Alessandra Mussi Ribeiro

Improvement in physiological and psychological parameters after 6 months of yoga practice.

Yoga is believed to have beneficial effects on cognition, attenuation of emotional intensity and stress reduction. Previous studies were mainly performed on eastern experienced practitioners or unhealthy subjects undergoing concomitant conventional therapies. Further investigation is needed on the effects of yoga per se, as well as its possible preventive benefits on healthy subjects. We investigated the effects of yoga on memory and psychophysiological parameters related to stress, comparing yoga practice and conventional physical exercises in healthy men (previously yoga-naïve). Memory tests, salivary cortisol levels and stress, anxiety, and depression inventories were assessed before and after 6 months of practice. Yoga practitioners showed improvement of the memory performance, as well as improvements in psychophysiological parameters. The present results suggest that regular yoga practice can improve aspects of cognition and quality of life for healthy individuals. An indirect influence of emotional state on cognitive improvement promoted by yoga practice can be proposed.

Differential roles of the dorsal hippocampal regions in the acquisition of spatial and temporal aspects of episodic-like memory

Episodic memory refers to the recollection of what, where and when an event occurred. Computational models suggest that the dentate gyrus (DG) and the CA3 hippocampal subregions are involved in pattern separation and the rapid acquisition of episodes, while CA1 is involved in the formation of a temporal context. Most of the studies performed to test this hypothesis failed to simultaneously address the aspects of episodic memory. Recently, a new task of object recognition was validated in rats. In the first sample trial, the rat is exposed to four copies of an object. In second sample, the rat is exposed to four copies of a different object. In the test trial, two copies of each of the previous objects are presented. One copy of the object used in sample trial one is located in a different place, and it is expected to be the most explored. Our goal was to evaluate whether the pharmacological inactivation of the dorsal DG/CA3 and CA1 subregions could differentially impair the acquisition of the task. Inactivation of the DG/CA3 subregions impaired the spatial discrimination, while the temporal discrimination was preserved. Rats treated with muscimol in CA1 explored all the objects equally well, irrespective of place or presentation time. Our results are consistent with computational models that postulate a role for DG/CA3 in rapid encoding and in spatial pattern separation, and a role for CA1 in the in the formation of the temporal context of events and as well as in detecting spatial novelty.

Repeated treatment with a low dose of reserpine as a progressive model of Parkinson's disease

Animal models are widely used to study alterations caused by Parkinsons disease (PD). However, in general, pharmacological models do not express the progressive nature of the disease, being characterized by immediate severe motor impairment after a single dose of the drug. Reserpine administration in rodents has been suggested as a pharmacological model of PD based on the effects of this monoamine-depleting agent on motor activity. Here, we describe that repeated administration with a low dose (0.1 mg/kg) of reserpine in rats induces a gradual appearance of motor signs, evaluated by catalepsy behavior. Furthermore, these motor signs are accompanied by increased levels of striatal lipid peroxidation. However, treatment with reserpine failed to induce memory impairments (evaluated by novel object recognition and discriminative avoidance tasks) and alterations in hippocampal lipid peroxidation. Thus, repeated treatment with low doses of reserpine progressively induces alterations in motor function and an increase in striatal oxidative stress, indicating a possible application of this model in the study of the neuroprogressive nature of the motor signs in PD.

Differential Cortical c-Fos and Zif-268 Expression after Object and Spatial Memory Processing in a Standard or Episodic-Like Object Recognition Task

Episodic memory reflects the capacity to recollect what, where, and when a specific event happened in an integrative manner. Animal studies have suggested that the medial temporal lobe and the medial pre-frontal cortex are important for episodic-like memory (ELM) formation. The goal of present study was to evaluate whether there are different patterns of expression of the immediate early genes c-Fos and Zif-268 in these cortical areas after rats are exposed to object recognition (OR) tasks with different cognitive demands. Male rats were randomly assigned to five groups: home cage control, empty open field (CTR-OF), open field with one object (CTR-OF + Obj), novel OR task, and ELM task and were killed 1 h after the last behavioral procedure. Rats were able to discriminate the objects in the OR task. In the ELM task, rats showed spatial (but not temporal) discrimination of the objects. We found an increase in the c-Fos expression in the dorsal dentate gyrus (DG) and in the perirhinal cortex (PRh) in the OR and ELM groups. The OR group also presented an increase of c-Fos expression in the medial prefrontal cortex (mPFC). Additionally, the OR and ELM groups had increased expression of Zif-268 in the mPFC. Moreover, Zif-268 was increased in the dorsal CA1 and PRh only in the ELM group. In conclusion, the pattern of activation was different in tasks with different cognitive demands. Accordingly, correlation tests suggest the engagement of different neural networks in the tasks used. Specifically, perirhinal-DG co-activation was detected after the what-where memory retrieval, but not after the novel OR task. Both regions correlated with the respective behavioral outcome. These findings can be helpful in the understanding of the neural networks underlying memory tasks with different cognitive demands.

Cognitive, motor and tyrosine hydroxylase temporal impairment in a model of parkinsonism induced by reserpine

Studies have suggested that cognitive deficits can precede motor alterations in Parkinsons disease (PD). However, in general, classic animal models are based on severe motor impairment after one single administration of neurotoxins, and thereby do not express the progressive nature of the pathology. A previous study showed that the repeated administration with a low dose (0.1mg/kg) of the monoamine depleting agent reserpine induces a gradual appearance of motor signs of pharmacological parkinsonism in rats. Here, we showed this repeated treatment with reserpine induced a memory impairment (evaluated by the novel object recognition task) before the gradual appearance of the motor signs. Additionally, these alterations were accompanied by decreased tyrosine hydroxylase (TH) striatal levels and reduced number of TH+ cells in substantia nigra pars compacta (SNpc). After 30 days without treatment, reserpine-treated animals showed normal levels of striatal TH, partial recovery of TH+ cells in SNpc, recovery of motor function, but not reversal of the memory impairment. Furthermore, the motor alterations were statistically correlated with decreased TH levels (GD, CA1, PFC and DS) and number of TH+ cells (SNpc and VTA) in the brain. Thus, we extended previous results showing that the gradual appearance of motor impairment induced by repeated treatment with a low dose of reserpine is preceded by short-term memory impairment, as well as accompanied by neurochemical alterations compatible with the pathology of PD.

Basolateral amygdala inactivation impairs learned (but not innate) fear response in rats

Numerous studies have suggested that the amygdala is involved in the formation of aversive memories, but the possibility that this structure is merely related to any kind of fear sensation or response could not be ruled out in previous studies. The present study investigated the effects of bilateral inactivation of the amygdaloid complex in rats tested in the plus-maze discriminative avoidance task. This task concomitantly evaluates aversive memory (by discrimination of the two enclosed arms) and innate fear (by open-arm exploration). Wistar rats (3-5 months-old) were implanted with bilateral guide cannulae into basolateral amygdala. After surgery, all subjects were given 1 week to recover before behavioral experiments. Afterwards, in experiment 1, 15 min prior to training, 0.5 μl of saline or muscimol (1 mg/ml) was infused in each side via microinjection needles. In experiment 2 the animals received injections immediately after the training session and in experiment 3 rats were injected prior to testing session (24 h after training). The main results showed that (1) pre-training muscimol prevented memory retention (evaluated by aversive arm exploration in the test session), but did not alter innate fear (evaluated by percent time in open arms); (2) post-training muscimol impaired consolidation, inducing increased percent in aversive arm exploration in the test session and (3) pre-testing muscimol did not affect retrieval (evaluated by aversive enclosed arm exploration in the test session). The results suggest that amygdala inactivation specifically modulated the learning of the aversive task, excluding a possible secondary effect of amygdala inactivation on general fear responses. Additionally, our data corroborate the hypothesis that basolateral amygdala is not the specific site of storage of aversive memories, since retention of the previously learned task was not affected by pre-testing inactivation.

Extending possible applications of an episodic-like memory task in rats

Recently, an object recognition episodic-like memory task was proposed in rodents. However, the short retention delay of the task narrows its applications. This study verifies whether this task can be evoked after 24h. Additionally, the effect of a classical amnestic agent (scopolamine) on episodic-like memory consolidation was investigated. Rats showed increased exploration of old over recent objects and spent more time exploring displaced over stationary object. Both old over recent and displaced over stationary objects preferences were abolished by pos-training scopolamine administration (1mg/kg i.p.), indicating impaired spatiotemporal retrieval. In conclusion, the object recognition task that accomplishes the what, where and when components of episodic-like memory in rats can persist for 24h.

Memory impairment induced by low doses of reserpine in rats: Possible relationship with emotional processing deficits in Parkinson disease

We have recently verified that the monoamine-depleting drug reserpine--at doses that do not modify motor function--impairs memory in a rodent model of aversive discrimination. In this study, the effects of reserpine (0.1-0.5 mg/kg) on the performance of rats in object recognition, spatial working memory (spontaneous alternation) and emotional memory (contextual freezing conditioning) tasks were investigated. While object recognition and spontaneous alternation behavior were not affected by reserpine treatment, contextual fear conditioning was impaired. Together with previous studies, these results suggest that low doses of reserpine would preferentially induce deficits in tasks involved with emotional contexts. Possible relationships with cognitive and emotional processing deficits in Parkinson disease are discussed.

Estresse e ansiedade em pacientes renais crônicos submetidos à hemodiálise

Abstract Chronic renal failure is a systemic disease that provokes the loss of autonomy of the patient leading to physical limitations, workrestrictions, and social losses. Patients with this type of pathology are usually treated by hemodialysis, a rigorous and debil itatingtreatment. The goal of this study was to assess levels of stress and anxiety in patients undergoing hemodialysis at the Instituto doRim clinic in Natal in the state of Rio Grande do Norte , Brazil. The Lipp Stress Symptoms Inventory and the Trait-State AnxietyInventory were used for the data collection. The sample (n=100) showed homogeneity in relation to gender, with a mean age of46 and a predominance of married and retired individuals, with low family incomes. The results showed that the majority of thepatients (71%) suffered high levels of stress, specifically in the resistance phase, and the incidence of psychological symptom s wasgreater than the physical manifestations. Furthermore, all the individuals presented moderate (66%) or high levels (34%) of anx iety.According to these data patients with chronic renal failure showed high levels of stress and anxiety.Uniterms

Alpha-Tocopherol Counteracts Cognitive and Motor Deficits Induced by Repeated Treatment with Reserpine

Previous studies showed that chronic administration of the monoamine depleting agent reserpine in low doses promotes progressive cognitive and motor impairments in rats, and this protocol has been used as a pharmacological progressive model of Parkinsons disease. These behavioral alterations are accompanied by increased brain oxidative stress. We aimed to verify the effects of the concomitant treatment with the antioxidant agent alpha-tocopherol on the motor and cognitive deficits induced by chronic reserpine in rats. Rats were repeatedly treated with 0.1 mg/kg reserpine with or without a concomitant treatment with 40 mg/kg alpha-tocopherol. Across the treatment, motor and cognitive performances were evaluated by the catalepsy and novel object recognition tests, respectively. As expected, reserpinetreated rats showed progressively increased duration of catalepsy together with short-term memory deficits in the object recognition test. Importantly, these detrimental outcomes due to reserpine treatment were prevented by concomitant daily administration of the antioxidant agent alpha-tocopherol. The results show a preventive role of alpha-tocopherol on behavioral alterations induced by repeated reserpine treatment. This is relevant to the investigation of possible neuroprotective interventions in Parkinson’s disease.