INFLUENCE OF BIOGENIC AMINES ON EXPRESSION OF KEY GENES INVOLVED IN STRUCTURAL AND FUNCTIONAL NETWORK ASSOCIATED WITH FORAGING ACTIVITY OF HONEYBEE <EM>APIS CERANA</EM>

Biogenic amines are known to regulate neuronal activity in the insects in a spatiotemporal manner during foraging. Their modulatory effects depend on the type of G-protein coupled to the receptor, which may be stimulatory or inhibitory. Studies have reported that Immediate Early Genes (IEGs) involved in honeybee foraging—such as Early Growth Response Protein 1 (EGR1), a major transcription regulator, Kakusei- the non-coding RNA and the circadian regulatory gene Cryptochrome 2 (Cry2)—are upregulated during foraging and localized in the mushroom bodies. Transcription of IEGs is regulated by transcription factor CAMP Response Element Binding protein (CREB), and also by kinases such as Protein Kinase A (PKA) and Calcium- Calmodulin dependent Protein Kinase II (CaMKII). We examined the expression of biogenic amines receptors, transcription regulators Egr1, Kakusei, Cry2 and kinases like CaMKII, PKA, following pharmacological manipulation of dopamine and serotonin synthesis, along with the associated structural changes in the neuronal populations, specifically dopaminergic neurons. Liquid Chromatography-Mass Spectrometry (LC-MS/MS) analysis confirmed that dopamine and serotonin levels were significantly higher during foraging compared to pre- and post-foraging groups. Further, qPCR analysis demonstrated that the expression of all examined genes were significantly downregulated following pharmacological inhibition of dopamine and serotonin synthesis. Structural alterations in the neurons were also detected following Golgi-Cox staining. The preliminary data confirmed the modulation of gene expression of key molecules associated with foraging activity. Overall, the study suggests a specific modulatory role for biogenic amines in regulating both structural and functional plasticity in the honey bee.
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