Effect of lithium on behavioral disinhibition induced by electrolytic lesion of the median raphe nucleus

Alterations in brainstem circuits have been proposed as a possible mechanism underlying the etiology of mood disorders. Projections from the median raphe nucleus (MnR) modulate dopaminergic activity in the forebrain and are also part of a behavioral disinhibition/inhibition system that produces phenotypes resembling behavioral variations manifested during manic and depressive phases of bipolar disorder.The aim of this study is to assess the effect of chronic lithium treatment on behavioral disinhibition induced by MnR lesions.MnR electrolytic lesions were performed in C57BL/6J mice, with sham-operated and intact animals as control groups. Following recovery, mice were chronically treated with lithium (LiCl, added in chow) followed by behavioral testing.MnR lesion induced manic-like behavioral alterations including hyperactivity in the open field (OF), stereotyped circling, anxiolytic/risk taking in the elevated plus maze (EPM) and light/dark box (LDB) tests, and increased basal body temperature. Lithium was specifically effective in reducing OF hyperactivity and stereotypy but did not reverse (EPM) or had a nonspecific effect (LDB) on anxiety/risk-taking measures. Additionally, lithium decreased saccharin preference and prevented weight loss during single housing.Our data support electrolytic lesions of the MnR as an experimental model of a hyper-excitable/disinhibited phenotype consistent with some aspects of mania that are attenuated by the mood stabilizer lithium. Given lithium's relatively specific efficacy in treating mania, these data support the hypothesis that manic symptoms derive not only from the stimulation of excitatory systems but also from inactivation or decreased activity of inhibitory mechanisms.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Effect of thermal treatment on the synthesis of NiAl 2 O 4 spinel oxide using chitosan as precursor

Abstract Nickel aluminate oxide (NiAl2O4) was prepared using chitosan as polymeric precursor and ammonia solution as a precipitating agent. In addition, nickel nitrate and aluminum nitrate salts were used as sources of Ni and Al, under stoichiometric amounts (molar ratio Ni:Al = 1:2). NiAl2O4 particles were prepared at different calcination temperatures and their properties were investigated. The synthesized materials were characterized by X-ray diffraction, infrared spectroscopy, atomic force microscopy, thermogravimetric analysis and nitrogen adsorption-desorption isotherms. The results showed that the thermal treatment process strongly influence on the formation of a single-phase structure of NiAl2O4 spinel. Nickel aluminate spinel with a porous structure and high surface area was obtained at temperatures above 700 ºC

The impact of a modified cutting flute implant design on osseointegration

Information concerning the effects of the implant cutting flute design on initial stability and its influence on osseointegration in vivo is limited. This study evaluated the early effects of implants with a specific cutting flute design placed in the sheep mandible. Forty-eight dental implants with two different macrogeometries (24 with a specific cutting flute design Blossom group; 24 with a self-tapping design - DT group) were inserted into the mandibular bodies of six sheep; the maximum insertion torque was recorded. Samples were retrieved and processed for histomorphometric analysis after 3 and 6 weeks. The mean insertion torque was lower for Blossom implants (P < 0.001). No differences in histomorphometric results were observed between the groups. At 3 weeks, P = 0.58 for bone-to-implant contact (BIC) and P = 0.52 for bone area fraction occupied (BAFO); at 6 weeks, P = 0.55 for BIC and P = 0.45 for BAFO. While no histomorphometric differences were observed, ground sections showed different healing patterns between the implants, with better peri-implant bone organization around those with the specific cutting flute design (Blossom group). Implants with the modified cutting flute design had a significantly reduced insertion torque compared to the DT implants with a traditional cutting thread, and resulted in a different healing pattern

A fast cholinergic modulation of the primary acoustic startle circuit in rats

Cochlear root neurons (CRNs) are the first brainstem neurons which initiate and participate in the full expression of the acoustic startle reflex. Although it has been suggested that a cholinergic pathway from the ventral nucleus of the trapezoid body (VNTB) conveys auditory prepulses to the CRNs, the neuronal origin of the VNTB-CRNs projection and the role it may play in the cochlear root nucleus remain uncertain. To determine the VNTB neuronal type which projects to CRNs, we performed tract-tracing experiments combined with mechanical lesions, and morphometric analyses. Our results indicate that a subpopulation of non-olivocochlear neurons projects directly and bilaterally to CRNs via the trapezoid body. We also performed a gene expression analysis of muscarinic and nicotinic receptors which indicates that CRNs contain a cholinergic receptor profile sufficient to mediate the modulation of CRN responses. Consequently, we investigated the effects of auditory prepulses on the neuronal activity of CRNs using extracellular recordings in vivo. Our results show that CRN responses are strongly inhibited by auditory prepulses. Unlike other neurons of the cochlear nucleus, the CRNs exhibited inhibition that depended on parameters of the auditory prepulse such as intensity and interstimulus interval, showing their strongest inhibition at short interstimulus intervals. In sum, our study supports the idea that CRNs are involved in the auditory prepulse inhibition of the acoustic startle reflex, and confirms the existence of multiple cholinergic pathways that modulate the primary acoustic startle circuit. © 2013 Springer-Verlag Berlin Heidelberg