Tactile stimulation during different developmental periods modifies hippocampal BDNF and GR, affecting memory and behavior in adult rats.

Recent studies have shown that tactile stimulation (TS) in pups is able to prevent and/or minimize fear, anxiety behaviors, and addiction to psychostimulant drugs in adult rats. In these studies, animals have been exposed to handling from postnatal day (PND) 1-21. This study was designed to precisely establish which period of preweaning development has a greater influence of TS on neuronal development. After birth, male pups were exposed to TS from PND1-7, PND8-14, and PND15-21. In adulthood, the different periods of postnatal TS were assessed through behavioral, biochemical, and molecular assessments. Animals that received TS from PND8-14 showed lower anxiety-like symptoms, as observed by decreased anxiety index in elevated plus maze. This same TS period was able to improve rats' working memory by increasing the percentage of alternation rate in Y-maze, and induce better ability to cope with stressful situations, as showed in the defensive burying test by a reduced time of burying behavior. On the other hand, animals receiving TS in the first week of life showed longest cumulative burying time, which is directly related to increased anxiety-like behavior. Moreover, TS from PND8-14 showed lower corticosterone levels and better oxidative status, as observed by decreased lipid peroxidation and increased catalase activity in the hippocampus. Brain-derived neurotrophic factor (BDNF) immunocontent was increased in the hippocampus of animals receiving TS from PND8-14, while glucocorticoid receptors immunocontent was decreased in both TS1-7 and TS15-21 , but not TS8-14 . To the best of our knowledge, this study is the first to show TS can be more efficient if applied over a focused period of neonatal development (PND8-14) and this beneficial influence can be reflected on reduced emotionality and increased ability to address stressful situations in adulthood. © 2016 Wiley Periodicals, Inc.

Cross-generational trans fat intake modifies BDNF mRNA in the hippocampus: Impact on memory loss in a mania animal model.

Recently, we have described the influence of dietary fatty acids (FA) on mania-like behavior of first generation animals. Here, two sequential generations of female rats were supplemented with soybean oil (SO, rich in n-6 FA, control group), fish oil (FO, rich in n-3 FA) and hydrogenated vegetable fat (HVF, rich in trans FA) from pregnancy and during lactation. In adulthood, half of each group was exposed to an amphetamine (AMPH)-induced mania animal model for behavioral, biochemical and molecular assessments. FO supplementation was associated with lower reactive species (RS) generation and protein carbonyl (PC) levels and increased dopamine transporter (DAT) levels, while HVF increased RS and PC levels, thus decreasing catalase (CAT) activity and DAT levels in hippocampus after AMPH treatment. AMPH impaired short- (1 h) and long- (24 h) term memory in the HVF group. AMPH exposure was able to reduce hippocampal BDNF- mRNA expression, which was increased in FO. While HVF was related to higher trans FA (TFA) incorporation in hippocampus, FO was associated with increased percentage of n-3 polyunsaturated FA (PUFA) together with lower n-6/n-3 PUFA ratio. Interestingly, our data showed a positive correlation between brain-derived neurotrophic factor (BDNF) mRNA and short- and long-term memory (r(2) = 0.53; P = 0.000/r(2) = 0.32; P = 0.011, respectively), as well as a negative correlation between PC and DAT levels (r(2) = 0.23; P = 0.015). Our findings confirm that provision of n-3 or TFA during development over two generations is able to change the neuronal membrane lipid composition, protecting or impairing the hippocampus, respectively, thus affecting neurothrophic factor expression such as BDNF mRNA. In this context, chronic consumption of trans fats over two generations can facilitate the development of mania-like behavior, so leading to memory impairment and emotionality, which are related to neuropsychiatric conditions.

Neonatal handling prevents anxiety-like symptoms in rats exposed to chronic mild stress: behavioral and oxidative parameters.

This study investigated the influence of neonatal handling on behavioral and biochemical consequences of chronic mild stress (CMS) in adulthood. Male rat pups were submitted to daily tactile stimulation (TS) or maternal separation (MS), from postnatal day 1 (PND1) to postnatal day 21 (PND21), for 10 min/day. In adulthood, half the number of animals were exposed to CMS for 3 weeks and submitted to behavioral testing, including sucrose preference (SP), elevated plus maze (EPM), and defensive burying tasks (DBTs), followed by biochemical assessments. CMS reduced SP, increased anxiety in EPM and DBT, and increased adrenal weight. In addition, CMS decreased plasma vitamin C (VIT C) levels and increased protein carbonyl (PC) levels, catalase (CAT) activity in hippocampus and cortex, and superoxide dismutase (SOD) levels in cortex. In contrast, both forms of neonatal handling were able to prevent reduction in SP, anxiety behavior in DBT, and CMS-induced adrenal weight increase. Furthermore, they were also able to prevent plasma VIT C reduction, hippocampal PC levels increase, CAT activity increase in hippocampus and cortex, and SOD levels increase in cortex following CMS. Only TS was able to prevent CMS-induced anxiety symptoms in EPM and PC levels in cortex. Taken together, these findings show the protective role of neonatal handling, especially TS, which may enhance ability to cope with stressful situations in adulthood.

Substitution therapy with amphetamine-isotherapic attenuates amphetamine toxicological aspects of addiction.

INTRODUCTION: amphetamine (AMPH) is related to development of addiction, anxiety-like behaviors and impairments of memory after chronic use. In the current experiment, an ultra-high dilution (10-24mg/mL) of AMPH was used, consisting of the AMPH isotherapic (AMPH-ISO), which can be used as a replacement therapy to treat AMPH addiction. AIM: To verify the influence of AMPH-ISO on toxicological aspects of AMPH addiction. METHODS: Rats received d,l-AMPH (4.0 mg/kg, i.p.) in the conditioned place preference (CPP) paradigm (8 days). Then, half of each experimental group (AMPH or saline) received AMPH-ISO/vehicle (0.2 mL per rat, once a day), for fourteen days. On the fifteenth day, animals were re-assessed in the CPP paradigm (to verify relapse behaviors) after a single dose of AMPH (2.0 mg/kg). Subsequently, anxiety-like behaviors were quantified, followed by ex vivo assays in the pre-frontal cortex. RESULTS: AMPH-ISO prevented relapse-like behavior of AMPH and reduced anxiety-like behavior per se in animals co-treated with AMPH. Molecular analysis evidenced that AMPH-ISO modulated dopaminergic targets (dopamine transporter, tyrosine hydroxylase and D1-R), whose immunoreactivity was increased by AMPH. Also, AMPH-ISO increased catalase activity and NPSH levels and reduced lipid peroxidation and protein carbonyl levels in the prefrontal cortex. CONCLUSION: This study shows that an ultra-high dilution of AMPH may be a useful alternative which can contribute with AMPH addiction treatment.

Toxicological aspects of the interesterified-fat from processed foods: Influences on opioid system and its reward effects in rats.

Considering the high consumption of processed foods, interesterified fat (IF) has been used to replace trans fat, since it may harm nervous system functions. Opioids are intensely used to alleviate pain, and have a highly addictive potential. Therefore, their improper use is related to addiction, tolerance, and withdrawal syndrome. Wistar rats received soybean oil (SO) or IF during gestation, lactation and post-weaning until pups' adolescence. On post-natal day 39, animals received morphine (4 mg/kg i.p.) in the conditioned place preference (CPP) paradigm. SO group showed morphine preference during drug withdrawal, while IF group showed no preference or withdrawal symptoms, but higher sensitivity to thermal stimuli than SO group. Morphine contidioning increased dopamine 1 receptor (D1R) and NMDAR: N-methyl-d-aspartate receptor (NMDAR) immunoreactivity in the hippocampus of SO, whereas these molecular changes were not observed in IF group. Regardless of morphine conditioning, IF group showed increased Kappa opioid receptor (KOR) immunoreactivity in the spinal cord, evidencing a negative correlation with thermal sensitivity. The chronic consumption of IF-rich foods during earlier periods of life may affect opioid neurotransmission, resulting in loss of rewarding effects related to this system.

Lifelong consumption of trans fatty acids promotes striatal impairments on Na(+)/K(+) ATPase activity and BDNF mRNA expression in an animal model of mania.

PURPOSE: To evaluate the toxicity of chronic consumption of processed foods that are rich in trans fat on the lipid composition of brain membranes, as well as its functional repercussions. METHODS: A second generation of male rats born from mothers and grandmothers supplemented with soybean oil (SOC, an isocaloric control group) or hydrogenated vegetable fat (HVF, rich in TFA) (3g/kg; p.o.) were kept under oral treatment until 90 days of age, when they were exposed to an AMPH-induced model of mania. RESULTS: The HVF group presented 0.38% of TFA incorporation in the striatum, affecting Na(+)/K(+) ATPase activity, which was decreased per se and following AMPH-exposure. The HVF group also showed increased protein carbonyl (PC) and brain-derived neurotrophic factor (BDNF) mRNA levels after AMPH administration, while these oxidative and molecular changes were not observed in the other experimental groups. Additionally, a negative correlation between striatal Na(+)/K(+) ATPase activity and PC levels (r(2)=0.49) was observed. CONCLUSION: The prolonged consumption of trans fat allows TFA incorporation and increases striatal oxidative status, thus impairing the functionality of Na(+)/K(+)-ATPase and affecting molecular targets as BDNF mRNA. We hypothesized that the chronic intake of processed foods (rich in TFA) facilitates the development of neuropsychiatric diseases, particularly bipolar disorder.

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.

Influence of neonatal tactile stimulation on amphetamine preference in young rats: parameters of addiction and oxidative stress.

This study investigated the influence of neonatal handling on amphetamine-induced conditioned place preference (CPP), as well as the consequent anxiety-like symptoms and oxidative status related to drug abstinence in young rats. Male pups were exposed to tactile stimulation (TS) or neonatal isolation (NI) for 10 min every day from postnatal day one (PND1) to PND21. After being weaned (PND22), pups were separated by handling type until PND40, when treatment with amphetamine (AMPH-4 mg/kg/mL ip, for 8 days) or vehicle (NaCl 0.9% ip, 1 mL/Kg) in CPP started. AMPH-conditioning evoked drug-preference (in 24h and 96 h) and abstinence symptoms in unhandled (UH) animals, followed by oxidative damage in the cortex, hippocampus and striatum. TS showed beneficial influence, as observed by the decreased drug-preference (24 and 96 h) in relation to UH and NI, showing no abstinence symptoms in this last period, as observed by the reduced anxiety-like symptoms. The oxidative status indicated a protective influence of TS on brain tissues: lower lipid peroxidation (LP) and reduced protein carbonylation (PC) in the cortex, hippocampus and striatum. Furthermore, TS also increased antioxidant defenses in brain tissues and blood: i) increased plasma levels of vitamin C; ii) increased activity of catalase (CAT) and iii) higher levels of glutathione (GSH) in red blood cells (RBC). Moreover, there were positive correlations of AMPH-CPP with PC and LP levels in all the brain areas assessed. In summary, TS modifies AMPH-preference in the CPP paradigm, reducing drug abstinence behaviors, and stimulating the antioxidant defense system, thus protecting the brain areas closely related to addiction in young rats. Studies about TS and addiction in animal models should be extended to the molecular level.

Tactile stimulation and neonatal isolation affect behavior and oxidative status linked to cocaine administration in young rats.

We investigated the influence of neonatal handling on cocaine-induced conditioned place preference (CPP), anxiety-like symptoms and oxidative status related to drug abstinence in young rats. Pups were submitted to tactile stimulation (TS) or neonatal isolation (NI10 or NI60) after birth, and then were submitted to CPP performed with cocaine. TS group did not show place preference, while unhandled (UH), NI10 and NI60 rats did. Handling was related to anxiety-like symptoms per se in UH and NI60 groups and this behavior was also observed in the cocaine-conditioned rats exposed to the same handlings. Both TS and NI10 pups treated or not with cocaine showed less anxiety-like behavior than animals submitted to other handlings. TS reduced protein carbonyl (PC) in cortex and NI60 increased PC in both striatum and hippocampus of cocaine-treated rats. Among cocaine-treated rats, both times of NI increased plasma lipoperoxidation levels, which was reduced by TS in erythrocytes. TS increased the catalase activity in brain areas, while other handlings did not change this. Both TS and NI10 increased plasma vitamin C levels. These findings indicate that neonatal handling can modify anxiety-like symptoms related to cocaine preference and abstinence, and its protective influence, especially TS, on the antioxidant system.

Influence of trans fat and omega-3 on the preference of psychostimulant drugs in the first generation of young rats.

The current Western diet often provides considerable amounts of saturated and trans fatty acids (TFA), whose incorporation into neuronal membranes has been implicated in changes of brain neurochemical functions. Such influence has caused concerns due to precipitation of neuropsychiatric disorders, whose data are still unclear. Here we evaluated the influence of different fats on preference parameters for amphetamine (AMPH): adolescent rats were orally supplemented with soybean oil (SO, rich in n-6 FA, which was considered an isocaloric control group), fish oil (FO, rich in n-3 FA) and hydrogenated vegetable fat (HVF, rich in saturated and trans FA) from weaning, which were born of dams supplemented with the same fat from pregnancy and lactation. AMPH preference, anxiety-like symptoms and locomotor index were evaluated in conditioned place preference (CPP), elevated plus maze (EPM) and open-field (OF), respectively, while brain oxidative status was determined in cortex, striatum and hippocampus. HVF increased AMPH-CPP and was associated with withdrawal signs, as observed by increased anxiety-like symptoms. Moreover, SO and FO were not associated with AMPH preference, but only FO-supplemented rats did not show any anxiety-like symptoms or increased locomotion. FO supplementation was related to lower oxidative damages to proteins and increased CAT activity in striatum and hippocampus, as well as increased GSH levels in blood, while HVF was related to increased oxidative status. In conclusion, our study showed the harmful influence of TFA on AMPH-CPP and drug craving symptoms, which can be related to dopaminergic neurotransmission.

Aqueous extract of pecan nut shell (Carya illinoensis [Wangenh.] K. Koch) exerts protection against oxidative damage induced by cyclophosphamide in rat testis.

This study investigated the protective effect of pecan nut (Carya illinoensis) shell aqueous extract (AE) on the oxidative and morphological status of rat testis treated with cyclophosphamide (CP). Wistar rats received water or AE (5%) ad libitum for 37 days. On day 30, half of each group received a single intraperitoneal administration of vehicle or CP 200 mg/kg. After 7 days, the animals were killed and their testis removed. Rats treated with CP presented reduced levels of lactate dehydrogenase, vitamin C, and gluthatione, as well as decreased catalase activity, increased lipid peroxidation levels and superoxide dismutase activity, no alteration in carbonyl protein levels, and a loss of morphological testicular integrity. In contrast, cotreatment with pecan shell AE totally prevented the decrease of lactate dehydrogenase and vitamin C levels and catalase activity and partially prevented the depletion of gluthatione levels. Moreover, it totally prevented the increase in superoxide dismutase activity and lipid peroxidation levels and maintained testicular integrity. These findings show the protective role of pecan shell AE in CP-induced testicular toxicity. The use of this phytotherapy may be considered to minimize deleterious effects related to this chemotherapy.

Neonatal tactile stimulation changes anxiety-like behavior and improves responsiveness of rats to diazepam.

In this study we evaluated the influence of neonatal tactile stimulation (TS) on behavioral and biochemical effects related to a low dose of diazepam (DZP) in adult rats. Male pups of Wistar rats were handled (TS) daily from PND1 to PND21 for 10 min, while unhandled (UH) rats were not touched. In adulthood, half the animals of each group received a single administration of diazepam (0.25mg/kg body weight i.p.) or vehicle and then were submitted to behavioral and biochemical evaluations. In the TS group, DZP administration reduced anxiety-like symptoms in different behavioral paradigms (elevated plus maze, EPM; staircase and open-field and defensive burying) and increased exploratory behavior. These findings show that neonatal TS increased DZP pharmacological responses in adulthood compared to neonatally UH animals, as observed by reduced anxiety-like symptoms and lower levels of plasma cortisol. TS also changed plasma levels of antioxidant defenses such as vitamin C and glutathione peroxidase, whose increase may be involved in lower oxidative damages to proteins in cortex, subthalamic region and hippocampus of these animals. Here we are showing for the first time that neonatal TS is able to change responsiveness to benzodiazepine drugs in adulthood and provides better pharmacological responses in novel situations of stress.

Comparative study between n-6, trans and n-3 fatty acids on repeated amphetamine exposure: a possible factor for the development of mania.

In the last decades, foods rich in omega-3 (ω-3) fatty acids (FA) have been replaced by omega-6 (ω-6) and trans FA, which are found in processed foods. The influence of ω-6 (soybean oil--SO), trans (hydrogenated vegetable fat--HVF) and ω-3 (fish oil--FO) fatty acids on locomotor and oxidative stress (OS) parameters were studied in an animal model of mania. Rats orally fed with SO, HVF and FO for 8 weeks received daily injections of amphetamine (AMPH--4 mg/kg/mL-ip) for the last week of oral supplementation. HVF induced hyperactivity, increased the protein carbonyl levels in the cortex and decreased the mitochondrial viability in cortex and striatum. AMPH-treatment increased the locomotion and decreased the mitochondrial viability in all groups, but its neurotoxicity was higher in the HVF group. Similarly, AMPH administration increased the protein carbonyl levels in striatum and cortex of HVF-supplemented rats. AMPH reduced the vitamin-C plasmatic levels of SO and HVF-fed rats, whereas no change was observed in the FO group. Our findings suggest that trans fatty acids increased the oxidative damage per se and exacerbated the AMPH-induced effects. The impact of trans fatty acids consumption on neuronal diseases and its consequences in brain functions must be further evaluated.