Seasonal effect of GnIH on gonadotrope functions in the pituitary of goldfish

► There are seasonal changes in the GnIH-mediated gonadotropin production in goldfish. ► GnIH both stimulates and inhibits LH and FSH production depending on gonadal stage in goldfish. ► GnIH exerts differential actions on LH and FSH secretion and mRNA production in goldfish.