Effect of 17beta-estradiol and progesterone on vitellogenesis in the spotted ray Torpedo marmorata Risso 1810 (Elasmobranchii: Torpediniformes): studies on females and on estrogen-treated males.
The influence of 17beta-estradiol (E(2)) on vertebrate vitellogenesis is well ascertained. The aim of the present paper is to study the involvement of E(2) and progesterone (P) in the induction and regulation of vitellogenesis in females and experimental E(2)-treated males of Torpedo marmorata. We analyzed females in various stages of the reproductive cycle and E(2) experimentally treated males. The presence of vitellogenin was investigated in the plasma and in the liver by western blot and immunohistochemistry; its site of synthesis was investigated by in situ hybridization. The steroid levels in the plasma were measured by Enzyme Immunoassay. In treated males, E(2) induces in the liver the synthesis of VTG which is then secreted into the bloodstream as a 205-kDa polypeptide, the same that is found in the plasma of non-pregnant vitellogenic females. In females, E(2) is naturally present in the plasma and its level is correlated with VTG synthesis in the liver and with the female reproductive cycle. Indeed, large amounts of E(2) are only found in mature vitellogenic females, whose liver is involved in VTG synthesis and secretion. By contrast, small amounts of E(2) are evident in juveniles whose ovaries are lacking in vitellogenic follicles and in females preparing for ovulation. Low titers are also found in gravid females, whose liver is not engaged in VTG synthesis. We show that P, which is absent in untreated males and juvenile females, is evident in the blood serum of E(2)-treated males and sexually mature females. Interestingly, in treated males P appears in the plasma just 24h after the first injection of E(2) and its titer increases; a week after the last injections, the P level is similar to that recorded in non-gravid vitellogenic females. Finally, it is noteworthy that the highest titer of P was recorded in pregnant females. We demonstrate that in Torpedo vitellogenin synthesis, as in other vertebrates, is under the control of E(2) but also that this synthesis is probably under the control of progesterone.
Prisco
Marina
M
Department of Biological Sciences, Evolutionary and Comparative Biology Division, University of Naples Federico II, Via Mezzocannone 8, 80134 Naples, Italy.
Marina
Prisco
P
Valiante
Salvatore
S
Salvatore
Valiante
V
Maddalena Di Fiore
Maria
M
Maria
Maddalena Di Fiore
MD
Raucci
Franca
F
Franca
Raucci
R
Del Giudice
Giuseppina
G
Giuseppina
Del Giudice
del G
Romano
Maurizio
M
Maurizio
Romano
R
Laforgia
Vincenza
V
Vincenza
Laforgia
L
Limatola
Ermelinda
E
Ermelinda
Limatola
L
Andreuccetti
Piero
P
Piero
Andreuccetti
A
D000818:Animals; D015153:Blotting, Western; D004591:Electrophoresis, Polyacrylamide Gel; D004797:Enzyme-Linked Immunosorbent Assay; D004958:Estradiol / Q000494:pharmacology*; D004967:Estrogens / Q000494:pharmacology*; D005260:Female; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D008297:Male; D011374:Progesterone / Q000494:pharmacology*; D014101:Torpedo / Q000235:genetics / Q000378:metabolism*; D014818:Vitellogenesis / Q000187:drug effects*; D014819:Vitellogenins / Q000097:blood / Q000235:genetics / Q000378:metabolism
D004967:Estrogens; D014819:Vitellogenins; D011374:Progesterone; D004958:Estradiol