Radu Lefter

The effects of a 6-OHDA induced lesion in murine nuccleus accumbens on memory and oxidative stress status

Nucleus accumbens (NAcc) are a collection of neurons that form the main part of the ventral striatum, which is a significant dopaminergic structure. Also, NAcc is thought to play an important role in reward, pleasure, laughter, addiction, aggression, fear, and the placebo effect. In the present work we were interested in studying the effects of a 6-OHDA induced lesion in the nucleus accumbens (NAcc), which is known as an important dopaminergic structure, on a specific behavioral task that involves both short term and long term spatial memory (the radial-8-arm-maze task), as well as on the oxidative stress markers (two antioxidant enzymes: superoxide dismutase-SOD and glutathione peroxidase-GPX and a lipid peroxidation marker: malondialdehyde-MDA, as well as the total antioxidant status-TAS) from the temporal lobe, which is considered to be the most vulnerable cortical area to oxygen levels fluctuations and hypoxia. Our results showed some significant effects of this lesion on the reference memory errors and time necessary to finish the test in the radial-8-arm-maze task. Additionally, increased oxidative stress status was demonstrated in the temporal lobe of the lesioned rats, as demonstrated by the high levels of lipid peroxidation and decreased total antioxidant status. Moreover, significant correlations are reported here between the behavioral parameters which we studied in the radial-8-arm-maze task and the aforementioned oxidative stress markers.

PRELIMINARY DATA ON SOME BEHAVIORAL CHANGES INDUCED BY SHORT-TERM INTRAPERITONEAL OXYTOCIN ADMINISTRATION IN AGED RATS

INTRODUCTION Oxytocin (OT) is a well-known neuropeptides which together with vasopressin, melatonin, insulin and other hormones can alter both behavior and physiological or neuronal functions. This growing interest on OT roles is also based on the demonstrated beneficial effects as a stress reliever and a social bonding agent. The association between old age and OT was only vaguely studied. Little or few is known on the effect of the OT hormone on the old body. Hereby, we present our preliminary results in the research on behavioral changes regarding the intraperitoneal administration of OT in aged rats. SUBJECTS AND METHODS OT was administered for 8 days in Wistar aged rats in parallel with saline administration for control group. Behavioral markers were assessed in some specific behavioral tasks, such as the Y-Maze test for short-term working memory, Open Field test, Elevated Plus Maze, and Forced Swim test for anxious and depressive behavior assessment, and Three-chambered Maze test for sociability assessment. RESULTS Increased mobility and decreased anxiety behaviors were reported for the aged intraperitoneal OT-treated animals, as compared with controls, during FST and OFT, and respectively FST, EPM, and OFT. Also, decreased depressive-like behaviors were observed in the same animal group during FST and ST. Moreover, a decrease in anxiolytic behavior was observed as exposed to stressful stimuli (such as grooming behavior in OFT, and forced grooming behavior in ST), and as exposed to social stimuli (such as grooming behavior in TCT). Similarly, significant differences were obtained regarding the social behavior of the intraperitoneal OT-treated animal as compared to control group, the animals showing increased sociability and social preference for the stranger animal in TCT. However, no significant effects on the working memory (assessed as spontaneous alternation in YMT) were observed. CONCLUSIONS Intraperitoneal administration of OT in aged rats has clear effects on anxious and depressive behavior, but no significant effects on the working memory. Also, several beneficial effects of OT on social preferences and sociability were observed.

The interaction between decreased short-term spatial memory and increased oxidative stress in a scopolamine-induced rat model of Alzheimer’s disease

Background: We compare results of differing PET scanner spatial resolution on effect size of standard uptake value ratio (SUVR) measurements in Florbetapir and FDG images from the ADNI database. Most reported ADNI analyses use “Level 4” preprocessed data [Koeppe] smoothed to a uniform isotropic resolution of 8mm FWHM, but there is the potential that the unsmoothed data contains more sensitive information. Methods:Freesurfer was used to obtain an ROI parcellation on T1 MRI data from 458 subjects (175 Normal, 92 EMCI, 153 LMCI, 39AD). Florbetapir and FDG data from two time points approximately 24 months apart were registered to the MRI data in T1 native space, and SUVR’s were computed at each time point. Results were obtained from both ADNI level 4 smoothed data, and from unsmoothed images (ADNI level 3). Cross sectional effect sizes between AD, EMCI, LMCI and Normal groups were evaluated using Cohen’s d. Effect size of longitudinal change in each group was also compared. Eight reference regions including whole cerebellum, brainstem and subcortical white matter were evaluated for the Florbetapir data, and FDG data were evaluated using whole brain and whole cerebellar reference regions. Results: Unsmoothed data consistently showed slightly higher effect size in both the cross sectional and