-
[show abstract]
[hide abstract]
ABSTRACT: Variables such as the photoperiod a bird experiences, or its sex, affect behavioral responses to song. The present experiment investigated whether song-induced expression of the immediate-early gene ZENK is also influenced by sex or photoperiod. We examined the expression of the protein product of ZENK in wild-caught male and female European starlings (Sturnus vulgaris) in different photoperiodic conditions. In the first experiment, adult reproductively active male and female starlings were presented with either conspecific male song or no song in experimental chambers. In the second experiment, conspecific male song was presented to reproductively active and reproductively inactive adult female starlings. Localization of the ZENK protein product revealed that song stimulation resulted in a significant increase in the number of ZENK immunoreactive (-ir) cells in the caudomedial neostriatum (NCM) and the caudomedial hyperstriatum ventrale (cmHV) compared with unstimulated birds. No differences in the number of ZENK-ir neurons were observed between males and females or between reproductively active and inactive females. Thus, the present data indicate that the number of cells expressing ZENK in NCM and cmHV following song playback does not vary with sex or photoperiod in starlings.
Brain Research 11/1999; 844(1-2):78-82. · 2.73 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: In the past 10 years, the study of the expression of immediate early genes, such as c-fos, in the brain has become a common method for the identification of brain areas involved in the regulation of specific physiological and behavioral functions. The use of this method in avian species has been limited by the paucity of suitable antibodies that cross-react with the FOS protein in birds. We describe in this paper the preparation of an antibody directed against a synthetic fragment of the protein product of the c-fos gene in chickens (Gallus domesticus). We demonstrate that this new antibody can be used in several avian species to study FOS expression induced by a variety of pharmacological, physiological and behavioral stimuli. Western blot studies indicated that this antibody recognizes a protein of the expected size (47 kDa) but also cross reacts to some extent with proteins of lower molecular weight that share sequence homology with FOS (Fos-related antigens). FOS immunocytochemistry was performed with this antibody in four species of birds in three different laboratories utilizing diverse variants of the immunocytochemical procedure. In all cases the antibody provided a reliable identification of the FOS antigen. The new antibody described here appears to be suitable for the study of FOS expression in several different avian species and situations. It is available in substantial amounts and will therefore make it possible to use FOS expression as a tool to map brain activity in birds as has now been done for several years in mammalian species.
Journal of Neuroscience Methods 10/1999; 91(1-2):31-45. · 1.98 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: A partial estrogen receptor-beta (ERbeta) cDNA had been previously cloned and sequenced in Japanese quail. The 3'- and 5'-rapid amplification of cDNA ends techniques were used here to identify a cDNA sequence of the quail ERbeta that contains a complete open reading frame. For the first time in an avian species, this cDNA sequence and the corresponding amino acid sequence are described. They are compared with the known ERbeta sequences previously described in mammals and with the ERalpha sequences identified in a selection of mammalian and avian species. The analysis by Northern blotting of the ERbeta mRNA expression in the brain and kidneys revealed the presence of several transcripts. The presence of ERbeta identified by reverse transcriptase-polymerase chain reaction demonstrated a widespread distribution quite different from the distribution of ERalpha. The complete neuroanatomical distribution of ERbeta mRNA as determined by in situ hybridization with 35S- and 33P-labeled oligoprobes is also presented. Transcripts are present in many nuclei implicated in the control of reproduction such as the medial preoptic nucleus, the nucleus striae terminalis, and the nucleus taeniae, the avian homologue of the amygdala. These data demonstrate the presence of ERbeta in a nonmammalian species and indicate that the (neuro)-anatomical distribution of this receptor type has been conserved in these two classes of vertebrates. The role of this receptor in the control of reproduction and other physiological processes should now be investigated.
Journal of Neurobiology 10/1999; 40(3):327-42. · 3.05 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Neuroplasticity in the vocal control system of songbirds is strongly influenced by seasonal fluctuations in circulating testosterone. These seasonally plastic telencephalic structures are implicated in the learning and production of song in songbirds. The role of the indoleamine melatonin in seasonal adaptations in birds has remained unclear. In this experiment, European starlings were castrated to remove the neuromodulating activity of gonadal steroids and were exposed to different photoperiods to induce reproductive states characteristic of different seasonal conditions. Long days increased the volume of the song-control nucleus high vocal center compared with its volume on short days. Exogenous melatonin attenuated the long-day-induced volumetric increase in high vocal center and also decreased the volume of another song-control nucleus, area X. This effect was observed regardless of reproductive state. To our knowledge, this is the first direct evidence of a role for melatonin in functional plasticity within the central nervous system of vertebrates.
Proceedings of the National Academy of Sciences 05/1999; 96(8):4674-9. · 9.68 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Studies in avian species have often been useful in elucidating basic concepts relevant to the regulation of reproductive behaviors by sex steroid hormones. Once a link between a steroid hormone and a behavioral response has been established, one can use the localization of steroid hormone receptors in the brain to facilitate the identification of neural circuits that control behavior. The recent identification of a second type of estrogen receptor called estrogen receptor beta or ERbeta has raised new issues about the action of steroid hormones in the brain. A hypothesis has been proposed by Kuiper et al. [1998] based on studies in mammalian species suggesting that ERalpha (the name given to the ER that was previously described) is important for reproduction while ERbeta is more important for non-reproductive functions. In this paper we apply this hypothesis more generally by examining possible functions of ERbeta in avian species. We have initiated studies of the ERbeta in the brain of two avian species, the Japanese quail (Coturnix japonica) and the European starling (Sturnus vulgaris). ERbeta was cloned in both species and the mRNA for this receptor type was localized in the brain employing in situ hybridization histochemistry methods. In both species ERbeta was found to be diffusely present in telencephalic areas consistent with a role for this receptor subtype in cognitive functions. However, ERbeta mRNA was also found in many brain areas that are traditionally thought to be important in the regulation of reproductive functions such as the preoptic region, the bed nucleus of the stria terminalis and the nucleus taeniae. Of the two receptor types, only mRNA for ERalpha was observed in the telencephalic vocal control nucleus HVc of male starlings. Steroid receptors in this nucleus are thought to be an example of an evolutionary specialization that has evolved to coordinate the production of courtship vocalizations with other aspects of reproduction. The lack of ERbeta mRNA expression in HVc is consistent with the hypothesis that ERalpha is preferentially involved in reproductive behaviors while ERbeta is involved in the steroid regulation of other neural functions. However, the widespread occurrence of ERbeta in other nuclei involved in reproductive function suggests that one must be cautious about the general applicability of the above hypothesis until more is known about ERbeta function in these other nuclei.
Brain Behavior and Evolution 02/1999; 54(1):28-40. · 2.21 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: This study examined the relationship between the volumes of four song control nuclei: the high vocal center (HVC), the lateral part of the magnocellular nucleus of the anterior neostriatum (IMAN), Area X, and the robust nucleus of the archistriatum (RA), as well as syrinx mass, with several measures of song output and song complexity in male zebra finches (Taeniopygia guttata). Male zebra finches' songs were recorded in standardized recording sessions. The syrinx and brain were subsequently collected from each bird. Volumes of the song control nuclei were reconstructed by measuring the cross-sectional area of serial sections. Syrinx mass was positively correlated with RA volume. The volume of IMAN was negatively related to element repertoire size and the number of elements per phrase. We found no other correlations between brain and behavioral measures. This study, combined with others, indicates that the evidence for a general relationship among songbirds between HVC volume and song complexity is equivocal. There are clear species differences in this brain-behavior correlation.
Journal of Neurobiology 10/1998; 36(3):421-30. · 3.05 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We examined the neural bases of song preferences in female zebra finches (Taeniopygia guttata). Females performed more courtship displays in response to conspecific songs than to heterospecific songs. Following electrolytic lesion to the HVc (sometimes referred to as high vocal center), females maintained normal song preferences. However, following lesion to cHV (caudal hyperstriatum ventrale, an auditory area) females performed courtship displays at high rates in response to both conspecific and heterospecific song. Thus cHV, but not HVc, must be intact for female zebra finches to exhibit normal song preferences. Differences between this study and those showing HVc lesions disrupting song preferences in female canaries (Serinus canaria) indicate interspecific variation in the function of HVc in female songbirds.
Neuroreport 10/1998; 9(13):3047-52. · 1.66 Impact Factor
-
Neuron 09/1998; 21(2):271-4. · 14.74 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Central testosterone aromatization is required for the activation of both appetitive (ASB) and consummatory (CSB) male sexual behavior in Japanese quail. There are two major clusters of aromatase immunoreactive (ARO-ir) cells in the rostral forebrain; these outline the nucleus preopticus medialis (POM) and the nucleus striae terminalis (BST). We investigated the role of these nuclei in the regulation of ASB and CSB. Appetitive male sexual behavior was measured with the use of a learned social proximity procedure that quantified the time spent by a male in front of a window with a view of a female who was subsequently released into the cage, providing an opportunity for CSB. Males first acquired the response and then received bilateral electrolytic lesions aimed at the POM or BST, followed by retesting for ASB and CSB. Brain sections were stained for ARO-ir, and lesions to the two ARO-ir cell groups were quantitatively characterized. Lesions damaging the POM completely abolished CSB and also significantly decreased ASB. Lesions of the rostral BST had no effect on ASB, but moderately decreased CSB. Detailed anatomical analysis revealed that lesions of a subdivision of the POM just rostral to the anterior commissure specifically impair CSB, whereas lesions that are more rostral to this subdivision induce a severe deficit in ASB. These data indicate that different subregions of the POM regulate ASB and CSB in a somewhat independent manner, whereas the BST is only important in the regulation of CSB.
Journal of Neuroscience 09/1998; 18(16):6512-27. · 7.11 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The effects of reproductive condition and exogenous melatonin on immune function were investigated in castrated European starlings, Sturnus vulgaris. Photorefractory and photostimulated starlings exposed to long days were implanted with melatonin or with blank capsules. Photostimulated starlings with blank capsules exhibited reduced splenocyte proliferation in response to the T-cell mitogen, concanavalin A, compared with the other long-day birds. Exogenous melatonin prevented the suppression of immune function by photostimulation. Photorefractory starlings, with or without melatonin implants, exhibited enhanced immune function compared with photostimulated starlings implanted with blanks. This enhancement was not mediated by endogenous melatonin, but appeared to be related to changes in reproductive state. In addition to the traditional costs of reproduction in birds (e.g. raising of young), there may be a cost of the reproductive state of starlings (i.e. whether they are photorefractory or photostimulated). These data are, we believe, the first to indicate a direct effect of reproductive state on immune function that is independent of both photoperiod (i.e., changes in the duration of melatonin secretion) and gonadal steroids.
Proceedings of the Royal Society B: Biological Sciences 08/1998; 265(1402):1191-5. · 5.41 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: In the brain, conversion of androgens into estrogens by the enzyme aromatase (estrogen synthase) is a key mechanism by which testosterone regulates many physiological and behavioral processes, including the activation of male sexual behavior, brain sexual differentiation and negative feedback effects of steroid hormones on gonadotropin secretion. Studies on the distribution and regulation of brain aromatase have led to a new perspective on the control and function of this enzyme. A growing body of evidence indicates that the estrogen regulation of aromatase is, at least in part, trans-synaptic. Afferent catecholamine pathways appear to regulate aromatase activity in some brain areas and thereby provide a way for environmental cues to modulate this enzyme. The localization of aromatase in pre-synaptic boutons suggests possible roles for estrogens at the synapse.
Trends in Neurosciences 07/1998; 21(6):243-9. · 14.23 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The distribution of androgen receptor-like immunoreactive (AR-ir) cells in the quail brain was analyzed by immunocytochemistry with the use of the affinity-purified antibody PG-21-19A raised against a synthetic peptide representing the first 21 N-terminal amino acids of the rat and human AR. This antibody is known to bind to the receptor in the absence as well as in the presence of endogenous ligands, and it was therefore expected that a more complete and accurate characterization of AR-ir cells would be obtained in comparison with previous studies using an antibody that preferentially recognizes the occupied receptor. Selected sections were double labeled for aromatase (ARO) by a technique that uses alkaline phosphatase as the reporter enzyme and Fast blue as the chromogen. AR-ir material was detected in the nucleus of cells located in a variety of brain areas in the preoptic region and the hypothalamus including the medial preoptic (POM), the supraoptic, the paraventricular (PVN), and the ventromedial (VMN) nuclei, but also in the tuberculum olfactorium, the nucleus accumbens/ventral striatum, the nucleus taeniae, the tuberal hypothalamus, the substantia grisea centralis (GCt), and the locus ceruleus. Cells exhibiting a dense AR-ir label were also detected in the nucleus intercollicularis. Preincubation of the primary antibody with an excess of the synthetic peptide used for immunization completely eliminated this nuclear staining. A significant number of AR-ir cells in the POM, VMN, PVN, and tuberal hypothalamus also contained ARO-ir material in their cytoplasm. These data confirm and extend previous studies localizing AR in the avian brain, and raise questions about the possible regulation by androgens of the metabolizing enzyme aromatase.
Journal of Neurobiology 07/1998; 35(3):323-40. · 3.05 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The activation of male sexual behavior in Japanese quail (Coturnix japonica) requires the transformation of testosterone to 17beta-estradiol by the enzyme aromatase (estrogen synthetase). There are prominent sex differences in aromatase activity that may be regulated in part by sex differences in catecholaminergic activity. In this study, we investigate, with double-label immunocytochemistry methods, the anatomical relationship between the catecholamine synthesizing enzyme, tyrosine hydroxylase (TH) and aromatase (ARO) in the quail brain. The immunoreactivity observed for each antigen generally matched the previously described distribution. One exception is the observation that cells weakly labeled for aromatase were found widely distributed throughout the telencephalon. The presence of telencephalic aromatase was confirmed independently by radioenzymatic assays. There was an extensive overlap between the distribution of the two antigens in many brain areas. In all densely labeled aromatase-immunoreactive (ARO-ir) cell groups, including the preoptic medial nucleus, nucleus of the stria terminalis, mediobasal hypothalamus, and paleostriatum ventrale, ARO-ir cells were found in close association with TH-ir fibers. These TH-ir fibers often converged on an ARO-ir cell, and one or more TH-ir punctate structure(s) were found in close contact with nearly every densely labeled ARO-ir cell. In the telencephalon (mostly the neostriatum), all TH-ir fibers were found to be part of fiber groups that surrounded weakly immunoreactive aromatase cells. The few cells exhibiting an intracellular colocalization were detected in the anteroventral periventricular nucleus. These results are consistent with the hypothesis that catecholaminergic inputs regulate brain aromatase.
The Journal of Comparative Neurology 03/1998; 391(2):214-26. · 3.81 Impact Factor
-
Annual review of sex research 02/1998; 9:96-176.
-
[show abstract]
[hide abstract]
ABSTRACT: Vocalizations used by birds for territory defense, mate attraction, or both are often referred to as a given species' song. Birdsong refers to the often complex vocalizations produced most frequently by males of species that are members of the songbird order (passeriformes). Unlike most species-typical vocalizations produced by nonhuman animals, some songbird vocalizations are learned. Studies of birdsong learning, production, and perception address issues of fundamental interest to psychologists and others interested in behavior and its physiological underpinnings and provide the basis for this review. This article highlights recent advances in knowledge as illustrations of the utility of birdsong as an arena for significant new developments in experimental psychology and behavioral neuroscience.
American Psychologist 02/1998; 53(1):37-58. · 6.87 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We mapped cells immunoreactive (ir) for the protein encoded by the immediate early gene zenk in the brains of male Japanese quail after they engaged in either appetitive or consummatory sexual behavior (i.e. copulation). Castrated males treated with testosterone were either allowed to copulate with a female or exhibited a learned social proximity response indicative of appetitive sexual behavior, and were compared with control males in their home cage or in the experimental chamber but not exhibiting the proximity response. Copulation increased the number of ZENK-ir cells in the nucleus striae terminalis and the nucleus intercollicularis, while both copulation and the proximity response induced increases in the medial and anterior ventral hyperstriatum. These results indicate that zenk is induced in the context of sexual behavior.
Neuroreport 10/1997; 8(13):2965-70. · 1.66 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Two experiments investigated the role of estrogens in the activation and sexual differentiation of appetitive sexual behavior (ASB) in Japanese quail (Coturnix japonica) as measured by a learned social proximity response. Injection of the aromatase inhibitor R767 13 in castrated, testosterone (T)-treated male quail completely suppressed ASB, confirming that, like consummatory sexual behavior, ASB is mediated by T aromatization. ASB is not observed in female quail, even if they are treated with T as adults. The role of embryonic estrogens in the sexual differentiation of ASB was tested by blocking estrogen synthesis in ovo. Control male and T-treated female quail deprived of estrogens during embryonic life learned the social proximity response used to assess ASB, whereas control female quail did not, despite the presence of high T. Thus, ASB is demasculinized by the action of embryonic estrogens during ontogeny as is consummatory behavior.
Behavioral Neuroscience 05/1997; 111(2):381-97. · 2.62 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Songbirds possess a specialized network of brain nuclei mediating song learning and production, the song system. In many species, the nuclei in this circuit are larger in volume in males housed on long photoperiods than in males housed on short photoperiods. Exposure to long days initially leads to increases in circulating levels of testosterone (T) and it is generally believed that volume changes in the song system are controlled by T-dependent effects of photoperiod. However, a growing body of evidence indicates that photoperiod can also have T-independent effects on song system morphology. Previous work in our laboratory suggested that photoperiodic condition may modulate the effects of exogenous testosterone on the volumes of song control nuclei in male European starlings (Sturnus vulgaris). In the present report, we tested the hypothesis that photorefractoriness attenuates the effects of T on the volumes of song control nuclei in starlings. One group of long-day photorefractory males (16L:8D) was exposed to exogenous T and two groups of short-day photosensitive birds (8L:16D) were either implanted with T or blank (control) capsules. After 8 weeks, T levels were elevated in both groups of T-implanted birds and were undetectable in control animals. Volumes of the high vocal center were larger in T-implanted photosensitive birds than in both T-implanted photorefractory and control photosensitive males, which did not differ. These results suggest that photorefractoriness renders the song nuclei of starlings less sensitive to stimulatory effects of T. Plasticity in the starling song system appears to require the coordination of the appropriate hormonal milieu with a permissive photoperiodic condition.
General and Comparative Endocrinology 03/1997; 105(2):276-83. · 3.27 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The vocal control system in many songbird species is a sexually dimorphic neural circuit that mediates learning and production of song. The mechanism by which this system is sexually differentiated has been investigated in only one species, the zebra finch (Taeniopygia guttata). Estradiol may be involved in the sexual differentiation of this system, as female zebra finches treated with estradiol as nestlings develop a male-like song system; however, blocking estradiol action in embryonic and nestling male zebra finches does not demasculinize the song system. Therefore, the role of estradiol in song system development is unclear. The role of estradiol in song system sexual differentiation was assessed in European starlings (Sturnus vulgaris). This species is of potential interest because it is less extreme in the degree of sexual dimorphism of the song system and song behavior than zebra finches. While in the field, starling nestlings were implanted with 500 microg of estradiol at 3 days of age. These birds were brought into the laboratory at Day 11 and hand-reared. In females, estradiol produces significant increases in the volumes of song control regions defined by Nissl stain, as well as by autoradiography for alpha2-adrenergic receptors; however, these estradiol-treated females have song systems that more closely resemble those of control females than control males. Estradiol-treated males exhibit significant hypermasculinization at 210 days of age, but this effect is transient and hypermasculinization is no longer evident at Day 345. The role of estradiol in sexual differentiation of the neural circuit mediating song behavior remains enigmatic.
Hormones and Behavior 01/1997; 30(4):387-406. · 3.87 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Cells immunoreactive for the enzyme aromatase were localized in the forebrain of male zebra finches with the use of an immunocytochemistry procedure. Two polyclonal antibodies, one directed against human placental aromatase and the other directed against quail recombinant aromatase, revealed a heterogeneous distribution of the enzyme in the telencephalon, diencephalon, and mesencephalon. Staining was enhanced in some birds by the administration of the nonsteroidal aromatase inhibitor, R76713 racemic Vorozole) prior to the perfusion of the birds as previously described in Japanese quail. Large numbers of cells immunoreactive for aromatase were found in nuclei in the preoptic region and in the tuberal hypothalamus. A nucleus was identified in the preoptic region based on the high density of aromatase immunoreactive cells within its boundaries that appears to be homologous to the preoptic medial nucleus (POM) described previously in Japanese quail. In several birds alternate sections were stained for immunoreactive vasotocin, a marker of the paraventricular nucleus (PVN). This information facilitated the clear separation of the POM in zebra finches from nuclei that are adjacent to the POM in the preoptic area-hypothalamus, such as the PVN and the ventromedial nucleus of the hypothalamus. Positively staining cells were also detected widely throughout the telencephalon. Cells were discerned in the medial parts of the ventral hyperstriatum and neostriatum near the lateral ventricle and in dorsal and medial parts of the hippocampus. They were most abundant in the caudal neostriatum where they clustered in the dorsomedial neostriatum, and as a band of cells coursing along the dorsal edge of the lamina archistriatalis dorsalis. They were also present in high numbers in the ventrolateral aspect of the neostriatum and in the nucleus taeniae. None of the telencephalic vocal control nuclei had appreciable numbers of cells immunoreactive for aromatase within their boundaries, with the possible exception of a group of cells that may correspond to the medial part of the magnocellular nucleus of the neostriatum. The distribution of immunoreactive aromatase cells in the zebra finch brain is in excellent agreement with the distribution of cells expressing the mRNA for aromatase recently described in the finch telencephalon. This widespread telencephalic distribution of cells immunoreactive for aromatase has not been described in non-songbird species such as the Japanese quail, the ring dove, and the domestic fowl.
Journal of Neurobiology 11/1996; 31(2):129-48. · 3.05 Impact Factor
