Mapping the distribution of the octopamine beta receptor subtype-2 in the honeybee (apis mellifera) brain

Official URL: https://risc01.sabanciuniv.edu/record=b2583872_(Table of contents)

In invertebrates, hemolymph substitutes the role of blood in vertebrates. The fluctuating sugar levels in the hemolymph provides a crosstalk between the neurotransmitters in the brain and the energetic need of honeybees. Therefore, trehalose, the major sugar content of the honeybee hemolymph may play an important role in appetite regulation of the honeybee. In this thesis, we investigated the relationships between 4 major neurotransmitters (octopamine, tyramine, dopamine, and serotonin) and different sugar levels in the hemolymph with high performance liquid chromatography techniques. According to our findings, the most significant changes in biogenic amines and the appetite occur in the oldest honeybee age class, which is foragers. A lowering of trehalose increases octopamine levels, lowers tyramine, and corresponds with an increase in appetite levels. We did not observe any significant changes of Insulin-Like Protein 1 and 2 gene expression after manipulating trehalose and glucose levels suggesting that the appetite regulation, we observed is independent of glucose-insulin signaling pathway A secondary aim was to design and optimize an antibody for the octopamine beta receptor subtype 2, so that we could map this receptor throughout the honeybee brain. The distribution of the octopamine beta receptor subtype 2 will provide insights to its possible function based on its spatial location in the bee brain. The final map will be used to indicate the localized injection sites required for CRISPR-Cas9 knockdown of the receptor and confirm whether octopamine plays a causal role in appetite regulation.