This study revisits the structural organization and expression of the BDNF gene in mice and rats. The authors identified and characterized several novel 5' untranslated exons in mouse and rat BDNF transcripts and introduced a new nomenclature for the exons. Both mouse and rat BDNF genes consist of eight 5' untranslated exons and one coding 3' exon. Transcription of the gene results in transcripts containing one of the eight 5' exons spliced to the coding exon, as well as transcripts containing only the extended coding exon. The study also reports distinct tissue-specific expression profiles of each 5' exon-specific transcript in different brain regions and non-neural tissues. Additionally, it shows that kainic acid-induced seizures, changes in cellular Ca2+ levels, inhibition of DNA methylation, and histone deacetylation contribute to the differential regulation of BDNF transcript expression. Finally, the study confirms that mouse and rat BDNF gene loci do not encode antisense mRNA transcripts, suggesting substantial differences in the regulatory mechanisms between rodent and human BDNF genes.This study revisits the structural organization and expression of the BDNF gene in mice and rats. The authors identified and characterized several novel 5' untranslated exons in mouse and rat BDNF transcripts and introduced a new nomenclature for the exons. Both mouse and rat BDNF genes consist of eight 5' untranslated exons and one coding 3' exon. Transcription of the gene results in transcripts containing one of the eight 5' exons spliced to the coding exon, as well as transcripts containing only the extended coding exon. The study also reports distinct tissue-specific expression profiles of each 5' exon-specific transcript in different brain regions and non-neural tissues. Additionally, it shows that kainic acid-induced seizures, changes in cellular Ca2+ levels, inhibition of DNA methylation, and histone deacetylation contribute to the differential regulation of BDNF transcript expression. Finally, the study confirms that mouse and rat BDNF gene loci do not encode antisense mRNA transcripts, suggesting substantial differences in the regulatory mechanisms between rodent and human BDNF genes.