Olfactory recognition and transduction mechanism in Small-tailed Han Sheep

In mammals, the olfactory system is essential for detecting odors and inducing responses associated with social behaviors, attraction, aversion, and fear. While the behavioral responses of sheep to predator stimuli have been intensively studied, knowledge regarding olfactory processing remains limited. In this study, we used leopard feces as a predator stimulus to explore the mechanisms involved in olfactory transduction in sheep. We found that exposure to leopard feces decreased the frequency of foraging and walking, as well as the duration of walking behavior. Furthermore, total cholesterol and globulin levels significantly increased after exposure. Subsequent RNA sequencing analysis of main olfactory epithelium (MOE) and olfactory bulb (OB) tissues identified 545 significantly differentially expressed unigenes in the MOE (217 upregulated, 328 downregulated) and 1506 in the OB (723 upregulated, 783 downregulated) when comparing leopard feces-stimulated and control groups. Subsequent Kyoto Encyclopedia of Genes and Genomes analysis of these unigenes indicated that they were mostly enriched in the cAMP signaling pathway in the MOE and ECM-receptor interaction and dopaminergic synapse pathways in the OB. These results offer new insights into how predator odor stimulation influences olfactory processing in sheep and expand our knowledge of the mechanisms underlying olfactory transduction and signal generation. Collectively, our findings provide comprehensive genomic insights into olfactory perception and anti-predator defence mechanisms in domestic sheep (Ovis aries).