Navegando por Palavras-chave "Inferior Colliculus"

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    Investigação do papel dos receptores glutamatérgicos do tipo ampa no colículo inferior sobre a catalepsia induzida pelo haloperidol em ratos
    (Universidade Federal de São Paulo (UNIFESP), 2013-12-16) Tonelli, Luan Castro [UNIFESP]; Santos, Ronaldo Vagner Thomatieli dos [UNIFESP]; Melo, Liana Lins; http://lattes.cnpq.br/9928572887023286; http://lattes.cnpq.br/2108039540261881; Universidade Federal de São Paulo (UNIFESP)
    O colículo inferior (CI) é uma estrutura mesencefálica primariamente envolvida no processamento da informação auditiva, mas também integra informação sensorial de natureza aversiva. A estimulação elétrica ou química dessa estrutura induz respostas típicas de medo tais como alerta, congelamento e fuga, eliciadas por ameaças ambientais. Evidências científicas sugerem que o substrato neural responsável pelo comportamento defensivo no colículo inferior pode também ser regulado por aminoácidos excitatórios uma vez que a microinjeção de NMDA nessa estrutura induz comportamento defensivo caracterizado por corrida, levantamentos e saltos. Entretanto, a microinjeção de AP7, um antagonista competitivo de receptores NMDA impede a expressão desses comportamentos. Tem sido demonstrado que a estimulação do substrato neural do medo no colículo inferior causa um aumento significante nos níveis extracelulares de dopamina em outras estruturas tais como o córtex frontal. Estudos prévios realizados em nosso laboratório mostram que a microinjeção de antagonistas de receptores glutamatérgicos do tipo NMDA no CI é capaz de reverter a catalepsia induzida pelo haloperidol. Mas ainda não se sabe se os receptores glutamatérgicos do tipo AMPA no CI também podem ser responsáveis por modular o processo de catalepsia. O presente trabalho investigou se a microinjeção de DNQX, um antagonista de receptores glutamatérgicos do tipo AMPA, diretamente no colículo inferior, foi capaz de influenciar a catalepsia induzida pela administração sistêmica do neuroléptico haloperidol. Os animais foram submetidos a uma cirurgia para implantação de uma cânula no CI e receberam microinjeções de DNQX (1,0μg/0,5μl e 2,5μg/0,5μl). Em seguida foi realizada a administração sistêmica de haloperidol (1,0 mg/kg) e imediatamente após, os animais foram colocados em uma arena onde foi realizada a avaliação da catalepsia. Os resultados mostram que a microinjeção de DNQX, um antagonista de receptores AMPA diretamente no colículo inferior na dose de 1,0μg/0,5μl, pode reverter a catalepsia induzida pelo haloperidol.
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    Participação da neurotransmissão serotoninérgica do colículo inferior na modulação da resposta de inibição por pré- pulso do reflexo de sobressalto acústico e interação social em ratos wistar
    (Universidade Federal de São Paulo (UNIFESP), 2017-03-23) Oliveira, Rodolpho Pereira de [UNIFESP]; Silva, Regina Cláudia Barbosa da [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    Schizophrenia is a devastating psychiatric disorder that affects approximately 1% of the population over a lifetime, and generally affects individuals in the prime of their productive potential. The relationship between serotonergic dysfunction and schizophrenia began with the discovery of the effects of lysergic acid diethylamide (LSD) that shows high affinity for the 5-HT2A receptor, and that generated delusions and hallucinations which are positive symptoms of schizophrenia. Another substance, 2,5-dimethoxy-4-iodoanfetamine (DOI), also displays hallucinogenic properties and 5- HT2A antagonism as LSD. An animal model widely used, based on attentional processes, is the model of pre-pulse inhibition (PPI) of the startle reflex. The primary neuronal pathway, mediating PPI response is in the brainstem, and the inferior colliculus (IC) is a key structure in this circuitry. One of the main negative symptoms of schizophrenia is the social withdrawal that leads to important losses in the personal and professional sphere of the individual. In this sense, the objective of this study was to investigate the role of serotonergic neurotransmission of the IC in the modulation of PPI response and social interaction. To this end, we microinjected an agonist and an antagonist of 5-HT2A receptors, DOI (10.0 ug/0.3uL ), and ritanserin (4 ug/0.3uL ), respectively in the IC of these animals. In an attempt to establish a parallel with the clinic, we verified whether pre-treatment with clozapine (5 mg/kg) prior to intracollicular microinjection of DOI could reverse the deficits of PPI and social interaction. The results showed that the microinjection of DOI into de IC produced deficits in PPI and social interaction that were reversed by pretreatment with clozapine. The microinjection of ritanserin in this structure did not produce any effect on PPI and social interaction responses. Together, our results point to the involvement of the serotonergic system of the IC as a critical neural substrate in mediating these responses.
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    Zinc supplementation for tinnitus
    (Inst Oceanografico, Univ Sao Paulo, 2016) Person, Osmar Clayton [UNIFESP]; Puga, Maria Eduarda dos Santos [UNIFESP]; Silva, Edina Mariko Koga da [UNIFESP]; Torloni, Maria Regina [UNIFESP]
    Background Tinnitus is the perception of sound without external acoustic stimuli. Patients with severe tinnitus may have physical and psychological complaints and their tinnitus can cause deterioration in their quality of life. At present no specific therapy for tinnitus has been found to be satisfactory in all patients. In recent decades, a number of reports have suggested that oral zinc supplementation may be effective in the management of tinnitus. Since zinc has a role in cochlear physiology and in the synapses of the auditory system, there is a plausible mechanism of action for this treatment. Objectives To evaluate the effectiveness and safety of oral zinc supplementation in the management of patients with tinnitus. Search methods The Cochrane ENT Information Specialist searched the ENT Trials Register; Central Register of Controlled Trials (CENTRAL 2016, Issue 6); PubMed; EMBASE; CINAHL; Web of Science; ClinicalTrials.gov; ICTRP and additional sources for published and unpublished trials. The date of the search was 14 July 2016. Selection criteria Randomised controlled trials comparing zinc supplementation versus placebo in adults (18 years and over) with tinnitus. Data collection and analysis We used the standard methodological procedures recommended by Cochrane. Our primary outcome measures were improvement in tinnitus severity and disability, measured by a validated tinnitus‐specific questionnaire, and adverse effects. Secondary outcomes were quality of life, change in socioeconomic impact associated with work, change in anxiety and depression disorders, change in psychoacoustic parameters, change in tinnitus loudness, change in overall severity of tinnitus and change in thresholds on pure tone audiometry. We used GRADE to assess the quality of the evidence for each outcome; this is indicated in italics. Main results We included three trials involving a total of 209 participants. The studies were at moderate to high risk of bias. All included studies had differences in participant selection criteria, length of follow‐up and outcome measurement, precluding a meta‐analysis. The participants were all adults over 18 years with subjective tinnitus, but one study conducted in 2013 (n = 109) included only elderly patients. Improvement in tinnitus severity and disability Only the study in elderly patients used a validated instrument (Tinnitus Handicap Questionnaire) for this primary outcome. The authors of this cross‐over study did not report the results of the two phases separately and found no significant differences in the proportion of patients reporting tinnitus improvement at four months of follow‐up: 5% (5/93) versus 2% (2/94) in the zinc and placebo groups, respectively (risk ratio (RR) 2.53, 95% confidence interval (CI) 0.50 to 12.70; very low‐quality evidence). None of the included studies reported any significant adverse effects. Secondary outcomes For the secondary outcome change in tinnitus loudness, one study reported no significant difference between the zinc and placebo groups after eight weeks: mean difference in tinnitus loudness ‐9.71 dB (95% CI ‐25.53 to 6.11; very low‐quality evidence). Another study also measured tinnitus loudness but used a 0‐ to 100‐point scale. The authors of this second study reported no significant difference between the zinc and placebo groups after four months: mean difference in tinnitus loudness rating scores 0.50 (95% CI ‐5.08 to 6.08; very low‐quality evidence). Two studies used unvalidated instruments to assess tinnitus severity. One (with 50 participants) reported the severity of tinnitus using a non‐validated scale (0 to 7 points) and found no significant difference in subjective tinnitus scores between the zinc and placebo groups at the end of eight weeks of follow‐up (mean difference (MD) ‐1.41, 95% CI ‐2.97 to 0.15; very low‐quality evidence). A third trial (n = 50) also evaluated the improvement of tinnitus using a non‐validated instrument (a 0 to 10 scale: 10 = severe and unbearable tinnitus). In this study, after eight weeks there was no difference in the proportion of patients with improvement in their tinnitus, 8.7% (2/23) treated with zinc versus 8% (2/25) of those who received a placebo (RR 1.09, 95% CI 0.17 to 7.10, very low‐quality evidence). None of the included studies reported any of our other secondary outcomes (quality of life, change in socioeconomic impact associated with work, change in anxiety and depression disorders, change in psychoacoustic parameters or change in thresholds on pure tone audiometry). Authors' conclusions We found no evidence that the use of oral zinc supplementation improves symptoms in adults with tinnitus.