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 (

Blockade of episodic secretion of luteinizing hormone in the ram by the administration of antibodies to luteinizing hormone releasing hormone.

BIOLOGY OF REPRODUCTION 21, 1239-1245 (1979) Blockade of Episodic Secretion of Luteinizing Hormone in the Ram by the Administration of Antibodi...
846KB Sizes 0 Downloads 0 Views