Comparison of the activities of two purified fish gonadotropins on adenyl cyclase activity in the goldfish ovary

Fontaine, Y.A.; Salmon, Christian; Fontaine-Bertrand, E; Burzawa-Gerard, E.; Donaldson, Edward M.

doi:10.1139/z72-220

Cited by 32 publications

(7 citation statements)

References 9 publications

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“…GtH has been shown to stimulate adenyl-cyclase activity in immature fish ovary (Fontaine et al 1972;Idler et al 1975) and we recently demonstrated an intrafollicular peak of cAMP after adding GtH in incubation of trout isolated follicles at 'P-GV' stage (A. Fostier, B. Jalabert, B. Finet, unpublished data). In addition, in vitro 17~,20/3-OH-P production by isolated follicles of amago salmon was enhanced by db-cAMP (Young et al 1983c).…”

Section: Discussionmentioning

confidence: 82%

Steroidogenesis in rainbow trout (Salmo gairdneri) at various preovulatory stages: changes in plasma hormone levels andin vivo andin vitro responses of the ovary to salmon gonadotropin

Fostier

Jalabert

1986

Fish Physiol Biochem

120

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In order to specify the timing of some changes in ovarian steroid production during the transition from vitellogenesis to ovulation, plasma hormones levels andin vivo andin vitro responses of the ovary to salmon gonadotropin (s-GtH) or dibutyryl-cyclic adenosine mono-phosphate (db-cAMP) were recorded in relationship with the state of germinal vesicle migration in the oocyte.In vivo, a small, but significant, increase of plasma 17α-hydroxy-20β-dihydroprogesterone (17α, 20β-OH-P) level was detected earlier (at the "subperipheral germinal vesicle" stage) than the increase of GtH level (detectable at the "peripheral germinal vesicle" stage) and the decline of oestradiol-17β (E2-17β) (also detectable at the "peripheral germinal vesicle" stage). Negative correlations were established between E2-17β levels and GtH (ρ=-0.53) or 17α,20β-OH-P (ρ=-0,43) levels while a positive correlation occurred between 17α,20β-OH-P and GtH levels (ρ=+0,54).In vivo no action of GtH on the decline of E2-17β levels was detected GtH did not stimulate 17α,20β-OH-P production, within 72h, in females at the "end of vitellogenesis" stage. It had significant effect in females at other stages closer to ovulation, but the pattern of responses changed according to the stage.In vitro db-cAMP like GtH was able to stimulate 17α,20β-OH-P output from ovarian follicles. The greatest response was observed at the later stage. (GVBD). Testosterone output was also increased by GtH, but the lowest response was observed at the later stage (GVBD). Androstenedione output was lower than testosterone output.In vitro, a small but significant decline of E2-17β output was induced by GtH. We conclude that substantial changes occur during the very last stages prior to ovulation, both in the steroidogenic potential of the ovary and in the ovarian sensitivity to GtH. 20β-oxydoreductase is probably progressively induced during GV migration when GtH basal levels are increasing but still relatively low. Without minimizing the role of discrete pulses of GtH on this induction, we could expect synergic actions of other hormones. Thus a high testosterone/oestradiol ratio in the follicle environment favours 17α,20β-OH-P secretion.

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Section: Discussionmentioning

confidence: 82%

Steroidogenesis in rainbow trout (Salmo gairdneri) at various preovulatory stages: changes in plasma hormone levels andin vivo andin vitro responses of the ovary to salmon gonadotropin

Fostier

Jalabert

1986

Fish Physiol Biochem

120

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“…In fish, gonadotropin (GTH) stimulates the production of maturational steroid by the follicle wall, and this process is mediated by adenylyl cyclase (Fontaine et al, 1972;Fostier et al, 1983;Nagahama et al, 1985a). Therefore, phosphodiesterase inhibitors or adenylyl cyclase stimulators potentially could elevate CAMP levels in the follicle wall as well as in the oocytes themselves.…”

Section: Introductionmentioning

confidence: 99%

Steroid-Induced Final Maturation in Brook Trout (Salvelinus Fontinalis) Oocytes in Vitro: The Effects of Forskolin and Phosphodiesterase Inhibitors1

DeManno¹,

Goetz²

1987

Biology of Reproduction

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The effects of phosphodiesterase inhibitors and forskolin on steroid-induced germinal vesicle breakdown (GVBD) were investigated in brook trout (Salvelinus fontinalis) oocytes using an in vitro incubation technique. Follicles were first treated with a collagenase solution to remove the follicle wall. Denuded oocytes were examined, using scanning electron microscopy. In all experiments GVBD was induced by the use of 17 alpha, 20 beta-dihydroxy-4-pregnen-3-one. Cyclic adenosine 3',5'-monophosphate (cAMP) levels were measured (by protein-binding assay) in control and forskolin-treated oocytes. Collagenase treatment removed a majority of the follicle wall, as shown by scanning electron microscopy. Partially denuded (PD) oocytes were slightly more sensitive to steroid treatment than intact follicles (IF), as shown by ED50 values; but PD oocytes did not respond to gonadotropin (GTH) stimulation. Both 3-isobutyl-1-methyl-xanthine (IBMX) and SQ20,006 (Squibb) blocked GVBD, but IBMX was more inhibitory. Forskolin also blocked steroid-induced GVBD. Kinetics of inhibition studies were performed using IBMX, forskolin, and cycloheximide. IBMX and cycloheximide inhibited GVBD if added during the first 18 h following steroid stimulation, whereas forskolin blocked GVBD if added within 12 h after steroid treatment. Forskolin, at levels that block GVBD in vitro, significantly increased cAMP in both IF and PD oocytes, but the response of IF was greater than that of PD oocytes.

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“…The (Fontaine et al, 1970 ;Menon and Smith, 1971 ;Fontaine et a/., 1972 (Tsafriri et al, 1972a, b), luteinization (Channing, 1970 ;Kolena and Channing, 1971), ovarian steroidogenesis (Pharrissetof., 1968 ;Speroff and Ramwell,1970 ;and (normal light cycle) ; the other timed the onset of the light phase at 6 p.m., and therefore reversed the conditions (reversed light cycle). At the end of the acclimation period, the oocytes developed beyond a mean diameter of 600 g, at which stage they are known to be effectively responsive to SG-G100 (Kuo et al, 1974).…”

Section: Introductionmentioning

confidence: 99%

“…In contrast, piscine pituitary gonadotropins were shown to be effective in teleost systems, although they showed a specificity among teleosts (Breton et al, 1973). Species specificity within teleosts was reported to be minor compared with that between teleost and mammalian species (Fontaine et al, 1972 (Labhsetwar, 1975). Okamura et al (1972), Jalabert and Szollosi (1975), and Jalabert (1976) …”

Section: Introductionmentioning

confidence: 99%

Circadian responses of teleostean oocytes to gonadotropins and prostaglandins determined by cyclic AMP concentration

Kuo¹,

Watanabe²

1978

Ann. Biol. anim. Bioch. Biophys.

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Comparison of the activities of two purified fish gonadotropins on adenyl cyclase activity in the goldfish ovary

Cited by 32 publications

References 9 publications

Steroidogenesis in rainbow trout (Salmo gairdneri) at various preovulatory stages: changes in plasma hormone levels andin vivo andin vitro responses of the ovary to salmon gonadotropin

Steroidogenesis in rainbow trout (Salmo gairdneri) at various preovulatory stages: changes in plasma hormone levels andin vivo andin vitro responses of the ovary to salmon gonadotropin

Steroid-Induced Final Maturation in Brook Trout (Salvelinus Fontinalis) Oocytes in Vitro: The Effects of Forskolin and Phosphodiesterase Inhibitors1

Circadian responses of teleostean oocytes to gonadotropins and prostaglandins determined by cyclic AMP concentration

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