Figure 5.

Proposed functional regulatory pathways of LH and FSH gonadotropes in adult female zebrafish. Gnrh3 directly acts on LH gonadotropes through Gnrhr2 to regulate gene expression of various non-Lhb hormone encoding genes, including fshb, by that contributing to LH-gonadotrope specialization. Alternatively, the upregulation of the nonprimary hormones in LH gonadotropes occurs during the preparation of the cells for single-cell RNA sequencing and is denoted by the question mark next to gene expression. The estrogenic pathway seems prominent in LH gonadotrope and manifested via 3 different estrogen nuclear receptors that facilitate LH synthesis and secretion. The expression of the receptors galr1b and cckrb, but not Gnrhr, in FSH gonadotropes infers a non-GnRH regulation of FSH synthesis and secretion. The estrogenic pathway is less prominent in FSH gonadotropes and is executed only via 1 nuclear receptor, Esr1.