Distribution of cholinergic and nitrergic regions in the blue-fronted parrot (Amazona aestiva) brain

• Grant number: 23/18094-3
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: April 01, 2024
• End date: August 01, 2025
• Field of knowledge: Agronomical Sciences - Veterinary Medicine
• Principal Investigator: José de Anchieta de Castro e Horta Júnior
• Grantee: Isadora Volpi
• Host Institution: Instituto de Biociências (IBB). Universidade Estadual Paulista (UNESP). Campus de Botucatu. Botucatu , SP, Brazil
• Associated scholarship(s): 24/09285-2 - Approaches in the avian neurobiology: description of blue-fronted Amazon parrot (Amazona aestiva) brain and comparison with other birds, BE.EP.IC

Abstract

Parrots have larger brains compared to other bird groups and twice the neuron density when compared to non-human primates. They possess brain regions homologous to mammals and exhibit cognitive abilities such as vocal learning, object manipulation, and complex social interaction. Despite the significant interest in these animals, little is known about their neurobiology. Citoarchitectonic study, mapping major myelinated nerve fiber bundles and neuronal cell bodies, is crucial for identifying specific regions and systems. Among these, the cholinergic and nitrergic systems have widespread distributions in avian brains, with some regions showing co-localization. Nitric oxide and acetylcholine play diverse roles and are implicated in the vocal learning pathway in birds. Therefore, this study aims to describe the myelocitoarchitecture and map the cholinergic and nitrergic areas of the brain in the Blue-fronted Amazon parrot (A. aestiva). The identification of these regions will aid in the descriptive, evolutionary, and pathogenic study of this species and other psittacids. Three individuals of Amazona aestiva from the Neuromorphology Laboratory brain bank (CEUA, Protocol 132/2016 and 0168/2021; SISBIO n° 6453531 and nº 78416-1) will be used. Histological sections from each animal will undergo NADPH-d, AChE, and Klüver-Barrera histochemical protocols. The identification of regions of interest, such as those related to vocal learning nuclei, and their cell density for the employed histochemical techniques, will be described based on studies of phylogenetically close birds, ensuring nomenclature standardization. This study, providing the first description of Nitric Oxide and Acetylcholine patterns in the Blue-fronted Amazon parrot's brain, represents one of the initial investigations into the neurobiology of psittacids in Brazil.