Table 4.

Function roles of 25 hub genes with degrees ≥10.

No.	Gene symbol	Full name	Function
1	OPRD1	Delta-type opioid receptor	Play a role in the perception of pain and in opiate-mediated analgesia and developing analgesic tolerance to morphine.
2	AVP	Vasopressin-neurophysin 2-copeptin	It has a direct antidiuretic action on the kidney; it also causes vasoconstriction of the peripheral vessels. Acts by binding to vasopressin receptors (V1bR/AVPR1B, V1aR/AVPR1A, and V2R/AVPR2)
3	BDKRB2	B2 bradykinin receptor	Associated with G proteins that activate a phosphatidylinositol-calcium second messenger system.
4	TAS2R4	Taste receptor type 2 member 4	Encode a 7-transmembrane receptor protein, functioning as a bitter taste receptor.
5	KNG1	Kininogen-1	A mediator of inflammation and causes increase in vascular permeability.
6	BDKRB1	B1 bradykinin receptor	This is a receptor for bradykinin. Could be a factor in chronic pain and inflammation.
7	AGT	Angiotensinogen	Essential component of the renin-angiotensin system, a potent regulator of blood pressure, body fluid and electrolyte homeostasis.
8	PTGDR2	Prostaglandin D2 receptor 2	PI3K signaling is implicated in mediating PTGDR2 effects.
9	LPAR6	Lysophosphatidic acid receptor 6	Bind to oleoyl-L-alpha-lysophosphatidic acid (LPA). Intracellular cAMP is involved in the receptor activation.
10	C5	Complement C5	A mediator of local inflammatory process. Binding to the receptor C5AR1 induces a variety of responses including intracellular calcium release, contraction of smooth muscle, increased vascular permeability, and histamine release from mast cells and basophilic leukocytes
11	OPRL1	Nociceptin receptor	Play a role in the regulation of locomotor activity by the neuropeptide nociceptin.
12	ADRA2C	Alpha-2C adrenergic receptor	Alpha-2 adrenergic receptors mediate the catecholamine-induced inhibition of adenylate cyclase through the action of G proteins.
13	CCL16	C-C motif chemokine 16	Shows potent myelosuppressive activity and suppresses proliferation of myeloid progenitor cells.
14	OXER1	Oxoeicosanoid receptor 1	Receptor for eicosanoids and polyunsaturated fatty acids
15	CORT	Cortistatin	Bind to all human somatostatin receptor (SSTR) subtypes. It also inhibits cAMP production induced by forskolin through SSTRs.
16	SSTR5	Somatostatin receptor type 5	Increases cell growth inhibition activity of SSTR2 following heterodimerization
17	PYY	Peptide YY	This gut peptide inhibits exocrine pancreatic secretion, has a vasoconstrictory action, and inhibits jejunal and colonic mobility.
18	MCHR1	Melanin-concentrating hormone receptor 1	Receptor for melanin-concentrating hormone, coupled to both G proteins that inhibit adenylyl cyclase and G proteins that activate phosphoinositide hydrolysis.
19	UTS2R	Urotensin-2 receptor	High affinity receptor for urotensin-2 and urotensin-2B.
20	ANXA1	Annexin A1	Play important roles in the innate immune response as effector of glucocorticoid-mediated responses and regulator of the inflammatory process. Has anti-inflammatory activity
21	ADCY1	Adenylate cyclase type 1	Catalyzes the formation of the signaling molecule cAMP in response to G-protein signaling. Mediates responses to increased cellular Ca2+/calmodulin levels
22	GPR68	Ovarian cancer G-protein coupled receptor 1	Proton-sensing receptor involved in pH homeostasis.
23	PIK3R1	Phosphatidylinositol 3-kinase regulatory subunit alpha	Modulates the cellular response to ER stress during metabolic overloading in the liver and hence plays a role in glucose tolerance improvement
24	P2RY4	P2Y purinoceptor 4	Receptor for UTP and UDP coupled to G-proteins that activate a phosphatidylinositol-calcium second messenger system
25	HCAR2	Hydroxycarboxylic acid receptor 2	Receptor activation by nicotinic acid results in reduced cAMP levels which may affect activity of cAMP-dependent protein kinase A and phosphorylation of target proteins, leading to neutrophil apoptosis.