Institute Neurociencias e Comportamento INeC

Ribeirão Preto, Brazil

Institute Neurociencias e Comportamento INeC

Ribeirão Preto, Brazil
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Colombo A.C.,University of Sao Paulo | Colombo A.C.,Institute Neurociencias e Comportamento INeC | De Oliveira A.R.,University of Sao Paulo | De Oliveira A.R.,Institute Neurociencias e Comportamento INeC | And 4 more authors.
Behavioural Brain Research | Year: 2013

Haloperidol is a dopamine D2 receptor antagonist that induces catalepsy when systemically administered to rodents. The haloperidol-induced catalepsy is a state of akinesia and rigidity very similar to that seen in Parkinson's disease. There exists great interest in knowing whether or not some degree of emotionality underlies catalepsy. If so, what kind of emotional distress would permeate such motor disturbance? This study is an attempt to shed some light on this issue through an analysis of ultrasound vocalizations (USVs) of 22. kHz, open-field test, and contextual conditioned fear in rats with some degree of catalepsy induced by haloperidol. Systemic administration of haloperidol caused catalepsy and decreased exploratory activity in the open-field. There was no difference in the emission of USVs between groups during the catalepsy or the exploratory behavior in the open-field test. In the contextual conditioned fear, when administered before training session, haloperidol did not change the emission of USVs or the freezing response. When administered before testing session, haloperidol enhanced the freezing response and decreased the emission of USVs on the test day. These findings suggest that the involvement of dopaminergic mechanisms in threatening situations depends on the nature of the aversive stimulus. Activation of D2 receptors occurs in the setting up of adaptive responses to conditioned fear stimuli so that these mechanisms seem to be important for the emission of 22. kHz USVs during the testing phase of the contextual conditioned fear, but not during the training session or the open-field test (unconditioned fear stimuli). Catalepsy, on the other hand, is the result of the blockage of D2 receptors in neural circuits associated to motor behavior that appears to be dissociated from those directly linked to dopamine-mediated neural mechanisms associated to fear. © 2013 Elsevier B.V.

Silva K.,University of Sao Paulo | Carvalho M.C.,Institute Neurociencias e Comportamento INeC | Carvalho M.C.,University of Sao Paulo | Padovan C.M.,University of Sao Paulo | Padovan C.M.,Institute Neurociencias e Comportamento INeC
Behavioural Brain Research | Year: 2016

Repeated exposure to aversive events leads to the development of tolerance to stress, which involves the serotonergic pathway originated in the Median Raphe Nucleus (MnRN) to the Dorsal Hippocampus (DH). However, it is not clear whether these lesion-induced deficits can be attenuated by treatment with antidepressants. Therefore, the aim of this work was to investigate the effects of chronic treatment with Imipramine (IMI) in rats with lesions in the MnRN and exposed to restraint stress. Male Wistar rats with or without neurochemical lesions of the MnRN serotonergic neurons with the neurotoxin 5,7-DHT were submitted to acute (2 h) or chronic restraint (2 h/day/seven consecutive days) and treated with saline (1 ml/kg) or imipramine (15 mg/kg) via intraperitoneal twice a day during the same period. In acutely restrained rats, stress occurred on the last day of treatment. Test in the elevated plus maze (EPM) was performed 24 h later. After EPM test, animals were sacrificed and had their brains removed. Dorsal hippocampus and striatum were dissected and the levels of 5-HT and 5-hydroxy-indoleacetic acid (5-HIAA) measured by HPLC analysis. Our results showed that in control rats exposure to acute restraint stress decreased exploration of the open and enclose arms of the EPM, an effect that was attenuated by imipramine. In rats with 5,7-DHT lesions, acute restraint did not change the exploration of the EPM, independently of the treatment. On the other hand, when chronically restrained, saline treated rat with 5,7-DHT lesion showed a reduced exploration of the open arms of the EPM. This effect was attenuated by simultaneous treatment with imipramine. HPLC analysis showed significantly decreases on 5-HT and 5-HIAA levels in the hippocampus, but not in the striatum. These later results confirm that 5,7-DHT lesions of the MnRN had significant impact on the serotonergic projections to the dorsal hippocampus which seems to be essential for the development of tolerance to repeated stress in the absence of any pharmacological treatment. © 2016 Elsevier B.V.

Reis F.M.C.V.,University of Sao Paulo | Reis F.M.C.V.,Institute Neurociencias e Comportamento INeC | Almada R.C.,University of Sao Paulo | Almada R.C.,Institute Neurociencias e Comportamento INeC | And 4 more authors.
Cerebral Cortex | Year: 2016

The aim of the present study was to investigate the role of glucocorticoids in medial prefrontal cortex (mPFC) activity and the expression of contextual conditioned fear (freezing). Rats were pretreated with vehicle or metyrapone, a corticosterone synthesis blocker, and exposed to a context previously paired with footshocks. Freezing and Fos-protein expression in different mPFC regions were assessed. Exposure to the aversive context led to increased freezing and Fos expression in the prelimbic (PrL), anterior cingulate areas 1 and 2 (Cg1/Cg2). Pretreatment with metyrapone decreased freezing and Fos expression in these areas. Administration of spironolactone, an MR antagonist, in the PrL before the test decreased freezing. Pretreatment with RU38486, a glucocorticoid receptor (GR) antagonist, reduced this effect of spironolactone, suggesting that the effects of this MR antagonist may be attributable to a redirection of endogenous corticosterone actions to GRs. Consistent with this result, the decrease in freezing that was induced by intra-PrL injections of corticosterone was attenuated by pretreatment with RU38486 but not spironolactone. These findings indicate that corticosterone release during aversive conditioning influences mPFC activity and the retrieval of conditioned fear memory indicating the importance of balance between MR:GR-mediated effects in this brain region in this process. © 2015 The Author. Published by Oxford University Press. All rights reserved.

Biagioni A.F.,University of Sao Paulo | Biagioni A.F.,Institute Neurociencias e Comportamento INeC | dos Anjos-Garcia T.,University of Sao Paulo | Ullah F.,University of Sao Paulo | And 8 more authors.
Behavioural Brain Research | Year: 2016

Inhibition of GABAergic neural inputs to dorsal columns of the periaqueductal grey matter (dPAG), posterior (PH) and dorsomedial (DMH) hypothalamic nuclei elicits distinct types of escape behavioural reactions. To differentiate between the variety and intensity of panic-related behaviours, the pattern of defensive behaviours evoked by blockade of GABAA receptors in the DMH, PH and dPAG were compared in a circular open-field test and in a recently designed polygonal arena. In the circular open-field, the defensive behaviours induced by microinjection of bicuculline into DMH and PH were characterised by defensive alertness behaviour and vertical jumps preceded by rearing exploratory behaviour. On the other hand, explosive escape responses interspersed with horizontal jumps and freezing were observed after the blockade of GABAA receptors on dPAG neurons. In the polygonal arena apparatus, the escape response produced by GABAergic inhibition of DMH and PH neurons was directed towards the burrow. In contrast, the blockade of GABAA receptors in dPAG evoked non-oriented escape behaviour characterised by vigorous running and horizontal jumps in the arena. Our findings support the hypothesis that the hypothalamic nuclei organise oriented escape behavioural responses whereas non-oriented escape is elaborated by dPAG neurons. Additionally, the polygonal arena with a burrow made it easy to discriminate and characterise these two different patterns of escape behavioural responses. In this sense, the polygonal arena with a burrow can be considered a good methodological tool to discriminate between these two different patterns of escape behavioural responses and is very useful as a new experimental animal model of panic attacks. © 2015 Elsevier B.V.

Pereira A.C.,University of Sao Paulo | Pereira A.C.,Institute Neurociencias e Comportamento INeC | Carvalho M.C.,Institute Neurociencias e Comportamento INeC | Carvalho M.C.,University of Sao Paulo | And 2 more authors.
Behavioural Brain Research | Year: 2017

Acute exposure to stress induces significant behavioural changes, while repeated exposure to the same stressor leads to the development of tolerance to stress. The development of tolerance appears to involve the serotonergic projections from the Median Raphe Nucleus (MnRN) to the dorsal Hippocampus (dH), since rats with lesions of this pathway does not develop tolerance to stress. Previous data from our laboratory showed that treatment with imipramine, a serotonin (5-HT) and noradrenaline (NA) reuptake inhibitor, lead to the development of tolerance. However, it remains to be elucidated whether such tolerance involves the participation of the noradrenergic system, apart from the serotonergic projections. Therefore, the aim of this work was to investigate the behavioural and neurochemical effects of chronic treatment with desipramine (NA reuptake inhibitor) or fluoxetine (5-HT reuptake inhibitor) in chronically stressed rats with lesions of the serotonergic neurons of the MnRN. Male Wistar rats with or without lesion in the MnRN were submitted or not to acute (2. h) or chronic restraint (2. h/seven days) stress and tested in the elevated pus maze (EPM).Treatment with fluoxetine, desipramine (10. mg/kg) or saline was performed twice daily (12-12. h interval), for 7 consecutive days. EPM test was conducted 24. h after the treatment. Fluoxetine attenuated the anxiogenic-induced effect of lesion in chronically restrained rats, without changing serotonin and noradrenaline levels in the hippocampus of lesioned rats. A similar profile was also observed after treatment with desipramine. These results suggest that both the serotonergic and the noradrenergic systems are involved in the development of tolerance to chronic stress. Additionally, the integrity of the serotonergic pathway of the MnRN-dH is not essential for the anxiolytic-like effects of these drugs. © 2017 Elsevier B.V.

de Oliveira A.R.,Federal University of São Carlos | de Oliveira A.R.,Institute Neurociencias e Comportamento INeC | de Oliveira A.R.,University of Sao Paulo | Reimer A.E.,Institute Neurociencias e Comportamento INeC | And 5 more authors.
Experimental Brain Research | Year: 2017

Considering the complexity of aversive information processing and defensive response expression, a combined action of stress modulators may be required for an optimal performance during threatening situations. Dopamine is now recognized as one of the most active modulators underlying states of fear and anxiety. On the other hand, activation of hypothalamic–pituitary–adrenocortical (HPA) axis, which leads to the release of corticosterone in rodents, has been considered a key part of the stress response. The current study is an extension of prior work investigating modulatory effects of dopamine and corticosterone on conditioned fear expression. We have showed that corticosterone, acting through mineralocorticoid receptors in the ventral tegmental area (VTA), upregulates dopaminergic system in the basolateral amygdala (BLA), enabling the expression of conditioned freezing response. The novel question addressed here is whether VTA–BLA dopaminergic signaling is necessary for increases in corticosterone during conditioned fear expression. Using site-specific treatment with D2-like agonist quinpirole (VTA) and D2-like antagonist sulpiride (BLA), we evaluated freezing and plasma corticosterone in rats exposed to a light used as aversive conditioned stimulus (CS). Intra-VTA quinpirole and intra-BLA sulpiride significantly decreased freezing expression in the conditioned fear test, but this anxiolytic-like effect of the dopaminergic drugs was not associated with changes in plasma corticosterone concentrations. Altogether, data suggest that interferences with the ability of the CS to activate the dopaminergic VTA–BLA pathway reduce the expression of freezing, but activation of the HPA axis seems to occur upstream of the recruitment of dopaminergic mechanisms in conditioned fear states. © 2016, Springer-Verlag Berlin Heidelberg.

Wietzikoski E.C.,Federal University of Paraná | Boschen S.L.,Federal University of Paraná | Miyoshi E.,Federal University of Paraná | Bortolanza M.,Federal University of Paraná | And 5 more authors.
Psychopharmacology | Year: 2012

Rationale: Aversively motivated learning is more poorly understood than appetitively motivated learning in many aspects, including the role of dopamine receptors in different regions of the striatum. Objectives: The present study investigated the roles of the D1-like DA receptors in the nucleus accumbens (NAc) and dorsolateral striatum (DLS) on learning and performance of conditioned avoidance responses (CARs). Methods: Adult male Wistar rats received intraperitoneal (i.p.), intra-NAc, or intra-DLS injections of the D1 dopamine receptor agonist SKF 81297 or the D1 receptor antagonist SCH 23390 20 min before or immediately after a training session in the CAR task two-way active avoidance, carried out 24 h before a test session. Results: Pre-training administration of SCH 23390, but not SKF 81297, caused a significant decrease in the number of CARs in the test, but not in the training session, when injected into the DLS, or in either session when injected into the NAc. It also caused a significant increase in the number of escape failures in the training session when injected into the NAc. Systemic administration caused a combination of these effects. Post-training administrations of these drugs caused no significant effect. Conclusions: The results suggest that the D1-like receptors in the NAc and DLS play important, though different, roles in learning and performance of CAR. © 2011 Springer-Verlag.

Almeida Pv.G.,University of Sao Paulo | Trovo M.C.,University of Sao Paulo | Tokumoto A.M.,University of Sao Paulo | Pereira A.C.,University of Sao Paulo | And 3 more authors.
Journal of Psychopharmacology | Year: 2013

Despite the intense research on the neurobiology of stress, the role of serotonin (5-HT)1A receptors still remains to be elucidated. In the hippocampus, post-synaptic 5-HT1A receptors activation induces anxiolytic effects in animals previously exposed to stressful situations. However, little is known about somatodendritic 5-HT1A receptors in the median raphe nucleus (MRN). Therefore, the aim of this study was to investigate the role of 5-HT1A receptors located in the MRN in rats exposed to forced swim stress. After recovering from surgery, rats were forced to swim for 15 min in a cylinder. Intra-MRN injections of saline, 8-OH-DPAT (3 nmol/0.2 μL) and/or WAY-100635 (0.3 nmol/0.2 μL) were performed immediately before or after pre-exposure or 24 h later (immediately before test). Non-stressed rats received the same treatment 24 h or 10 min before test. Our data showed that 8-OH-DPAT increased latency to display immobility while decreasing time spent immobile in almost all experimental conditions. These effects were not prevented by previous treatment with WAY-100635. No effects of different treatments were described in non-stressed animals. Taken together, our data suggest that in addition to activation of 5-HT1A, 5-HT7 receptors may also be involved in the behavioural consequences of exposure to swim stress. © The Author(s) 2013.

De Oliveira A.R.,University of Sao Paulo | De Oliveira A.R.,Institute Neurociencias e Comportamento INeC | Reimer A.E.,University of Sao Paulo | Reimer A.E.,Institute Neurociencias e Comportamento INeC | And 2 more authors.
Psychoneuroendocrinology | Year: 2014

Despite the recognized involvement of corticosteroids in the modulation of emotional behavior, the specific role of mineralocorticoid receptors (MRs) and glucocorticoid receptors (GRs) in the expression of conditioned fear responses is still open to investigation. The present study sought to clarify the involvement of both types of corticosteroid receptors in two different brain regions - the ventral tegmental area (VTA) and the basolateral amygdala complex (BLA) - on the expression of conditioned fear. The first experiment assessed the effects of intra-VTA or intra-BLA administration of spironolactone (MR antagonist) or mifepristone (GR antagonist) on the expression of conditioned freezing to a light-CS and on motor performance in the open-field test. Intra-VTA spironolactone, but not mifepristone, attenuated the expression of the conditioned freezing response whereas intra-BLA spironolactone or mifepristone had no significant effects. These treatments did not affect motor performance in the open-field test. Since dopamine is released in the BLA from the VTA during the expression of conditioned fear, the anxiolytic-like effect of decreased corticosteroid activity in the first experiment could be associated with changes in dopaminergic neurotransmission. The second experiment, using in vivo microdialysis, investigated the role of MRs in the VTA on dopamine levels in the BLA during the expression of conditioned fear. Blocking MRs locally in the VTA with spironolactone reduced dopamine efflux in the BLA and decreased the expression of conditioned freezing in response to the CS. Taken together, the data indicate that corticosterone, acting locally on MRs in the VTA, stimulates dopamine efflux in the BLA, which facilitates the expression of conditioned freezing to a light-CS. © 2014 Elsevier Ltd.

Reis F.M.C.V.,University of Ribeirão Preto | Reis F.M.C.V.,Institute Neurociencias e Comportamento INeC | Pestana-Oliveira N.,University of Sao Paulo | Leite C.M.,University of Sao Paulo | And 7 more authors.
Psychoneuroendocrinology | Year: 2014

Perimenopause, a transition period that precedes menopause, is characterized by neuroendocrine, metabolic and behavioral changes, and is associated with increased vulnerability to affective disorders. The decrease in ovarian follicles during perimenopause contributes to a dynamic and complex hormonal milieu that is not yet well characterized. In rodents, 4-vinylcyclohexene diepoxide (VCD) induces a gradual depletion of ovarian follicles, modeling the transition to menopause in women. This study was aimed to investigate, in VCD-treated rats, the hormonal status and the behavior in the elevated plus-maze (EPM), a widely used test to assess anxiety-like behavior. From the postnatal day 28, rats were treated with VCD or vehicle for 15 days. At 80. ±. 5 days after the beginning of treatment the experiments were performed at proestrus and diestrus. In the first experiment rats were decapitated, ovary was collected and blood samples were taken for estradiol, progesterone, follicle stimulant hormone (FSH), testosterone, dihydrotestosterone (DHT) and corticosterone measurements. In the second experiment, rats were subjected to the EPM for 5. min, and behavioral categories recorded. Administration of VCD induced follicular depletion as well as an increase of the number of atretic follicles demonstrating the treatment efficacy. The transitional follicular depletion was accompanied by lower progesterone, testosterone and DHT with no changes in the FSH, estradiol and corticosterone plasma levels. On the EPM, rats showed decreased open arm exploration and increased risk assessment behavior, indicating increased anxiety. These findings show that administration of VCD to induce ovarian failure results in endocrine and anxiety-related changes that are similar to the symptoms exhibited by women during menopause transition. Thus, this model seems to be promising in the study of perimenopause-related changes. © 2014 Elsevier Ltd.

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