Effects of the Aromatase Inhibitor R76713 On Sexual Differentiation of Brain and Behavior in Zebra Finches

Behaviour ◽  
1994 ◽  
Vol 131 (3-4) ◽  
pp. 225-259 ◽  
Author(s):  
Gregory F. Ball ◽  
Jacques Balthazart ◽  
Veronique Fiasse ◽  
Phillipe Absil
Keyword(s):  
Aromatase Inhibitor ◽  
Zebra Finch ◽  
Behavioral Effect ◽  
Copulatory Behavior ◽  
Zebra Finches ◽  
Morphological Effect ◽  
Singing Behavior ◽  
Song Control Nuclei ◽  
Silastic Implant ◽  
Song Control

AbstractNeonatal estradiol injections masculinize both the singing behavior and some morphological aspects of the song control nuclei in female zebra finches (Taeniopygia guttata), but there is to date no physiological evidence that estrogens are responsible for the differentiation of song and the song control nuclei in male zebra finches during normal ontogeny. Injections of estrogen into young males demasculinizes their copulatory behavior, so that it is difficult to understand how the same endocrine environment could simultaneously masculinize song and demasculinize copulation. Attempts to block early estrogen action in males have resulted in a paradoxical hypermasculinization of several aspects of the song control nuclei. In the present experiment, we tried to evaluate the role played by estrogens during zebra finch differentiation by blocking their secretion with the non-steroidal aromatase inhibitor, R76713 or racemic vorozole. Zebra finches received at 2-3 days post-hatch one Silastic implant filled with R76713 or left empty as a control. Implants were left in place until about 45 days of age and birds were then gonadectomized. At the age of 105 days, all birds received a Silastic implant filled with T and, starting two weeks later, they were repeatedly tested for singing and copulatory behavior during a period of 3 weeks. They were then perfused and their brains were analyzed by histological methods to measure the volume of the song control nuclei, HVc, RA, area X and MAN. Treatment with R76713 significantly decreased (± 50%) the number of song bouts produced by the birds but did not affect the copulatory behavior of the males. The behavior of females was not changed by the aromatase inhibitor and, in particular, no increase in mounting behavior was seen in the treated females. The presence of a strong sex dimorphism in the size of all 4 song control nuclei was confirmed but no significant effect of R76713 on these measures could be detected. These data are therefore consistent with the idea that estrogens are implicated in the differentiation of singing behavior in the zebra finch but the small amplitude of the behavioral effect observed and the absence of morphological effect suggest that either other factors also play a major role at this level or that higher doses or longer treatments with the aromatase blocker should be tested.

Auditory-vocal cholinergic pathway in the songbird brain

2000 ◽  
Vol 78 (12) ◽  
pp. 1072-1076 ◽  
Author(s):  
Rui Li ◽  
Ikuo Taniguchi ◽  
Hironobu Sakaguchi
Keyword(s):  
Zebra Finch ◽  
Basal Forebrain ◽  
Cholinergic Neurons ◽  
Auditory Pathway ◽  
Song Learning ◽  
Cholinergic Innervation ◽  
Auditory Information ◽  
Cholinergic Pathway ◽  
Song Control Nuclei ◽  
Song Control

Male zebra finches learn to imitate a tutor's song through auditory and motor learning. The two main song control nuclei in the zebra finch forebrain, the higher vocal center (HVC) and the robust nucleus of the archistriatum (RA), receive cholinergic innervation from the ventral paleostriatum (VP) of the basal forebrain which may play a key role in song learning. By injecting neuroanatomical tracers, we found a topographically segregated pathway from nucleus ovoidalis (Ov) to VP that in turn projects in a topographic fashion to HVC and RA. Ov is a major relay in the main ascending auditory pathway. The results suggest that the cholinergic neurons in the VP responsible for song learning are regulated by auditory information from the Ov.Key words: auditory pathway, cholinergic pathway, song control nucleus, zebra finch.

scholarly journals Androgen Receptor, Estrogen Receptor α, and Estrogen Receptorβ Show Distinct Patterns of Expression in Forebrain Song Control Nuclei of European Starlings1

Endocrinology ◽  
1999 ◽  
Vol 140 (10) ◽  
pp. 4633-4643 ◽  
Author(s):  
Daniel J. Bernard ◽  
George E. Bentley ◽  
Jacques Balthazart ◽  
Fred W. Turek ◽  
Gregory F. Ball
Keyword(s):  
Estrogen Receptor ◽  
Messenger Rna ◽  
Preoptic Area ◽  
Receptor Subtype ◽  
Song System ◽  
Singing Behavior ◽  
Estrogenic Effects ◽  
Song Control Nuclei ◽  
Magnocellular Nucleus ◽  
Song Control

Abstract In songbirds, singing behavior is controlled by a discrete network of interconnected brain nuclei known collectively as the song control system. Both the development of this system and the expression of singing behavior in adulthood are strongly influenced by sex steroid hormones. Although both androgenic and estrogenic steroids have effects, androgen receptors (AR) are more abundantly and widely expressed in song nuclei than are estrogen receptors (ERα). The recent cloning of a second form of the estrogen receptor in mammals, ERβ, raises the possibility that a second receptor subtype is present in songbirds and that estrogenic effects in the song system may be mediated via ERβ. We therefore cloned the ERβ complementary DNA (cDNA) from a European starling preoptic area-hypothalamic cDNA library and used in situ hybridization histochemistry to examine its expression in forebrain song nuclei, relative to the expression of AR and ERα messenger RNA (mRNA), in the adjacent brain sections. The starling ERβ cDNA has an open reading frame of 1662-bp, predicted to encode a protein of 554 amino acids. This protein shares greater than 70% sequence identity with ERβ in other species. We report that starling ERβ is expressed in a variety of tissues, including brain, pituitary, skeletal muscle, liver, adrenal, kidney, intestine, and ovary. Similar to reports in other songbird species, we detected AR mRNA-containing cells in several song control nuclei, including the high vocal center (HVc), the medial and lateral portions of the magnocellular nucleus of the anterior neostriatum, and the robust nucleus of the archistriatum. We detected ERα expression in the medial portion of HVc (also called paraHVc) and along the medial border of the caudal neostriatum. ERβ was not expressed in HVc, in the medial and lateral portions of the magnocellular nucleus of the anterior neostriatum, in the robust nucleus of the archistriatum, or in area X. In contrast, ERβ mRNA-containing cells were detected in the caudomedial neostriatum and medial preoptic area in a pattern reminiscent of P450 aromatase expression in the same brain regions in other songbirds. These data suggest that estrogenic effects on the song system are not mediated via ERβ-producing cells within song nuclei. Nonetheless, the overlapping expression of ERβ- and aromatase-producing cells in the caudomedial neostriatum suggests that locally synthesized estrogens may act via ERβ, in addition to ERα, to mediate seasonal or developmental effects on nearby song nuclei (e.g. HVc).

scholarly journals Learning to breathe and sing: development of respiratory-vocal coordination in young songbirds

2011 ◽  
Vol 106 (4) ◽  
pp. 1747-1765 ◽  
Author(s):  
Lena Veit ◽  
Dmitriy Aronov ◽  
Michale S. Fee
Keyword(s):  
Developmental Changes ◽  
Respiratory Pattern ◽  
Zebra Finches ◽  
Vocal Production ◽  
Song Control Nuclei ◽  
Before And After ◽  
Proper Name ◽  
Song Control ◽  
Striking Contrast

How do animals with learned vocalizations coordinate vocal production with respiration? Songbirds such as the zebra finch learn their songs, beginning with highly variable babbling vocalizations known as subsong. After several weeks of practice, zebra finches are able to produce a precisely timed pattern of syllables and silences, precisely coordinated with expiratory and inspiratory pulses (Franz M, Goller F. J Neurobiol 51: 129–141, 2002). While respiration in adult song is well described, relatively little is known about respiratory patterns in subsong or about the processes by which respiratory and vocal patterns become coordinated. To address these questions, we recorded thoracic air sac pressure in juvenile zebra finches prior to the appearance of any consistent temporal or acoustic structure in their songs. We found that subsong contains brief inspiratory pulses (50 ms) alternating with longer pulses of sustained expiratory pressure (50–500 ms). In striking contrast to adult song, expiratory pulses often contained multiple (0–8) variably timed syllables separated by expiratory gaps and were only partially vocalized. During development, expiratory pulses became shorter and more stereotyped in duration with shorter and fewer nonvocalized parts. These developmental changes eventually resulted in the production of a single syllable per expiratory pulse and a single inspiratory pulse filling each gap, forming a coordinated sequence similar to that of adult song. To examine the role of forebrain song-control nuclei in the development of respiratory patterns, we performed pressure recordings before and after lesions of nucleus HVC (proper name) and found that this manipulation reverses the developmental trends in measures of the respiratory pattern.

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