BIOLOGY
OF
REPRODUCTION
21,
1239-1245
(1979)
Blockade
of Episodic Secretion of Luteinizing Hormone in the Ram by the Administration of Antibodies to Luteinizing Hormone Releasing Hormone G. A.
Medical
LINCOLN
Research
and
Council
Centre for Edinburgh,
H. M.
FRASER
Reproductive
Reproductive EH3 9EW,
Biology
Unit,
Biology, Scotland
ABSTRACT Administration autumn period The concentration
of ovine serum containing LHRH antibodies to adult Soay rams during the sexual activity resulted in an immediate blockade of episodic secretion of LH. of LH in the peripheral blood remained low for at least a day, but was increased
of
24 days later when episodic peaks of high frequency were again apparent. The plasma concentration of testosterone changed in close parallel with the changes in LU while the levels of FSH were unaffected and there were no clear effects on the size of the testes. The release of LH and testosterone following the i.v. injection of 200 ng synthetic LHRH was blocked on the day following the administration of the antiserum but the response returned to normal within 46 days by which time the antibodies to LHRH were virtually undetectable in the blood plasma. These results show that the episodic secretion of LU in the ram is dependent on LHRH from the hypothalamus and that neutralization of the neurohormonc results in a rapid decline in the circulating levels of LH. FSH on the other hand is largely unresponsive to changes in LHRH and secretion of FSH may occur for several days even after the complete neutralization of LHRH.
INTRODUCTION Episodic luteinizing
fluctuations hormone in
described been
all
schke
et
1971),
al.,
1978)
and
have
al.,
1972),
dogs
1979)
rabbits
et
episodic
hypophysial
deer et
output
sheep,
of
LH
peaks in the short
have
being
(Butler
et
mittent
secretion
small
in
1972).
secretion
by
anterior
of
the
the
for
One
possibility
pattern
in
been
have episodic
is
that
gonado-
all
species.
of
LH
the
pattern
to
21, 1979.
monkey, supply
tary
is
given hormone,
in
and
Ferin,
peripheral to variations and Mortimer,
an
fluctuations
is
in
have
to
and
the
of
the
1974). of
of
LH
manner
to
in
shown
infusion levels
in-
response
surgically
episodic
that
an
Studies
LHRH
blood of man in pituitary 1974).
(Cannel
reflects
pituitary
circulating
LHRH
monkey
LU
example,
constant the
that
been
limited
explanation
endogenous
fluctuate
indicate
the
stimulus.
for of
not
have the
of the
interrupted a
to
1239
of
the portal
However,
second
LHRH
the
of
1979.
The discharge
chronous September April 23,
in
constant
Wide
Accepted Received
does
hypo-
pituitary
blood
available
of
normal pituitary,
in
episodically
and
collection
anterior
systemic
property
release.
LU
in
1976).
rhesus
of
cause
proposed
nature
a
inter-
be the
LU
episodic
herent
periods
the
block monkey, Peet
very the
LHRH
which
sheep,
the
simultaneously.
al.;
the
cells
to
et
a few
of
and
is released
from
gonadotroph
fluctuations
explanations
the
This
is assumed
episodic
Two
of intervening
to of
information
transitory
only
of
hypothalamus.
(rhesus
disrupts
stimulus
measured
cranial
result
the
the
pituitary
account
the
lasting
amounts
released al.,
the
that
the
concentration
of
only
tropin
of
shown
hormone
episodes
minutes,
measurements
blood
thalamic
LU
1972;
Since
concentrations
YoungLai,
of
al.,
1977).
blood the
secretion
the
of
secretion et
Lincoln,
1975). In
episodic
neurones
Battacharya
Palatis
and
(Moor
the
al.,
red
(Dc
reflects
the
by
This is probable because anesthetics are known to inhibit neuronal activity
humans (Dier-
monkeys
(Katongole
et
Kay,
been
that
including
cattle
(Butler
and
have
rhesus
1970),
sheep
blood species
simply
LHRH
of
concentration
in
detail, 1973),
al.,
al.,
(Lincoln
(LU)
in
et
secretion the
mammalian
studied
(Naftolin
in
the
that the
if
pitui-
animal
is
releasing continue (Vande
Similarly, LU and
the asynFSH in the
have been responsiveness
attributed (Besser
1240
LINCOLN
In the
the
present
control
investigated the
study,
of in
aim
The
circulating what
period from
was
of
LU
changes
during the
of a to
in
has
been
blocking LURU
using LHRH
establish
whether
influences and
occur
which
LHRH
specific
immediately levels
of
temporarily
with
treatment
cribe
by
role secretion
secretion
immunization
antiserum. the
LH
rams
endogenous
passive
the
episodic
the
FSH over
AND
the
and the
antibody
to
des-
recovery is
cleared
FRASER
collections
were made using the method described above. The LHRH antiserum was tested for specificity against a variety of peptides including synthetic fragments of LHRH. No significant cross reaction (