Implications of male birdsong in female reproduction in the domestic canary (Serinus canaria)

On sait que chez les oiseaux chanteurs le chant est le principal caractère sexuel secondaire et qu il a une influence majeure sur la reproduction. Le chant peut influencer une femelle dans le choix de son partenaire et agir sur la façon dont elle s investira pour optimiser chaque tentative de reproduction. Le propos général de cette thèse est d étudier l impact du chant sur la reproduction chez le canari. Dans une première partie, nous avons étudié l importance de ce chant par rapport à d autres stimuli susceptibles d influer sur le comportement sexuel des femelles. Nous avons montré que dans le choix de leur partenaire, les femelles prennent en compte la relation de dominance entre les mâles quand elle se manifeste par le chant et non pas par des interactions physiques entre eux. Dans une seconde partie, nous nous sommes demandés si le chant d un mâle pouvait permettre à la femelle d apprécier son degré de fertilité. Nous avons montré que meilleure était la qualité du chant (longueur et rythme d émission), meilleure était la qualité du sperme, suggérant que le chant pouvait être un indicateur de fertilité. Dans la dernière partie, nous avons étudié l impact du chant sur le système reproducteur de la femelle. Nous avons trouvé que des phrases moyennement attractives chantées par un mâle induisaient un dépôt plus important de testostérone dans l œuf par la femelle, alors que les mêmes phrases produites par ordinateur, donc en l absence de mâle, n avaient pas d effet. Cela suggère que si le chant n est que moyennement attractif, des stimuli supplémentaires sont requis pour entraîner une augmentation du dépôt de testostérone dans l œuf. Enfin, nous avons présenté le projet de recherche en cours. Il s agira d étudier l activation des différentes régions du cerveau en réponse au chant. Ce projet pourrait permettre d identifier les voies neuronales impliquées dans le dépôt différentiel de testostérone dans l œuf en réponse à ce stimulus.In songbirds, song is known to be the primary sexually selected trait with extensive influences on reproduction. Song can influence a female in her choice for a mate and can also influence how she adjusts her own investment in order to optimize each reproductive attempt. The general aim of this thesis was to investigate the impact of song on reproduction in canary. In the first section, we investigated the importance of song compared to other cues for females to direct their sexual behavior. We showed that females pay attention, in order to direct this sexual behavior, to dominance manifested via song and not via physical interactions. In a second part of this thesis, we wanted to know if song could be a cue for the female that would allow her to judge the fertilization capacities of a male. We showed that the better the song quality was (song length and emission rate) the better the quality of sperm was, suggesting that song could signal male fertility. In the last section, we investigated the impact of song on the female reproductive system. We found that mildly attractive song phrases sung by a live male induced the female to deposit more testosterone in her eggs. However, these same songs, but computer generated, (i.e. without the presence of the male), did not induce females to deposit more T. This suggests that other cues, in addition to mildly attractive song, may be necessary to increase T deposit. Finally, we present an on-going project, investigating the activation of different brain regions in response to song. This project could help to elucidate a neuronal pathway involved in the differential testosterone deposit in eggs in response to song.NANTERRE-BU PARIS10 (920502102) / SudocSudocFranceF

Conspecific discrimination in an object-choice task in African grey parrots (Psittacus erithacus)

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Auditory forebrain activation in the female canary is modulated by male song quality.

One of the chief functions of birdsong is to attract and stimulate females. In canaries (Serinus canaria), specific phrases (“A” phrases) sung by males have been identified as especially attractive for females. These phrases unite a number of characteristics that are particularly difficult to combine, including large frequency bandwidth, high repetition rate and multiple-note syllables. Females exposed to “A” phrases produce more copulation displays and deposit more testosterone into their eggs. However, the neuroendocrine pathway underlying the translation of song audition to changes in testosterone deposition in yolks is not understood. Increased expression of several immediate early genes including c-fos and zenk (also called egr-1 in mammals) in other songbird species has been observed in the auditory forebrain of females hearing attractive song, and such differential activation may represent a first step in signal processing linking auditory input to egg testosterone deposition. Female canaries in breeding condition were exposed to 60 minutes of “sexy” song with a preponderance of “A” phrases, “non-sexy” song lacking “A” phrases, or white noise. Thirty minutes after the end of song playback, brains were collected, fixed in acrolein and sectioned and stained by immunohistochemistry for quantification of the Fos protein, an indicator of neuronal activity, in several regions involved in audition and auditory processing. The endocrine condition of each female was determined by measuring ovarian and oviduct weight at the time of autopsy. In the caudomedial mesopallium (CMM), Fos expression was higher in females that had heard sexy song than those that heard non-sexy song or white noise. Expression of Fos in the caudomedial nidopallium (NCM), the nucleus spiriformis medialis (SPM), the nucleus ovoidalis (OV), and the song nucleus HVC was unaffected by song quality. Thus differential auditory processing in the CMM may be an initial stage in the assessment by a female of song information to differential testosterone deposition in the egg

Male Song Quality Modulates c-Fos Expression in the Auditory Forebrain of the Female Canary

International audienceIn canaries, specific phrases of male song (sexy songs, SS) that are difficult to produce are especially attractive for females. Females exposed to SS produce more copulation displays and deposit more testosterone into their eggs than females exposed to non-sexy songs (NS). Increased expression of the immediate early genes c-Fos or zenk (a.k.a. egr-1) has been observed in the auditory forebrain of female songbirds hearing attractive songs. C-Fos immunoreactive (Fos-ir) cell numbers were quantified here in the brain of female canaries that had been collected 30min after they had been exposed for 60min to the playback of SS or NS or control white noise. Fos-ir cell numbers increased in the caudomedial mesopallium (CMM) and caudomedial nidopallium (NCM) of SS birds as compared to controls. Song playback (pooled SS and NS) also tended to increase average Fos-ir cell numbers in the mediobasal hypothalamus (MBH) but this effect did not reach full statistical significance. At the individual level, Fos expression in CMM was correlated with its expression in NCM and in MBH but also with the frequency of calls that females produced in response to the playbacks. These data thus indicate that male songs of different qualities induce a differential metabolic activation of NCM and CMM. The correlation between activation of auditory regions and of the MBH might reflect the link between auditory stimulation and changes in behavior and reproductive physiology

LRRK2 modifies α-syn pathology and spread in mouse models and human neurons

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A Pharmacological Screening Approach for Discovery of Neuroprotective Compounds in Ischemic Stroke

<div><p>With the availability and ease of small molecule production and design continuing to improve, robust, high-throughput methods for screening are increasingly necessary to find pharmacologically relevant compounds amongst the masses of potential candidates. Here, we demonstrate that a primary oxygen glucose deprivation assay in primary cortical neurons followed by secondary assays (i.e. post-treatment protocol in organotypic hippocampal slice cultures and cortical neurons) can be used as a robust screen to identify neuroprotective compounds with potential therapeutic efficacy. In our screen about 50% of the compounds in a library of pharmacologically active compounds displayed some degree of neuroprotective activity if tested in a pre-treatment toxicity assay but just a few of these compounds, including Carbenoxolone, remained active when tested in a post-treatment protocol. When further examined, Carbenoxolone also led to a significant reduction in infarction size and neuronal damage in the ischemic penumbra when administered six hours post middle cerebral artery occlusion in rats. Pharmacological testing of Carbenoxolone-related compounds, acting by inhibition of 11-β-hydroxysteroid dehydrogenase-1 (11β-HSD1), gave rise to similarly potent <i>in vivo</i> neuroprotection. This indicates that the increase of intracellular glucocorticoid levels mediated by 11β-HSD1 may be involved in the mechanism that exacerbates ischemic neuronal cell death, and inhibiting this enzyme could have potential therapeutic value for neuroprotective therapies in ischemic stroke and other neurodegenerative disorders associated with neuronal injury.</p></div

Molecular structure and neuroprotection of Carbenoxolone.

<p>Molecular structure of Carbenoxolone, a synthetic derivative (succinyl ester) of Glycyrrhetinic acid (constituent of licorice). Carbenoxolone is an inhibitor of 11β steroid dehydrogenase enzymes (HSD1 and HSD2) and gap junctions (<b>a</b>). Protection against OGD-induced neuronal damage by Carbenoxolone. Primary cortical neurons were subjected to 2 hours of OGD and neuronal damage was assayed using the Cell Titer Glo assay at 24 hours of recovery, in presence of vehicle, 10 µM Carbenoxolone pre-during-post (PDP) (***p<0.001 vs. Vehicle; n = 10–13), or exclusively post OGD (Post) (*p<0.05 vs. Vehicle; n = 10–13). Carbenoxolone demonstrated neuroprotective activity in both PDP and post treatment experiments (n = 10–13) (<b>b</b>). Data were assessed via one-way ANOVA and significant results of the Dunnett’s post-test are shown with lines representing mean.</p

Profiling flow-chart to identify neuroprotective compounds with potential therapeutic efficacy.

<p>Profiling flow-chart to identify neuroprotective compounds with potential therapeutic efficacy.</p