Progestin increases the expression of gonadotropins in pituitaries of male zebrafish

Abstract

Our previous study showed that the in vivo positive effects of 17α,20β-dihydroxy-4-pregnen-3-one (DHP), the major progestin in zebrafish, on early spermatogenesis was much stronger than the ex vivo ones, which may suggest an effect of DHP on the expression of gonadotropins. In our present study, we first observed that fshb and lhb mRNA levels in the pituitary of male adult zebrafish were greatly inhibited by 3 wk exposure to 10 nM estradiol (E2). However, an additional 24 hr 100 nM DHP exposure not only reversed the E2-induced inhibition, but also significantly increased the expression of fshb and lhb mRNA. These stimulatory effects were also observed in male adult fish without E2 pretreatment, and a time course experiment showed that it took 24 hr for fshb and 12 hr for lhb to respond significantly. Because these stimulatory activities were partially antagonized by a nuclear progesterone receptor (Pgr) antagonist mifepristone, we generated a Pgr-knock out (pgr−/−) model using the TALEN technique. With and without DHP in vivo treatment, fshb and lhb mRNA levels of pgr−/− were significantly lower than those of pgr+/+. Furthermore, ex vivo treatment of pituitary fragments of pgr−/− with DHP stimulated lhb, but not fshb mRNA expression. Results from double-colored fluorescent in situ hybridization showed that pgr mRNA was expressed only in fshb-expressing cells. Taken together, our results indicated that DHP participated in the regulation of neuroendocrine control of reproduction in male zebrafish, and exerted a Pgr-mediated direct stimulatory effect on fshb mRNA at pituitary level.

Progestin and Nuclear Progestin Receptor Are Essential for Upregulation of Metalloproteinase in Zebrafish Preovulatory Follicles

“…The wt zebrafish used in this study are a Tübingen strain initially obtained from the Zebrafish International Resource Center and propagated in our lab. Pgr gene knockout lines used in this study were generated and characterized previously ( 24 , 27 ). Fish were kept under a photoperiod of 14 h (h) light and 10 h dark (lights on at 09:00, lights off at 23:00), at a water temperature around 28.5°C, pH ~7.2, and salinity conductivity ranging from 500 to 1,200 μS in automatically controlled zebrafish rearing systems (Aquatic Habitats Z-Hab Duo systems, Florida, USA).…”

Steroid Transport, Local Synthesis, and Signaling within the Brain: Roles in Neurogenesis, Neuroprotection, and Sexual Behaviors

“…Gene knockout using the TALENs strategy allowed to generate zebrafish lines with null Pgr expression to assess the in vivo function of this receptor. Unfortunately, all studies performed with these models have focused at the gonadal levels and none of them looked at the effect of Pgr expression disruption in the brain (Zhu et al, 2015 ; Tang et al, 2016 ; Wang et al, 2016 ).…”

Involvement of Membrane Progestin Receptor Beta (mPRβ/Paqr8) in Sex Pheromone Progestin-Induced Expression of Luteinizing Hormone in the Pituitary of Male Chinese Black Sleeper (Bostrychus Sinensis)

“…Western blot assay was performed as previous described ( 23 ). In brief, total protein samples were extracted by immediately placing freshly excised tissues or cells into 2 × SDS buffer, denatured by boiling for 5 min, and then cooled on ice.…”