Manuel Megías

Manuel Megías
University of Vigo | UVIGO · Department of Functional Biology and Health Sciences

About

52
Publications
8,667
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2,210
Citations
Introduction
Manuel Megías currently works at the Department of Functional Biology and Health Sciences, University of Vigo. Manuel does research in Anatomy, Neuroscience and Cell Biology.
Additional affiliations
January 2000 - December 2013
University of Vigo
Description
  • Assistan professor
March 1997 - March 1999
Russian Academy of Medical Sciences
Position
  • Total number and type of synapses in hippocampal neurons
January 1995 - December 1997
Universidad de Cantabria

Publications

Publications (52)
Preprint
Full-text available
The skin is a barrier between the internal and external environment of an organism. Depending on the species, it participates in multiple functions. The skin is the organ that holds the body together, covers and protects it, and provides communication with its environment. It is also the body's primary line of defense, especially for anamniotes. Al...
Article
Full-text available
The theory of evolution is one of the greatest scientific achievements in the intellectual history of humankind, yet it is still contentious within certain social groups. Despite being as robust and evidence-based as any other notable scientific theory, some people show a strong reluctance to accept it. In this study, we used the Measure of Accepta...
Chapter
Lampreys and hagfishes, also identified as cyclostomes, are the only two extant representatives of agnathans. Although accumulating experimental data had solved important aspects of vertebrate brain evolution, there remain some unsettled questions regarding the evolutionary relationships of agnathans considering their remarkable anatomical and life...
Article
Full-text available
Background: Mustn1 is a specific musculoskeletal protein that plays a critical role in myogenesis and chondrogenesis in vertebrates. Whole-mount in situ hybridization revealed that mustn1b mRNAs are specifically expressed in skeletal and cardiac muscles in zebrafish embryos. However, the precise function and the regulatory elements required for it...
Article
Dorsoventral pigment patterning, characterized by a light ventrum and a dark dorsum, is one of the most widespread chromatic adaptations in vertebrate body coloration. In mammals, this countershading depends on differential expression of agouti-signaling protein (ASIP), which drives a switch of synthesis of one type of melanin to another within mel...
Article
Full-text available
The development of the epidermis of sea lamprey Petromyzon marinus along the whole life cycle was studied using conventional staining techniques and lectin histochemistry. The epidermis undergoes variations in morphology and thickness throughout development. The simple cuboidal epithelium found in the epidermis of prolarvae becomes stratified cubic...
Article
Lampreys, together with hagfishes, are the only extant representatives of the oldest branch of vertebrates, the agnathans, which are the sister group of gnathostomes; therefore, studies on these animals are of great evolutionary significance. Lampreys exhibit a particular life cycle with remarkable changes in their behavior, concomitant, in part, w...
Chapter
The agnathan brain is of interest for research on the fundamental properties of the vertebrate central nervous system, on the organization of nerve cells in functional systems, and more recently for molecular and developmental studies. The available information on its neuroanatomical organization indicates that the nervous system of lampreys contai...
Chapter
Lampreys and hagfishes, also identified as cyclostomes, are the only two extant representatives of agnathans. Although accumulating experimental data had solved important aspects of vertebrate brain evolution, there remain some unsettled questions regarding the evolutionary relationships of agnathans considering their remarkable anatomical and life...
Article
Full-text available
Numerous data reported in lampreys, which belong to the phylogenetically oldest branch of vertebrates, show that the dopaminergic system was already well developed at the dawn of vertebrate evolution. The expression of dopamine in the lamprey brain is well conserved when compared to other vertebrates, and this is also true for the D2 receptor. Addi...
Article
Full-text available
Self-fertilization (selfing) favours reproductive success when mate availability is low, but renders populations more vulnerable to environmental change by reducing genetic variability. A mixed-breeding strategy (alternating selfing and outcrossing) may allow species to balance these needs, but requires a system for regulating sexual identity. We e...
Article
Full-text available
The NPY receptors known as Y receptors are classified in three subfamilies, Y1, Y2 and Y5, and are involved in different physiological functions. The Y5 receptor is the only member of the Y5 subfamily, and it is present in all vertebrate groups, excepting teleosts. Both molecular and pharmacological studies show that Y5 receptor is highly conserved...
Article
Full-text available
The neuropeptide Y system consists of several neuropeptides acting through a broad number of receptor subtypes, the NPY family of receptors. NPY receptors are divided in three subfamilies: Y1, Y2, and Y5 that display a complex evolutionary history due to local and large scale gene duplication events and gene losses. Lampreys emerged from a basal br...
Article
Full-text available
Lampreys, together with hagfishes, represent the sister group of gnathostome vertebrates. There is an increasing interest for comparing the forebrain organization observed in lampreys and gnathostomes to shed light on vertebrate brain evolution. Within the prosencephalon, there is now a general agreement on the major subdivisions of the lamprey die...
Article
The agnathan brain is of interest for research on the fundamental properties of the vertebrate central nervous system, on the organization of nerve cells in functional systems, and more recently for molecular and developmental studies. The available information on its neuroanatomical organization indicates that the nervous system of lampreys contai...
Poster
[9] Nuevas aportaciones sobre la organización prosomerica en lampreas. MA Pombal, M Megias, SM Bardet, L Puelles – Poster 13th congress of Spanish Society of Neuroscience (SENC) (Tarragona, Espagne) – 2009
Article
Full-text available
Ten years ago, we published the first detailed prosomeric map of the forebrain in lampreys. In the interim, the prosomeric model has been modified and simplified to better explain numerous data on the expression patterns of regulatory genes, as well as data from chemical, hodological and neuroembryological experiments, mostly in amniote vertebrates...
Article
The role of the dopamine D(4) receptor in cognitive processes and its association with several neuropsychiatric disorders have been related to its preferential localization in the cerebral cortex. In the present work we have studied in detail the regional and cellular localization of the dopamine D(4) receptor immunoreactivity (IR) in the rat cereb...
Article
Adrenomedullin (AM) is a neuropeptide widely distributed in vertebrates. In jawed vertebrates it has been localized in distinct regions of the central nervous system by means of antisera against human AM because the molecule seems to be well conserved across species. In this study, we have analyzed the localization of AM-like immunoreactive (AM-ir)...
Article
Full-text available
We studied the distribution of calretinin immunoreactivity (CR-ir) in the rostral and intermediate levels of the spinal cord of lampreys from embryonic to adult periods. CR-ir was first observed at hatching in motoneurons and primary sensory neurons of the spinal cord, the dorsal cells. During the prolarval period two new cell types showed CR-ir: g...
Article
Full-text available
The epicardium is the outer layer of the vertebrate heart. Both the embryonic epicardium and its derived mesenchyme are critical to heart development, contributing to the coronary vasculature and modulating the proliferation of the ventricular myocardium. The embryonic epicardium arises from an extracardiac, originally paired progenitor tissue call...
Article
LIM-homeodomain genes encode a family of transcription factors with highly conserved roles in the patterning and regionalisation of the vertebrate brain. The expression of one of those genes, Lhx15, in the embryonic lamprey brain, characterises precise functional subdivisions. In order to analyse the non-embryonic development of the lamprey brain,...
Article
Introduction the senescence-accelerated mouse (SAM) is a murine model of rapid ageing once adulthood has been reached and there is a concomitant cognitive decline. The neurosecretory system of the hypothalamus is composed of the supraoptic and paraventricular nuclei, and their neurons synthesize the hormones oxytocin and vasopressin. A feature of t...
Article
The hypothalamic supraoptic and paraventricular nuclei form the neurosecretory system and synthesize the neurohormones oxytocin and arginine-vasopressin. The senescence-accelerated mouse is a model of rapid aging that displays senile amyloidosis and memory problems. This paper presents the characterization of the neurosecretory system and describes...
Article
The neuropeptide FF (NPFF) is an octapeptide of the RFamide-related peptides (FaRPs) that was primarily isolated from the bovine brain. Its distribution in the CNS has been reported in several mammalian species, as well as in some amphibians. Therefore, in order to gain insight in the evolution on the expression pattern of this neuropeptide in vert...
Article
The changes in distribution and number of GABA immunoreactive (GABA-ir) fibers from postembryonic stages to adulthood in the lamprey spinal cord white matter were studied by using immunocytochemical techniques. From prolarvae to adult spawning animals there was an increase of the number of GABA-ir fibers. Three phases can be distinguished: (a) from...
Article
Normal aging is commonly associated with a decline in memory, mainly for that related with newly acquired information. The hippocampal formation (HF) is a brain region that has been implicated in this dysfunction. Within the HF there are several cellular types, such as pyramidal cells, granule neurons of the dentate gyrus, and astrocytes. CDP-choli...
Article
Full-text available
The lamprey spinal cord increases in length and size during all its life cycle; thus, it is expected that new cells will be generated. This expectation suggests that the locomotor circuits must be continuously remodeled. Key elements in the cellular network controlling locomotor behavior are inhibitory cells. Here, we studied the gamma-aminobutyric...
Article
The central pattern generator for locomotion in vertebrates is composed of different spinal neuronal populations that generate locomotor movement. In the lamprey spinal cord, several classes of interneurons have been identified based on morphologic and physiological criteria and integrated in the spinal cord circuits implicated in the generation of...
Article
The distribution of calretinin immunoreactive (CR-ir) structures in the adult lamprey (Lampetra fluviatilis) olfactory system was studied by using immunocytochemical techniques. In the olfactory epithelium, a subpopulation of olfactory receptor cells was CR-ir. In the olfactory bulbs, three different cell populations were observed. Large CR-ir cell...
Article
To elucidate the role of dendritic morphology in signal transfer, the passive propagation of somatic and dendritic potentials was compared in multi-compartment models of three interneuron subpopulations in the CA1 region. Nine calbindin-, 15 calretinin- and 10 parvalbumin-containing cells were modelled incorporating the detailed geometry, the curre...
Article
Full-text available
The integrative properties of neurons depend strongly on the number, proportions and distribution of excitatory and inhibitory synaptic inputs they receive. In this study the three-dimensional geometry of dendritic trees and the density of symmetrical and asymmetrical synapses on different cellular compartments of rat hippocampal CA1 area pyramidal...
Article
D1-like (D1 and D5) and D2-like (D2, D3 and D4) dopamine receptor subtypes interact synergistically in many paradigms, such as dopamine (DA) agonist-stimulated motor behaviour and striatal c-Fos expression in intact and DA-depleted striatum. However, it is not clear which subtypes of dopamine receptor are involved in these process. We now report th...
Article
The least known aspect of the functional architecture of hippocampal microcircuits is the quantitative distribution of synaptic inputs of identified cell classes. The complete dendritic trees of functionally distinct interneuron types containing parvalbumin (PV), calbindin D(28k) (CB), or calretinin (CR) were reconstructed at the light microscopic...
Article
Ts65Dn mouse displays a partial triplication of chromosome 16 and is adopted as a model for Down syndrome (DS). It is known that Ts65Dn mice present memory deficiencies. In order to gain insight into the cause of these deficiencies, we studied the possibility of changes in volumes and neuronal numbers in different regions of the hippocampus (dentat...
Article
The aim of this study was to look for morphological or functional differences between the circadian system of two substrains of Senescence Accelerated Mice (SAM): senescence-prone (SAMP8; average median survival time = 10.0 months) and senescence-resistant (SAMR1; average median survival time = 18.9 months). Neither the general structure nor the qu...
Article
Ts65DN mice were developed as a model of Down syndrome (DS); they are trisomic for the distal segment of chromosome 16 (MMU16), which contains genes syntenic with some of the genes located on the critical region of human chromosome 21 (HSA21). Since behavioral and neurochemical disturbances have been observed in this animal model, it seemed interes...
Article
The effect of chronic intake of cytidine-5'-diphosphate choline (CDP choline), a precursor of the membrane lipid phosphatidylcholine, was analyzed in secretory cells of the Harderian gland (HG) of aged (26-month-old) female Swiss mice. These mice were treated with the drug from 12 months of age until they were 26 months old. The results obtained we...
Article
Co-localization of calretinin immunoreactivity and nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d) activity was studied in the rat hippocampus and dentate gyrus. Neurons co-expressing both markers (CR/NADPH-d) were observed throughout the hippocampus and dentate gyrus. However, they were more abundant in the stratum pyramidale and...
Article
Since melatonin has direct inhibitory effects on some tumor cells in vitro, the aim of the present work was to study whether the growth and structural characteristics of the human neuroblastoma cell line SK-N-SH in vitro are influenced by this indoleamine. Concentrations of melatonin of 10(-9) and 10(-11) M significantly inhibited (P < 0.05) cell p...
Article
The influence of chronic administration of cytidine-5'-diphosphate choline (CDP-choline), a precursor of the membrane lipid phosphatidylcholine, was studied in neurosecretory neurons (NSNs) of the supraoptic nucleus (SON) of aged mouse hypothalamus. Animals were treated with CDP-choline from 12 months of age until 26 months. They were studied for b...
Article
We analyzed the distribution and light-microscopic features of the NADPH diaphorase-containing structures in the lizard hippocampus, likely to correspond to nitric oxide synthase-containing cells and fibers, and thus likely to release nitric oxide. We also studied co-localization of NADPH diaphorase with the neurotransmitter GABA, the calcium-bindi...
Article
Different subpopulations of GABA neurons containing the neuropeptides somatostatin and neuropeptide Y, and the calcium binding protein parvalbumin were studied by immunocytochemistry using light and electron microscopy in the dorsomedial cortex of the lizard Psammodromus algirus to investigate the connectivity of different subsets of GABA neurons i...
Article
The aim of the present study was to analyze the distribution and characteristics of NPY immunoreactive structures in the cerebral cortex of lizards and to investigate the degree of co-existence of this neuropeptide with somatostatin and GABA. The immunoperoxidase method was applied to vibratome sections as well as to semithin sections. NPY neurons...

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