RESUMO
The genomics era has brought along the completed sequencing of a large number of bird genomes that cover a broad range of the avian phylogenetic tree (>30 orders), leading to major novel insights into avian biology and evolution. Among recent findings, the discovery that birds lack a large number of protein coding genes that are organized in highly conserved syntenic clusters in other vertebrates is very intriguing, given the physiological importance of many of these genes. A considerable number of them play prominent endocrine roles, suggesting that birds evolved compensatory genetic or physiological mechanisms that allowed them to survive and thrive in spite of these losses. While further studies are needed to establish the exact extent of avian gene losses, these findings point to birds as potentially highly relevant model organisms for exploring the genetic basis and possible therapeutic approaches for a wide range of endocrine functions and disorders.
Assuntos
Aves/genética , Sistema Endócrino/fisiologia , Genômica , Animais , GenesRESUMO
The song system of songbirds, a set of brain nuclei necessary for song learning and production, has distinctive morphological and functional properties. Utilizing differential display, we searched for molecular components involved in song system regulation. We identified a cDNA (zRalDH) that encodes a class 1 aldehyde dehydrogenase. zRalDH was highly expressed in various song nuclei and synthesized retinoic acid efficiently. Brain areas expressing zRalDH generated retinoic acid. Within song nucleus HVC, only projection neurons not undergoing adult neurogenesis expressed zRalDH. Blocking zRalDH activity in the HVC of juveniles interfered with normal song development. Our results provide conclusive evidence for localized retinoic acid synthesis in an adult vertebrate brain and indicate that the retinoic acid-generating system plays a significant role in the maturation of a learned behavior.
Assuntos
Aldeído Desidrogenase/metabolismo , Encéfalo/metabolismo , Proteínas do Tecido Nervoso , Aves Canoras/metabolismo , Tretinoína/metabolismo , Vocalização Animal/fisiologia , Aldeído Desidrogenase/genética , Família Aldeído Desidrogenase 1 , Aldeído Oxirredutases/genética , Aldeído Oxirredutases/metabolismo , Animais , Autorradiografia , Sequência de Bases , Encéfalo/citologia , Células Cultivadas , Clonagem Molecular , Dissulfiram/administração & dosagem , Implantes de Medicamento , Expressão Gênica , Isoenzimas/genética , Isoenzimas/metabolismo , Masculino , Dados de Sequência Molecular , Neurônios/citologia , Neurônios/metabolismo , Especificidade de Órgãos/genética , Especificidade de Órgãos/fisiologia , Retinal Desidrogenase , Análise de Sequência de DNA , Homologia de Sequência de Aminoácidos , Aves Canoras/genética , Especificidade por Substrato , Vocalização Animal/efeitos dos fármacosRESUMO
We show that presentation of individual canary song syllables results in distinct expression patterns of the immediate-early gene ZENK in the caudomedial neostriatum (NCM) of adult canaries. Information on the spatial distribution and labeling of stained cells provides for a classification of ZENK patterns that (1) accords to the organization of stimuli into families, (2) preserves the stimuli intrafamily relationships, and (3) confers salience to natural over artificial stimuli, resulting in a nonclassical tonotopic map. Moreover, complex syllable maps cannot be reduced to any linear combinations of simple syllable maps. These properties arise from the collective response of NCM neurons to auditory stimuli, rather than from the behavior of single neurons. The syllabic representation described here may constitute an important step toward deciphering the rules of birdsong auditory representation.
Assuntos
Percepção Auditiva/fisiologia , Mapeamento Encefálico/métodos , Canários/fisiologia , Regulação da Expressão Gênica/fisiologia , Genes Precoces , Vocalização Animal/fisiologia , Animais , Habituação Psicofisiológica/fisiologia , Neostriado/metabolismo , Estatística como AssuntoRESUMO
High-throughput methods for analyzing genome structure and function are having a large impact in songbird neurobiology. Methods include genome sequencing and annotation, comparative genomics, DNA microarrays and transcriptomics, and the development of a brain atlas of gene expression. Key emerging findings include the identification of complex transcriptional programs active during singing, the robust brain expression of non-coding RNAs, evidence of profound variations in gene expression across brain regions, and the identification of molecular specializations within song production and learning circuits. Current challenges include the statistical analysis of large datasets, effective genome curations, the efficient localization of gene expression changes to specific neuronal circuits and cells, and the dissection of behavioral and environmental factors that influence brain gene expression. The field requires efficient methods for comparisons with organisms like chicken, which offer important anatomical, functional and behavioral contrasts. As sequencing costs plummet, opportunities emerge for comparative approaches that may help reveal evolutionary transitions contributing to vocal learning, social behavior and other properties that make songbirds such compelling research subjects.
Assuntos
Encéfalo/fisiologia , Técnicas Genéticas , Aves Canoras/fisiologia , Vocalização Animal/fisiologia , Animais , Galinhas , Expressão Gênica , Genômica , Sequenciamento de Nucleotídeos em Larga Escala , Aves Canoras/genéticaRESUMO
The dopamine transporter (DAT) is a major regulator of synaptic dopamine (DA) availability. It plays key roles in motor control and motor learning, memory formation, and reward-seeking behavior, is a major target of cocaine and methamphetamines, and has been assumed to be conserved among vertebrates. We have found, however, that birds, crocodiles, and lizards lack the DAT gene. We also found that the unprecedented loss of this important gene is compensated for by the expression of the noradrenaline transporter (NAT) gene, and not the serotonin transporter genes, in dopaminergic cells, which explains the peculiar pharmacology of the DA reuptake activity previously noted in bird striatum. This unexpected pattern contrasts with that of ancestral vertebrates (e.g. fish) and mammals, where the NAT gene is selectively expressed in noradrenergic cells. DA circuits in birds/reptiles and mammals thus operate with an analogous reuptake mechanism exerted by different genes, bringing new insights into gene expression regulation in dopaminergic cells and the evolution of a key molecular player in reward and addiction pathways.
Assuntos
Proteínas da Membrana Plasmática de Transporte de Dopamina/metabolismo , Animais , Aves , Corpo Estriado/metabolismo , Dopamina/metabolismo , Proteínas da Membrana Plasmática de Transporte de Dopamina/classificação , Proteínas da Membrana Plasmática de Transporte de Dopamina/genética , Neurônios Dopaminérgicos/metabolismo , Masculino , Proteínas da Membrana Plasmática de Transporte de Norepinefrina/genética , Proteínas da Membrana Plasmática de Transporte de Norepinefrina/metabolismo , Filogenia , Regiões Promotoras Genéticas , Elementos Reguladores de Transcrição/genética , RépteisRESUMO
Auditory and vocal regulation of gene expression occurs in separate discrete regions of the songbird brain. Here we demonstrate that regulated gene expression also occurs during vocal communication in a parrot, belonging to an order whose ability to learn vocalizations is thought to have evolved independently of songbirds. Adult male budgerigars (Melopsittacus undulatus) were stimulated to vocalize with playbacks of conspecific vocalizations (warbles), and their brains were analyzed for expression of the transcriptional regulator ZENK. The results showed that there was distinct separation of brain areas that had hearing- or vocalizing-induced ZENK expression. Hearing warbles resulted in ZENK induction in large parts of the caudal medial forebrain and in 1 midbrain region, with a pattern highly reminiscent of that observed in songbirds. Vocalizing resulted in ZENK induction in nine brain structures, seven restricted to the lateral and anterior telencephalon, one in the thalamus, and one in the midbrain, with a pattern partially reminiscent of that observed in songbirds. Five of the telencephalic structures had been previously described as part of the budgerigar vocal control pathway. However, functional boundaries defined by the gene expression patterns for some of these structures were much larger and different in shape than previously reported anatomical boundaries. Our results provide the first functional demonstration of brain areas involved in vocalizing and auditory processing of conspecific sounds in budgerigars. They also indicate that, whether or not vocal learning evolved independently, some of the gene regulatory mechanisms that accompany learned vocal communication are similar in songbirds and parrots.
Assuntos
Encéfalo/anatomia & histologia , Encéfalo/fisiologia , Proteínas de Ligação a DNA/genética , Periquitos/anatomia & histologia , Periquitos/fisiologia , Fatores de Transcrição/genética , Vocalização Animal/fisiologia , Animais , Vias Auditivas/anatomia & histologia , Vias Auditivas/fisiologia , Mapeamento Encefálico , Contagem de Células , Regulação da Expressão Gênica , Audição/fisiologia , Masculino , RNA Mensageiro/análiseRESUMO
When songbirds hear the song of another individual of the same species or when they sing, the mRNA levels of the ZENK gene increase rapidly in forebrain areas involved in vocal communication. This gene induction is thought to be related to long-term neuronal change and possibly the formation of song-related memories. We used immunocytochemistry to study the levels and distribution of ZENK protein in the brain of zebra finches and canaries after presentation of song playbacks. Birds that heard the playbacks and did not sing in response showed increased ZENK protein levels in auditory brain areas, including the caudomedial neostriatum and hyperstriatum ventrale, fields L1 and L3, the shelf adjacent to the high vocal center (HVC), the cup adjacent to the nucleus robustus archistriatalis (RA), and the nucleus mesencephalicus lateralis pars dorsalis (MLd). No ZENK expression was seen in song nuclei in these birds. Males that sang in response to the playbacks showed, in addition to auditory areas, increased ZENK protein in several song control nuclei, most prominently in HVC, RA, area X, and the dorsomedial nucleus (DN) of the intercollicular complex. The rise in ZENK protein followed that described previously for ZENK mRNA by a short lag, and the distribution of ZENK-labeled cells was in agreement with previous analysis of mRNA distribution. Thus, ZENK protein regulation can be used to assess activation of brain areas involved in perceptual and motor aspects of song. Possible implications of ZENK induction in these areas are discussed.
Assuntos
Aves/fisiologia , Encéfalo/metabolismo , Proteínas de Ligação a DNA/metabolismo , Proteínas de Ligação a DNA/fisiologia , Fatores de Transcrição/metabolismo , Fatores de Transcrição/fisiologia , Vocalização Animal/fisiologia , Sequência de Aminoácidos , Animais , Especificidade de Anticorpos , Aves/anatomia & histologia , Encéfalo/fisiologia , Mapeamento Encefálico , Canários/anatomia & histologia , Canários/fisiologia , Proteínas de Ligação a DNA/imunologia , Feminino , Soros Imunes/química , Immunoblotting , Cinética , Masculino , Dados de Sequência Molecular , Neostriado/metabolismo , Pentilenotetrazol , Fatores de Transcrição/imunologiaRESUMO
Oscine birds are among the few animal groups that have vocal learning, and their brains contain a specialized system for song learning and production. We describe here the immunocytochemical distribution of dopamine-beta-hydroxylase (DBH), a noradrenergic marker, in the brain of an oscine, the zebra finch (Taeniopygia guttata). DBH-positive cells were seen in the locus coeruleus, the nucleus subcoeruleus ventralis, the nucleus of the solitary tract, and the caudolateral medulla. Immunoreactive fibers and varicosities had a much wider brain distribution. They were particularly abundant in the hippocampus, septum, hypothalamus, area ventralis of Tsai, and substantia nigra, where they formed dense pericellular arrangements. Significant immunoreactivity was observed in auditory nuclei, including the nucleus mesencephalicus lateralis pars dorsalis, the thalamic nucleus ovoidalis, field L, the shelf of the high vocal center (HVC), and the cup of the nucleus robustus archistriatalis (RA), as well as in song control nuclei, including the HVC, RA, the lateral magnocellular nucleus of the anterior neostriatum, and the dorsomedial nucleus (DM) of the intercollicular complex. Except for the DM, DBH immunoreactivity within song nuclei was comparable to that of surrounding tissues. Conspicuously negative were the lobus paraolfactorius, including song nucleus area X, and the paleostriatum. Our results are in agreement with previous studies of the noradrenergic system performed in nonoscines. More importantly, they provide direct evidence for a noradrenergic innervation of auditory and song control nuclei involved in song perception and production, supporting the notion that noradrenaline is involved in vocal communication and learning in oscines.
Assuntos
Encéfalo/fisiologia , Dopamina beta-Hidroxilase/análise , Norepinefrina/fisiologia , Aves Canoras/fisiologia , Vocalização Animal/fisiologia , Animais , Percepção Auditiva/fisiologia , Encéfalo/citologia , Feminino , Imuno-Histoquímica , Aprendizagem/fisiologia , Masculino , Fibras Nervosas/fisiologiaRESUMO
Auditory information is critical for vocal imitation and other elements of social life in song birds. In zebra finches, neural centers that are necessary for the acquisition and production of learned vocalizations are known, and they all respond to acoustic stimulation. However, the circuits by which conspecific auditory signals are perceived, processed, and stored in long-term memory have not been well documented. In particular, no evidence exists of direct connections between auditory and vocal motor pathways, and two newly identified centers for auditory processing, caudomedial neostriatum (Ncm) and caudomedial hyperstriatum ventrale (cmHV), have no documented place among known auditory circuits. Our goal was to describe anatomically the auditory pathways in adult zebra finch males and, specifically, to show the projections by which Ncm and vocal motor centers may receive auditory input. By using injections of different kinds of neuroanatomical tracers (biotinylated dextran amines, rhodamine-linked dextran amines, biocytin, fluorogold, and rhodamine-linked latex beads), we have shown that, as in other avian groups, the neostriatal field L complex in caudal telencephalon is the primary forebrain relay for pathways originating in the auditory thalamus, i.e., the nucleus ovoidalis complex (Ov). In addition, Ncm and cmHV also receive input from the Ov complex. Ov has been broken down into two parts, the Ov "core" and "shell," which project in parallel to different targets in the caudal telencephalon. Parts of the field L complex are connected among themselves and to Ncm, cmHV, and caudolateral Hv (clHV) through a complex web of largely reciprocal pathways. In addition, clHV and parts of the field L complex project strongly to the "shelf" of neostriatum underneath the song control nucleus high vocal center (HVC) and to the "cup" of archistriatum rostrodorsal to another song-control nucleus, the robust nucleus of the archistriatum (RA). We have documented two points at which the vocal motor pathway may pick up auditory signals: the HVC-shelf interface and a projection from clHV to the nucleus interfacialis (NIf), which projects to HVC. These data represent the most complete survey to date of auditory pathways in the adult male zebra finch brain, and of their projections to motor stations of the song system.
Assuntos
Vias Auditivas/fisiologia , Aves/fisiologia , Mapeamento Encefálico , Maturidade Sexual/fisiologia , Telencéfalo/fisiologia , Vocalização Animal/fisiologia , Estimulação Acústica , Animais , Vias Eferentes/fisiologia , Masculino , Microinjeções , Tálamo/fisiologiaRESUMO
Here, we examine the connectivity of two previously identified telencephalic stations of the auditory system of adult zebra finches, the neostriatal "shelf" that underlies the high vocal center (HVC) and the archistriatal "cup" adjacent to the robust nucleus of the archistriatum (RA). We used different kinds of neuroanatomical tracers to visualize the projections from the shelf to the HVC. In addition, we show that the shelf projects to the cup and that the cup projects to thalamic, midbrain, and pontine nuclei of the ascending auditory pathway. Our observations extend to songbirds anatomical features that are found in the auditory pathways of a nonoscine bird, the pigeon (Wild et al. [1993] J. Comp. Neurol. 337:32-62), and we suggest that the descending auditory projections found in mammals may also be a general property of the avian brain. Finally, we show that the oscine song control system is closely apposed to auditory pathways at many levels. Our observations may help in understanding the evolution and organization of networks for vocal communication and vocal learning in songbirds.
Assuntos
Vias Auditivas/fisiologia , Aves/fisiologia , Vocalização Animal/fisiologia , Animais , Vias Auditivas/anatomia & histologia , Tronco Encefálico/anatomia & histologia , Tronco Encefálico/fisiologia , Masculino , Neostriado/anatomia & histologia , Neostriado/fisiologia , Neurônios Eferentes/fisiologia , Filogenia , Tálamo/anatomia & histologia , Tálamo/fisiologiaRESUMO
Disulfiram, an aldehyde dehydrogenase inhibitor, interferes with normal song maturation when applied to brain nucleus HVC of male zebra finches. We present here evidence from Western blots and enzymatic assays showing that known disulfiram targets other than retinaldehyde-specific aldehyde dehydrogenase (zRalDH) are absent in HVC. These findings are consistent with the conclusion that disulfiram disrupts song maturation by interfering with retinoic acid production.
Assuntos
Dissulfiram/farmacologia , Inibidores Enzimáticos/farmacologia , Aves Canoras/fisiologia , Vocalização Animal/efeitos dos fármacos , Aldeído Desidrogenase/antagonistas & inibidores , Animais , Encéfalo/enzimologia , Química Encefálica/efeitos dos fármacos , Condicionamento Psicológico/efeitos dos fármacos , Masculino , Tretinoína/metabolismo , Vocalização Animal/fisiologiaRESUMO
Previous studies have shown that song presentation results in a rapid rise in mRNA levels for the ZENK gene (the avian homologue of zif-268, Egr-1, NGFI-A, and Krox-24) in specific parts of the songbird forbrain. Metrazole-induced seizures also cause an increase in ZENK mRNA, even more widely throughout the telencephalon. Surprisingly, however, little or no ZENK induction by either stimulus was observed in several forebrain areas involved in auditory processing and song production. To learn whether this pattern of regulation is specific to ZENK, we examined the response of another 'immediate-early' gene, c-jun. Here we first describe the identification, cloning and sequence analysis of a canary cDNA encoding c-jun. Then, by in situ hybridization we show that c-jun is also induced by song or seizure, and in a pattern mostly similar to ZENK. As with ZENK, no induction of c-jun is observed in the androgen receptor-containing song nuclei or within the primary thalamo-recipient auditory area of the forebrain. Thus common immediate early gene responses appear to be selectively uncoupled from physiological activation in these specific forebrain regions, which are also characterized by tight developmental, hormonal and seasonal regulation.
Assuntos
Aves , Clonagem Molecular , Expressão Gênica/genética , Genes jun/genética , Animais , Canários , DNA Complementar , Dados de Sequência Molecular , Pentilenotetrazol/farmacologiaRESUMO
The examination of haematoxylin and eosin stained sections of normal and neoplastic pituitary glands under ultraviolet light illumination discloses fluorescence of acidophil cells. The distinction between prolactin and growth hormone-producing cells is not possible. Such fluorescence depends on previous eosin staining.
Assuntos
Hipófise/citologia , Adenoma/patologia , Amarelo de Eosina-(YS) , Humanos , Microscopia de Fluorescência , Neoplasias Hipofisárias/patologiaRESUMO
To investigate the ecological relevance of brain gene regulation associated with singing behavior in songbirds, we challenged freely ranging song sparrows with conspecific song playbacks within their breeding territories. Males responded by approaching the speaker, searching for an intruder and actively singing. In situ hybridization of brain sections revealed significantly higher expression of the transcriptional regulator ZENK in challenged birds than in unstimulated controls in several auditory structures and song control nuclei. We conclude that singing behavior in the context of territorial defense is associated with gene regulation in brain centers that control song perception and production, and that behaviorally regulated gene expression can be used to investigate brain areas involved in the natural behaviors of freely ranging animals.
Assuntos
Aves/fisiologia , Regulação da Expressão Gênica/fisiologia , Territorialidade , Vocalização Animal/fisiologia , Animais , Aves/anatomia & histologia , Feminino , Genes Precoces/genética , Histocitoquímica , Hibridização In Situ , MasculinoRESUMO
We describe here an automated system that accurately maps tissue sections stained by immunocytochemistry for an inducible nuclear protein. The sections are scanned with a computer-controlled microscope setup hooked to a CCD camera. Raw images captured at high resolution are filtered using highly selective criteria for the recognition of labeled cell nuclei. The total population of recognized labeled nuclei is then divided into separate bins, according to their labeling intensities. Finally, information about both the position and labeling intensity of labeled nuclei is represented in average density maps. The system was optimized for the quantitative mapping of neuronal cells expressing the inducible gene ZENK in the brain of songbirds, in response to stimulation with song, but should be of general applicability for the mapping of inducible nuclear proteins.
Assuntos
Mapeamento Encefálico/métodos , Proteínas de Ligação a DNA/metabolismo , Processamento de Imagem Assistida por Computador/métodos , Imuno-Histoquímica/métodos , Fatores de Transcrição/metabolismo , Algoritmos , Animais , Encéfalo/citologia , Encéfalo/metabolismo , Química Encefálica/fisiologia , Canários/anatomia & histologia , Canários/metabolismo , Núcleo Celular/metabolismo , Feminino , Neurônios/citologia , Neurônios/metabolismo , SoftwareRESUMO
Expression mapping of activity-dependent genes has been very useful to reveal brain activation patterns associated with specific stimuli or behavioral contexts. In addition, activity-induced neuronal gene expression is likely associated with neuronal plasticity and may be part of the mechanism(s) involved in long-term memory formation. Analysis of the immediate-early gene zenk has been used to generate high-resolution maps of brain activation associated with perceptual and motor aspects of vocal communication in songbirds and other avian groups. This molecular approach has generated novel insights into the organization of perceptual and motor control pathways for vocal communication in birds. Its impact on the neurobiology of birdsong will be reviewed here. Emphasis will be given to the caudomedial neostriatum, the area that shows the most robust zenk induction upon presentation of song to songbirds. Another focal point will be the comparative analysis of vocally induced zenk expression patterns across the avian orders that evolved vocal learning (i.e., songbirds, parrots, and hummingbirds). New research directions indicated by this molecular analysis will be discussed throughout.
Assuntos
Comunicação Animal , Mapeamento Encefálico , Aves Canoras/fisiologia , Voz/fisiologia , Animais , Vias Auditivas/metabolismo , Encéfalo/diagnóstico por imagem , Encéfalo/metabolismo , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Expressão Gênica , Genes fos/genética , Genes fos/fisiologia , Atividade Motora/genética , Atividade Motora/fisiologia , Neostriado/citologia , Neostriado/metabolismo , Radiografia , Aves Canoras/genética , Espectrografia do Som/métodos , Especificidade da Espécie , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismoRESUMO
The ZENK gene encodes a zinc-finger-containing transcriptional regulator and can be rapidly activated in songbird brain by presentation of birdsong (Mello et al., 1992). Here we map the areas of the songbird forebrain that show this genomic response to birdsong, using in situ hybridization. After 30 min of song presentation ZENK mRNA levels reach a peak in the caudomedial telencephalon, in areas adjacent to or closely related with primary auditory structures. These areas include subfields of field L (L1 and L3), the caudomedial neostriatum (NCM), the caudomedial hyperstriatum ventrale (CMHV) anterior to field L, the caudal paleostriatum, and two field L targets, HVC shelf and RA cup. In contrast, ZENK induction is absent in some areas that show a response to song by other measures and where ZENK induction might have been expected. These include the direct thalamo-recipient field L subfield L2, and the nuclei of the circuit involved in the acquisition and production of learned song. These results demonstrate that ZENK induction following song presentation occurs only in a subset of areas physiologically activated by song, and draw attention to areas previously unsuspected as related to processing of complex auditory stimuli. Based on what is known about ZENK function in mammalian systems (Christy et al., 1989; Cole et al., 1989; Wisden et al., 1990), we speculate that areas revealed by ZENK induction might correspond to sites where critical neuronal modifications occur in response to birdsong presentation, possibly leading to the formation of song-related memories.
Assuntos
Vias Auditivas/fisiologia , Aves/fisiologia , Encéfalo/fisiologia , Expressão Gênica , Fatores de Transcrição/genética , Vocalização Animal/fisiologia , Animais , Mapeamento Encefálico , Canários , Cinética , Masculino , Dedos de ZincoRESUMO
ZENK is an immediate early gene (IEG) that encodes a transcription factor protein, and its induction has been proposed as a necessary step in the cellular process underlying long-term memory formation. We have previously shown that ZENK is induced in adult songbird brain by the sound of birdsong, but, interestingly, induction did not occur in several areas known to respond to song stimuli. Conceivably, the ZENK gene may be repressed in these areas in adult birds. As a further test of this hypothesis, we administered metrazole, a strong GABAergic antagonist that leads to widespread excitation in the brain. Following metrazole, ZENK mRNA increases more than 10-fold throughout most of the telencephalon in both canaries and zebra finches, and primarily in neurons. In contrast, ZENK induction is much lower or absent in the archistriatum, the primary telencephalic sensory-recipient areas (including auditory field L), and the three telencephalic androgen receptor-containing song nuclei (high vocal center, lateral magnocellular nucleus of the anterior neostriatum, and the robust nucleus of the archistriatum). We did not observe any differences in ZENK induction patterns in juvenile versus adult zebra finches, or fall versus spring male canaries. Together with our previous studies of induction by song, these results suggest that in specific parts of the forebrain, including most of the song control system, IEG expression is subject to different constraints than in the rest of the forebrain. Understanding the molecular basis for this differential gene regulation may prove invaluable in understanding the organization of the song control circuit and the avian telencephalon.
Assuntos
Aves/fisiologia , Antagonistas GABAérgicos/farmacologia , Expressão Gênica/efeitos dos fármacos , Genes Precoces/efeitos dos fármacos , Pentilenotetrazol/farmacologia , Prosencéfalo/crescimento & desenvolvimento , Vocalização Animal/efeitos dos fármacos , Animais , Autorradiografia , Hibridização In Situ , Masculino , Plasticidade Neuronal/efeitos dos fármacos , Plasticidade Neuronal/fisiologia , Prosencéfalo/anatomia & histologia , Prosencéfalo/efeitos dos fármacos , RNA/biossíntese , Sondas RNA , Estações do Ano , Especificidade da EspécieRESUMO
We investigated the participation of genomic regulatory events in the response of the songbird brain to a natural auditory stimulus of known physiological and behavioral relevance, birdsong. Using in situ hybridization, we detected a rapid increase in forebrain mRNA levels of an immediate-early gene encoding a transcriptional regulator (ZENK; also known as zif-268, egr-1, NGFI-A, or Krox-24) following presentation of tape-recorded songs to canaries (Serinus canaria) and zebra finches (Taeniopygia guttata). ZENK induction is most marked in a forebrain region believed to participate in auditory processing and is greatest when birds hear the song of their own species. A significantly lower level of induction occurs when birds hear the song of a different species and no induction is seen after exposure to tone bursts. Cellular analysis indicates that the level of induction reflects the proportion of neurons recruited to express the gene. These results suggest a role for genomic responses in neural processes linked to song pattern recognition, discrimination, or the formation of auditory associations.