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- Prenatal exposure to cocaine and enriched environmentPublication . Magalhães, Ana; Summavielle, Teresa; Melo, Pedro; Rosa, Rui; Tavares, Maria Amélia; Sousa, Liliana deExposure to cocaine throughout gestation may produce several deleterious outcomes in the offspring that include effects on neurotransmitter systems and structure of the central nervous system. Such changes are most likely correlated with behavioral alterations. Environmental enrichment (EE) in early stages is a factor that affects structural and behavioral development. This article examines the effects, upon social interactions, of EE during the first month of life in rats prenatally exposed to cocaine. Wistar dams were subcutaneously exposed to 60 mg/kg of cocaine divided in two daily doses from gestational day (GD)8 to GD22. Pair-fed controls were given saline vehicle in the same protocol. Offspring were distributed to the different environments in four experimental groups. Group 1: offspring from dams prenatally exposed to cocaine as previously described and reared in EE from postnatal day (PND)1 to PND28; Group 2: pups from cocaine-exposed dams and reared in a standard environment (SE); Group 3: pups from pair-fed saline-exposed dams and reared in EE; Group 4: offspring from saline-exposed dams and reared in SE. On PND21, 24, and 28, rats were examined in several social behavioral categories (play fighting, social investigation, comfort behaviors, and solicitation to play) for 10 min. Animals reared in SE do not display any differences due to treatment in the behavioral categories analyzed. Control offspring reared in EE presented decreased play fighting, decreased solicitation to play, and decreased social investigation compared to the control SE group, while cocaine-exposed animals reared in EE did not present these variations. These results suggest that EE rearing may unmask hidden effects of prenatal cocaine exposure.
- Effects of embryonic exposure to venlafaxine on a zebrafish modelPublication . Barros, Eduarda; Abreu, Isabel; Guimarães, Laura; Melo, PedroMajor depressive disorder affects over 350 million people around the world, and might result from a complex interaction of epigenetic, genetic, environmental and developmental factors. Antidepressants are a class of neuroactive compounds that are used mostly in the treatment of clinically severe mood and anxiety disorders, and can be divided into three major classes: tricyclic antidepressants, monoamine oxidase inhibitors and selective serotonin reuptake inhibitors. The boost on antidepressants’ prescription and consumption is related to an increase in the prevalence of psychiatric disorders and knowledge of mental health problems. These are considered emerging pollutants due to their omnipresence at trace levels in the environment. Nonetheless, the lack of knowledge concerning their impact on the environment, and consequently on aquatic species, highlights this topic as a pivotal concern. Even in low concentrations, antidepressants may cause several effects on the aquatic environment as a result of disturbing homeostasis throughout the central and peripheral nervous systems, both in vertebrates and in vertebrates, and by modifying the regulation of neurotransmitters such as serotonin, norepinephrine and dopamine. Zebrafish (Danio rerio), an aquatic vertebrate species, is one of the most important model organisms in developmental biology, considered extremely valuable for the study of translational neuroscience of complex human brain disorders, being particularly useful for studying genetic and pharmacological mechanisms of depression and antidepressant action.
- Ketamine alone or combined with midazolam or dexmedetomidine does not affect anxiety-like behaviours and memory in adult Wistar ratsPublication . Magalhães, Ana; Valentim, Ana; Venâncio, Carlos; Pereira, Mariana; Melo, Pedro; Summavielle, Teresa; Antunes, LuisKetamine administration has been associated with controversial behavioural impairments and psychotic episodes. Even though ketamine alone and in combination with midazolam or dexmedetomidine are frequently used in laboratory animals, the side-effects of such protocols are not well known. Therefore, our aim was to evaluate the effects of ketamine alone and in combination with midazolam or dexmedetomidine on emotional reactivity, as well as the effects on learning and memory in adult rats at least 48 h after anaesthesia. The evaluation of the potential influence of 100 mg/kg ketamine administered alone and in combination with midazolam (5 mg/kg), or dexmedetomidine (0.25 mg/kg) on spatial learning and recognition memory was studied in adult Wistar rats using the radial maze as well as object recognition and location tests. The influence of these combinations on emotional reactivity was investigated using the new exploration test and the elevated plus maze. Results showed that ketamine alone or in combination with midazolam or dexmedetomidine affected neither spatial and recognition memory, nor emotional reactivity. These results reinforce the safe clinical use of ketamine and its combinations in rats in a research context since the administration of these anaesthetic combinations did not produce significant changes with regard to spatial and recognition memory or emotional reactivity. Furthermore, these results indicate that the quality of scientific data produced in adult rat neurobehavioural research is not jeopardized by the use of these anaesthetic protocols.
- Methamphetamine mimics the neurochemical profile of aging in rats and impairs recognition memoryPublication . Melo, Pedro; Magalhães, Ana; Alves, Cecília J.; Tavares, Maria Amélia; Sousa, Liliana de; Summavielle, Teresa; Moradas-Ferreira, PedroBrain neurochemistry and cognition performance are thought to decline with age. Accumulating data indicate that similar events occur after prolonged methamphetamine (MA) exposure. Using the rat as a model, the present study was designed to uncover common alteration patterns in brain neurochemistry and memory performance between aging and prolonged MA exposure. To this end, animals were treated with a chronic binge MA administration paradigm (20 mg/kg/day from postnatal day 91 to 100). Three-age control groups received isovolumetric saline treatment and were tested at the MA age-matched period, and at 12 and 20 months. We observed that both MA and aged animals presented a long, but not short, time impairment in novelty preference and an increased anxiety-like behavior. Neurochemical analysis indicated similar MA- and age-related impairments in dopamine, serotonin and metabolites in the striatum, prefrontal cortex and hippocampus. Thus, the present data illustrate that MA may be used to mimic age-related effects on neurotransmitter systems and advocate MA treatment as a feasible animal model to study neuronal processes associated with aging.