Fig 2: Semi- quantitative determination of immunohistochemistry (IHC) reactions. a Immunoexpression of phoenixin (PNX) expressed as the ratio of mean gray value (mgv) to nuclei number (nn) in the gastrointestinal tract (GIT) of cattle calves (dots) and adults (squares). b-d Immunoexpression of GPR173 expressed as the mgv-to-area ratio in the GIT of cattle calves (dots) and adults (squares), measured in the mucosal layer (b), submucosal layer (c), and muscular layer (d)

Fig 3: Immunolocalization of phoenixin (PNX) in the intestines of domestic cattle. Immunoreactions in the duodenum, jejunum, ileum and colon in calves and adult domestic cattle. Black arrow indicate immunoreaction in the epithelial cells. In the top right corner, a magnified view of the reaction. Scale bar: 40 µm for the main image and 15 µm for the magnified reaction inset

Fig 4: The effects of phoenixin (PNX) at various levels of the gonadal axis. PNX binds to GPR173, activating the cyclic adenosine monophosphate/protein kinase A pathway and increasing CREB phosphorylation, thereby mediating biological functions. At the hypothalamic, PNX enhances the synthesis and secretion of gonadotropin-releasing hormone. At the pituitary, PNX increases the synthesis of gonadotropin-releasing hormone receptor and upregulates the expression of gonadotropins in pituitary gonadotrope cells. At the ovary, PNX promotes the production of estradiol and follicular maturation.

Fig 5: Reference receiver operating characteristic curve for serum PNX-14 in diagnosing central precocious puberty.