxiety-like symptoms. In addition, AMPH exposure increased reactive species (RS) generation and protein carbonyl (PC) levels together with decreased activity of catalase- and Na(+)K(+)-ATPase in hippocampus. On the other hand, while all AMPH-induced effects were prevented by physical activity, there was a negative correlation between PC levels (r=0.65; p<0.003) and CAT activity, and a positive correlation between RS generation and PC levels (r=0.54; r=0.52, p<0.05) with AMPH-CPP after exercise. These results indicate that exercise has a clear beneficial influence on the prevention of psychostimulant drug relapse.

Chronic consumption of trans fat can facilitate the development of hyperactive behavior in rats

In recent decades, the increased consumption of processed foods, which are rich in hydrogenated vegetable fat (HVF), has led to a decreased consumption of fish and oilseed, rich in omega-3 fatty acids. This eating habit provides an increased intake of trans fatty acids (TFA), which may be related to neuropsychiatric conditions, including inattention and hyperactivity. In this study, we evaluated the potential connection between prolonged trans fat consumption and development of hyperactivity-like symptoms in rats using different behavioral paradigms. Trans fat intake for 10 months (Experiment 1), as well as during pregnancy and lactation across two sequential generations of rats, (Experiment 4) induced active coping in the forced swimming task (FST). In addition, HVF supplementation was associated with increased locomotion before and after amphetamine (AMPH) administration (Experiment 2). Similarly, HVF supplementation during pregnancy and lactation were associated with increased locomotion in both young and adult rats (Experiment 3). Furthermore, trans fat intake across two sequential generations increased locomotor and exploratory activities following stressors (Experiment 4). From these results, we suggest that chronic consumption of trans fat is able to enhance impulsiveness and reactivity to novelty, facilitating hyperactive behaviors.

Cross-Generational trans Fat Consumption Favors Self-Administration of Amphetamine and Changes Molecular Expressions of BDNF, DAT, and D1/D2 Receptors in the Cortex and Hippocampus of Rats.

Amphetamine (AMPH) is an addictive psychostimulant drug whose use has been related to neurotoxicity. Experimentally, AMPH increases anxiety-like symptoms, showing addictive properties. In the last decades, the growing consumption of processed foods has provided an excess of saturated and trans fats in detriment of essential fatty acids, which may modify the lipid profile of brain membranes, thus modifying its permeability and dopaminergic neurotransmission. Here, we assessed the influence of brain incorporation of different fatty acids (FA) on AMPH self-administration. Three groups of young male rats were orally supplemented from weaning with a mixture of soybean oil (SO, rich in n-6 FA) and fish oil (FO, rich in n-3 FA), hydrogenated vegetable fat (HVF, rich in trans fatty acids—TFA), or water (control group). These animals were born from dams that were supplemented with the same fat from pregnancy to lactation. Anxiety-like symptoms and locomotor index were assessed in elevated plus maze and open-field (OF), respectively, while brain molecular expressions of dopaminergic receptors, dopamine transporter (DAT), and BDNF were determined in the cortex and hippocampus. HVF increased the frequency of AMPH self-administration and was associated with reinforcement and withdrawal signs as observed by increased anxiety-like symptoms. Contrarily, SO/FO decreased these parameters. Increased BDNF protein together with decreased DAT expression was observed in the hippocampus of HVF group. Based on these findings, our study points to a harmful influence of trans fats on drug addiction and craving symptoms, whose mechanism may be related to changes in the dopaminergic neurotransmission.

Maternal trans fat intake during pregnancy or lactation impairs memory and alters BDNF and TrkB levels in the hippocampus of adult offspring exposed to chronic mild stress

This study aimed to assess the influence of maternal dietary fat intake during pregnancy or lactation on memory of adult offspring after chronic mild stress (CMS) exposure. Female Wistar rats were supplemented daily with soybean oil/fish oil (SO/FO) or hydrogenated vegetable fat (HVF) by oral gavage (3.0g/kg body weight) during pregnancy or lactation. On post-natal day (PND) 60, half of the animals were exposed to CMS following behavioral assessments. While the adult offspring born under influence of SO/FO and HVF supplementations during pregnancy showed higher levels of n-3 and n-6 fatty acids (FA) series DHA and ARA metabolites, respectively, in the hippocampus, adult offspring born from supplemented dams during lactation showed higher levels of their precursors: ALA and LA. However, only HVF supplementation allowed TFA incorporation of adult offspring, and levels were higher in lactation period. Adult offspring born from dams supplemented with trans fat in both pregnancy and lactation showed short and long-term memory impairments before and after CMS. Furthermore, our study also showed higher memory impairment in offspring born from HVF-supplemented dams during lactation in comparison to pregnancy. BDNF expression was increased by stress exposure in offspring from both SO/FO- and HVF-supplemented dams during pregnancy. In addition, offspring from HVF-supplemented dams showed decreased TrkB expression in both supplemented periods, regardless of stress exposure. In conclusion, these findings show for the first time that the type of dietary FA as well as the period of brain development is able to change FA incorporation in brain neural membranes.

Trans fat intake across gestation and lactation increases morphine preference in females but not in male rats: Behavioral and biochemical parameters

The abuse of morphine has risen considerably in recent years, mainly due to the increase of its prescription in clinical medicine. Also, increased consumption of processed foods, rich in trans fatty acids (TFA), has caused concerns about human health. Thus, the aim of our study was to determine whether trans fat consumption in the perinatal period may affect preference for morphine in adolescent female and male rats. Dams were orally supplemented with water (C-control) or hydrogenated vegetable fat (HVF-rich in TFA) during gestation and lactation periods. On post-natal day 43, pups were exposed to morphine (4mg/kg i.p., for 4 days) and assessed in the conditioned place preference paradigm. Anxiety-like symptoms were assessed, and oxidative status of the brain was estimated by reactive species (RS) generation. Female rats with HVF supplementation showed increased morphine preference and less anxiety-like symptoms. Additionally, both male and female rats from HVF-supplementation showed increased RS generation in the ventral tegmental area, whose level was similar in morphine-conditioned female rats. RS generation was increased in the hippocampus of morphine-conditioned female rats, regardless of the supplementation of their dams. We may infer that gender is a predictive factor to opioid preference, since adolescent female rats showed more susceptibility to addiction than males. Furthermore, trans fat consumption across the perinatal period is able to modify parameters of opioid preference in female rats, possibly due to TFA incorporation in phospholipid membranes, modifying the endogenous opioid system and the oxidative status in brain areas related to drug addiction.

Stress during the gestational period modifies pups' emotionality parameters and favors preference for morphine in adolescent rats.

Experimental animal studies have shown that early life periods are highly vulnerable to environmental factors, which may exert prolonged impact on HPA axis function and on subsequent neurochemical and behavioral responses in adulthood. Here we evaluated the influence of environmental stressful situations in two different early life stages on stress-related behaviors, and morphine-conditioned place preference (CPP), which is indicative of addiction. While in the gestational stress (Gest-S) dams were exposed to daily sessions of chronic mild stress (CMS) for 2 weeks, in the postnatal stress (post-NS) the offspring were exposed daily to neonatal isolation from postnatal day (PND) 2 to PND 9 for 60 min. Animals exposed to post-NS showed lesser anxiety in different behavioral paradigms (elevated plus maze-EPM and defensive burying test-DBT) as well as increased exploratory behavior (open-field task-OFT), and no preference for morphine in CPP. In contrast, animals exposed to Gest-S showed increased corticosterone plasma levels together with anxiety symptoms and greater preference for morphine following three days of drug withdrawal. Our findings indicate that the gestational period is critical for stress, whose effects may be manifest throughout life. On the other hand, post-NS can trigger neuroadaptations able to overcome emotional consequences of early life. We hypothesized that Gest-S is able to modify responses to opioids along adulthood, which may facilitate development of addiction to these drugs.

Influence of Trans Fat on Skin Damage in First-Generation Rats Exposed to UV Radiation

The influence of trans fatty acids (TFA) on lipid profile, oxidative damage and mitochondrial function in the skin of rats exposed to ultraviolet radiation (UVR) was assessed. The first‐generation offspring of female Wistar rats supplemented from pregnancy with either soybean oil (C‐SO, rich in n–6 FA; control group) or hydrogenated vegetable fat (HVF, rich in TFA) were continued with the same supplements until adulthood, when half of each group was exposed to UVR for 12 weeks. The HVF group showed higher TFA cutaneous incorporation, increased protein carbonyl (PC) levels, decreased functionality of mitochondrial enzymes and antioxidant defenses of the skin. After UVR, the HVF group showed increased skin thickness and reactive species (RS) generation, with decreased skin antioxidant defenses. RS generation was positively correlated with skin thickness, wrinkles and PC levels. Once incorporated to skin, TFA make it more susceptible to developing UVR‐induced disorders.

Toxicological aspects of interesterified fat: Brain damages in rats

In recent years, interesterified fat (IF) has been used to replace hydrogenated vegetable fat (HVF), rich in trans isomers, being found in processed foods. Studies involving IF have shown deleterious influences on the metabolic system, similarly to HVF, whereas no studies regarding its influence on the central nervous system (CNS) were performed. Rats from first generation born and maintained under supplementation (3g/Kg, p.o.) of soybean-oil or IF until adulthood were assessed on memory, biochemical and molecular markers in the hippocampus. IF group showed higher saturated fatty acids and linoleic acid and lower docosahexaenoic acid incorporation in the hippocampus. In addition, IF supplementation impaired short and long-term memory, which were related to increased reactive species generation and protein carbonyl levels, decreased catalase activity, BDNF and TrkB levels in the hippocampus. To the best of our knowledge, this is the first study to show that lifelong IF consumption may be related to brain oxidative damage, memory impairments and neurotrophins modifications, which collectively may be present indifferent neurological disorders. In fact, the use of IF in foods was intended to avoid damage from HVF consumption; however this substitute should be urgently reviewed, since this fat can be as harmful as trans fat.

Neonatal tactile stimulation decreases depression-like and anxiety-like behaviors and potentiates sertraline action in young rats.

It is well known that events which occur in early life exert a significant influence on brain development, what can be reflected throughout adulthood. This study was carried out in order to assess the influence of neonatal tactile stimulation (TS) on behavioral and morphological responses related to depression‐like and anxiety‐like behaviors, assessed following the administration of sertraline (SERT), a selective serotonin re‐uptake inhibitor (SSRI). Male pups were submitted to daily TS, from postnatal day 8 (PND8) to postnatal day 14 (PND14), for 10 min every day. On PND50, adult animals were submitted to forced swimming training (15 min). On PND51, half of each experimental group (UH and TS) received a single sub‐therapeutic dose of sertraline (SER, 0.3 mg/kg body weight, i.p.) or its vehicle (C, control group). Thirty minutes after injection, depression‐like behaviors were quantified in forced swimming test (FST, for 5 min). On the following day, anxiety‐like behaviors were assessed in elevated plus maze (EPM), followed by biochemical assessments. TS per se increased swimming time, decreasing immobility time in FST. Besides, TS per se was able to increase frequency of head dipping and time spent in the open arms of EPM, resulting in decreased anxiety index. In addition, groups exposed to TS showed decreased plasma levels of corticosterone per se. Interestingly, while TS exposure significantly potentiated the antidepressant activity of a subtherapeutic dose of SERT, this drug was able to exacerbate TS‐induced anxiolytic activity, as observed in FST and EPM, respectively. Decreased plasma levels of both corticosterone and cortisol in animals exposed to TS and treated with SERT are able to confirm the interesting interaction between this neonatal handling and the antidepressant drug. From our results, we conclude that neonatal TS is able to exert beneficial influence on the ability to cope with stressful situations in adulthood, preventing depression and favorably modulating the action of antidepressant drugs.

Role of the adjunctive antimicrobial photodynamic therapy to periodontal treatment at plasmatic oxidative stress and vascular behavior

BACKGROUND To evaluate for the first time in vivo the effects of methylene blue (MB) photosensitizer dissolved in ethanol in antimicrobial photodynamic therapy (aPDT) as adjuvant periodontal treatment, at plasmatic oxidative stress and vascular behavior in rat model. METHODS Wistar rats were divided into negative control (NC, no periodontitis) and positive control (PC, with periodontitis, without any treatment). The other groups had periodontitis and were treated with scaling and root planing (SRP); SRP+aPDT+MB dissolved in water (aPDT I); SRP+aPDT+MB dissolved in ethanol (aPDT II). The periodontitis was induced by ligature at the mandibular right first molar. At 7/15/30days, rats were euthanized, the plasma was used to determine oxidative stress parameters and gingival tissue for histomorphometric analysis. RESULTS PC showed higher thiobarbituric acid reactive substances levels in 7/15/30days. aPDT II was able to block the lipid peroxidation, especially between 15th and 30th days. Glutathione reduced levels were consumed in PC, aPDT I and II groups throughout the experiment. aPDT II increased the vitamin C levels which were restored in this group in the 30th day. aPDT II group showed the highest number of blood vessels. CONCLUSION In summary, the aPDT with MB dissolved in ethanol provides better therapeutic responses in periodontitis treatment.