Título del libro: Neural Synapse Research Trends
Título del capítulo: Synaptic alterations of the striatum: Two different models of dopamine deafferentation
MARIA ROSA DE LOURDES AVILA COSTA; VERONICA ANAYA MARTINEZ; ENRIQUE MONTIEL FLORES; LAURA COLIN BARENQUE; PATRICIA ROSA ALEY MEDINA; JOSE DE JESUS ESPINOSA VILLANUEVA; LEONARDO REYNOSO ERAZO; TERESA IMELDA FORTOUL VANDER GOES;
Autores externos:
Idioma:
Inglés
Año de publicación:
2007
Resumen:
The synapse is the site of functional contact between two excitable cells, and is comprised of the pre and postsynaptic terminals. The complexity of the synapse is highlighted by the enormous diversity of proteins and molecular mechanism required for both, the assembly of a synaptic contact, and for the physiology and regulation of neurotransmission. An interesting finding of recent years is that synapses are extremely dynamic structures that may change not only their functioning with activity but also their morphology. An ultrastructural morphometric study was made in order to elucidate the possible synaptic alterations in rat corpus striatum after two different models of dopamine depletion: 1) 6-OHDA-inducing rapid nigrostriatal dopamine deafferentation and 2) Manganese inhalationinducing slow loss of striatum dopamine concentrations. In both models the ultrastructural analysis was performed in 50 randomly selected synaptic endings. In each synaptic button we observed all its membrane and organelles features, and measured: a) the diameter of the presynaptic button; b) The number of dendritic spines or dendrites as postsynaptic targets, and d) the number of perforated synapses. Beside the ultrastructural analysis, we evaluated the motor behavior and count the number of dopaminergic neurons through the Tyrosine manganese groups exhibited alterations in the motor task and an important loss of dopaminergic neurons. At ultrastructural level we found a damaged neuropile compared with controls, the alterations consisted in: great number of pre-synaptic endings with edema, significant increment of perforated synapses and an important loss of axo-spinous synaptic contacts. It is well known that most of dopaminergic synaptic contacts are symmetric made onto the spine neck, and the excitatory contacts are asymmetric on the spine head, and because the dopamine is lost, the synaptic contacts to the spines that remained, probably are glutamatergic and excitatory. Thus, we can conclude that although manganese group had less dopaminergic loss, the great number of excitatory synapses might induce more neuronal death due to excitotoxicity. Finally, the significant increment of perforated synapses in both groups might suggest brain plasticity as an attempt to recuperate the contact surface lost after the aggression. After the data obtained, we can assume the manganese model is a useful model in the study of Parkinson's disease. We consider that the study of the mechanisms that mediate the synaptic changes under experimental conditions may be of fundamental importance to understanding mechanisms of neuronal injury. © 2007 Nova Science Publishers, Inc. All rights reserved.
Entidades citadas de la UNAM:
ISBN:
9781614703563
Editorial:
Nova Science Publishers, Inc. Nombre de la publicación:
Synaptic alterations of the striatum: Two different models of dopamine deafferentation
Página inicial:
97
Página final:
132
Tipo de producto:
Capítulo de un Libro
