ABSTRACT
The position of the caudal intralaminar nuclei within basal ganglia circuitry has largely been neglected in most studies dealing with basal ganglia function. During the past few years, there has been a growing body of evidence suggesting that the thalamic parafascicular nucleus in rodents (PF) exerts a multifaceted modulation of basal ganglia nuclei, at different levels. Our aim was to study the activity of the thalamostriatal pathway in rats with unilateral dopaminergic depletion. The experimental approach comprised first unilateral delivery of 6-OHDA in the medial forebrain bundle. Thirty days post-lesioning, animals showing a clear asymmetry were then subjected to bilateral injection of Fluoro-Gold (FG) within the striatum. Subsequently, expression of the mRNA encoding the vesicular glutamate transporter 2 (vGLUT2) was detected within thalamostriatal-projecting neurons (FG-labeled) by in situ hybridization and the results were confirmed by laser-guided capture microdissection microscopy followed by real-time PCR. The data showed that there was a marked neuronal loss restricted to PF neurons projecting to the dopamine-depleted striatum. Moreover, PF neurons innervating the dopamine-depleted striatum were intensely hyperactive. These neurons showed a marked increase on the expression of vGLUT2 mRNA as well as for the mRNA encoding the subunit I of cytochrome oxidase as compared with those neurons projecting to the striatum with normal dopamine content. Thus, the selective neurodegeneration of PF neurons innervating the striatum together with the increased activity of the thalamostriatal pathway coexist after nigrostriatal denervation.
Subject(s)
Denervation , Functional Laterality/physiology , Neostriatum/physiology , Neural Pathways/physiology , Substantia Nigra/physiology , Thalamus/physiology , Animals , Behavior, Animal , Cell Count/methods , Electron Transport Complex IV/metabolism , In Situ Hybridization/methods , Male , Motor Activity/physiology , Neural Pathways/injuries , Oxidopamine/adverse effects , RNA, Messenger/biosynthesis , Rats , Rats, Wistar , Reverse Transcriptase Polymerase Chain Reaction/methods , Rotarod Performance Test/methods , Stilbamidines/pharmacokinetics , Tyrosine 3-Monooxygenase/genetics , Tyrosine 3-Monooxygenase/metabolism , Vesicular Glutamate Transport Protein 2/genetics , Vesicular Glutamate Transport Protein 2/metabolismABSTRACT
Major life events, recent life stressors, and childhood diseases were examined among children and adolescents who were offspring, siblings, or other relatives of persons with type 1 diabetes mellitus (DM). All youth were recruited as part of a multi-site nationwide trial on the prevention of type 1 DM; parents of 347 children (4 to 18 yr) completed measures that asked about children's life events, recent stressors, and childhood illnesses. Analyses compared age groups (young child, preadolescent, adolescent) and relative type (offspring, sibling, other relative). Findings revealed offspring and siblings did not differ from "other relatives" in terms of life events, recent life stress, and disease/illness variables. However, siblings were reported to have fewer major life events and fewer life stressors in the past 12 months than offspring; siblings also had fewer infectious diseases during the first two years of life compared to offspring. Few age-related differences were found. Overall, results suggest that offspring and siblings of persons with type 1 DM are not at a disadvantage in terms of early life stress or disease in comparison to youth who have other family members with diabetes. However, siblings may have some advantages relative to children who are offspring. The mechanisms underlying these relationships require further elucidation and study.
Subject(s)
Diabetes Mellitus, Type 1/psychology , Family Health , Stress, Psychological/physiopathology , Stress, Psychological/psychology , Aging/physiology , Aging/psychology , Child , Child, Preschool , Female , Humans , Life Change Events , MaleABSTRACT
6-Hydroxydopamine (6-OHDA) is a dopaminergic neurotoxin putatively involved in the pathogenesis of Parkinson's disease (PD). Its neurotoxicity has been related to the production of reactive oxygen species. In this study we examine the effects of the antioxidants ascorbic acid (AA), glutathione (GSH), cysteine (CySH), and N-acetyl-CySH (NAC) on the autoxidation and neurotoxicity of 6-OHDA. In vitro, the autoxidation of 6-OHDA proceeds rapidly with the formation of H2O2 and with the participation of the H2O2 produced in the reaction. The presence of AA induced a reduction in the consumption of O2 during the autoxidation of 6-OHDA and a negligible presence of the p-quinone, which demonstrates the efficiency of AA to act as a redox cycling agent. The presence of GSH, CySH, and NAC produced a significant reduction in the autoxidation of 6-OHDA. In vivo, the presence of sulfhydryl antioxidants protected against neuronal degeneration in the striatum, which was particularly remarkable in the case of CySH and was attributed to its capacity to remove the H2O2 produced in the autoxidation of 6-OHDA. These results corroborate the involvement of oxidative stress as the major mechanism in the neurotoxicity of 6-OHDA and the putative role of CySH as a scavenger in relation to PD.
