Figure 5.

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.