In ovo Sound Stimulation Mediated Regulation of BDNF in the Auditory Cortex and Hippocampus of Neonatal Chicks. (1st June 2019) - Kathpalia, Poorti
Abstract: Brain-derived neurotrophic factor (BDNF) is known to mediate activity-dependent changes in the developing auditory system. Its expression in the brainstem auditory nuclei, auditory cortex and hippocampus of neonatal chicks ( Gallus gallus domesticus ) in response to in ovo high intensity sound exposure at 110 dB (arrhythmic sound: recorded traffic noise, 30–3000 Hz with peak at 2700 Hz, rhythmic sound: sitar music, 100–4000 Hz) was examined to understand the previously reported altered volume and neuronal number in these regions. In the brainstem auditory nuclei, no mature BDNF, but proBDNF at the protein level was detected, and no change in its levels was observed after in ovo sound stimulation (music and noise). Increased ProBDNF protein levels were found in the auditory cortex in response to arrhythmic sound, along with decreased levels of one of the BDNF mRNA transcripts, in response to both rhythmic and arrhythmic sound stimulation. In the hippocampus, increased levels of mature BDNF were found in response to music. Expression microarray analysis was performed to understand changes in gene expression in the hippocampus in response to music and noise, followed by gene ontology analysis showing enrichment of probable signaling pathways. Differentially expressed genes like CAMK1 and STAT1 were found to be involved in downstream signaling on comparing music versus noise-exposed chicks. In conclusion, we report that BDNF is differentially regulated in the auditory cortex at the transcriptional and post-translational level, and in the hippocampus at the post-translational level in response to in ovo sound stimulation. Graphical abstract: Unlabelled Image Highlights: BDNF is differentially regulated in auditory cortex (transcriptional) and in hippocampus (post-translational) in response to sound. Acetylated histone H4 is enriched at the BDNF promoter in response to music in auditory cortex. Multiple signaling pathways are activated in neonatal hippocampus after in ovo sound stimulation. CAMK1 and STAT1 might mediate sound exposure associated changes in neonatal hippocampus.