The honey bee, Apis mellifera, has a defense system, including detoxification, antioxidation, and immunity pathways, against external stimulation such as chemicals, stress, and pathogens. However, pesticides, particularly neonicotinoids and butenolids, have been recently reported to alter physiological changes in honey bee. In this study, we investigated the expression levels of eight genes categorized into detoxification (CYPQ3), antioxidation (CAT and SOD2), and immune system (Abaecin, Apidaecin, Defensin1, Defensin2, and Hymenoptaecin), in five tissues (Head, Thorax, Gut, Fat body, and Carcass) of honey bee treated with three pesticides (Acetamiprid, Imidacloprid, and Flupyradifurone) using quantitative real-time PCR. Gene expression patterns was varied depending on the type of pesticides and tissues. However, among eight genes, the expression levels of CYPQ3 was notably induced, but those of AMPs were generally reduced by all pesticides tested in this study in five tissues. These suggest that CYPQ3-mediated detoxification pathway is induced, but AMP-mediated immune system might be disrupted when honey bee is exposed to neonicotinoids and butenolid.

Melatonin is a neurotransmitter that modulates various physiological phenomena including regulation and maintenance of the circadian rhythm. Nicotinic acetylcholine receptors (nAChRs) play an important role in oral functions including orofacial muscle contraction, salivary secretion, and tooth development. However, knowledge regarding physiological crosstalk between melatonin and nAChRs is limited. In the present study, the melatoninmediated modulation of nAChR functions using bovine adrenal chromaffin cells, a representative model for the study of nAChRs, was investigated. Melatonin inhibited the nicotinic agonist dimethylphenylpiperazinium (DMPP) iodide-induced cytosolic free Ca2+ concentration ([Ca2+]i) increase and norepinephrine secretion in a concentrationdependent manner. The inhibitory effect of melatonin on the DMPP-induced [Ca2+]i increase was observed when the melatonin treatment was performed simultaneously with DMPP. The results indicate that melatonin inhibits nAChR functions in both peripheral and central nervous systems.

Acetylcholine receptors (AChR) including muscarinic and nicotinic AChR are widely expressed and mediate a variety of physiological cellular responses in neuronal and non-neuronal cells. Notably, a functional cholinergic system exists in oral epithelial cells, and nicotinic AChR (nAChR) mediates cholinergic anti-inflammatory responses. However, the pathophysiological roles of AChR in periodontitis are unclear. Here, we show that activation of AChR elicits increased cytosolic Ca2+ ([Ca2+]i), transient cytotoxicity, and induction of receptor activator of nuclear factor kappa-B ligand (RANKL) expression. Intracellular Ca2+ mobilization in human gingival fibroblast-1 (hGF-1) cells was measured using the fluorescent Ca2+ indicator, fura-2/AM. Cytotoxicity and induction of gene expression were evaluated by measuring the release of glucose-6-phosphate dehydrogenase and RT-PCR. Activation of AChR in hGF-1 cells by carbachol (Cch) induced [Ca2+]i increase in a dose-dependent manner. Treatment with a high concentration of Cch on hGF-1 cells caused transient cytotoxicity. Notably, treatment of hGF-1 cells with Cch resulted in upregulated RANKL expression. The findings may indicate potential roles of AChR in gingival fibroblast cells in bone remodeling.