ADNP is a protein necessary for brain development, important for brain plasticity, cognitive and social functioning, characteristics that are all impaired in autism and in the Adnp(+/-) mouse model, in a sex-dependent manner. ADNP was originally discovered as a protein that is secreted from glial cells in response to vasoactive intestinal peptide (VIP). VIP is a major neuroprotective peptide in the CNS and PNS and was also associated with social recognition in rodents and aggression, pair-bonding and parental behaviors in birds. Comparative sequence alignment revealed high evolutionary conservation of ADNP in Chordata. Despite its importance in brain function, ADNP has never been studied in birds. Zebra finches (Taeniopygia guttata) are highly social songbirds that have a sexually dichotomous anatomical brain structure, with males demonstrating a developed song system, presenting a model to study behavior and potential sexually dependent fundamental differences. Here, using quantitative real time polymerase chain reaction (qRT-PCR), we discovered sexually dichotomous and age related differences in ADNP mRNA expression in three different regions of the song bird brain-cerebellum, cerebrum, and brain stem. Higher levels of ADNP mRNA were specifically found in young male compared to the female cerebrum, while aging caused a significant 2 and 3-fold decrease in the female and male cerebrum, respectively. Furthermore, a comparison between the three tested brain regions revealed unique sex-dependent ADNP mRNA distribution patterns, affected by aging. Future studies are aimed at deciphering the function of ADNP in birds, toward a better molecular understanding of sexual dichotomy in singing behavior in birds.
Keywords: Activity-dependent neuroprotective protein (ADNP); Aging; Sexual dimorphism; Songbird brain; Zebra finch; qRT-PCR.
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