Os núcleos dopaminérgicos do mesencéfalo do mocó (kerodon rupestris): caracterização citoarquitetônica e por imunoistoquímica para tirosina-hidroxilase

The 3-hydroxytyramine/dopamine (DA) is a monoamine of catecholamineric group and consists in the progenitor substantia of synthesis of noradrenaline and adrenaline, having the enzyme tyrosine hydroxylase as a regulator of this process. Nuclei of midbrain expressing DA are the retrorubral field (RRF, A8 group), the substantia nigra pars compacta (SNc, A9 group) and the ventral tegmental area (VTA, A10 group). These nuclei are involved in three complex circuitry called mesostriatal, mesocortical and mesolimbic, which are related directly with various behavioral manifestations such as motor control, reward signaling in behavioural learning, motivation and pathological manifestations of Parkinson s disease and schizophrenia. The aim of this study was describe the morphology of midbrain dopaminergic neurons (A8, A9 and A10) of the rock cavy (Kerodon rupestris), a rodent belonging to the family Caviidae typical of the Brazilian Northeast, which is being adopted as a model for neuroanatomical studies in laboratory of neuroanatomy of the Federal University of Rio Grande do Norte. Coronal sections of brains of the rock cavies were submitted to staining by Nissl s method and immunohistochemistry against tyrosine hydroxylase. The nuclear organization of the midbrain dopaminergic nuclei of the rock cavy is very similar to that found in other animals of the order Rodentia, except by the presence of the tail of substantia nigra, which was found only in the studied species. We concluded that the midbrain dopaminergic nuclei are phylogenetically stable among species, but we think to be it necessary to expand the studies about the particularity found the rock cavy, investigating its occurrence in other species of rodents or investigating its functional relevance

Increased hippocampal excitability and impaired spatial memory function in mice lacking VGLUT2 selectively in neurons defined by tyrosine hydroxylase promoter activity

Three populations of neurons expressing the vesicular glutamate transporter 2 (Vglut2) were recently described in the A10 area of the mouse midbrain, of which two populations were shown to express the gene encoding, the rate-limiting enzyme for catecholamine synthesis, tyrosine hydroxylase (TH).One of these populations (‘‘TH– Vglut2 Class1’’) also expressed the dopamine transporter (DAT) gene while one did not ("TH–Vglut2 Class2"), and the remaining population did not express TH at all ("TH-Vglut2-only"). TH is known to be expressed by a promoter which shows two phases of activation, a transient one early during embryonal development, and a later one which gives rise to stable endogenous expression of the TH gene. The transient phase is, however, not specific to catecholaminergic neurons, a feature taken to advantage here as it enabled Vglut2 gene targeting within all three A10 populations expressing this gene, thus creating a new conditional knockout. These knockout mice showed impairment in spatial memory function. Electrophysiological analyses revealed a profound alteration of oscillatory activity in the CA3 region of the hippocampus. In addition to identifying a novel role for Vglut2 in hippocampus function, this study points to the need for improved genetic tools for targeting of the diversity of subpopulations of the A10 area

Increased hippocampal excitability and impaired spatial memory function in mice lacking VGLUT2 selectively in neurons defined by tyrosine hydroxylase promoter activity

Three populations of neurons expressing the vesicular glutamate transporter 2 (Vglut2) were recently described in the A10 area of the mouse midbrain, of which two populations were shown to express the gene encoding, the rate-limiting enzyme for catecholamine synthesis, tyrosine hydroxylase (TH).One of these populations (‘‘TH– Vglut2 Class1’’) also expressed the dopamine transporter (DAT) gene while one did not ("TH–Vglut2 Class2"), and the remaining population did not express TH at all ("TH-Vglut2-only"). TH is known to be expressed by a promoter which shows two phases of activation, a transient one early during embryonal development, and a later one which gives rise to stable endogenous expression of the TH gene. The transient phase is, however, not specific to catecholaminergic neurons, a feature taken to advantage here as it enabled Vglut2 gene targeting within all three A10 populations expressing this gene, thus creating a new conditional knockout. These knockout mice showed impairment in spatial memory function. Electrophysiological analyses revealed a profound alteration of oscillatory activity in the CA3 region of the hippocampus. In addition to identifying a novel role for Vglut2 in hippocampus function, this study points to the need for improved genetic tools for targeting of the diversity of subpopulations of the A10 area