Prostaglandin E₂ activates the brain-pituitary axis via olfactory pathways in male Bostrychus sinensis

Prostaglandin E₂ (PGE₂) has been identified as a key sex pheromone in male Bostrychus sinensis, yet its molecular and neural mechanisms remain unclear. Here, we performed transcriptome sequencing on male B. sinensis brains following exposure to 50 nM PGE₂ to uncover genes and pathways involved in reproductive regulation. RNA-seq analysis revealed significant upregulation of key genes associated with the activation of the brain-pituitary axis. RT-PCR validation further confirmed the significant upregulation the expression of gnrh1 and kiss2 in the brain, as well as lhβ mRNA levels in the pituitary, supporting activation of the reproductive axis. To further elucidate the role of kiss2 in this regulatory pathway, we synthesized the core peptide of BsKiss2-12 and examined its functional effects. Administration of BsKiss2-12 (1μg/g) significantly increased the gnrh1 and kiss1ra mRNA levels in the brain, along with lhβ expression in the pituitary. Additionally, c-fos induction and DiI tracing experiments demonstrated that PGE₂ activated olfactory sensory neurons, relaying signals from the olfactory epithelium to the olfactory bulb and higher brain centers implicated in reproductive behavior. Collectively, our findings reveal that key molecular and neural mechanisms by which the sex pheromone PGE₂ modulates the reproductive axis in male B. sinensis.