1
1
128
C. Weil et al.
by indomethacine
(an inhibitor of prostaglandin synthesis) treatment (KAPUR
and
TOOR
1979).
In cyprinid this technique has been used only at a research level.
D — Action of factors
acting on oocyte maturation.
!
As
mentionned above corticosteroids as well as progestins and particu—
|
larly 17ŒZOB
OH
P
have
a
role in inducing in vitro oocyte maturation in
goldfish and
carp.
Corticosteroids
and progestins were tested for induction
of ovulation
activity
in
vivo.
In
goldfish
trials were
successful with
deoxycorticosterone (DOC),
cortisone
and
corticosterone
(100pg/g)
(KHOO
197A) while
only partial ovulation was obtained with deoxycortisol (LAM and
PANDEY
cited in LAM
1982). Metopirone, an inhibitor of 11 —hydroxylase indu—
ced
ovulation
in goldfish (PANDEY et al 1977). With regard to progestogens,
progesterone (100pg/g)
was
effective
(KHOO 1974) while 17ŒZOB OH P (12ug/g
daily for
5
days) was
ineffective
in goldfish.
(PANDEY et al Cited in LAM
et al.
1978). In carp, neither 17d 208 OH P (2mg/kg) nor DOC (1mg/Kg) alone
or
in
combination, induced ovulation at 13—15°C (JALABERT et al.
1977)… 17d
208 OH
P gave positive results when administered 1 day after priming with a
low
dose
of carp
pituitary extract (0.6mg/kg). At such temperatures classi—
cal hypophysation
yielded worse results since only partial ovulation followed
by resorption was observed. Priming with a low dose of pituitary extract
induced migration
of
the GV toward the periphery of the oocyte, indicating
that responsivness
to
17ŒZOB OH P seems dependent on GV migration. However
BIENIARZ et
al.
1985 obtained in vitro oocyte maturation only in some fema—
les
altough ovarian fragments were in the same stage i.e. with oocytes befo—
re
migration
of
the
GV.
This
indicates
that
oocytes in the same stage as
determined by
position
of
the
nucleus have variable
responsivness to the
same
hormonal
treatment.
Altough
thyroid hormones act synergistically with gonadotropin hormone
to
induce
vitellogenesis (HURLBURT 1977) and T3 influences the maturational
response
to
gonadotropic
and
steroid treatments
(EPLER and BIENIARZ
they have not yet been tested in vivo.
These techniques are not used in fish farm.
E
—
Influence
of
factors promoting ovulation by action on follicular con—
traction and rupture.
As mentioned above prostaglandins and catecholamines can trigger ovula—
îiâh
in
vitro.
In vivo only the role of prostaglandins (PG) was investiga—
e
.
Indomethacine,
an
inhibitor of prostaglandins biosynthesis, blocks the
ovulatory response of goldfish to a combination of HCG and 20°C warmed water
while a single IP injection of PGE1, PGE2 or PGE2d (5ug/g) restores the res—
ponse
(STACEY
and
PANDEY
1975). In carp KAPUR and TOOR (1979) demonstrated
that a
single
injection of indomethacine (10ug/g) blocked ovulation for 12
days in
females
held
in
conditions
in which
control
fish
ovulated sponta—
neously. The
role
of prostaglandins mediated by and stimulation of GtH se—
cretion is
unlikely
since PETER and BILLARD
(1976) found that injection of
PGF2(xor
PGE2
but not PGE1
into
the
third ventricle of the brain decreased
serum
GtH
in
the
female. A direct action on follicular rupture via smooth
muscle
contraction
seems
more
likely
(STACEY and PANDEY 1975, KAGAWA and
NAGAHAMA
1981)
for
goldfish (EPLER 1978, EPLER et al. 1985) for carp. Fur—
thermore prostaglandins
have
a
role
in
spawning
behavior
in
goldfish
(STACEY, 1976). Thus it may be possible to use prostaglandins to induce ovu—
lation as well as
spawning behavior in fish with mature oocytes.
1
128
C. Weil et al.
by indomethacine
(an inhibitor of prostaglandin synthesis) treatment (KAPUR
and
TOOR
1979).
In cyprinid this technique has been used only at a research level.
D — Action of factors
acting on oocyte maturation.
!
As
mentionned above corticosteroids as well as progestins and particu—
|
larly 17ŒZOB
OH
P
have
a
role in inducing in vitro oocyte maturation in
goldfish and
carp.
Corticosteroids
and progestins were tested for induction
of ovulation
activity
in
vivo.
In
goldfish
trials were
successful with
deoxycorticosterone (DOC),
cortisone
and
corticosterone
(100pg/g)
(KHOO
197A) while
only partial ovulation was obtained with deoxycortisol (LAM and
PANDEY
cited in LAM
1982). Metopirone, an inhibitor of 11 —hydroxylase indu—
ced
ovulation
in goldfish (PANDEY et al 1977). With regard to progestogens,
progesterone (100pg/g)
was
effective
(KHOO 1974) while 17ŒZOB OH P (12ug/g
daily for
5
days) was
ineffective
in goldfish.
(PANDEY et al Cited in LAM
et al.
1978). In carp, neither 17d 208 OH P (2mg/kg) nor DOC (1mg/Kg) alone
or
in
combination, induced ovulation at 13—15°C (JALABERT et al.
1977)… 17d
208 OH
P gave positive results when administered 1 day after priming with a
low
dose
of carp
pituitary extract (0.6mg/kg). At such temperatures classi—
cal hypophysation
yielded worse results since only partial ovulation followed
by resorption was observed. Priming with a low dose of pituitary extract
induced migration
of
the GV toward the periphery of the oocyte, indicating
that responsivness
to
17ŒZOB OH P seems dependent on GV migration. However
BIENIARZ et
al.
1985 obtained in vitro oocyte maturation only in some fema—
les
altough ovarian fragments were in the same stage i.e. with oocytes befo—
re
migration
of
the
GV.
This
indicates
that
oocytes in the same stage as
determined by
position
of
the
nucleus have variable
responsivness to the
same
hormonal
treatment.
Altough
thyroid hormones act synergistically with gonadotropin hormone
to
induce
vitellogenesis (HURLBURT 1977) and T3 influences the maturational
response
to
gonadotropic
and
steroid treatments
(EPLER and BIENIARZ
they have not yet been tested in vivo.
These techniques are not used in fish farm.
E
—
Influence
of
factors promoting ovulation by action on follicular con—
traction and rupture.
As mentioned above prostaglandins and catecholamines can trigger ovula—
îiâh
in
vitro.
In vivo only the role of prostaglandins (PG) was investiga—
e
.
Indomethacine,
an
inhibitor of prostaglandins biosynthesis, blocks the
ovulatory response of goldfish to a combination of HCG and 20°C warmed water
while a single IP injection of PGE1, PGE2 or PGE2d (5ug/g) restores the res—
ponse
(STACEY
and
PANDEY
1975). In carp KAPUR and TOOR (1979) demonstrated
that a
single
injection of indomethacine (10ug/g) blocked ovulation for 12
days in
females
held
in
conditions
in which
control
fish
ovulated sponta—
neously. The
role
of prostaglandins mediated by and stimulation of GtH se—
cretion is
unlikely
since PETER and BILLARD
(1976) found that injection of
PGF2(xor
PGE2
but not PGE1
into
the
third ventricle of the brain decreased
serum
GtH
in
the
female. A direct action on follicular rupture via smooth
muscle
contraction
seems
more
likely
(STACEY and PANDEY 1975, KAGAWA and
NAGAHAMA
1981)
for
goldfish (EPLER 1978, EPLER et al. 1985) for carp. Fur—
thermore prostaglandins
have
a
role
in
spawning
behavior
in
goldfish
(STACEY, 1976). Thus it may be possible to use prostaglandins to induce ovu—
lation as well as
spawning behavior in fish with mature oocytes.