Food odors elicit feeding behavior through the activation of the olfactory system in blunt snout bream (Megalobrama amblycephala)

Abstract

Olfaction plays an important role in the survival and reproduction of various organisms. Aside from being a nutrient, in many fish species, amino acids also function as attractants to induce feeding behaviors. As the herbivorous fish, blunt snout bream (Megalobrama amblycephala) commonly consumes an aquatic plant, Hydrilla verticillata. Here, we studied the effect of food odors on the feeding behavior of blunt snout bream using a mixture of amino acids and H. verticillata extract. The behavioral and electro-olfactogram tests demonstrated that the mixture of amino acids and H. verticillata extract induced an attractive reaction and olfactory response in blunt snout bream, respectively. Through Western blotting and immunohistochemical analyses, we confirmed that ciliated and microvillus neurons are distributed on the olfactory placode. The results of phospho-extracellular regulated protein kinases (pERK) showed that a large number of microvillus and ciliated neurons were activated under the stimulation of 10−5 mol/L amino acid mixture and 0.005× H. verticillata extract. The calcium signal imagery demonstrated that the nerve signals of the olfactory bulb were activated by the food odors. The quantitative real-time PCR (qPCR) analysis revealed significant changes in the expression of representative olfactory receptor genes in the olfactory bulb and brain of blunt snout bream upon stimulation with food odor. Collectively, these results provided evidence and preliminary explanations for the mediating role of olfaction in the feeding behavior of fish.

Keywords

• Megalobrama amblycephala
• Olfaction
• Electrophysiology
• Behavior
• Herbivorous