Adenosine A2A receptors: localization and function

Adenosine is an endogenous purine nucleoside present in all mammalian tissues, that originates from the breakdown of ATP. By binding to its four receptor subtypes (A1, A2A, A2B, and A3), adenosine regulates several important physiological functions at both the central and peripheral levels. Therefore, ligands for the different adenosine receptors are attracting increasing attention as new potential drugs to be used in the treatment of several diseases. This chapter is aimed at providing an overview of adenosine metabolism, adenosine receptors localization and their signal transduction pathways. Particular attention will be paid to the biochemistry and pharmacology of A2A receptors, since antagonists of these receptors have emerged as promising new drugs for the treatment of Parkinson's disease. The interactions of A2A receptors with other nonadenosinergic receptors, and the effects of the pharmacological manipulation of A2A receptors on different body organs will be discussed, together with the usefulness of A2A receptor antagonists for the treatment of Parkinson's disease and the potential adverse effects of these drugs

Immunohistochemical distribution of neuropeptides in the amygdaloid complex of the cat. A comparative study in mammals.

The distribution of several neuropeptides in the amygdaloid complex of the cat is described. Five of the neuropeptides studied (luteinizing hormone- releasing hormone, b-endorphin, dynorphin A (1-17), g-melanocyte-stimulating hormone or galanin) did not show immunoreactive profiles, whereas neuropeptide Y and somatostatin displayed the widest distribution throughout the amygdaloid nuclei. The medial amygdala (medial nucleus, medial division of the central nucleus) contained the highest number of the n e u ropeptides studied, whereas the lateral nucleus displayed the lowest amount of immunoreactive profiles. In addition, the morphological data suggest the possible co-existence of several neuropeptides in the same fibers and/or cell bodies, and a comparison with previous studies on the projections of the amygdaloid nuclei in the cat allows us to speculate about the possible peptidergic content of these pathways. The distribution of the neuropeptides studied in the cat is compared with the location of the same peptides in the amygdaloid complex of other mammalian species. Finally, the possible physiological functions of the neuropeptides, as well as aspects of future research into the morphology of neuropeptides in the cat amygdala are discusse

Mapping of CGRP in the alpaca diencephalon

This work has been supported by the Ministerio de Educación y Ciencia (BFU2005-02241/BFI), Spain and by the CONCYTEC: PROCYT project 2006, Peru. The authors thank Ewing Rafael Duque for his technical assistance, N. Skinner for stylistic revision of the English text and Professor Gerard Tramu (University of Bordeaux I, France) for kindly providing the CGRP antiserum.Consejo Nacional de Ciencia, Tecnología e Innovación Tecnológica - Concyte

Immunohistochemical mapping of pro-opiomelanocortin- and pro-dynorphin-derived peptides in the alpaca (Lama pacos) diencephalon

The authors thank Professor Gérard Tramu (University of Bordeaux I, France) for kindly providing the first antisera and N. Skinner (University of Salamanca, Spain) for stylistic revision of the English text. This work has been supported by the Ministerio de Educación y Ciencia (BFU2005-02241/BFI), Spain and the Ministerio de Ciencia e Innovación (BFU2008-03369/BFI), Spain and by the CONCYTEC: PROCYT project 2006, Peru.Consejo Nacional de Ciencia, Tecnología e Innovación Tecnológica - Concyte

Special Issue on Galanin Role of galanin and galanin(1-15) on central cardiovascular control

Abstract Galanin and the N-terminal fragment Galanin(1-15) are involved in central cardiovascular regulation. The present paper reviews the recent cardiovascular results obtained by intracisternal injections of showing that: (A) the Galanin antagonist M40 blocks the central cardiovascular responses induced by Galanin(1-15) but not those elicited by Galanin; (B) both Galanin and Galanin(1-15) induce the expression of c-Fos in cardiovascular nuclei of the medulla oblongata with different temporal and spatial profiles; (C) the cardiovascular action of Galanin(1-15), but not Galanin, is mediated by peripheral b-receptor stimulation; (D) and it is demonstrated an antagonistic Galanin/a2-adrenoceptors interaction as well as a differential modulation of central cardiovascular responses of Angiotensin II by Galanin or Galanin(1-15). All these data strengthen the involvement of both Galanin molecules as neuromodulators on central cardiovascular regulation

Mapping of CGRP in the alpaca (Lama pacos) brainstem

This work has been supported by the Ministerio de Educación y Ciencia (BFU2005-02241/BFI), Spain and by the CONCYTEC: PROCYT project 2006, Peru. The authors thank Ewing Rafael Duque for his technical assistance, N. Skinner for stylistic revision of the English text and Professor Gerard Tramu (University of Bordeaux I, France) for kindly providing the CGRP antiserum.Consejo Nacional de Ciencia, Tecnología e Innovación Tecnológica - Concyte

Brain Dopamine Transmission in Health and Parkinson's Disease: Modulation of Synaptic Transmission and Plasticity Through Volume Transmission and Dopamine Heteroreceptors

This perspective article provides observations supporting the view that nigro-striatal dopamine neurons and meso-limbic dopamine neurons mainly communicate through short distance volume transmission in the um range with dopamine diffusing into extrasynaptic and synaptic regions of glutamate and GABA synapses. Based on this communication it is discussed how volume transmission modulates synaptic glutamate transmission onto the D1R modulated direct and D2R modulated indirect GABA pathways of the dorsal striatum. Each nigro-striatal dopamine neuron was first calculated to form large numbers of neostriatal DA nerve terminals and then found to give rise to dense axonal arborizations spread over the neostriatum, from which dopamine is released. These neurons can through DA volume transmission directly influence not only the striatal GABA projection neurons but all the striatal cell types in parallel. It includes the GABA nerve cells forming the island-/striosome GABA pathway to the nigral dopamine cells, the striatal cholinergic interneurons and the striatal GABA interneurons. The dopamine modulation of the different striatal nerve cell types involves the five dopamine receptor subtypes, D1R to D5R receptors, and their formation of multiple extrasynaptic and synaptic dopamine homo and heteroreceptor complexes. These features of the nigro-striatal dopamine neuron to modulate in parallel the activity of practically all the striatal nerve cell types in the dorsal striatum, through the dopamine receptor complexes allows us to understand its unique and crucial fine-tuning of movements, which is lost in Parkinson's disease. Integration of striatal dopamine signals with other transmitter systems in the striatum mainly takes place via the receptor-receptor interactions in dopamine heteroreceptor complexes. Such molecular events also participate in the integration of volume transmission and synaptic transmission. Dopamine modulation of the glutamate synapses on the dorsal striato-pallidal GABA pathway involves D2R heteroreceptor complexes such as D2R-NMDAR, A2AR-D2R, and NTSR1-D2R heteroreceptor complexes. The dopamine modulation of glutamate synapses on the striato-entopeduncular/nigral pathway takes place mainly via D1R heteroreceptor complexes such as D1R-NMDAR, A2R-D1R, and D1R-D3R heteroreceptor complexes. Dopamine modulation of the island/striosome compartment of the dorsal striatum projecting to the nigral dopamine cells involve D4R-MOR heteroreceptor complexes. All these receptor-receptor interactions have relevance for Parkinson's disease and its treatment